Move "loop" related tests in their own dir. This is just to break the ice... ideally...

[gnash.git] / libbase / jemalloc.c

/*-
 * Copyright (C) 2006-2008 Jason Evans <jasone@FreeBSD.org>.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice(s), this list of conditions and the following disclaimer as
 *    the first lines of this file unmodified other than the possible
 *    addition of one or more copyright notices.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice(s), this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *******************************************************************************
 *
 * This allocator implementation is designed to provide scalable performance
 * for multi-threaded programs on multi-processor systems.  The following
 * features are included for this purpose:
 *
 *   + Multiple arenas are used if there are multiple CPUs, which reduces lock
 *     contention and cache sloshing.
 *
 *   + Cache line sharing between arenas is avoided for internal data
 *     structures.
 *
 *   + Memory is managed in chunks and runs (chunks can be split into runs),
 *     rather than as individual pages.  This provides a constant-time
 *     mechanism for associating allocations with particular arenas.
 *
 * Allocation requests are rounded up to the nearest size class, and no record
 * of the original request size is maintained.  Allocations are broken into
 * categories according to size class.  Assuming runtime defaults, 4 kB pages
 * and a 16 byte quantum, the size classes in each category are as follows:
 *
 *   |=====================================|
 *   | Category | Subcategory    |    Size |
 *   |=====================================|
 *   | Small    | Tiny           |       2 |
 *   |          |                |       4 |
 *   |          |                |       8 |
 *   |          |----------------+---------|
 *   |          | Quantum-spaced |      16 |
 *   |          |                |      32 |
 *   |          |                |      48 |
 *   |          |                |     ... |
 *   |          |                |     480 |
 *   |          |                |     496 |
 *   |          |                |     512 |
 *   |          |----------------+---------|
 *   |          | Sub-page       |    1 kB |
 *   |          |                |    2 kB |
 *   |=====================================|
 *   | Large                     |    4 kB |
 *   |                           |    8 kB |
 *   |                           |   12 kB |
 *   |                           |     ... |
 *   |                           | 1012 kB |
 *   |                           | 1016 kB |
 *   |                           | 1020 kB |
 *   |=====================================|
 *   | Huge                      |    1 MB |
 *   |                           |    2 MB |
 *   |                           |    3 MB |
 *   |                           |     ... |
 *   |=====================================|
 *
 * A different mechanism is used for each category:
 *
 *   Small : Each size class is segregated into its own set of runs.  Each run
 *           maintains a bitmap of which regions are free/allocated.
 *
 *   Large : Each allocation is backed by a dedicated run.  Metadata are stored
 *           in the associated arena chunk header maps.
 *
 *   Huge : Each allocation is backed by a dedicated contiguous set of chunks.
 *          Metadata are stored in a separate red-black tree.
 *
 *******************************************************************************
 */

/*
 * This has been hacked on heavily by Rob Savoye, so it compiles
 * within Gnash, using the same configuration settings as
 * everything else in Gnash.
 */
#ifdef HAVE_CONFIG_H
# include "gnashconfig.h"
#endif

#include "dsodefs.h"

/*
 * MALLOC_PRODUCTION disables assertions and statistics gathering.  It also
 * defaults the A and J runtime options to off.  These settings are appropriate
 * for production systems.
 */
#ifndef USE_STATS_MEMORY
# define MALLOC_PRODUCTION 1
#endif

#ifndef MALLOC_PRODUCTION
   /*
    * MALLOC_DEBUG enables assertions and other sanity checks, and disables
    * inline functions.
    */
#  define MALLOC_DEBUG 1

   /* MALLOC_STATS enables statistics calculation. */
#  define MALLOC_STATS 1

   /* Memory filling (junk/zero). */
#  define MALLOC_FILL 1

   /* Allocation tracing. */
#  define MALLOC_UTRACE 1

   /* Support optional abort() on OOM. */
#  define MALLOC_XMALLOC 1

   /* Support SYSV semantics. */
#  define MALLOC_SYSV 1
#endif

/*
 * MALLOC_LAZY_FREE enables the use of a per-thread vector of slots that free()
 * can atomically stuff object pointers into.  This can reduce arena lock
 * contention.
 */
/* #define      MALLOC_LAZY_FREE 1 */

/*
 * MALLOC_BALANCE enables monitoring of arena lock contention and dynamically
 * re-balances arena load if exponentially averaged contention exceeds a
 * certain threshold.
 */
/* #define      MALLOC_BALANCE 1 */

/*
 * MALLOC_DSS enables use of sbrk(2) to allocate chunks from the data storage
 * segment (DSS).  In an ideal world, this functionality would be completely
 * unnecessary, but we are burdened by history and the lack of resource limits
 * for anonymous mapped memory.
 */
#if (!defined(DARWIN) && !defined(WIN32))
# define MALLOC_DSS 
#endif

#ifdef LINUX_HOST
# define        _GNU_SOURCE /* For mremap(2). */
# define        issetugid() 0
# if 0 /* Enable in order to test decommit code on Linux. */
#  define MALLOC_DECOMMIT 1
/*
 * The decommit code for Unix doesn't bother to make sure deallocated DSS
 * chunks are writable.
 */
# undef MALLOC_DSS
# endif
#endif

#include <sys/types.h>

#include <errno.h>
#include <limits.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef WIN32
# include <cruntime.h>
# include <internal.h>
# include <windows.h>
# include <io.h>
# include "jemtree.h"

# pragma warning( disable: 4267 4996 4146 )

# define        bool BOOL
# define        false FALSE
# define        true TRUE
# define        inline __inline
# define        SIZE_T_MAX SIZE_MAX
# define        STDERR_FILENO 2
# define        PATH_MAX MAX_PATH
# define        vsnprintf _vsnprintf
# define        assert(f) /* we can't assert in the CRT */

static unsigned long tlsIndex = 0xffffffff;

# define        __thread
# define        _pthread_self() __threadid()
# define        issetugid() 0

/* use MSVC intrinsics */
# pragma intrinsic(_BitScanForward)
static __forceinline int
ffs(int x)
{
        unsigned long i;

        if (_BitScanForward(&i, x) != 0)
                return (i + 1);

        return (0);
}

typedef unsigned char uint8_t;
typedef unsigned uint32_t;
typedef unsigned long long uint64_t;
typedef unsigned long long uintmax_t;

# define        MALLOC_DECOMMIT
#endif  /* end of WIN32 */

#ifdef HAVE_PTHREADS
# include <pthread.h>
#endif

#ifndef WIN32
# include <sys/cdefs.h>
# ifndef __DECONST
#  define __DECONST(type, var)  ((type)(uintptr_t)(const void *)(var))
# endif
# include <sys/mman.h>
# ifndef MADV_FREE
#  define MADV_FREE     MADV_DONTNEED
# endif
# include <sys/param.h>
# include <sys/time.h>
# include <sys/types.h>
# include <sys/sysctl.h>
# include "jemtree.h"
# include <sys/uio.h>

# include <errno.h>
# include <limits.h>
# ifndef SIZE_T_MAX
#  define SIZE_T_MAX    SIZE_MAX
# endif
# if defined(DARWIN) || defined(LINUX_HOST)
#  define _pthread_self pthread_self
#  define _pthread_mutex_init pthread_mutex_init
#  define _pthread_mutex_trylock pthread_mutex_trylock
#  define _pthread_mutex_lock pthread_mutex_lock
#  define _pthread_mutex_unlock pthread_mutex_unlock
# endif
# include <sched.h>
# include <stdarg.h>
# include <stdbool.h>
# include <stdio.h>
# include <stdint.h>
# include <stdlib.h>
# include <string.h>
# ifndef DARWIN
#  include <strings.h>
# endif
# include <unistd.h>

# ifdef DARWIN
#  include <libkern/OSAtomic.h>
#  include <mach/mach_error.h>
#  include <mach/mach_init.h>
#  include <mach/vm_map.h>
#  include <malloc/malloc.h>
# endif  /* end of DARWIN */
#endif   /* end of WIN32 */


#ifdef DARWIN
DSOEXPORT void *moz_memalign(size_t alignment, size_t size);
DSOEXPORT size_t moz_malloc_usable_size(const void *ptr)
DSOEXPORT void *moz_calloc(size_t num, size_t size);
DSOEXPORT void *moz_realloc(void *ptr, size_t size);
DSOEXPORT void *moz_valloc(size_t size);
DSOEXPORT size_t moz_malloc_usable_size(const void *ptr);
#else
DSOEXPORT void *memalign(size_t alignment, size_t size);
DSOEXPORT size_t malloc_usable_size(const void *ptr);
DSOEXPORT void *calloc(size_t num, size_t size);
DSOEXPORT void *realloc(void *ptr, size_t size);
DSOEXPORT void *valloc(size_t size);
DSOEXPORT size_t malloc_usable_size(const void *ptr);
#endif
void _malloc_postfork(void);
void _malloc_prefork(void);

#ifdef DARWIN
static const bool g_isthreaded = true;
#endif

#define __DECONST(type, var) ((type)(uintptr_t)(const void *)(var))

#ifdef MALLOC_DEBUG
# ifdef NDEBUG
#  undef NDEBUG
# endif
#else
# ifndef NDEBUG
#  define NDEBUG
# endif
#endif
#ifndef WIN32
# include <assert.h>
#endif

#ifdef MALLOC_DEBUG
/* Disable inlining to make debugging easier. */
# ifdef inline
#  undef inline
# endif

# define inline
#endif  /* end of MALLOC_DEBUG */

/* Size of stack-allocated buffer passed to strerror_r(). */
#define STRERROR_BUF            64

/* Minimum alignment of allocations is 2^QUANTUM_2POW_MIN bytes. */
#define QUANTUM_2POW_MIN      4
#ifdef MOZ_MEMORY_SIZEOF_PTR_2POW
# define SIZEOF_PTR_2POW                MOZ_MEMORY_SIZEOF_PTR_2POW
#else
# define SIZEOF_PTR_2POW       2
#endif
// __as __isthreaded is already defined on FreeBSD with a different value that does
// the same thing, rename our version to be unique. Althought jemalloc is the default
// allocator on FreeBSD< we still want to use our own version, as it has additional Gnash
// specific tweaks.
#ifndef DARWIN
static const bool g_isthreaded = true;
#else
# define NO_TLS
#endif
#if 0
#ifdef __i386__
#  define QUANTUM_2POW_MIN      4
#  define SIZEOF_PTR_2POW       2
#  define CPU_SPINWAIT          __asm__ volatile("pause")
#endif
#ifdef __ia64__
#  define QUANTUM_2POW_MIN      4
#  define SIZEOF_PTR_2POW       3
#endif
#ifdef __alpha__
#  define QUANTUM_2POW_MIN      4
#  define SIZEOF_PTR_2POW       3
#  define NO_TLS
#endif
#ifdef __sparc64__
#  define QUANTUM_2POW_MIN      4
#  define SIZEOF_PTR_2POW       3
#  define NO_TLS
#endif
#ifdef __amd64__
#  define QUANTUM_2POW_MIN      4
#  define SIZEOF_PTR_2POW       3
#  define CPU_SPINWAIT          __asm__ volatile("pause")
#endif
#ifdef __arm__
#  define QUANTUM_2POW_MIN      3
#  define SIZEOF_PTR_2POW       2
#  define NO_TLS
#endif
#ifdef __powerpc__
#  define QUANTUM_2POW_MIN      4
#  define SIZEOF_PTR_2POW       2
#endif
#endif

#define SIZEOF_PTR              (1U << SIZEOF_PTR_2POW)

/* sizeof(int) == (1U << SIZEOF_INT_2POW). */
#ifndef SIZEOF_INT_2POW
# define SIZEOF_INT_2POW        2
#endif

/* We can't use TLS in non-PIC programs, since TLS relies on loader magic. */
#if (!defined(PIC) && !defined(NO_TLS))
# define NO_TLS
#endif

#ifdef NO_TLS
   /* MALLOC_BALANCE requires TLS. */
#  ifdef MALLOC_BALANCE
#    undef MALLOC_BALANCE
#  endif
   /* MALLOC_LAZY_FREE requires TLS. */
#  ifdef MALLOC_LAZY_FREE
#    undef MALLOC_LAZY_FREE
#  endif
#endif

/*
 * Size and alignment of memory chunks that are allocated by the OS's virtual
 * memory system.
 */
#define CHUNK_2POW_DEFAULT      20

/* Maximum number of dirty pages per arena. */
#define DIRTY_MAX_DEFAULT       (1U << 9)

/*
 * Maximum size of L1 cache line.  This is used to avoid cache line aliasing,
 * so over-estimates are okay (up to a point), but under-estimates will
 * negatively affect performance.
 */
#define CACHELINE_2POW          6
#define CACHELINE               ((size_t)(1U << CACHELINE_2POW))

/* Smallest size class to support. */
#define TINY_MIN_2POW           1

/*
 * Maximum size class that is a multiple of the quantum, but not (necessarily)
 * a power of 2.  Above this size, allocations are rounded up to the nearest
 * power of 2.
 */
#define SMALL_MAX_2POW_DEFAULT  9
#define SMALL_MAX_DEFAULT       (1U << SMALL_MAX_2POW_DEFAULT)

/*
 * RUN_MAX_OVRHD indicates maximum desired run header overhead.  Runs are sized
 * as small as possible such that this setting is still honored, without
 * violating other constraints.  The goal is to make runs as small as possible
 * without exceeding a per run external fragmentation threshold.
 *
 * We use binary fixed point math for overhead computations, where the binary
 * point is implicitly RUN_BFP bits to the left.
 *
 * Note that it is possible to set RUN_MAX_OVRHD low enough that it cannot be
 * honored for some/all object sizes, since there is one bit of header overhead
 * per object (plus a constant).  This constraint is relaxed (ignored) for runs
 * that are so small that the per-region overhead is greater than:
 *
 *   (RUN_MAX_OVRHD / (reg_size << (3+RUN_BFP))
 */
#define RUN_BFP                 12
/*                                    \/   Implicit binary fixed point. */
#define RUN_MAX_OVRHD           0x0000003dU
#define RUN_MAX_OVRHD_RELAX     0x00001800U

/*
 * Put a cap on small object run size.  This overrides RUN_MAX_OVRHD.  Note
 * that small runs must be small enough that page offsets can fit within the
 * CHUNK_MAP_POS_MASK bits.
 */
#define RUN_MAX_SMALL_2POW      15
#define RUN_MAX_SMALL           (1U << RUN_MAX_SMALL_2POW)

#ifdef MALLOC_LAZY_FREE
   /* Default size of each arena's lazy free cache. */
#  define LAZY_FREE_2POW_DEFAULT 8
   /*
    * Number of pseudo-random probes to conduct before considering the cache to
    * be overly full.  It takes on average n probes to detect fullness of
    * (n-1)/n.  However, we are effectively doing multiple non-independent
    * trials (each deallocation is a trial), so the actual average threshold
    * for clearing the cache is somewhat lower.
    */
#  define LAZY_FREE_NPROBES     5
#endif

/*
 * Hyper-threaded CPUs may need a special instruction inside spin loops in
 * order to yield to another virtual CPU.  If no such instruction is defined
 * above, make CPU_SPINWAIT a no-op.
 */
#ifndef CPU_SPINWAIT
#  define CPU_SPINWAIT
#endif

/*
 * Adaptive spinning must eventually switch to blocking, in order to avoid the
 * potential for priority inversion deadlock.  Backing off past a certain point
 * can actually waste time.
 */
#define SPIN_LIMIT_2POW         11

/*
 * Conversion from spinning to blocking is expensive; we use (1U <<
 * BLOCK_COST_2POW) to estimate how many more times costly blocking is than
 * worst-case spinning.
 */
#define BLOCK_COST_2POW         4

#ifdef MALLOC_BALANCE
   /*
    * We use an exponential moving average to track recent lock contention,
    * where the size of the history window is N, and alpha=2/(N+1).
    *
    * Due to integer math rounding, very small values here can cause
    * substantial degradation in accuracy, thus making the moving average decay
    * faster than it would with precise calculation.
    */
#  define BALANCE_ALPHA_INV_2POW        9

   /*
    * Threshold value for the exponential moving contention average at which to
    * re-assign a thread.
    */
#  define BALANCE_THRESHOLD_DEFAULT     (1U << (SPIN_LIMIT_2POW-4))
#endif

/******************************************************************************/

/*
 * Mutexes based on spinlocks.  We can't use normal pthread spinlocks in all
 * places, because they require malloc()ed memory, which causes bootstrapping
 * issues in some cases.
 */
#if defined(WIN32)
#define malloc_mutex_t CRITICAL_SECTION
#define malloc_spinlock_t CRITICAL_SECTION
#elif defined(DARWIN)
typedef struct {
        OSSpinLock      lock;
} malloc_mutex_t;
typedef struct {
        OSSpinLock      lock;
} malloc_spinlock_t;
#elif defined(USE_JEMALLOC)
typedef pthread_mutex_t malloc_mutex_t;
typedef pthread_mutex_t malloc_spinlock_t;
#else
/* XXX these should #ifdef these for freebsd (and linux?) only */
typedef struct {
        spinlock_t      lock;
} malloc_mutex_t;
typedef malloc_spinlock_t malloc_mutex_t;
#endif

/* Set to true once the allocator has been initialized. */
static bool malloc_initialized = false;

#ifdef WIN32
/* No init lock for Windows. */
#elif defined(DARWIN)
static malloc_mutex_t init_lock = {OS_SPINLOCK_INIT};
#elif defined(LINUX_HOST)
static malloc_mutex_t init_lock = PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP;
#elif defined(USE_JEMALLOC)
static malloc_mutex_t init_lock = PTHREAD_MUTEX_INITIALIZER;
#else
static malloc_mutex_t init_lock = {_SPINLOCK_INITIALIZER};
#endif

/******************************************************************************/
/*
 * Statistics data structures.
 */

#ifdef MALLOC_STATS

/* Borrowed from malloc.h, as this is Linux specific. This has been
 * added to jemalloc so the existing memory profiling in Gnash will
 * continue to work. Most of these fields aren't used by the Gnash
 * memory profiling, but we leave them here for a semblance of
 * portability. The only fields Gnash uses are arena, uordblks. and
 * fordblks.
 *
 * This gets more interesting, as jemalloc maintains multiple
 * arenas, one for each CPU in a multiprocessor system. We cheat
 * by just accumulating the stats for all arenas, since our primary
 * purpose is to track memory leaks.
 */
struct mallinfo {
  int arena;    /* non-mmapped space allocated from system */
  int ordblks;  /* number of free chunks UNUSED */
  int smblks;   /* number of fastbin blocks UNUSED */
  int hblks;    /* number of mmapped regions UNUSED */
  int hblkhd;   /* space in mmapped regions UNUSED */
  int usmblks;  /* maximum total allocated space UNUSED */
  int fsmblks;  /* space available in freed fastbin blocks UNUSED */
  int uordblks; /* total allocated space */
  int fordblks; /* total free space */
  int keepcost; /* top-most, releasable space UNUSED */
};

typedef struct malloc_bin_stats_s malloc_bin_stats_t;
struct malloc_bin_stats_s {
        /*
         * Number of allocation requests that corresponded to the size of this
         * bin.
         */
        uint64_t        nrequests;

        /* Total number of runs created for this bin's size class. */
        uint64_t        nruns;

        /*
         * Total number of runs reused by extracting them from the runs tree for
         * this bin's size class.
         */
        uint64_t        reruns;

        /* High-water mark for this bin. */
        unsigned long   highruns;

        /* Current number of runs in this bin. */
        unsigned long   curruns;
};

typedef struct arena_stats_s arena_stats_t;
struct arena_stats_s {
        /* Number of bytes currently mapped. */
        size_t          mapped;

        /*
         * Total number of purge sweeps, total number of madvise calls made,
         * and total pages purged in order to keep dirty unused memory under
         * control.
         */
        uint64_t        npurge;
        uint64_t        nmadvise;
        uint64_t        purged;
#ifdef MALLOC_DECOMMIT
        /*
         * Total number of decommit/commit operations, and total number of
         * pages decommitted.
         */
        uint64_t        ndecommit;
        uint64_t        ncommit;
        uint64_t        decommitted;
#endif

        /* Per-size-category statistics. */
        size_t          allocated_small;
        uint64_t        nmalloc_small;
        uint64_t        ndalloc_small;

        size_t          allocated_large;
        uint64_t        nmalloc_large;
        uint64_t        ndalloc_large;

#ifdef MALLOC_BALANCE
        /* Number of times this arena reassigned a thread due to contention. */
        uint64_t        nbalance;
#endif
};

typedef struct chunk_stats_s chunk_stats_t;
struct chunk_stats_s {
        /* Number of chunks that were allocated. */
        uint64_t        nchunks;

        /* High-water mark for number of chunks allocated. */
        unsigned long   highchunks;

        /*
         * Current number of chunks allocated.  This value isn't maintained for
         * any other purpose, so keep track of it in order to be able to set
         * highchunks.
         */
        unsigned long   curchunks;
};

#endif /* #ifdef MALLOC_STATS */

/******************************************************************************/
/*
 * Extent data structures.
 */

/* Tree of extents. */
typedef struct extent_node_s extent_node_t;
struct extent_node_s {
        /* Linkage for the size/address-ordered tree. */
        RB_ENTRY(extent_node_s) link_szad;

        /* Linkage for the address-ordered tree. */
        RB_ENTRY(extent_node_s) link_ad;

        /* Pointer to the extent that this tree node is responsible for. */
        void    *addr;

        /* Total region size. */
        size_t  size;
};
typedef struct extent_tree_szad_s extent_tree_szad_t;
RB_HEAD(extent_tree_szad_s, extent_node_s);
typedef struct extent_tree_ad_s extent_tree_ad_t;
RB_HEAD(extent_tree_ad_s, extent_node_s);

/******************************************************************************/
/*
 * Arena data structures.
 */

typedef struct arena_s arena_t;
typedef struct arena_bin_s arena_bin_t;

/*
 * Each map element contains several flags, plus page position for runs that
 * service small allocations.
 */
typedef uint8_t arena_chunk_map_t;
#define CHUNK_MAP_UNTOUCHED     0x80U
#define CHUNK_MAP_DIRTY         0x40U
#define CHUNK_MAP_LARGE         0x20U
#ifdef MALLOC_DECOMMIT
#define CHUNK_MAP_DECOMMITTED   0x10U
#define CHUNK_MAP_POS_MASK      0x0fU
#else
#define CHUNK_MAP_POS_MASK      0x1fU
#endif

/* Arena chunk header. */
typedef struct arena_chunk_s arena_chunk_t;
struct arena_chunk_s {
        /* Arena that owns the chunk. */
        arena_t         *arena;

        /* Linkage for the arena's chunk tree. */
        RB_ENTRY(arena_chunk_s) link;

        /*
         * Number of pages in use.  This is maintained in order to make
         * detection of empty chunks fast.
         */
        size_t          pages_used;

        /* Number of dirty pages. */
        size_t          ndirty;

        /*
         * Tree of extent nodes that are embedded in the arena chunk header
         * page(s).  These nodes are used by arena_chunk_node_alloc().
         */
        extent_tree_ad_t nodes;
        extent_node_t   *nodes_past;

        /*
         * Map of pages within chunk that keeps track of free/large/small.  For
         * free runs, only the map entries for the first and last pages are
         * kept up to date, so that free runs can be quickly coalesced.
         */
        arena_chunk_map_t map[1]; /* Dynamically sized. */
};
typedef struct arena_chunk_tree_s arena_chunk_tree_t;
RB_HEAD(arena_chunk_tree_s, arena_chunk_s);

typedef struct arena_run_s arena_run_t;
struct arena_run_s {
        /* Linkage for run trees. */
        RB_ENTRY(arena_run_s) link;

#ifdef MALLOC_DEBUG
        uint32_t        magic;
#  define ARENA_RUN_MAGIC 0x384adf93
#endif

        /* Bin this run is associated with. */
        arena_bin_t     *bin;

        /* Index of first element that might have a free region. */
        unsigned        regs_minelm;

        /* Number of free regions in run. */
        unsigned        nfree;

        /* Bitmask of in-use regions (0: in use, 1: free). */
        unsigned        regs_mask[1]; /* Dynamically sized. */
};
typedef struct arena_run_tree_s arena_run_tree_t;
RB_HEAD(arena_run_tree_s, arena_run_s);

struct arena_bin_s {
        /*
         * Current run being used to service allocations of this bin's size
         * class.
         */
        arena_run_t     *runcur;

        /*
         * Tree of non-full runs.  This tree is used when looking for an
         * existing run when runcur is no longer usable.  We choose the
         * non-full run that is lowest in memory; this policy tends to keep
         * objects packed well, and it can also help reduce the number of
         * almost-empty chunks.
         */
        arena_run_tree_t runs;

        /* Size of regions in a run for this bin's size class. */
        size_t          reg_size;

        /* Total size of a run for this bin's size class. */
        size_t          run_size;

        /* Total number of regions in a run for this bin's size class. */
        uint32_t        nregs;

        /* Number of elements in a run's regs_mask for this bin's size class. */
        uint32_t        regs_mask_nelms;

        /* Offset of first region in a run for this bin's size class. */
        uint32_t        reg0_offset;

#ifdef MALLOC_STATS
        /* Bin statistics. */
        malloc_bin_stats_t stats;
#endif
};

struct arena_s {
#ifdef MALLOC_DEBUG
        uint32_t                magic;
#  define ARENA_MAGIC 0x947d3d24
#endif

        /* All operations on this arena require that lock be locked. */
        malloc_spinlock_t       lock;

#ifdef MALLOC_STATS
        arena_stats_t           stats;
#endif

        /*
         * Tree of chunks this arena manages.
         */
        arena_chunk_tree_t      chunks;

        /*
         * In order to avoid rapid chunk allocation/deallocation when an arena
         * oscillates right on the cusp of needing a new chunk, cache the most
         * recently freed chunk.  The spare is left in the arena's chunk tree
         * until it is deleted.
         *
         * There is one spare chunk per arena, rather than one spare total, in
         * order to avoid interactions between multiple threads that could make
         * a single spare inadequate.
         */
        arena_chunk_t           *spare;

        /*
         * Current count of pages within unused runs that are potentially
         * dirty, and for which madvise(... MADV_FREE) has not been called.  By
         * tracking this, we can institute a limit on how much dirty unused
         * memory is mapped for each arena.
         */
        size_t                  ndirty;

        /*
         * Trees of this arena's available runs.  Two trees are maintained
         * using one set of nodes, since one is needed for first-best-fit run
         * allocation, and the other is needed for coalescing.
         */
        extent_tree_szad_t      runs_avail_szad;
        extent_tree_ad_t        runs_avail_ad;

        /* Tree of this arena's allocated (in-use) runs. */
        extent_tree_ad_t        runs_alloced_ad;

#ifdef MALLOC_BALANCE
        /*
         * The arena load balancing machinery needs to keep track of how much
         * lock contention there is.  This value is exponentially averaged.
         */
        uint32_t                contention;
#endif

#ifdef MALLOC_LAZY_FREE
        /*
         * Deallocation of small objects can be lazy, in which case free_cache
         * stores pointers to those objects that have not yet been deallocated.
         * In order to avoid lock contention, slots are chosen randomly.  Empty
         * slots contain NULL.
         */
        void                    **free_cache;
#endif

        /*
         * bins is used to store rings of free regions of the following sizes,
         * assuming a 16-byte quantum, 4kB pagesize, and default MALLOC_OPTIONS.
         *
         *   bins[i] | size |
         *   --------+------+
         *        0  |    2 |
         *        1  |    4 |
         *        2  |    8 |
         *   --------+------+
         *        3  |   16 |
         *        4  |   32 |
         *        5  |   48 |
         *        6  |   64 |
         *           :      :
         *           :      :
         *       33  |  496 |
         *       34  |  512 |
         *   --------+------+
         *       35  | 1024 |
         *       36  | 2048 |
         *   --------+------+
         */
        arena_bin_t             bins[1]; /* Dynamically sized. */
};

/******************************************************************************/
/*
 * Data.
 */

/* Number of CPUs. */
static unsigned         ncpus;

/* VM page size. */
static size_t           pagesize;
static size_t           pagesize_mask;
static size_t           pagesize_2pow;

/* Various bin-related settings. */
static size_t           bin_maxclass; /* Max size class for bins. */
static unsigned         ntbins; /* Number of (2^n)-spaced tiny bins. */
static unsigned         nqbins; /* Number of quantum-spaced bins. */
static unsigned         nsbins; /* Number of (2^n)-spaced sub-page bins. */
static size_t           small_min;
static size_t           small_max;

/* Various quantum-related settings. */
static size_t           quantum;
static size_t           quantum_mask; /* (quantum - 1). */

/* Various chunk-related settings. */
static size_t           chunksize;
static size_t           chunksize_mask; /* (chunksize - 1). */
static size_t           chunk_npages;
static size_t           arena_chunk_header_npages;
static size_t           arena_maxclass; /* Max size class for arenas. */

/********/
/*
 * Chunks.
 */

/* Protects chunk-related data structures. */
static malloc_mutex_t   huge_mtx;

/* Tree of chunks that are stand-alone huge allocations. */
static extent_tree_ad_t huge;

#ifdef MALLOC_DSS
/*
 * Protects sbrk() calls.  This avoids malloc races among threads, though it
 * does not protect against races with threads that call sbrk() directly.
 */
static malloc_mutex_t   dss_mtx;
/* Base address of the DSS. */
static void             *dss_base;
/* Current end of the DSS, or ((void *)-1) if the DSS is exhausted. */
static void             *dss_prev;
/* Current upper limit on DSS addresses. */
static void             *dss_max;

/*
 * Trees of chunks that were previously allocated (trees differ only in node
 * ordering).  These are used when allocating chunks, in an attempt to re-use
 * address space.  Depending on function, different tree orderings are needed,
 * which is why there are two trees with the same contents.
 */
static extent_tree_szad_t dss_chunks_szad;
static extent_tree_ad_t dss_chunks_ad;
#endif

#ifdef MALLOC_STATS
/* Huge allocation statistics. */
static uint64_t         huge_nmalloc;
static uint64_t         huge_ndalloc;
static size_t           huge_allocated;
#endif

/****************************/
/*
 * base (internal allocation).
 */

/*
 * Current pages that are being used for internal memory allocations.  These
 * pages are carved up in cacheline-size quanta, so that there is no chance of
 * false cache line sharing.
 */
static void             *base_pages;
static void             *base_next_addr;
static void             *base_past_addr; /* Addr immediately past base_pages. */
static extent_node_t    *base_nodes;
static malloc_mutex_t   base_mtx;
#ifdef MALLOC_STATS
static size_t           base_mapped;
#endif

/********/
/*
 * Arenas.
 */

/*
 * Arenas that are used to service external requests.  Not all elements of the
 * arenas array are necessarily used; arenas are created lazily as needed.
 */
static arena_t          **arenas;
static unsigned         narenas;
#ifndef NO_TLS
#  ifdef MALLOC_BALANCE
static unsigned         narenas_2pow;
#  else
static unsigned         next_arena;
#  endif
#endif
static malloc_spinlock_t arenas_lock; /* Protects arenas initialization. */

#ifndef NO_TLS
/*
 * Map of pthread_self() --> arenas[???], used for selecting an arena to use
 * for allocations.
 */
#ifdef HAVE_LOCAL_THREAD_STORAGE
static __thread arena_t *arenas_map;
#endif
#endif

#ifdef MALLOC_STATS
/* Chunk statistics. */
static chunk_stats_t    stats_chunks;
#endif

/*******************************/
/*
 * Runtime configuration options.
 */
const char      *_malloc_options
#ifdef WIN32
= "A10n2F"
#elif (defined(DARWIN))
= "AP10n"
#elif (defined(LINUX_HOST))
= "A10n2F"
#endif
;

#ifndef MALLOC_PRODUCTION
static bool     opt_abort = true;
#ifdef MALLOC_FILL
static bool     opt_junk = true;
#endif
#else
static bool     opt_abort = false;
#ifdef MALLOC_FILL
static bool     opt_junk = false;
#endif
#endif
#ifdef MALLOC_DSS
static bool     opt_dss = true;
static bool     opt_mmap = true;
#endif
static size_t   opt_dirty_max = DIRTY_MAX_DEFAULT;
#ifdef MALLOC_LAZY_FREE
static int      opt_lazy_free_2pow = LAZY_FREE_2POW_DEFAULT;
#endif
#ifdef MALLOC_BALANCE
static uint64_t opt_balance_threshold = BALANCE_THRESHOLD_DEFAULT;
#endif
/*
 * this toggles the printing of statistics when the program exists.
 */
static bool     opt_print_stats = false;
static size_t   opt_quantum_2pow = QUANTUM_2POW_MIN;
static size_t   opt_small_max_2pow = SMALL_MAX_2POW_DEFAULT;
static size_t   opt_chunk_2pow = CHUNK_2POW_DEFAULT;
#ifdef MALLOC_UTRACE
static bool     opt_utrace = false;
#endif
#ifdef MALLOC_SYSV
static bool     opt_sysv = false;
#endif
#ifdef MALLOC_XMALLOC
static bool     opt_xmalloc = false;
#endif
#ifdef MALLOC_FILL
static bool     opt_zero = false;
#endif
static int      opt_narenas_lshift = 0;

#ifdef MALLOC_UTRACE
typedef struct {
        void    *p;
        size_t  s;
        void    *r;
} malloc_utrace_t;

#define UTRACE(a, b, c)                                                 \
        if (opt_utrace) {                                               \
                malloc_utrace_t ut;                                     \
                ut.p = (a);                                             \
                ut.s = (b);                                             \
                ut.r = (c);                                             \
                utrace(&ut, sizeof(ut));                                \
        }
#else
#define UTRACE(a, b, c)
#endif

/******************************************************************************/
/*
 * Begin function prototypes for non-inline static functions.
 */

static bool     malloc_mutex_init(malloc_mutex_t *mutex);
static bool     malloc_spin_init(malloc_spinlock_t *lock);
static void     wrtmessage(const char *p1, const char *p2, const char *p3,
                const char *p4);
#ifdef MALLOC_STATS
#ifdef DARWIN
/* Avoid namespace collision with OS X's malloc APIs. */
#define malloc_printf xmalloc_printf
#endif
static void     malloc_printf(const char *format, ...);
#endif
static char     *umax2s(uintmax_t x, char *s);
#ifdef MALLOC_DSS
static bool     base_pages_alloc_dss(size_t minsize);
#endif
static bool     base_pages_alloc_mmap(size_t minsize);
static bool     base_pages_alloc(size_t minsize);
static void     *base_alloc(size_t size);
static void     *base_calloc(size_t number, size_t size);
static extent_node_t *base_node_alloc(void);
static void     base_node_dealloc(extent_node_t *node);
#ifdef MALLOC_STATS
static void     stats_print(arena_t *arena);
#endif
static void     *pages_map(void *addr, size_t size);
static void     pages_unmap(void *addr, size_t size);
#ifdef MALLOC_DSS
static void     *chunk_alloc_dss(size_t size);
static void     *chunk_recycle_dss(size_t size, bool zero);
#endif
static void     *chunk_alloc_mmap(size_t size);
static void     *chunk_alloc(size_t size, bool zero);
#ifdef MALLOC_DSS
static extent_node_t *chunk_dealloc_dss_record(void *chunk, size_t size);
static bool     chunk_dealloc_dss(void *chunk, size_t size);
#endif
static void     chunk_dealloc_mmap(void *chunk, size_t size);
static void     chunk_dealloc(void *chunk, size_t size);
#ifndef NO_TLS
static arena_t  *choose_arena_hard(void);
#endif
static extent_node_t *arena_chunk_node_alloc(arena_chunk_t *chunk);
static void     arena_chunk_node_dealloc(arena_chunk_t *chunk,
    extent_node_t *node);
static void     arena_run_split(arena_t *arena, arena_run_t *run, size_t size,
    bool small, bool zero);
static arena_chunk_t *arena_chunk_alloc(arena_t *arena);
static void     arena_chunk_dealloc(arena_t *arena, arena_chunk_t *chunk);
static arena_run_t *arena_run_alloc(arena_t *arena, size_t size, bool small,
    bool zero);
static void     arena_purge(arena_t *arena);
static void     arena_run_dalloc(arena_t *arena, arena_run_t *run, bool dirty);
static void     arena_run_trim_head(arena_t *arena, arena_chunk_t *chunk,
    extent_node_t *nodeB, arena_run_t *run, size_t oldsize, size_t newsize);
static void     arena_run_trim_tail(arena_t *arena, arena_chunk_t *chunk,
    extent_node_t *nodeA, arena_run_t *run, size_t oldsize, size_t newsize,
    bool dirty);
static arena_run_t *arena_bin_nonfull_run_get(arena_t *arena, arena_bin_t *bin);
static void *arena_bin_malloc_hard(arena_t *arena, arena_bin_t *bin);
static size_t arena_bin_run_size_calc(arena_bin_t *bin, size_t min_run_size);
#ifdef MALLOC_BALANCE
static void     arena_lock_balance_hard(arena_t *arena);
#endif
static void     *arena_malloc_large(arena_t *arena, size_t size, bool zero);
static void     *arena_palloc(arena_t *arena, size_t alignment, size_t size,
    size_t alloc_size);
static size_t   arena_salloc(const void *ptr);
#ifdef MALLOC_LAZY_FREE
static void     arena_dalloc_lazy_hard(arena_t *arena, arena_chunk_t *chunk,
    void *ptr, size_t pageind, arena_chunk_map_t *mapelm);
#endif
static void     arena_dalloc_large(arena_t *arena, arena_chunk_t *chunk,
    void *ptr);
static void     arena_ralloc_large_shrink(arena_t *arena, arena_chunk_t *chunk,
    void *ptr, size_t size, size_t oldsize);
static bool     arena_ralloc_large_grow(arena_t *arena, arena_chunk_t *chunk,
    void *ptr, size_t size, size_t oldsize);
static bool     arena_ralloc_large(void *ptr, size_t size, size_t oldsize);
static void     *arena_ralloc(void *ptr, size_t size, size_t oldsize);
static bool     arena_new(arena_t *arena);
static arena_t  *arenas_extend(unsigned ind);
static void     *huge_malloc(size_t size, bool zero);
static void     *huge_palloc(size_t alignment, size_t size);
static void     *huge_ralloc(void *ptr, size_t size, size_t oldsize);
static void     huge_dalloc(void *ptr);
static void     malloc_print_stats(void);
#ifndef WIN32
static
#endif
bool            malloc_init_hard(void);

/*
 * End function prototypes.
 */
/******************************************************************************/
/*
 * Begin mutex.  We can't use normal pthread mutexes in all places, because
 * they require malloc()ed memory, which causes bootstrapping issues in some
 * cases.
 */

static bool
malloc_mutex_init(malloc_mutex_t *mutex)
{
#if defined(WIN32)
        if (g_isthreaded)
                if (! __crtInitCritSecAndSpinCount(mutex, _CRT_SPINCOUNT))
                        return (true);
#elif defined(DARWIN)
        mutex->lock = OS_SPINLOCK_INIT;
#elif defined(LINUX_HOST)
        pthread_mutexattr_t attr;
        if (pthread_mutexattr_init(&attr) != 0)
                return (true);
        pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ADAPTIVE_NP);
        if (pthread_mutex_init(mutex, &attr) != 0) {
                pthread_mutexattr_destroy(&attr);
                return (true);
        }
        pthread_mutexattr_destroy(&attr);
#elif defined(USE_JEMALLOC)
        if (pthread_mutex_init(mutex, NULL) != 0)
                return (true);
#else
        static const spinlock_t lock = _SPINLOCK_INITIALIZER;

        mutex->lock = lock;
#endif
        return (false);
}

static inline void
malloc_mutex_lock(malloc_mutex_t *mutex)
{

#if defined(WIN32)
        EnterCriticalSection(mutex);
#elif defined(DARWIN)
        OSSpinLockLock(&mutex->lock);
#elif defined(USE_JEMALLOC)
        pthread_mutex_lock(mutex);
#else
        if (g_isthreaded)
                _SPINLOCK(&mutex->lock);
#endif
}

static inline void
malloc_mutex_unlock(malloc_mutex_t *mutex)
{

#if defined(WIN32)
        LeaveCriticalSection(mutex);
#elif defined(DARWIN)
        OSSpinLockUnlock(&mutex->lock);
#elif defined(USE_JEMALLOC)
        pthread_mutex_unlock(mutex);
#else
        if (g_isthreaded)
                _SPINUNLOCK(&mutex->lock);
#endif
}

static bool
malloc_spin_init(malloc_spinlock_t *lock)
{
#if defined(WIN32)
        if (g_isthreaded)
                if (! __crtInitCritSecAndSpinCount(lock, _CRT_SPINCOUNT))
                        return (true);
#elif defined(DARWIN)
        lock->lock = OS_SPINLOCK_INIT;
#elif defined(LINUX_HOST)
        pthread_mutexattr_t attr;
        if (pthread_mutexattr_init(&attr) != 0)
                return (true);
        pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ADAPTIVE_NP);
        if (pthread_mutex_init(lock, &attr) != 0) {
                pthread_mutexattr_destroy(&attr);
                return (true);
        }
        pthread_mutexattr_destroy(&attr);
#elif defined(USE_JEMALLOC)
        if (pthread_mutex_init(lock, NULL) != 0)
                return (true);
#else
        lock->lock = _SPINLOCK_INITIALIZER;
#endif
        return (false);
}

static inline void
malloc_spin_lock(malloc_spinlock_t *lock)
{

#if defined(WIN32)
        EnterCriticalSection(lock);
#elif defined(DARWIN)
        OSSpinLockLock(&lock->lock);
#elif defined(USE_JEMALLOC)
        pthread_mutex_lock(lock);
#else
        if (g_isthreaded)
                _SPINLOCK(&lock->lock);
#endif
}

static inline void
malloc_spin_unlock(malloc_spinlock_t *lock)
{
#if defined(WIN32)
        LeaveCriticalSection(lock);
#elif defined(DARWIN)
        OSSpinLockUnlock(&lock->lock);
#elif defined(USE_JEMALLOC)
        pthread_mutex_unlock(lock);
#else
        if (g_isthreaded)
                _SPINUNLOCK(&lock->lock);
#endif
}

/*
 * End mutex.
 */
/******************************************************************************/
/*
 * Begin spin lock.  Spin locks here are actually adaptive mutexes that block
 * after a period of spinning, because unbounded spinning would allow for
 * priority inversion.
 */

#ifndef DARWIN
#  define       malloc_spin_init        malloc_mutex_init
#  define       malloc_spin_lock        malloc_mutex_lock
#  define       malloc_spin_unlock      malloc_mutex_unlock
#endif

/*
 * End spin lock.
 */

/******************************************************************************/
/*
 * Begin Utility functions/macros.
 */

/* Return the chunk address for allocation address a. */
#define CHUNK_ADDR2BASE(a)                                              \
        ((void *)((uintptr_t)(a) & ~chunksize_mask))

/* Return the chunk offset of address a. */
#define CHUNK_ADDR2OFFSET(a)                                            \
        ((size_t)((uintptr_t)(a) & chunksize_mask))

/* Return the smallest chunk multiple that is >= s. */
#define CHUNK_CEILING(s)                                                \
        (((s) + chunksize_mask) & ~chunksize_mask)

/* Return the smallest cacheline multiple that is >= s. */
#define CACHELINE_CEILING(s)                                            \
        (((s) + (CACHELINE - 1)) & ~(CACHELINE - 1))

/* Return the smallest quantum multiple that is >= a. */
#define QUANTUM_CEILING(a)                                              \
        (((a) + quantum_mask) & ~quantum_mask)

/* Return the smallest pagesize multiple that is >= s. */
#define PAGE_CEILING(s)                                                 \
        (((s) + pagesize_mask) & ~pagesize_mask)

/* Compute the smallest power of 2 that is >= x. */
static inline size_t
pow2_ceil(size_t x)
{

        x--;
        x |= x >> 1;
        x |= x >> 2;
        x |= x >> 4;
        x |= x >> 8;
        x |= x >> 16;
#if (SIZEOF_PTR == 8)
        x |= x >> 32;
#endif
        x++;
        return (x);
}

#if (defined(MALLOC_LAZY_FREE) || defined(MALLOC_BALANCE))
/*
 * Use a simple linear congruential pseudo-random number generator:
 *
 *   prn(y) = (a*x + c) % m
 *
 * where the following constants ensure maximal period:
 *
 *   a == Odd number (relatively prime to 2^n), and (a-1) is a multiple of 4.
 *   c == Odd number (relatively prime to 2^n).
 *   m == 2^32
 *
 * See Knuth's TAOCP 3rd Ed., Vol. 2, pg. 17 for details on these constraints.
 *
 * This choice of m has the disadvantage that the quality of the bits is
 * proportional to bit position.  For example. the lowest bit has a cycle of 2,
 * the next has a cycle of 4, etc.  For this reason, we prefer to use the upper
 * bits.
 */
#  define PRN_DEFINE(suffix, var, a, c)                                 \
static inline void                                                      \
sprn_##suffix(uint32_t seed)                                            \
{                                                                       \
        var = seed;                                                     \
}                                                                       \
                                                                        \
static inline uint32_t                                                  \
prn_##suffix(uint32_t lg_range)                                         \
{                                                                       \
        uint32_t ret, x;                                                \
                                                                        \
        assert(lg_range > 0);                                           \
        assert(lg_range <= 32);                                         \
                                                                        \
        x = (var * (a)) + (c);                                          \
        var = x;                                                        \
        ret = x >> (32 - lg_range);                                     \
                                                                        \
        return (ret);                                                   \
}
#  define SPRN(suffix, seed)    sprn_##suffix(seed)
#  define PRN(suffix, lg_range) prn_##suffix(lg_range)
#endif

/*
 * Define PRNGs, one for each purpose, in order to avoid auto-correlation
 * problems.
 */

#ifdef MALLOC_LAZY_FREE
/* Define the per-thread PRNG used for lazy deallocation. */
static __thread uint32_t lazy_free_x;
PRN_DEFINE(lazy_free, lazy_free_x, 12345, 12347)
#endif

#ifdef MALLOC_BALANCE
/* Define the PRNG used for arena assignment. */
static __thread uint32_t balance_x;
PRN_DEFINE(balance, balance_x, 1297, 1301)
#endif

#ifdef MALLOC_UTRACE
static int
utrace(const void *addr, size_t len)
{
        malloc_utrace_t *ut = (malloc_utrace_t *)addr;

        assert(len == sizeof(malloc_utrace_t));

        if (ut->p == NULL && ut->s == 0 && ut->r == NULL)
                malloc_printf("%d x USER malloc_init()\n", getpid());
        else if (ut->p == NULL && ut->r != NULL) {
                malloc_printf("%d x USER %p = malloc(%zu)\n", getpid(), ut->r,
                    ut->s);
        } else if (ut->p != NULL && ut->r != NULL) {
                malloc_printf("%d x USER %p = realloc(%p, %zu)\n", getpid(),
                    ut->r, ut->p, ut->s);
        } else
                malloc_printf("%d x USER free(%p)\n", getpid(), ut->p);

        return (0);
}
#endif

static inline const char *
_getprogname(void)
{

        return ("<jemalloc>");
}

static void
wrtmessage(const char *p1, const char *p2, const char *p3, const char *p4)
{
#ifndef WIN32
#define _write  write
#endif
        size_t ret =_write(STDERR_FILENO, p1, (unsigned int) strlen(p1));
        ret = _write(STDERR_FILENO, p2, (unsigned int) strlen(p2));
        ret = _write(STDERR_FILENO, p3, (unsigned int) strlen(p3));
        ret = _write(STDERR_FILENO, p4, (unsigned int) strlen(p4));
}

#define _malloc_message malloc_message

void    (*_malloc_message)(const char *p1, const char *p2, const char *p3,
            const char *p4) = wrtmessage;

#ifdef MALLOC_STATS
/*
 * Print to stderr in such a way as to (hopefully) avoid memory allocation.
 */
static void
malloc_printf(const char *format, ...)
{
        char buf[4096];
        va_list ap;

        va_start(ap, format);
        vsnprintf(buf, sizeof(buf), format, ap);
        va_end(ap);
        _malloc_message(buf, "", "", "");
}
#endif

/*
 * We don't want to depend on vsnprintf() for production builds, since that can
 * cause unnecessary bloat for static binaries.  umax2s() provides minimal
 * integer printing functionality, so that malloc_printf() use can be limited to
 * MALLOC_STATS code.
 */
#define UMAX2S_BUFSIZE  21
static char *
umax2s(uintmax_t x, char *s)
{
        unsigned i;

        /* Make sure UMAX2S_BUFSIZE is large enough. */
        assert(sizeof(uintmax_t) <= 8);

        i = UMAX2S_BUFSIZE - 1;
        s[i] = '\0';
        do {
                i--;
                s[i] = "0123456789"[x % 10];
                x /= 10;
        } while (x > 0);

        return (&s[i]);
}

/******************************************************************************/

#ifdef MALLOC_DSS
static bool
base_pages_alloc_dss(size_t minsize)
{

        /*
         * Do special DSS allocation here, since base allocations don't need to
         * be chunk-aligned.
         */
        malloc_mutex_lock(&dss_mtx);
        if (dss_prev != (void *)-1) {
                intptr_t incr;
                size_t csize = CHUNK_CEILING(minsize);

                do {
                        /* Get the current end of the DSS. */
                        dss_max = sbrk(0);

                        /*
                         * Calculate how much padding is necessary to
                         * chunk-align the end of the DSS.  Don't worry about
                         * dss_max not being chunk-aligned though.
                         */
                        incr = (intptr_t)chunksize
                            - (intptr_t)CHUNK_ADDR2OFFSET(dss_max);
                        assert(incr >= 0);
                        if ((size_t)incr < minsize)
                                incr += csize;

                        dss_prev = sbrk(incr);
                        if (dss_prev == dss_max) {
                                /* Success. */
                                dss_max = (void *)((intptr_t)dss_prev + incr);
                                base_pages = dss_prev;
                                base_next_addr = base_pages;
                                base_past_addr = dss_max;
#ifdef MALLOC_STATS
                                base_mapped += incr;
#endif
                                malloc_mutex_unlock(&dss_mtx);
                                return (false);
                        }
                } while (dss_prev != (void *)-1);
        }
        malloc_mutex_unlock(&dss_mtx);

        return (true);
}
#endif

static bool
base_pages_alloc_mmap(size_t minsize)
{
        size_t csize;

        assert(minsize != 0);
        csize = PAGE_CEILING(minsize);
        base_pages = pages_map(NULL, csize);
        if (base_pages == NULL)
                return (true);
        base_next_addr = base_pages;
        base_past_addr = (void *)((uintptr_t)base_pages + csize);
#ifdef MALLOC_STATS
        base_mapped += csize;
#endif

        return (false);
}

static bool
base_pages_alloc(size_t minsize)
{

#ifdef MALLOC_DSS
        if (opt_dss) {
                if (base_pages_alloc_dss(minsize) == false)
                        return (false);
        }

        if (opt_mmap && minsize != 0)
#endif
        {
                if (base_pages_alloc_mmap(minsize) == false)
                        return (false);
        }

        return (true);
}

static void *
base_alloc(size_t size)
{
        void *ret;
        size_t csize;

        /* Round size up to nearest multiple of the cacheline size. */
        csize = CACHELINE_CEILING(size);

        malloc_mutex_lock(&base_mtx);
        /* Make sure there's enough space for the allocation. */
        if ((uintptr_t)base_next_addr + csize > (uintptr_t)base_past_addr) {
                if (base_pages_alloc(csize))
                        return (NULL);
        }
        /* Allocate. */
        ret = base_next_addr;
        base_next_addr = (void *)((uintptr_t)base_next_addr + csize);
        malloc_mutex_unlock(&base_mtx);

        return (ret);
}

static void *
base_calloc(size_t number, size_t size)
{
        void *ret;

        ret = base_alloc(number * size);
        memset(ret, 0, number * size);

        return (ret);
}

static extent_node_t *
base_node_alloc(void)
{
        extent_node_t *ret;

        malloc_mutex_lock(&base_mtx);
        if (base_nodes != NULL) {
                ret = base_nodes;
                base_nodes = *(extent_node_t **)ret;
                malloc_mutex_unlock(&base_mtx);
        } else {
                malloc_mutex_unlock(&base_mtx);
                ret = (extent_node_t *)base_alloc(sizeof(extent_node_t));
        }

        return (ret);
}

static void
base_node_dealloc(extent_node_t *node)
{

        malloc_mutex_lock(&base_mtx);
        *(extent_node_t **)node = base_nodes;
        base_nodes = node;
        malloc_mutex_unlock(&base_mtx);
}

/******************************************************************************/

#ifdef MALLOC_STATS
static void
stats_print(arena_t *arena)
{
        unsigned i, gap_start;

#ifdef WIN32
        malloc_printf("dirty: %Iu page%s dirty, %I64u sweep%s,"
            " %I64u madvise%s, %I64u page%s purged\n",
            arena->ndirty, arena->ndirty == 1 ? "" : "s",
            arena->stats.npurge, arena->stats.npurge == 1 ? "" : "s",
            arena->stats.nmadvise, arena->stats.nmadvise == 1 ? "" : "s",
            arena->stats.purged, arena->stats.purged == 1 ? "" : "s");
#  ifdef MALLOC_DECOMMIT
        malloc_printf("decommit: %I64u decommit%s, %I64u commit%s,"
            " %I64u page%s decommitted\n",
            arena->stats.ndecommit, (arena->stats.ndecommit == 1) ? "" : "s",
            arena->stats.ncommit, (arena->stats.ncommit == 1) ? "" : "s",
            arena->stats.decommitted,
            (arena->stats.decommitted == 1) ? "" : "s");
#  endif

        malloc_printf("            allocated      nmalloc      ndalloc\n");
        malloc_printf("small:   %12Iu %12I64u %12I64u\n",
            arena->stats.allocated_small, arena->stats.nmalloc_small,
            arena->stats.ndalloc_small);
        malloc_printf("large:   %12Iu %12I64u %12I64u\n",
            arena->stats.allocated_large, arena->stats.nmalloc_large,
            arena->stats.ndalloc_large);
        malloc_printf("total:   %12Iu %12I64u %12I64u\n",
            arena->stats.allocated_small + arena->stats.allocated_large,
            arena->stats.nmalloc_small + arena->stats.nmalloc_large,
            arena->stats.ndalloc_small + arena->stats.ndalloc_large);
        malloc_printf("mapped:  %12Iu\n", arena->stats.mapped);
#else
        malloc_printf("dirty: %zu page%s dirty, %llu sweep%s,"
            " %llu madvise%s, %llu page%s purged\n",
            arena->ndirty, arena->ndirty == 1 ? "" : "s",
            arena->stats.npurge, arena->stats.npurge == 1 ? "" : "s",
            arena->stats.nmadvise, arena->stats.nmadvise == 1 ? "" : "s",
            arena->stats.purged, arena->stats.purged == 1 ? "" : "s");
#  ifdef MALLOC_DECOMMIT
        malloc_printf("decommit: %llu decommit%s, %llu commit%s,"
            " %llu page%s decommitted\n",
            arena->stats.ndecommit, (arena->stats.ndecommit == 1) ? "" : "s",
            arena->stats.ncommit, (arena->stats.ncommit == 1) ? "" : "s",
            arena->stats.decommitted,
            (arena->stats.decommitted == 1) ? "" : "s");
#  endif

        malloc_printf("            allocated      nmalloc      ndalloc\n");
        malloc_printf("small:   %12zu %12llu %12llu\n",
            arena->stats.allocated_small, arena->stats.nmalloc_small,
            arena->stats.ndalloc_small);
        malloc_printf("large:   %12zu %12llu %12llu\n",
            arena->stats.allocated_large, arena->stats.nmalloc_large,
            arena->stats.ndalloc_large);
        malloc_printf("total:   %12zu %12llu %12llu\n",
            arena->stats.allocated_small + arena->stats.allocated_large,
            arena->stats.nmalloc_small + arena->stats.nmalloc_large,
            arena->stats.ndalloc_small + arena->stats.ndalloc_large);
        malloc_printf("mapped:  %12zu\n", arena->stats.mapped);
#endif
        malloc_printf("bins:     bin   size regs pgs  requests   newruns"
            "    reruns maxruns curruns\n");
        for (i = 0, gap_start = UINT_MAX; i < ntbins + nqbins + nsbins; i++) {
                if (arena->bins[i].stats.nrequests == 0) {
                        if (gap_start == UINT_MAX)
                                gap_start = i;
                } else {
                        if (gap_start != UINT_MAX) {
                                if (i > gap_start + 1) {
                                        /* Gap of more than one size class. */
                                        malloc_printf("[%u..%u]\n",
                                            gap_start, i - 1);
                                } else {
                                        /* Gap of one size class. */
                                        malloc_printf("[%u]\n", gap_start);
                                }
                                gap_start = UINT_MAX;
                        }
                        malloc_printf(
#if defined(WIN32)
                            "%13u %1s %4u %4u %3u %9I64u %9I64u"
                            " %9I64u %7u %7u\n",
#else
                            "%13u %1s %4u %4u %3u %9llu %9llu"
                            " %9llu %7lu %7lu\n",
#endif
                            i,
                            i < ntbins ? "T" : i < ntbins + nqbins ? "Q" : "S",
                            arena->bins[i].reg_size,
                            arena->bins[i].nregs,
                            arena->bins[i].run_size >> pagesize_2pow,
                            arena->bins[i].stats.nrequests,
                            arena->bins[i].stats.nruns,
                            arena->bins[i].stats.reruns,
                            arena->bins[i].stats.highruns,
                            arena->bins[i].stats.curruns);
                }
        }
        if (gap_start != UINT_MAX) {
                if (i > gap_start + 1) {
                        /* Gap of more than one size class. */
                        malloc_printf("[%u..%u]\n", gap_start, i - 1);
                } else {
                        /* Gap of one size class. */
                        malloc_printf("[%u]\n", gap_start);
                }
        }
}
#endif

/*
 * End Utility functions/macros.
 */
/******************************************************************************/
/*
 * Begin extent tree code.
 */

static inline int
extent_szad_comp(extent_node_t *a, extent_node_t *b)
{
        int ret;
        size_t a_size = a->size;
        size_t b_size = b->size;

        ret = (a_size > b_size) - (a_size < b_size);
        if (ret == 0) {
                uintptr_t a_addr = (uintptr_t)a->addr;
                uintptr_t b_addr = (uintptr_t)b->addr;

                ret = (a_addr > b_addr) - (a_addr < b_addr);
        }

        return (ret);
}

/* Generate red-black tree code for size/address-ordered extents. */
RB_GENERATE_STATIC(extent_tree_szad_s, extent_node_s, link_szad,
    extent_szad_comp)

static inline int
extent_ad_comp(extent_node_t *a, extent_node_t *b)
{
        uintptr_t a_addr = (uintptr_t)a->addr;
        uintptr_t b_addr = (uintptr_t)b->addr;

        return ((a_addr > b_addr) - (a_addr < b_addr));
}

/* Generate red-black tree code for address-ordered extents. */
RB_GENERATE_STATIC(extent_tree_ad_s, extent_node_s, link_ad, extent_ad_comp)


/*
 * End extent tree code.
 */
/******************************************************************************/
/*
 * Begin chunk management functions.
 */

#ifdef WIN32
static void *
pages_map(void *addr, size_t size)
{
        void *ret;

        ret = VirtualAlloc(addr, size, MEM_COMMIT | MEM_RESERVE,
            PAGE_READWRITE);

        return (ret);
}

static void
pages_unmap(void *addr, size_t size)
{

        if (VirtualFree(addr, 0, MEM_RELEASE) == 0) {
                _malloc_message(_getprogname(),
                    ": (malloc) Error in VirtualFree()\n", "", "");
                if (opt_abort)
                        abort();
        }
}
#elif (defined(DARWIN))
static void *
pages_map(void *addr, size_t size)
{
        void *ret;
        kern_return_t err;
        int flags;

        if (addr != NULL) {
                ret = addr;
                flags = 0;
        } else
                flags = VM_FLAGS_ANYWHERE;

        err = vm_allocate((vm_map_t)mach_task_self(), (vm_address_t *)&ret,
            (vm_size_t)size, flags);
        if (err != KERN_SUCCESS)
                ret = NULL;

        assert(ret == NULL || (addr == NULL && ret != addr)
            || (addr != NULL && ret == addr));
        return (ret);
}

static void
pages_unmap(void *addr, size_t size)
{
        kern_return_t err;

        err = vm_deallocate((vm_map_t)mach_task_self(), (vm_address_t)addr,
            (vm_size_t)size);
        if (err != KERN_SUCCESS) {
                malloc_message(_getprogname(),
                    ": (malloc) Error in vm_deallocate(): ",
                    mach_error_string(err), "\n");
                if (opt_abort)
                        abort();
        }
}

#define VM_COPY_MIN (pagesize << 5)
static inline void
pages_copy(void *dest, const void *src, size_t n)
{

        assert((void *)((uintptr_t)dest & ~pagesize_mask) == dest);
        assert(n >= VM_COPY_MIN);
        assert((void *)((uintptr_t)src & ~pagesize_mask) == src);

        vm_copy(mach_task_self(), (vm_address_t)src, (vm_size_t)n,
            (vm_address_t)dest);
}
#else /* DARWIN */
static void *
pages_map(void *addr, size_t size)
{
        void *ret;

        /*
         * We don't use MAP_FIXED here, because it can cause the *replacement*
         * of existing mappings, and we only want to create new mappings.
         */
        ret = mmap(addr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON,
            -1, 0);
        assert(ret != NULL);

        if (ret == MAP_FAILED)
                ret = NULL;
        else if (addr != NULL && ret != addr) {
                /*
                 * We succeeded in mapping memory, but not in the right place.
                 */
                if (munmap(ret, size) == -1) {
                        char buf[STRERROR_BUF];

                        strerror_r(errno, buf, sizeof(buf));
                        _malloc_message(_getprogname(),
                            ": (malloc) Error in munmap(): ", buf, "\n");
                        if (opt_abort)
                                abort();
                }
                ret = NULL;
        }

        assert(ret == NULL || (addr == NULL && ret != addr)
            || (addr != NULL && ret == addr));
        return (ret);
}

static void
pages_unmap(void *addr, size_t size)
{

        if (munmap(addr, size) == -1) {
                char buf[STRERROR_BUF];

                strerror_r(errno, buf, sizeof(buf));
                _malloc_message(_getprogname(),
                    ": (malloc) Error in munmap(): ", buf, "\n");
                if (opt_abort)
                        abort();
        }
}
#endif

#ifdef MALLOC_DECOMMIT
static inline void
pages_decommit(void *addr, size_t size)
{

#ifdef WIN32
        VirtualFree(addr, size, MEM_DECOMMIT);
#else
        if (mmap(addr, size, PROT_NONE, MAP_FIXED | MAP_PRIVATE | MAP_ANON, -1,
            0) == MAP_FAILED)
                abort();
#endif
}

static inline void
pages_commit(void *addr, size_t size)
{

#  ifdef WIN32
        VirtualAlloc(addr, size, MEM_COMMIT, PAGE_READWRITE);
#  else
        if (mmap(addr, size, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_PRIVATE |
            MAP_ANON, -1, 0) == MAP_FAILED)
                abort();
#  endif
}
#endif

#ifdef MALLOC_DSS
static void *
chunk_alloc_dss(size_t size)
{

        malloc_mutex_lock(&dss_mtx);
        if (dss_prev != (void *)-1) {
                intptr_t incr;

                /*
                 * The loop is necessary to recover from races with other
                 * threads that are using the DSS for something other than
                 * malloc.
                 */
                do {
                        void *ret;

                        /* Get the current end of the DSS. */
                        dss_max = sbrk(0);

                        /*
                         * Calculate how much padding is necessary to
                         * chunk-align the end of the DSS.
                         */
                        incr = (intptr_t)size
                            - (intptr_t)CHUNK_ADDR2OFFSET(dss_max);
                        if (incr == (intptr_t)size)
                                ret = dss_max;
                        else {
                                ret = (void *)((intptr_t)dss_max + incr);
                                incr += size;
                        }

                        dss_prev = sbrk(incr);
                        if (dss_prev == dss_max) {
                                /* Success. */
                                dss_max = (void *)((intptr_t)dss_prev + incr);
                                malloc_mutex_unlock(&dss_mtx);
                                return (ret);
                        }
                } while (dss_prev != (void *)-1);
        }
        malloc_mutex_unlock(&dss_mtx);

        return (NULL);
}

static void *
chunk_recycle_dss(size_t size, bool zero)
{
        extent_node_t *node, key;

        key.addr = NULL;
        key.size = size;
        malloc_mutex_lock(&dss_mtx);
        node = RB_NFIND(extent_tree_szad_s, &dss_chunks_szad, &key);
        if (node != NULL) {
                void *ret = node->addr;

                /* Remove node from the tree. */
                RB_REMOVE(extent_tree_szad_s, &dss_chunks_szad, node);
                if (node->size == size) {
                        RB_REMOVE(extent_tree_ad_s, &dss_chunks_ad, node);
                        base_node_dealloc(node);
                } else {
                        /*
                         * Insert the remainder of node's address range as a
                         * smaller chunk.  Its position within dss_chunks_ad
                         * does not change.
                         */
                        assert(node->size > size);
                        node->addr = (void *)((uintptr_t)node->addr + size);
                        node->size -= size;
                        RB_INSERT(extent_tree_szad_s, &dss_chunks_szad, node);
                }
                malloc_mutex_unlock(&dss_mtx);

                if (zero)
                        memset(ret, 0, size);
                return (ret);
        }
        malloc_mutex_unlock(&dss_mtx);

        return (NULL);
}
#endif

#ifdef WIN32
static inline void *
chunk_alloc_mmap(size_t size)
{
        void *ret;
        size_t offset;

        /*
         * Windows requires that there be a 1:1 mapping between VM
         * allocation/deallocation operations.  Therefore, take care here to
         * acquire the final result via one mapping operation.  This means
         * unmapping any preliminary result that is not correctly aligned.
         */

        ret = pages_map(NULL, size);
        if (ret == NULL)
                return (NULL);

        offset = CHUNK_ADDR2OFFSET(ret);
        if (offset != 0) {
                /* Deallocate, then try to allocate at (ret + size - offset). */
                pages_unmap(ret, size);
                ret = pages_map((void *)((uintptr_t)ret + size - offset), size);
                while (ret == NULL) {
                        /*
                         * Over-allocate in order to map a memory region that
                         * is definitely large enough.
                         */
                        ret = pages_map(NULL, size + chunksize);
                        if (ret == NULL)
                                return (NULL);
                        /*
                         * Deallocate, then allocate the correct size, within
                         * the over-sized mapping.
                         */
                        offset = CHUNK_ADDR2OFFSET(ret);
                        pages_unmap(ret, size + chunksize);
                        if (offset == 0)
                                ret = pages_map(ret, size);
                        else {
                                ret = pages_map((void *)((uintptr_t)ret +
                                    chunksize - offset), size);
                        }
                        /*
                         * Failure here indicates a race with another thread, so
                         * try again.
                         */
                }
        }

        return (ret);
}
#else
static inline void *
chunk_alloc_mmap(size_t size)
{
        void *ret;
        size_t offset;

        /*
         * Ideally, there would be a way to specify alignment to mmap() (like
         * NetBSD has), but in the absence of such a feature, we have to work
         * hard to efficiently create aligned mappings.  The reliable, but
         * expensive method is to create a mapping that is over-sized, then
         * trim the excess.  However, that always results in at least one call
         * to pages_unmap().
         *
         * A more optimistic approach is to try mapping precisely the right
         * amount, then try to append another mapping if alignment is off.  In
         * practice, this works out well as long as the application is not
         * interleaving mappings via direct mmap() calls.  If we do run into a
         * situation where there is an interleaved mapping and we are unable to
         * extend an unaligned mapping, our best option is to momentarily
         * revert to the reliable-but-expensive method.  This will tend to
         * leave a gap in the memory map that is too small to cause later
         * problems for the optimistic method.
         */

        ret = pages_map(NULL, size);
        if (ret == NULL)
                return (NULL);

        offset = CHUNK_ADDR2OFFSET(ret);
        if (offset != 0) {
                /* Try to extend chunk boundary. */
                if (pages_map((void *)((uintptr_t)ret + size),
                    chunksize - offset) == NULL) {
                        /*
                         * Extension failed.  Clean up, then revert to the
                         * reliable-but-expensive method.
                         */
                        pages_unmap(ret, size);

                        /* Beware size_t wrap-around. */
                        if (size + chunksize <= size)
                                return NULL;

                        ret = pages_map(NULL, size + chunksize);
                        if (ret == NULL)
                                return (NULL);

                        /* Clean up unneeded leading/trailing space. */
                        offset = CHUNK_ADDR2OFFSET(ret);
                        if (offset != 0) {
                                /* Leading space. */
                                pages_unmap(ret, chunksize - offset);

                                ret = (void *)((uintptr_t)ret +
                                    (chunksize - offset));

                                /* Trailing space. */
                                pages_unmap((void *)((uintptr_t)ret + size),
                                    offset);
                        } else {
                                /* Trailing space only. */
                                pages_unmap((void *)((uintptr_t)ret + size),
                                    chunksize);
                        }
                } else {
                        /* Clean up unneeded leading space. */
                        pages_unmap(ret, chunksize - offset);
                        ret = (void *)((uintptr_t)ret + (chunksize - offset));
                }
        }

        return (ret);
}
#endif

static void *
chunk_alloc(size_t size, bool zero)
{
        void *ret;

        assert(size != 0);
        assert((size & chunksize_mask) == 0);

#ifdef MALLOC_DSS
        if (opt_dss) {
                ret = chunk_recycle_dss(size, zero);
                if (ret != NULL) {
                        goto RETURN;
                }

                ret = chunk_alloc_dss(size);
                if (ret != NULL)
                        goto RETURN;
        }

        if (opt_mmap)
#endif
        {
                ret = chunk_alloc_mmap(size);
                if (ret != NULL)
                        goto RETURN;
        }

        /* All strategies for allocation failed. */
        ret = NULL;
RETURN:
#ifdef MALLOC_STATS
        if (ret != NULL) {
                stats_chunks.nchunks += (size / chunksize);
                stats_chunks.curchunks += (size / chunksize);
        }
        if (stats_chunks.curchunks > stats_chunks.highchunks)
                stats_chunks.highchunks = stats_chunks.curchunks;
#endif

        assert(CHUNK_ADDR2BASE(ret) == ret);
        return (ret);
}

#ifdef MALLOC_DSS
static extent_node_t *
chunk_dealloc_dss_record(void *chunk, size_t size)
{
        extent_node_t *node, *prev, key;

        key.addr = (void *)((uintptr_t)chunk + size);
        node = RB_NFIND(extent_tree_ad_s, &dss_chunks_ad, &key);
        /* Try to coalesce forward. */
        if (node != NULL && node->addr == key.addr) {
                /*
                 * Coalesce chunk with the following address range.  This does
                 * not change the position within dss_chunks_ad, so only
                 * remove/insert from/into dss_chunks_szad.
                 */
                RB_REMOVE(extent_tree_szad_s, &dss_chunks_szad, node);
                node->addr = chunk;
                node->size += size;
                RB_INSERT(extent_tree_szad_s, &dss_chunks_szad, node);
        } else {
                /*
                 * Coalescing forward failed, so insert a new node.  Drop
                 * dss_mtx during node allocation, since it is possible that a
                 * new base chunk will be allocated.
                 */
                malloc_mutex_unlock(&dss_mtx);
                node = base_node_alloc();
                malloc_mutex_lock(&dss_mtx);
                if (node == NULL)
                        return (NULL);
                node->addr = chunk;
                node->size = size;
                RB_INSERT(extent_tree_ad_s, &dss_chunks_ad, node);
                RB_INSERT(extent_tree_szad_s, &dss_chunks_szad, node);
        }

        /* Try to coalesce backward. */
        prev = RB_PREV(extent_tree_ad_s, &dss_chunks_ad, node);
        if (prev != NULL && (void *)((uintptr_t)prev->addr + prev->size) ==
            chunk) {
                /*
                 * Coalesce chunk with the previous address range.  This does
                 * not change the position within dss_chunks_ad, so only
                 * remove/insert node from/into dss_chunks_szad.
                 */
                RB_REMOVE(extent_tree_szad_s, &dss_chunks_szad, prev);
                RB_REMOVE(extent_tree_ad_s, &dss_chunks_ad, prev);

                RB_REMOVE(extent_tree_szad_s, &dss_chunks_szad, node);
                node->addr = prev->addr;
                node->size += prev->size;
                RB_INSERT(extent_tree_szad_s, &dss_chunks_szad, node);

                base_node_dealloc(prev);
        }

        return (node);
}

static bool
chunk_dealloc_dss(void *chunk, size_t size)
{

        malloc_mutex_lock(&dss_mtx);
        if ((uintptr_t)chunk >= (uintptr_t)dss_base
            && (uintptr_t)chunk < (uintptr_t)dss_max) {
                extent_node_t *node;

                /* Try to coalesce with other unused chunks. */
                node = chunk_dealloc_dss_record(chunk, size);
                if (node != NULL) {
                        chunk = node->addr;
                        size = node->size;
                }

                /* Get the current end of the DSS. */
                dss_max = sbrk(0);

                /*
                 * Try to shrink the DSS if this chunk is at the end of the
                 * DSS.  The sbrk() call here is subject to a race condition
                 * with threads that use brk(2) or sbrk(2) directly, but the
                 * alternative would be to leak memory for the sake of poorly
                 * designed multi-threaded programs.
                 */
                if ((void *)((uintptr_t)chunk + size) == dss_max
                    && (dss_prev = sbrk(-(intptr_t)size)) == dss_max) {
                        /* Success. */
                        dss_max = (void *)((intptr_t)dss_prev - (intptr_t)size);

                        if (node != NULL) {
                                RB_REMOVE(extent_tree_szad_s, &dss_chunks_szad,
                                    node);
                                RB_REMOVE(extent_tree_ad_s, &dss_chunks_ad,
                                    node);
                                base_node_dealloc(node);
                        }
                        malloc_mutex_unlock(&dss_mtx);
                } else {
                        malloc_mutex_unlock(&dss_mtx);
#ifdef WIN32
                        VirtualAlloc(chunk, size, MEM_RESET, PAGE_READWRITE);
#elif (defined(DARWIN))
                        mmap(chunk, size, PROT_READ | PROT_WRITE, MAP_PRIVATE
                            | MAP_ANON | MAP_FIXED, -1, 0);
#else
                        madvise(chunk, size, MADV_FREE);
#endif
                }

                return (false);
        }
        malloc_mutex_unlock(&dss_mtx);

        return (true);
}
#endif

static void
chunk_dealloc_mmap(void *chunk, size_t size)
{

        pages_unmap(chunk, size);
}

static void
chunk_dealloc(void *chunk, size_t size)
{

        assert(chunk != NULL);
        assert(CHUNK_ADDR2BASE(chunk) == chunk);
        assert(size != 0);
        assert((size & chunksize_mask) == 0);

#ifdef MALLOC_STATS
        stats_chunks.curchunks -= (size / chunksize);
#endif

#ifdef MALLOC_DSS
        if (opt_dss) {
                if (chunk_dealloc_dss(chunk, size) == false)
                        return;
        }

        if (opt_mmap)
#endif
                chunk_dealloc_mmap(chunk, size);
}

/*
 * End chunk management functions.
 */
/******************************************************************************/
/*
 * Begin arena.
 */

/*
 * Choose an arena based on a per-thread value (fast-path code, calls slow-path
 * code if necessary).
 */
static inline arena_t *
choose_arena(void)
{
        arena_t *ret;

        /*
         * We can only use TLS if this is a PIC library, since for the static
         * library version, libc's malloc is used by TLS allocation, which
         * introduces a bootstrapping issue.
         */
#ifndef NO_TLS
        if (g_isthreaded == false) {
            /* Avoid the overhead of TLS for single-threaded operation. */
            return (arenas[0]);
        }

#  ifdef WIN32
        ret = TlsGetValue(tlsIndex);
#  else
        ret = arenas_map;
#  endif

        if (ret == NULL) {
                ret = choose_arena_hard();
                assert(ret != NULL);
        }
#else
        if (g_isthreaded && narenas > 1) {
                unsigned long ind;

                /*
                 * Hash _pthread_self() to one of the arenas.  There is a prime
                 * number of arenas, so this has a reasonable chance of
                 * working.  Even so, the hashing can be easily thwarted by
                 * inconvenient _pthread_self() values.  Without specific
                 * knowledge of how _pthread_self() calculates values, we can't
                 * easily do much better than this.
                 */
                ind = (unsigned long) _pthread_self() % narenas;

                /*
                 * Optimistially assume that arenas[ind] has been initialized.
                 * At worst, we find out that some other thread has already
                 * done so, after acquiring the lock in preparation.  Note that
                 * this lazy locking also has the effect of lazily forcing
                 * cache coherency; without the lock acquisition, there's no
                 * guarantee that modification of arenas[ind] by another thread
                 * would be seen on this CPU for an arbitrary amount of time.
                 *
                 * In general, this approach to modifying a synchronized value
                 * isn't a good idea, but in this case we only ever modify the
                 * value once, so things work out well.
                 */
                ret = arenas[ind];
                if (ret == NULL) {
                        /*
                         * Avoid races with another thread that may have already
                         * initialized arenas[ind].
                         */
                        malloc_spin_lock(&arenas_lock);
                        if (arenas[ind] == NULL)
                                ret = arenas_extend((unsigned)ind);
                        else
                                ret = arenas[ind];
                        malloc_spin_unlock(&arenas_lock);
                }
        } else
                ret = arenas[0];
#endif

        assert(ret != NULL);
        return (ret);
}

#ifndef NO_TLS
/*
 * Choose an arena based on a per-thread value (slow-path code only, called
 * only by choose_arena()).
 */
static arena_t *
choose_arena_hard(void)
{
        arena_t *ret;

        assert(g_isthreaded);

#ifdef MALLOC_LAZY_FREE
        /*
         * Seed the PRNG used for lazy deallocation.  Since seeding only occurs
         * on the first allocation by a thread, it is possible for a thread to
         * deallocate before seeding.  This is not a critical issue though,
         * since it is extremely unusual for an application to to use threads
         * that deallocate but *never* allocate, and because even if seeding
         * never occurs for multiple threads, they will tend to drift apart
         * unless some aspect of the application forces deallocation
         * synchronization.
         */
        SPRN(lazy_free, (uint32_t)(uintptr_t)(_pthread_self()));
#endif

#ifdef MALLOC_BALANCE
        /*
         * Seed the PRNG used for arena load balancing.  We can get away with
         * using the same seed here as for the lazy_free PRNG without
         * introducing autocorrelation because the PRNG parameters are
         * distinct.
         */
        SPRN(balance, (uint32_t)(uintptr_t)(_pthread_self()));
#endif

        if (narenas > 1) {
#ifdef MALLOC_BALANCE
                unsigned ind;

                ind = PRN(balance, narenas_2pow);
                if ((ret = arenas[ind]) == NULL) {
                        malloc_spin_lock(&arenas_lock);
                        if ((ret = arenas[ind]) == NULL)
                                ret = arenas_extend(ind);
                        malloc_spin_unlock(&arenas_lock);
                }
#else
                malloc_spin_lock(&arenas_lock);
                if ((ret = arenas[next_arena]) == NULL)
                        ret = arenas_extend(next_arena);
                next_arena = (next_arena + 1) % narenas;
                malloc_spin_unlock(&arenas_lock);
#endif
        } else
                ret = arenas[0];

#ifdef WIN32
        TlsSetValue(tlsIndex, ret);
#else
        arenas_map = ret;
#endif

        return (ret);
}
#endif

static inline int
arena_chunk_comp(arena_chunk_t *a, arena_chunk_t *b)
{
        uintptr_t a_chunk = (uintptr_t)a;
        uintptr_t b_chunk = (uintptr_t)b;

        assert(a != NULL);
        assert(b != NULL);

        return ((a_chunk > b_chunk) - (a_chunk < b_chunk));
}

/* Generate red-black tree code for arena chunks. */
RB_GENERATE_STATIC(arena_chunk_tree_s, arena_chunk_s, link, arena_chunk_comp)

static inline int
arena_run_comp(arena_run_t *a, arena_run_t *b)
{
        uintptr_t a_run = (uintptr_t)a;
        uintptr_t b_run = (uintptr_t)b;

        assert(a != NULL);
        assert(b != NULL);

        return ((a_run > b_run) - (a_run < b_run));
}

/* Generate red-black tree code for arena runs. */
RB_GENERATE_STATIC(arena_run_tree_s, arena_run_s, link, arena_run_comp)

static extent_node_t *
arena_chunk_node_alloc(arena_chunk_t *chunk)
{
        extent_node_t *ret;

        ret = RB_MIN(extent_tree_ad_s, &chunk->nodes);
        if (ret != NULL)
                RB_REMOVE(extent_tree_ad_s, &chunk->nodes, ret);
        else {
                ret = chunk->nodes_past;
                chunk->nodes_past = (extent_node_t *)
                    ((uintptr_t)chunk->nodes_past + sizeof(extent_node_t));
                assert((uintptr_t)ret + sizeof(extent_node_t) <=
                    (uintptr_t)chunk + (arena_chunk_header_npages <<
                    pagesize_2pow));
        }

        return (ret);
}

static void
arena_chunk_node_dealloc(arena_chunk_t *chunk, extent_node_t *node)
{

        node->addr = (void *)node;
        RB_INSERT(extent_tree_ad_s, &chunk->nodes, node);
}

static inline void *
arena_run_reg_alloc(arena_run_t *run, arena_bin_t *bin)
{
        void *ret;
        unsigned i, mask, bit, regind;

        assert(run->magic == ARENA_RUN_MAGIC);
        assert(run->regs_minelm < bin->regs_mask_nelms);

        /*
         * Move the first check outside the loop, so that run->regs_minelm can
         * be updated unconditionally, without the possibility of updating it
         * multiple times.
         */
        i = run->regs_minelm;
        mask = run->regs_mask[i];
        if (mask != 0) {
                /* Usable allocation found. */
                bit = ffs((int)mask) - 1;

                regind = ((i << (SIZEOF_INT_2POW + 3)) + bit);
                assert(regind < bin->nregs);
                ret = (void *)(((uintptr_t)run) + bin->reg0_offset
                    + (bin->reg_size * regind));

                /* Clear bit. */
                mask ^= (1U << bit);
                run->regs_mask[i] = mask;

                return (ret);
        }

        for (i++; i < bin->regs_mask_nelms; i++) {
                mask = run->regs_mask[i];
                if (mask != 0) {
                        /* Usable allocation found. */
                        bit = ffs((int)mask) - 1;

                        regind = ((i << (SIZEOF_INT_2POW + 3)) + bit);
                        assert(regind < bin->nregs);
                        ret = (void *)(((uintptr_t)run) + bin->reg0_offset
                            + (bin->reg_size * regind));

                        /* Clear bit. */
                        mask ^= (1U << bit);
                        run->regs_mask[i] = mask;

                        /*
                         * Make a note that nothing before this element
                         * contains a free region.
                         */
                        run->regs_minelm = i; /* Low payoff: + (mask == 0); */

                        return (ret);
                }
        }
        /* Not reached. */
        assert(0);
        return (NULL);
}

static inline void
arena_run_reg_dalloc(arena_run_t *run, arena_bin_t *bin, void *ptr, size_t size)
{
        /*
         * To divide by a number D that is not a power of two we multiply
         * by (2^21 / D) and then right shift by 21 positions.
         *
         *   X / D
         *
         * becomes
         *
         *   (X * size_invs[(D >> QUANTUM_2POW_MIN) - 3]) >> SIZE_INV_SHIFT
         */
#define SIZE_INV_SHIFT 21
#define SIZE_INV(s) (((1U << SIZE_INV_SHIFT) / (s << QUANTUM_2POW_MIN)) + 1)
        static const unsigned size_invs[] = {
            SIZE_INV(3),
            SIZE_INV(4), SIZE_INV(5), SIZE_INV(6), SIZE_INV(7),
            SIZE_INV(8), SIZE_INV(9), SIZE_INV(10), SIZE_INV(11),
            SIZE_INV(12),SIZE_INV(13), SIZE_INV(14), SIZE_INV(15),
            SIZE_INV(16),SIZE_INV(17), SIZE_INV(18), SIZE_INV(19),
            SIZE_INV(20),SIZE_INV(21), SIZE_INV(22), SIZE_INV(23),
            SIZE_INV(24),SIZE_INV(25), SIZE_INV(26), SIZE_INV(27),
            SIZE_INV(28),SIZE_INV(29), SIZE_INV(30), SIZE_INV(31)
#if (QUANTUM_2POW_MIN < 4)
            ,
            SIZE_INV(32), SIZE_INV(33), SIZE_INV(34), SIZE_INV(35),
            SIZE_INV(36), SIZE_INV(37), SIZE_INV(38), SIZE_INV(39),
            SIZE_INV(40), SIZE_INV(41), SIZE_INV(42), SIZE_INV(43),
            SIZE_INV(44), SIZE_INV(45), SIZE_INV(46), SIZE_INV(47),
            SIZE_INV(48), SIZE_INV(49), SIZE_INV(50), SIZE_INV(51),
            SIZE_INV(52), SIZE_INV(53), SIZE_INV(54), SIZE_INV(55),
            SIZE_INV(56), SIZE_INV(57), SIZE_INV(58), SIZE_INV(59),
            SIZE_INV(60), SIZE_INV(61), SIZE_INV(62), SIZE_INV(63)
#endif
        };
        unsigned diff, regind, elm, bit;

        assert(run->magic == ARENA_RUN_MAGIC);
        assert(((sizeof(size_invs)) / sizeof(unsigned)) + 3
            >= (SMALL_MAX_DEFAULT >> QUANTUM_2POW_MIN));

        /*
         * Avoid doing division with a variable divisor if possible.  Using
         * actual division here can reduce allocator throughput by over 20%!
         */
        diff = (unsigned)((uintptr_t)ptr - (uintptr_t)run - bin->reg0_offset);
        if ((size & (size - 1)) == 0) {
                /*
                 * log2_table allows fast division of a power of two in the
                 * [1..128] range.
                 *
                 * (x / divisor) becomes (x >> log2_table[divisor - 1]).
                 */
                static const unsigned char log2_table[] = {
                    0, 1, 0, 2, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 4,
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5,
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6,
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 7
                };

                if (size <= 128)
                        regind = (diff >> log2_table[size - 1]);
                else if (size <= 32768)
                        regind = diff >> (8 + log2_table[(size >> 8) - 1]);
                else {
                        /*
                         * The run size is too large for us to use the lookup
                         * table.  Use real division.
                         */
                        regind = diff / size;
                }
        } else if (size <= ((sizeof(size_invs) / sizeof(unsigned))
            << QUANTUM_2POW_MIN) + 2) {
                regind = size_invs[(size >> QUANTUM_2POW_MIN) - 3] * diff;
                regind >>= SIZE_INV_SHIFT;
        } else {
                /*
                 * size_invs isn't large enough to handle this size class, so
                 * calculate regind using actual division.  This only happens
                 * if the user increases small_max via the 'S' runtime
                 * configuration option.
                 */
                regind = diff / size;
        };
        assert(diff == regind * size);
        assert(regind < bin->nregs);

        elm = regind >> (SIZEOF_INT_2POW + 3);
        if (elm < run->regs_minelm)
                run->regs_minelm = elm;
        bit = regind - (elm << (SIZEOF_INT_2POW + 3));
        assert((run->regs_mask[elm] & (1U << bit)) == 0);
        run->regs_mask[elm] |= (1U << bit);
#undef SIZE_INV
#undef SIZE_INV_SHIFT
}

static void
arena_run_split(arena_t *arena, arena_run_t *run, size_t size, bool small,
    bool zero)
{
        arena_chunk_t *chunk;
        size_t run_ind, total_pages, need_pages, rem_pages, i;
        extent_node_t *nodeA, *nodeB, key;

        /* Insert a node into runs_alloced_ad for the first part of the run. */
        chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(run);
        nodeA = arena_chunk_node_alloc(chunk);
        nodeA->addr = run;
        nodeA->size = size;
        RB_INSERT(extent_tree_ad_s, &arena->runs_alloced_ad, nodeA);

        key.addr = run;
        nodeB = RB_FIND(extent_tree_ad_s, &arena->runs_avail_ad, &key);
        assert(nodeB != NULL);

        run_ind = (unsigned)(((uintptr_t)run - (uintptr_t)chunk)
            >> pagesize_2pow);
        total_pages = nodeB->size >> pagesize_2pow;
        need_pages = (size >> pagesize_2pow);
        assert(need_pages > 0);
        assert(need_pages <= total_pages);
        assert(need_pages <= CHUNK_MAP_POS_MASK || small == false);
        rem_pages = total_pages - need_pages;

        for (i = 0; i < need_pages; i++) {
#ifdef MALLOC_DECOMMIT
                /*
                 * Commit decommitted pages if necessary.  If a decommitted
                 * page is encountered, commit all needed adjacent decommitted
                 * pages in one operation, in order to reduce system call
                 * overhead.
                 */
                if (chunk->map[run_ind + i] & CHUNK_MAP_DECOMMITTED) {
                        size_t j;

                        /*
                         * Advance i+j to just past the index of the last page
                         * to commit.  Clear CHUNK_MAP_DECOMMITTED along the
                         * way.
                         */
                        for (j = 0; i + j < need_pages && (chunk->map[run_ind +
                            i + j] & CHUNK_MAP_DECOMMITTED); j++) {
                                chunk->map[run_ind + i + j] ^=
                                    CHUNK_MAP_DECOMMITTED;
                        }

                        pages_commit((void *)((uintptr_t)chunk + ((run_ind + i)
                            << pagesize_2pow)), (j << pagesize_2pow));
#  ifdef MALLOC_STATS
                        arena->stats.ncommit++;
#  endif
                }
#endif

                /* Zero if necessary. */
                if (zero) {
                        if ((chunk->map[run_ind + i] & CHUNK_MAP_UNTOUCHED)
                            == 0) {
                                memset((void *)((uintptr_t)chunk + ((run_ind
                                    + i) << pagesize_2pow)), 0, pagesize);
                                /* CHUNK_MAP_UNTOUCHED is cleared below. */
                        }
                }

                /* Update dirty page accounting. */
                if (chunk->map[run_ind + i] & CHUNK_MAP_DIRTY) {
                        chunk->ndirty--;
                        arena->ndirty--;
                }

                /* Initialize the chunk map. */
                if (small)
                        chunk->map[run_ind + i] = (uint8_t)i;
                else
                        chunk->map[run_ind + i] = CHUNK_MAP_LARGE;
        }

        /* Keep track of trailing unused pages for later use. */
        RB_REMOVE(extent_tree_szad_s, &arena->runs_avail_szad, nodeB);
        if (rem_pages > 0) {
                /*
                 * Update nodeB in runs_avail_*.  Its position within
                 * runs_avail_ad does not change.
                 */
                nodeB->addr = (void *)((uintptr_t)nodeB->addr + size);
                nodeB->size -= size;
                RB_INSERT(extent_tree_szad_s, &arena->runs_avail_szad, nodeB);
        } else {
                /* Remove nodeB from runs_avail_*. */
                RB_REMOVE(extent_tree_ad_s, &arena->runs_avail_ad, nodeB);
                arena_chunk_node_dealloc(chunk, nodeB);
        }

        chunk->pages_used += need_pages;
}

static arena_chunk_t *
arena_chunk_alloc(arena_t *arena)
{
        arena_chunk_t *chunk;
        extent_node_t *node;

        if (arena->spare != NULL) {
                chunk = arena->spare;
                arena->spare = NULL;
        } else {
                chunk = (arena_chunk_t *)chunk_alloc(chunksize, true);
                if (chunk == NULL)
                        return (NULL);
#ifdef MALLOC_STATS
                arena->stats.mapped += chunksize;
#endif

                chunk->arena = arena;

                RB_INSERT(arena_chunk_tree_s, &arena->chunks, chunk);

                /*
                 * Claim that no pages are in use, since the header is merely
                 * overhead.
                 */
                chunk->pages_used = 0;
                chunk->ndirty = 0;

                /*
                 * Initialize the map to contain one maximal free untouched
                 * run.
                 */
                memset(chunk->map, (CHUNK_MAP_LARGE | CHUNK_MAP_POS_MASK),
                    arena_chunk_header_npages);
                memset(&chunk->map[arena_chunk_header_npages],
                    (CHUNK_MAP_UNTOUCHED
#ifdef MALLOC_DECOMMIT
                    | CHUNK_MAP_DECOMMITTED
#endif
                    ), (chunk_npages -
                    arena_chunk_header_npages));

                /* Initialize the tree of unused extent nodes. */
                RB_INIT(&chunk->nodes);
                chunk->nodes_past = (extent_node_t *)QUANTUM_CEILING(
                    (uintptr_t)&chunk->map[chunk_npages]);

#ifdef MALLOC_DECOMMIT
                /*
                 * Start out decommitted, in order to force a closer
                 * correspondence between dirty pages and committed untouched
                 * pages.
                 */
                pages_decommit((void *)((uintptr_t)chunk +
                    (arena_chunk_header_npages << pagesize_2pow)),
                    ((chunk_npages - arena_chunk_header_npages) <<
                    pagesize_2pow));
#  ifdef MALLOC_STATS
                arena->stats.ndecommit++;
                arena->stats.decommitted += (chunk_npages -
                    arena_chunk_header_npages);
#  endif
#endif
        }

        /* Insert the run into the runs_avail_* red-black trees. */
        node = arena_chunk_node_alloc(chunk);
        node->addr = (void *)((uintptr_t)chunk + (arena_chunk_header_npages <<
            pagesize_2pow));
        node->size = chunksize - (arena_chunk_header_npages << pagesize_2pow);
        RB_INSERT(extent_tree_szad_s, &arena->runs_avail_szad, node);
        RB_INSERT(extent_tree_ad_s, &arena->runs_avail_ad, node);

        return (chunk);
}

static void
arena_chunk_dealloc(arena_t *arena, arena_chunk_t *chunk)
{
        extent_node_t *node, key;

        if (arena->spare != NULL) {
                RB_REMOVE(arena_chunk_tree_s, &chunk->arena->chunks,
                    arena->spare);
                arena->ndirty -= arena->spare->ndirty;
                chunk_dealloc((void *)arena->spare, chunksize);
#ifdef MALLOC_STATS
                arena->stats.mapped -= chunksize;
#endif
        }

        /*
         * Remove run from the runs trees, regardless of whether this chunk
         * will be cached, so that the arena does not use it.  Dirty page
         * flushing only uses the chunks tree, so leaving this chunk in that
         * tree is sufficient for that purpose.
         */
        key.addr = (void *)((uintptr_t)chunk + (arena_chunk_header_npages <<
            pagesize_2pow));
        node = RB_FIND(extent_tree_ad_s, &arena->runs_avail_ad, &key);
        assert(node != NULL);
        RB_REMOVE(extent_tree_szad_s, &arena->runs_avail_szad, node);
        RB_REMOVE(extent_tree_ad_s, &arena->runs_avail_ad, node);
        arena_chunk_node_dealloc(chunk, node);

        arena->spare = chunk;
}

static arena_run_t *
arena_run_alloc(arena_t *arena, size_t size, bool small, bool zero)
{
        arena_chunk_t *chunk;
        arena_run_t *run;
        extent_node_t *node, key;

        assert(size <= (chunksize - (arena_chunk_header_npages <<
            pagesize_2pow)));
        assert((size & pagesize_mask) == 0);

        /* Search the arena's chunks for the lowest best fit. */
        key.addr = NULL;
        key.size = size;
        node = RB_NFIND(extent_tree_szad_s, &arena->runs_avail_szad, &key);
        if (node != NULL) {
                run = (arena_run_t *)node->addr;
                arena_run_split(arena, run, size, small, zero);
                return (run);
        }

        /*
         * No usable runs.  Create a new chunk from which to allocate the run.
         */
        chunk = arena_chunk_alloc(arena);
        if (chunk == NULL)
                return (NULL);
        run = (arena_run_t *)((uintptr_t)chunk + (arena_chunk_header_npages <<
            pagesize_2pow));
        /* Update page map. */
        arena_run_split(arena, run, size, small, zero);
        return (run);
}

static void
arena_purge(arena_t *arena)
{
        arena_chunk_t *chunk;
#ifdef MALLOC_DEBUG
        size_t ndirty;

        ndirty = 0;
        RB_FOREACH(chunk, arena_chunk_tree_s, &arena->chunks) {
                ndirty += chunk->ndirty;
        }
        assert(ndirty == arena->ndirty);
#endif
        assert(arena->ndirty > opt_dirty_max);

#ifdef MALLOC_STATS
        arena->stats.npurge++;
#endif

        /*
         * Iterate downward through chunks until enough dirty memory has been
         * purged.
         */
        RB_FOREACH_REVERSE(chunk, arena_chunk_tree_s, &arena->chunks) {
                if (chunk->ndirty > 0) {
                        size_t i;

                        for (i = chunk_npages - 1; i >=
                            arena_chunk_header_npages; i--) {
                                if (chunk->map[i] & CHUNK_MAP_DIRTY) {
                                        size_t npages;

                                        chunk->map[i] = (CHUNK_MAP_LARGE |
#ifdef MALLOC_DECOMMIT
                                            CHUNK_MAP_DECOMMITTED |
#endif
                                            CHUNK_MAP_POS_MASK);
                                        chunk->ndirty--;
                                        arena->ndirty--;
                                        /* Find adjacent dirty run(s). */
                                        for (npages = 1; i >
                                            arena_chunk_header_npages &&
                                            (chunk->map[i - 1] &
                                            CHUNK_MAP_DIRTY); npages++) {
                                                i--;
                                                chunk->map[i] = (CHUNK_MAP_LARGE
#ifdef MALLOC_DECOMMIT
                                                    | CHUNK_MAP_DECOMMITTED
#endif
                                                    | CHUNK_MAP_POS_MASK);
                                                chunk->ndirty--;
                                                arena->ndirty--;
                                        }

#ifdef MALLOC_DECOMMIT
                                        pages_decommit((void *)((uintptr_t)
                                            chunk + (i << pagesize_2pow)),
                                            (npages << pagesize_2pow));
#  ifdef MALLOC_STATS
                                        arena->stats.ndecommit++;
                                        arena->stats.decommitted += npages;
#  endif
#else
                                        madvise((void *)((uintptr_t)chunk + (i
                                            << pagesize_2pow)), pagesize *
                                            npages, MADV_FREE);
#endif
#ifdef MALLOC_STATS
                                        arena->stats.nmadvise++;
                                        arena->stats.purged += npages;
#endif
                                }
                        }
                }
        }
}

static void
arena_run_dalloc(arena_t *arena, arena_run_t *run, bool dirty)
{
        arena_chunk_t *chunk;
        extent_node_t *nodeA, *nodeB, *nodeC, key;
        size_t size, run_ind, run_pages;

        /* Remove run from runs_alloced_ad. */
        key.addr = run;
        nodeB = RB_FIND(extent_tree_ad_s, &arena->runs_alloced_ad, &key);
        assert(nodeB != NULL);
        RB_REMOVE(extent_tree_ad_s, &arena->runs_alloced_ad, nodeB);
        size = nodeB->size;

        chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(run);
        run_ind = (unsigned)(((uintptr_t)run - (uintptr_t)chunk)
            >> pagesize_2pow);
        assert(run_ind >= arena_chunk_header_npages);
        assert(run_ind < (chunksize >> pagesize_2pow));
        run_pages = (size >> pagesize_2pow);

        /* Subtract pages from count of pages used in chunk. */
        chunk->pages_used -= run_pages;

        if (dirty) {
                size_t i;

                for (i = 0; i < run_pages; i++) {
                        assert((chunk->map[run_ind + i] & CHUNK_MAP_DIRTY) ==
                            0);
                        chunk->map[run_ind + i] |= CHUNK_MAP_DIRTY;
                        chunk->ndirty++;
                        arena->ndirty++;
                }
        }
#ifdef MALLOC_DEBUG
        /* Set map elements to a bogus value in order to aid error detection. */
        {
                size_t i;

                for (i = 0; i < run_pages; i++) {
                        chunk->map[run_ind + i] |= (CHUNK_MAP_LARGE |
                            CHUNK_MAP_POS_MASK);
                }
        }
#endif

        /* Try to coalesce forward. */
        key.addr = (void *)((uintptr_t)run + size);
        nodeC = RB_NFIND(extent_tree_ad_s, &arena->runs_avail_ad, &key);
        if (nodeC != NULL && nodeC->addr == key.addr) {
                /*
                 * Coalesce forward.  This does not change the position within
                 * runs_avail_ad, so only remove/insert from/into
                 * runs_avail_szad.
                 */
                RB_REMOVE(extent_tree_szad_s, &arena->runs_avail_szad, nodeC);
                nodeC->addr = (void *)run;
                nodeC->size += size;
                RB_INSERT(extent_tree_szad_s, &arena->runs_avail_szad, nodeC);
                arena_chunk_node_dealloc(chunk, nodeB);
                nodeB = nodeC;
        } else {
                /*
                 * Coalescing forward failed, so insert nodeB into runs_avail_*.
                 */
                RB_INSERT(extent_tree_szad_s, &arena->runs_avail_szad, nodeB);
                RB_INSERT(extent_tree_ad_s, &arena->runs_avail_ad, nodeB);
        }

        /* Try to coalesce backward. */
        nodeA = RB_PREV(extent_tree_ad_s, &arena->runs_avail_ad, nodeB);
        if (nodeA != NULL && (void *)((uintptr_t)nodeA->addr + nodeA->size) ==
            (void *)run) {
                /*
                 * Coalesce with previous run.  This does not change nodeB's
                 * position within runs_avail_ad, so only remove/insert
                 * from/into runs_avail_szad.
                 */
                RB_REMOVE(extent_tree_szad_s, &arena->runs_avail_szad, nodeA);
                RB_REMOVE(extent_tree_ad_s, &arena->runs_avail_ad, nodeA);

                RB_REMOVE(extent_tree_szad_s, &arena->runs_avail_szad, nodeB);
                nodeB->addr = nodeA->addr;
                nodeB->size += nodeA->size;
                RB_INSERT(extent_tree_szad_s, &arena->runs_avail_szad, nodeB);

                arena_chunk_node_dealloc(chunk, nodeA);
        }

        /* Deallocate chunk if it is now completely unused. */
        if (chunk->pages_used == 0)
                arena_chunk_dealloc(arena, chunk);

        /* Enforce opt_dirty_max. */
        if (arena->ndirty > opt_dirty_max)
                arena_purge(arena);
}

static void
arena_run_trim_head(arena_t *arena, arena_chunk_t *chunk, extent_node_t *nodeB,
    arena_run_t *run, size_t oldsize, size_t newsize)
{
        extent_node_t *nodeA;

        assert(nodeB->addr == run);
        assert(nodeB->size == oldsize);
        assert(oldsize > newsize);

        /*
         * Update the run's node in runs_alloced_ad.  Its position does not
         * change.
         */
        nodeB->addr = (void *)((uintptr_t)run + (oldsize - newsize));
        nodeB->size = newsize;

        /*
         * Insert a node into runs_alloced_ad so that arena_run_dalloc() can
         * treat the leading run as separately allocated.
         */
        nodeA = arena_chunk_node_alloc(chunk);
        nodeA->addr = (void *)run;
        nodeA->size = oldsize - newsize;
        RB_INSERT(extent_tree_ad_s, &arena->runs_alloced_ad, nodeA);

        arena_run_dalloc(arena, (arena_run_t *)run, false);
}

static void
arena_run_trim_tail(arena_t *arena, arena_chunk_t *chunk, extent_node_t *nodeA,
    arena_run_t *run, size_t oldsize, size_t newsize, bool dirty)
{
        extent_node_t *nodeB;

        assert(nodeA->addr == run);
        assert(nodeA->size == oldsize);
        assert(oldsize > newsize);

        /*
         * Update the run's node in runs_alloced_ad.  Its position does not
         * change.
         */
        nodeA->size = newsize;

        /*
         * Insert a node into runs_alloced_ad so that arena_run_dalloc() can
         * treat the trailing run as separately allocated.
         */
        nodeB = arena_chunk_node_alloc(chunk);
        nodeB->addr = (void *)((uintptr_t)run + newsize);
        nodeB->size = oldsize - newsize;
        RB_INSERT(extent_tree_ad_s, &arena->runs_alloced_ad, nodeB);

        arena_run_dalloc(arena, (arena_run_t *)((uintptr_t)run + newsize),
            dirty);
}

static arena_run_t *
arena_bin_nonfull_run_get(arena_t *arena, arena_bin_t *bin)
{
        arena_run_t *run;
        unsigned i, remainder;

        /* Look for a usable run. */
        if ((run = RB_MIN(arena_run_tree_s, &bin->runs)) != NULL) {
                /* run is guaranteed to have available space. */
                RB_REMOVE(arena_run_tree_s, &bin->runs, run);
#ifdef MALLOC_STATS
                bin->stats.reruns++;
#endif
                return (run);
        }
        /* No existing runs have any space available. */

        /* Allocate a new run. */
        run = arena_run_alloc(arena, bin->run_size, true, false);
        if (run == NULL)
                return (NULL);

        /* Initialize run internals. */
        run->bin = bin;

        for (i = 0; i < bin->regs_mask_nelms; i++)
                run->regs_mask[i] = UINT_MAX;
        remainder = bin->nregs & ((1U << (SIZEOF_INT_2POW + 3)) - 1);
        if (remainder != 0) {
                /* The last element has spare bits that need to be unset. */
                run->regs_mask[i] = (UINT_MAX >> ((1U << (SIZEOF_INT_2POW + 3))
                    - remainder));
        }

        run->regs_minelm = 0;

        run->nfree = bin->nregs;
#ifdef MALLOC_DEBUG
        run->magic = ARENA_RUN_MAGIC;
#endif

#ifdef MALLOC_STATS
        bin->stats.nruns++;
        bin->stats.curruns++;
        if (bin->stats.curruns > bin->stats.highruns)
                bin->stats.highruns = bin->stats.curruns;
#endif
        return (run);
}

/* bin->runcur must have space available before this function is called. */
static inline void *
arena_bin_malloc_easy(arena_t *arena, arena_bin_t *bin, arena_run_t *run)
{
        void *ret;
        arena = 0;              /* this is just to quiet a compiler warning */

        assert(run->magic == ARENA_RUN_MAGIC);
        assert(run->nfree > 0);

        ret = arena_run_reg_alloc(run, bin);
        assert(ret != NULL);
        run->nfree--;

        return (ret);
}

/* Re-fill bin->runcur, then call arena_bin_malloc_easy(). */
static void *
arena_bin_malloc_hard(arena_t *arena, arena_bin_t *bin)
{

        bin->runcur = arena_bin_nonfull_run_get(arena, bin);
        if (bin->runcur == NULL)
                return (NULL);
        assert(bin->runcur->magic == ARENA_RUN_MAGIC);
        assert(bin->runcur->nfree > 0);

        return (arena_bin_malloc_easy(arena, bin, bin->runcur));
}

/*
 * Calculate bin->run_size such that it meets the following constraints:
 *
 *   *) bin->run_size >= min_run_size
 *   *) bin->run_size <= arena_maxclass
 *   *) bin->run_size <= RUN_MAX_SMALL
 *   *) run header overhead <= RUN_MAX_OVRHD (or header overhead relaxed).
 *
 * bin->nregs, bin->regs_mask_nelms, and bin->reg0_offset are
 * also calculated here, since these settings are all interdependent.
 */
static size_t
arena_bin_run_size_calc(arena_bin_t *bin, size_t min_run_size)
{
        size_t try_run_size, good_run_size;
        unsigned good_nregs, good_mask_nelms, good_reg0_offset;
        unsigned try_nregs, try_mask_nelms, try_reg0_offset;

        assert(min_run_size >= pagesize);
        assert(min_run_size <= arena_maxclass);
        assert(min_run_size <= RUN_MAX_SMALL);

        /*
         * Calculate known-valid settings before entering the run_size
         * expansion loop, so that the first part of the loop always copies
         * valid settings.
         *
         * The do..while loop iteratively reduces the number of regions until
         * the run header and the regions no longer overlap.  A closed formula
         * would be quite messy, since there is an interdependency between the
         * header's mask length and the number of regions.
         */
        try_run_size = min_run_size;
        try_nregs = ((try_run_size - sizeof(arena_run_t)) / bin->reg_size)
            + 1; /* Counter-act try_nregs-- in loop. */
        do {
                try_nregs--;
                try_mask_nelms = (try_nregs >> (SIZEOF_INT_2POW + 3)) +
                    ((try_nregs & ((1U << (SIZEOF_INT_2POW + 3)) - 1)) ? 1 : 0);
                try_reg0_offset = try_run_size - (try_nregs * bin->reg_size);
        } while (sizeof(arena_run_t) + (sizeof(unsigned) * (try_mask_nelms - 1))
            > try_reg0_offset);

        /* run_size expansion loop. */
        do {
                /*
                 * Copy valid settings before trying more aggressive settings.
                 */
                good_run_size = try_run_size;
                good_nregs = try_nregs;
                good_mask_nelms = try_mask_nelms;
                good_reg0_offset = try_reg0_offset;

                /* Try more aggressive settings. */
                try_run_size += pagesize;
                try_nregs = ((try_run_size - sizeof(arena_run_t)) /
                    bin->reg_size) + 1; /* Counter-act try_nregs-- in loop. */
                do {
                        try_nregs--;
                        try_mask_nelms = (try_nregs >> (SIZEOF_INT_2POW + 3)) +
                            ((try_nregs & ((1U << (SIZEOF_INT_2POW + 3)) - 1)) ?
                            1 : 0);
                        try_reg0_offset = try_run_size - (try_nregs *
                            bin->reg_size);
                } while (sizeof(arena_run_t) + (sizeof(unsigned) *
                    (try_mask_nelms - 1)) > try_reg0_offset);
        } while (try_run_size <= arena_maxclass && try_run_size <= RUN_MAX_SMALL
            && RUN_MAX_OVRHD * (bin->reg_size << 3) > RUN_MAX_OVRHD_RELAX
            && (try_reg0_offset << RUN_BFP) > RUN_MAX_OVRHD * try_run_size);

        assert(sizeof(arena_run_t) + (sizeof(unsigned) * (good_mask_nelms - 1))
            <= good_reg0_offset);
        assert((good_mask_nelms << (SIZEOF_INT_2POW + 3)) >= good_nregs);

        /* Copy final settings. */
        bin->run_size = good_run_size;
        bin->nregs = good_nregs;
        bin->regs_mask_nelms = good_mask_nelms;
        bin->reg0_offset = good_reg0_offset;

        return (good_run_size);
}

#ifdef MALLOC_BALANCE
static inline void
arena_lock_balance(arena_t *arena)
{
        unsigned contention;

        contention = malloc_spin_lock(&arena->lock);
        if (narenas > 1) {
                /*
                 * Calculate the exponentially averaged contention for this
                 * arena.  Due to integer math always rounding down, this value
                 * decays somewhat faster then normal.
                 */
                arena->contention = (((uint64_t)arena->contention
                    * (uint64_t)((1U << BALANCE_ALPHA_INV_2POW)-1))
                    + (uint64_t)contention) >> BALANCE_ALPHA_INV_2POW;
                if (arena->contention >= opt_balance_threshold)
                        arena_lock_balance_hard(arena);
        }
}

static void
arena_lock_balance_hard(arena_t *arena)
{
        uint32_t ind;

        arena->contention = 0;
#ifdef MALLOC_STATS
        arena->stats.nbalance++;
#endif
        ind = PRN(balance, narenas_2pow);
        if (arenas[ind] != NULL) {
#ifdef WIN32
                TlsSetValue(tlsIndex, arenas[ind]);
#else
                arenas_map = arenas[ind];
#endif
        } else {
                malloc_spin_lock(&arenas_lock);
                if (arenas[ind] != NULL) {
#ifdef WIN32
                        TlsSetValue(tlsIndex, arenas[ind]);
#else
                        arenas_map = arenas[ind];
#endif
                } else {
#ifdef WIN32
                        TlsSetValue(tlsIndex, arenas_extend(ind));
#else
                        arenas_map = arenas_extend(ind);
#endif
                }
                malloc_spin_unlock(&arenas_lock);
        }
}
#endif

static inline void *
arena_malloc_small(arena_t *arena, size_t size, bool zero)
{
        void *ret;
        arena_bin_t *bin;
        arena_run_t *run;

        if (size < small_min) {
                /* Tiny. */
                size = pow2_ceil(size);
                bin = &arena->bins[ffs((int)(size >> (TINY_MIN_2POW +
                    1)))];
#if (!defined(NDEBUG) || defined(MALLOC_STATS))
                /*
                 * Bin calculation is always correct, but we may need
                 * to fix size for the purposes of assertions and/or
                 * stats accuracy.
                 */
                if (size < (1U << TINY_MIN_2POW))
                        size = (1U << TINY_MIN_2POW);
#endif
        } else if (size <= small_max) {
                /* Quantum-spaced. */
                size = QUANTUM_CEILING(size);
                bin = &arena->bins[ntbins + (size >> opt_quantum_2pow)
                    - 1];
        } else {
                /* Sub-page. */
                size = pow2_ceil(size);
                bin = &arena->bins[ntbins + nqbins
                    + (ffs((int)(size >> opt_small_max_2pow)) - 2)];
        }
        assert(size == bin->reg_size);

#ifdef MALLOC_BALANCE
        arena_lock_balance(arena);
#else
        malloc_spin_lock(&arena->lock);
#endif
        if ((run = bin->runcur) != NULL && run->nfree > 0)
                ret = arena_bin_malloc_easy(arena, bin, run);
        else
                ret = arena_bin_malloc_hard(arena, bin);

        if (ret == NULL) {
                malloc_spin_unlock(&arena->lock);
                return (NULL);
        }

#ifdef MALLOC_STATS
        bin->stats.nrequests++;
        arena->stats.nmalloc_small++;
        arena->stats.allocated_small += size;
#endif
        malloc_spin_unlock(&arena->lock);

        if (zero == false) {
#ifdef MALLOC_FILL
                if (opt_junk)
                        memset(ret, 0xa5, size);
                else if (opt_zero)
                        memset(ret, 0, size);
#endif
        } else
                memset(ret, 0, size);

        return (ret);
}

static void *
arena_malloc_large(arena_t *arena, size_t size, bool zero)
{
        void *ret;

        /* Large allocation. */
        size = PAGE_CEILING(size);
#ifdef MALLOC_BALANCE
        arena_lock_balance(arena);
#else
        malloc_spin_lock(&arena->lock);
#endif
        ret = (void *)arena_run_alloc(arena, size, false, zero);
        if (ret == NULL) {
                malloc_spin_unlock(&arena->lock);
                return (NULL);
        }
#ifdef MALLOC_STATS
        arena->stats.nmalloc_large++;
        arena->stats.allocated_large += size;
#endif
        malloc_spin_unlock(&arena->lock);

        if (zero == false) {
#ifdef MALLOC_FILL
                if (opt_junk)
                        memset(ret, 0xa5, size);
                else if (opt_zero)
                        memset(ret, 0, size);
#endif
        }

        return (ret);
}

static inline void *
arena_malloc(arena_t *arena, size_t size, bool zero)
{

        assert(arena != NULL);
        assert(arena->magic == ARENA_MAGIC);
        assert(size != 0);
        assert(QUANTUM_CEILING(size) <= arena_maxclass);

/* #ifdef USE_STATS_MEMORY */
/*     arena->mi.uordblks += size; */
/* #endif */
        if (size <= bin_maxclass) {
                return (arena_malloc_small(arena, size, zero));
        } else
                return (arena_malloc_large(arena, size, zero));
}

static inline void *
imalloc(size_t size)
{

        assert(size != 0);
        if (size <= arena_maxclass)
                return (arena_malloc(choose_arena(), size, false));
        else
                return (huge_malloc(size, false));
}

static inline void *
icalloc(size_t size)
{
        if (size <= arena_maxclass)
                return (arena_malloc(choose_arena(), size, true));
        else
                return (huge_malloc(size, true));
}

/* Only handles large allocations that require more than page alignment. */
static void *
arena_palloc(arena_t *arena, size_t alignment, size_t size, size_t alloc_size)
{
        void *ret;
        size_t offset;
        arena_chunk_t *chunk;
        extent_node_t *node, key;

        assert((size & pagesize_mask) == 0);
        assert((alignment & pagesize_mask) == 0);

#ifdef MALLOC_BALANCE
        arena_lock_balance(arena);
#else
        malloc_spin_lock(&arena->lock);
#endif
        ret = (void *)arena_run_alloc(arena, alloc_size, false, false);
        if (ret == NULL) {
                malloc_spin_unlock(&arena->lock);
                return (NULL);
        }

        chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(ret);

        offset = (uintptr_t)ret & (alignment - 1);
        assert((offset & pagesize_mask) == 0);
        assert(offset < alloc_size);
        if (offset == 0) {
                /*
                 * Update the run's node in runs_alloced_ad.  Its position
                 * does not change.
                 */
                key.addr = ret;
                node = RB_FIND(extent_tree_ad_s, &arena->runs_alloced_ad, &key);
                assert(node != NULL);

                arena_run_trim_tail(arena, chunk, node, ret, alloc_size, size,
                    false);
        } else {
                size_t leadsize, trailsize;

                /*
                 * Update the run's node in runs_alloced_ad.  Its position
                 * does not change.
                 */
                key.addr = ret;
                node = RB_FIND(extent_tree_ad_s, &arena->runs_alloced_ad, &key);
                assert(node != NULL);

                leadsize = alignment - offset;
                if (leadsize > 0) {
                        arena_run_trim_head(arena, chunk, node, ret, alloc_size,
                            alloc_size - leadsize);
                        ret = (void *)((uintptr_t)ret + leadsize);
                }

                trailsize = alloc_size - leadsize - size;
                if (trailsize != 0) {
                        /* Trim trailing space. */
                        assert(trailsize < alloc_size);
                        arena_run_trim_tail(arena, chunk, node, ret, size +
                            trailsize, size, false);
                }
        }

#ifdef MALLOC_STATS
        arena->stats.nmalloc_large++;
        arena->stats.allocated_large += size;
#endif
        malloc_spin_unlock(&arena->lock);

#ifdef MALLOC_FILL
        if (opt_junk)
                memset(ret, 0xa5, size);
        else if (opt_zero)
                memset(ret, 0, size);
#endif
        return (ret);
}

static inline void *
ipalloc(size_t alignment, size_t size)
{
        void *ret;
        size_t ceil_size;

        /*
         * Round size up to the nearest multiple of alignment.
         *
         * This done, we can take advantage of the fact that for each small
         * size class, every object is aligned at the smallest power of two
         * that is non-zero in the base two representation of the size.  For
         * example:
         *
         *   Size |   Base 2 | Minimum alignment
         *   -----+----------+------------------
         *     96 |  1100000 |  32
         *    144 | 10100000 |  32
         *    192 | 11000000 |  64
         *
         * Depending on runtime settings, it is possible that arena_malloc()
         * will further round up to a power of two, but that never causes
         * correctness issues.
         */
        ceil_size = (size + (alignment - 1)) & (-alignment);
        /*
         * (ceil_size < size) protects against the combination of maximal
         * alignment and size greater than maximal alignment.
         */
        if (ceil_size < size) {
                /* size_t overflow. */
                return (NULL);
        }

        if (ceil_size <= pagesize || (alignment <= pagesize
            && ceil_size <= arena_maxclass))
                ret = arena_malloc(choose_arena(), ceil_size, false);
        else {
                size_t run_size;

                /*
                 * We can't achieve sub-page alignment, so round up alignment
                 * permanently; it makes later calculations simpler.
                 */
                alignment = PAGE_CEILING(alignment);
                ceil_size = PAGE_CEILING(size);
                /*
                 * (ceil_size < size) protects against very large sizes within
                 * pagesize of SIZE_T_MAX.
                 *
                 * (ceil_size + alignment < ceil_size) protects against the
                 * combination of maximal alignment and ceil_size large enough
                 * to cause overflow.  This is similar to the first overflow
                 * check above, but it needs to be repeated due to the new
                 * ceil_size value, which may now be *equal* to maximal
                 * alignment, whereas before we only detected overflow if the
                 * original size was *greater* than maximal alignment.
                 */
                if (ceil_size < size || ceil_size + alignment < ceil_size) {
                        /* size_t overflow. */
                        return (NULL);
                }

                /*
                 * Calculate the size of the over-size run that arena_palloc()
                 * would need to allocate in order to guarantee the alignment.
                 */
                if (ceil_size >= alignment)
                        run_size = ceil_size + alignment - pagesize;
                else {
                        /*
                         * It is possible that (alignment << 1) will cause
                         * overflow, but it doesn't matter because we also
                         * subtract pagesize, which in the case of overflow
                         * leaves us with a very large run_size.  That causes
                         * the first conditional below to fail, which means
                         * that the bogus run_size value never gets used for
                         * anything important.
                         */
                        run_size = (alignment << 1) - pagesize;
                }

                if (run_size <= arena_maxclass) {
                        ret = arena_palloc(choose_arena(), alignment, ceil_size,
                            run_size);
                } else if (alignment <= chunksize)
                        ret = huge_malloc(ceil_size, false);
                else
                        ret = huge_palloc(alignment, ceil_size);
        }

        assert(((uintptr_t)ret & (alignment - 1)) == 0);
        return (ret);
}

/* Return the size of the allocation pointed to by ptr. */
static size_t
arena_salloc(const void *ptr)
{
        size_t ret;
        arena_chunk_t *chunk;
        arena_chunk_map_t mapelm;
        size_t pageind;

        assert(ptr != NULL);
        assert(CHUNK_ADDR2BASE(ptr) != ptr);

        chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(ptr);
        pageind = (((uintptr_t)ptr - (uintptr_t)chunk) >> pagesize_2pow);
        mapelm = chunk->map[pageind];
        if ((mapelm & CHUNK_MAP_LARGE) == 0) {
                arena_run_t *run;

                /* Small allocation size is in the run header. */
                pageind -= (mapelm & CHUNK_MAP_POS_MASK);
                run = (arena_run_t *)((uintptr_t)chunk + (pageind <<
                    pagesize_2pow));
                assert(run->magic == ARENA_RUN_MAGIC);
                ret = run->bin->reg_size;
        } else {
                arena_t *arena = chunk->arena;
                extent_node_t *node, key;

                /* Large allocation size is in the extent tree. */
                assert((mapelm & CHUNK_MAP_POS_MASK) == 0);
                arena = chunk->arena;
                malloc_spin_lock(&arena->lock);
                key.addr = (void *)ptr;
                node = RB_FIND(extent_tree_ad_s, &arena->runs_alloced_ad, &key);
                assert(node != NULL);
                ret = node->size;
                malloc_spin_unlock(&arena->lock);
        }

        return (ret);
}

static inline size_t
isalloc(const void *ptr)
{
        size_t ret;
        arena_chunk_t *chunk;

        assert(ptr != NULL);

        chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(ptr);
        if (chunk != ptr) {
                /* Region. */
                assert(chunk->arena->magic == ARENA_MAGIC);

                ret = arena_salloc(ptr);
        } else {
                extent_node_t *node, key;

                /* Chunk (huge allocation). */

                malloc_mutex_lock(&huge_mtx);

                /* Extract from tree of huge allocations. */
                key.addr = __DECONST(void *, ptr);
                node = RB_FIND(extent_tree_ad_s, &huge, &key);
                assert(node != NULL);

                ret = node->size;

                malloc_mutex_unlock(&huge_mtx);
        }

        return (ret);
}

static inline void
arena_dalloc_small(arena_t *arena, arena_chunk_t *chunk, void *ptr,
    size_t pageind, arena_chunk_map_t mapelm)
{
        arena_run_t *run;
        arena_bin_t *bin;
        size_t size;

        pageind -= (mapelm & CHUNK_MAP_POS_MASK);

        run = (arena_run_t *)((uintptr_t)chunk + (pageind << pagesize_2pow));
        assert(run->magic == ARENA_RUN_MAGIC);
        bin = run->bin;
        size = bin->reg_size;

/* #ifdef USE_STATS_MEMORY */
/*         arena->mi.fordblks += size; */
/* #endif */
#ifdef MALLOC_FILL
        if (opt_junk)
                memset(ptr, 0x5a, size);
#endif

        arena_run_reg_dalloc(run, bin, ptr, size);
        run->nfree++;

        if (run->nfree == bin->nregs) {
                /* Deallocate run. */
                if (run == bin->runcur)
                        bin->runcur = NULL;
                else if (bin->nregs != 1) {
                        /*
                         * This block's conditional is necessary because if the
                         * run only contains one region, then it never gets
                         * inserted into the non-full runs tree.
                         */
                        RB_REMOVE(arena_run_tree_s, &bin->runs, run);
                }
#ifdef MALLOC_DEBUG
                run->magic = 0;
#endif
                arena_run_dalloc(arena, run, true);
#ifdef MALLOC_STATS
                bin->stats.curruns--;
#endif
        } else if (run->nfree == 1 && run != bin->runcur) {
                /*
                 * Make sure that bin->runcur always refers to the lowest
                 * non-full run, if one exists.
                 */
                if (bin->runcur == NULL)
                        bin->runcur = run;
                else if ((uintptr_t)run < (uintptr_t)bin->runcur) {
                        /* Switch runcur. */
                        if (bin->runcur->nfree > 0) {
                                /* Insert runcur. */
                                RB_INSERT(arena_run_tree_s, &bin->runs,
                                    bin->runcur);
                        }
                        bin->runcur = run;
                } else
                        RB_INSERT(arena_run_tree_s, &bin->runs, run);
        }
#ifdef MALLOC_STATS
        arena->stats.allocated_small -= size;
        arena->stats.ndalloc_small++;
#endif
}

#ifdef MALLOC_LAZY_FREE
static inline void
arena_dalloc_lazy(arena_t *arena, arena_chunk_t *chunk, void *ptr,
    size_t pageind, arena_chunk_map_t *mapelm)
{
        void **free_cache = arena->free_cache;
        unsigned i, slot;

        if (g_isthreaded == false || opt_lazy_free_2pow < 0) {
                malloc_spin_lock(&arena->lock);
                arena_dalloc_small(arena, chunk, ptr, pageind, *mapelm);
                malloc_spin_unlock(&arena->lock);
                return;
        }

        for (i = 0; i < LAZY_FREE_NPROBES; i++) {
                slot = PRN(lazy_free, opt_lazy_free_2pow);
                if (atomic_cmpset_ptr((uintptr_t *)&free_cache[slot],
                    (uintptr_t)NULL, (uintptr_t)ptr)) {
                        return;
                }
        }

        arena_dalloc_lazy_hard(arena, chunk, ptr, pageind, mapelm);
}

static void
arena_dalloc_lazy_hard(arena_t *arena, arena_chunk_t *chunk, void *ptr,
    size_t pageind, arena_chunk_map_t *mapelm)
{
        void **free_cache = arena->free_cache;
        unsigned i, slot;

        malloc_spin_lock(&arena->lock);
        arena_dalloc_small(arena, chunk, ptr, pageind, *mapelm);

        /*
         * Check whether another thread already cleared the cache.  It is
         * possible that another thread cleared the cache *and* this slot was
         * already refilled, which could result in a mostly fruitless cache
         * sweep, but such a sequence of events causes no correctness issues.
         */
        if ((ptr = (void *)atomic_readandclear_ptr(
            (uintptr_t *)&free_cache[slot]))
            != NULL) {
                unsigned lazy_free_mask;
                
                /*
                 * Clear the cache, since we failed to find a slot.  It is
                 * possible that other threads will continue to insert objects
                 * into the cache while this one sweeps, but that is okay,
                 * since on average the cache is still swept with the same
                 * frequency.
                 */

                /* Handle pointer at current slot. */
                chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(ptr);
                pageind = (((uintptr_t)ptr - (uintptr_t)chunk) >>
                    pagesize_2pow);
                mapelm = &chunk->map[pageind];
                arena_dalloc_small(arena, chunk, ptr, pageind, *mapelm);

                /* Sweep remainder of slots. */
                lazy_free_mask = (1U << opt_lazy_free_2pow) - 1;
                for (i = (slot + 1) & lazy_free_mask;
                     i != slot;
                     i = (i + 1) & lazy_free_mask) {
                        ptr = (void *)atomic_readandclear_ptr(
                            (uintptr_t *)&free_cache[i]);
                        if (ptr != NULL) {
                                chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(ptr);
                                pageind = (((uintptr_t)ptr - (uintptr_t)chunk)
                                    >> pagesize_2pow);
                                mapelm = &chunk->map[pageind];
                                arena_dalloc_small(arena, chunk, ptr, pageind,
                                    *mapelm);
                        }
                }
        }

        malloc_spin_unlock(&arena->lock);
}
#endif

static void
arena_dalloc_large(arena_t *arena, arena_chunk_t *chunk, void *ptr)
{
        /* Large allocation. */
        malloc_spin_lock(&arena->lock);

        chunk = 0;              /* this is just to quiet a compiler warning */
#ifdef MALLOC_FILL
#ifndef MALLOC_STATS
        if (opt_junk)
#endif
#endif
        {
                extent_node_t *node, key;
                size_t size;

                key.addr = ptr;
                node = RB_FIND(extent_tree_ad_s,
                    &arena->runs_alloced_ad, &key);
                assert(node != NULL);
                size = node->size;
#ifdef MALLOC_FILL
#ifdef MALLOC_STATS
                if (opt_junk)
#endif
                        memset(ptr, 0x5a, size);
#endif
/* #ifdef USE_STATS_MEMORY */
/*         arena->mi.fordblks += size; */
/* #endif */
#ifdef MALLOC_STATS
                arena->stats.allocated_large -= size;
#endif
        }
#ifdef MALLOC_STATS
        arena->stats.ndalloc_large++;
#endif

        arena_run_dalloc(arena, (arena_run_t *)ptr, true);
        malloc_spin_unlock(&arena->lock);
}

static inline void
arena_dalloc(arena_t *arena, arena_chunk_t *chunk, void *ptr)
{
        size_t pageind;
        arena_chunk_map_t *mapelm;

        assert(arena != NULL);
        assert(arena->magic == ARENA_MAGIC);
        assert(chunk->arena == arena);
        assert(ptr != NULL);
        assert(CHUNK_ADDR2BASE(ptr) != ptr);

        pageind = (((uintptr_t)ptr - (uintptr_t)chunk) >> pagesize_2pow);
        mapelm = &chunk->map[pageind];
        if ((*mapelm & CHUNK_MAP_LARGE) == 0) {
                /* Small allocation. */
#ifdef MALLOC_LAZY_FREE
                arena_dalloc_lazy(arena, chunk, ptr, pageind, mapelm);
#else
                malloc_spin_lock(&arena->lock);
                arena_dalloc_small(arena, chunk, ptr, pageind, *mapelm);
                malloc_spin_unlock(&arena->lock);
#endif
        } else {
                assert((*mapelm & CHUNK_MAP_POS_MASK) == 0);
                arena_dalloc_large(arena, chunk, ptr);
        }
}

static inline void
idalloc(void *ptr)
{
        arena_chunk_t *chunk;

        assert(ptr != NULL);

        chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(ptr);
        if (chunk != ptr)
                arena_dalloc(chunk->arena, chunk, ptr);
        else
                huge_dalloc(ptr);
}

static void
arena_ralloc_large_shrink(arena_t *arena, arena_chunk_t *chunk, void *ptr,
    size_t size, size_t oldsize)
{
        extent_node_t *node, key;

        assert(size < oldsize);

        /*
         * Shrink the run, and make trailing pages available for other
         * allocations.
         */
        key.addr = (void *)((uintptr_t)ptr);
#ifdef MALLOC_BALANCE
        arena_lock_balance(arena);
#else
        malloc_spin_lock(&arena->lock);
#endif
        node = RB_FIND(extent_tree_ad_s, &arena->runs_alloced_ad, &key);
        assert(node != NULL);
        arena_run_trim_tail(arena, chunk, node, (arena_run_t *)ptr, oldsize,
            size, true);
#ifdef MALLOC_STATS
        arena->stats.allocated_large -= oldsize - size;
#endif
        malloc_spin_unlock(&arena->lock);
}

static bool
arena_ralloc_large_grow(arena_t *arena, arena_chunk_t *chunk, void *ptr,
    size_t size, size_t oldsize)
{
        extent_node_t *nodeC, key;

        /* Try to extend the run. */
        assert(size > oldsize);
        key.addr = (void *)((uintptr_t)ptr + oldsize);
#ifdef MALLOC_BALANCE
        arena_lock_balance(arena);
#else
        malloc_spin_lock(&arena->lock);
#endif
        nodeC = RB_FIND(extent_tree_ad_s, &arena->runs_avail_ad, &key);
        if (nodeC != NULL && oldsize + nodeC->size >= size) {
                extent_node_t *nodeA, *nodeB;

                /*
                 * The next run is available and sufficiently large.  Split the
                 * following run, then merge the first part with the existing
                 * allocation.  This results in a bit more tree manipulation
                 * than absolutely necessary, but it substantially simplifies
                 * the code.
                 */
                arena_run_split(arena, (arena_run_t *)nodeC->addr, size -
                    oldsize, false, false);

                key.addr = ptr;
                nodeA = RB_FIND(extent_tree_ad_s, &arena->runs_alloced_ad,
                    &key);
                assert(nodeA != NULL);

                key.addr = (void *)((uintptr_t)ptr + oldsize);
                nodeB = RB_FIND(extent_tree_ad_s, &arena->runs_alloced_ad,
                    &key);
                assert(nodeB != NULL);

                nodeA->size += nodeB->size;

                RB_REMOVE(extent_tree_ad_s, &arena->runs_alloced_ad, nodeB);
                arena_chunk_node_dealloc(chunk, nodeB);

#ifdef MALLOC_STATS
                arena->stats.allocated_large += size - oldsize;
#endif
                malloc_spin_unlock(&arena->lock);
                return (false);
        }
        malloc_spin_unlock(&arena->lock);

        return (true);
}

/*
 * Try to resize a large allocation, in order to avoid copying.  This will
 * always fail if growing an object, and the following run is already in use.
 */
static bool
arena_ralloc_large(void *ptr, size_t size, size_t oldsize)
{
        size_t psize;

        psize = PAGE_CEILING(size);
        if (psize == oldsize) {
                /* Same size class. */
#ifdef MALLOC_FILL
                if (opt_junk && size < oldsize) {
                        memset((void *)((uintptr_t)ptr + size), 0x5a, oldsize -
                            size);
                }
#endif
                return (false);
        } else {
                arena_chunk_t *chunk;
                arena_t *arena;

                chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(ptr);
                arena = chunk->arena;
                assert(arena->magic == ARENA_MAGIC);

                if (psize < oldsize) {
#ifdef MALLOC_FILL
                        /* Fill before shrinking in order avoid a race. */
                        if (opt_junk) {
                                memset((void *)((uintptr_t)ptr + size), 0x5a,
                                    oldsize - size);
                        }
#endif
                        arena_ralloc_large_shrink(arena, chunk, ptr, psize,
                            oldsize);
                        return (false);
                } else {
                        bool ret = arena_ralloc_large_grow(arena, chunk, ptr,
                            psize, oldsize);
#ifdef MALLOC_FILL
                        if (ret == false && opt_zero) {
                                memset((void *)((uintptr_t)ptr + oldsize), 0,
                                    size - oldsize);
                        }
#endif
                        return (ret);
                }
        }
}

static void *
arena_ralloc(void *ptr, size_t size, size_t oldsize)
{
        void *ret;
        size_t copysize;

        /* Try to avoid moving the allocation. */
        if (size < small_min) {
                if (oldsize < small_min &&
                    ffs((int)(pow2_ceil(size) >> (TINY_MIN_2POW + 1)))
                    == ffs((int)(pow2_ceil(oldsize) >> (TINY_MIN_2POW + 1))))
                        goto IN_PLACE; /* Same size class. */
        } else if (size <= small_max) {
                if (oldsize >= small_min && oldsize <= small_max &&
                    (QUANTUM_CEILING(size) >> opt_quantum_2pow)
                    == (QUANTUM_CEILING(oldsize) >> opt_quantum_2pow))
                        goto IN_PLACE; /* Same size class. */
        } else if (size <= bin_maxclass) {
                if (oldsize > small_max && oldsize <= bin_maxclass &&
                    pow2_ceil(size) == pow2_ceil(oldsize))
                        goto IN_PLACE; /* Same size class. */
        } else if (oldsize > bin_maxclass && oldsize <= arena_maxclass) {
                assert(size > bin_maxclass);
                if (arena_ralloc_large(ptr, size, oldsize) == false)
                        return (ptr);
        }

        /*
         * If we get here, then size and oldsize are different enough that we
         * need to move the object.  In that case, fall back to allocating new
         * space and copying.
         */
        ret = arena_malloc(choose_arena(), size, false);
        if (ret == NULL)
                return (NULL);

        /* Junk/zero-filling were already done by arena_malloc(). */
        copysize = (size < oldsize) ? size : oldsize;
#ifdef VM_COPY_MIN
        if (copysize >= VM_COPY_MIN)
                pages_copy(ret, ptr, copysize);
        else
#endif
                memcpy(ret, ptr, copysize);
        idalloc(ptr);
        return (ret);
IN_PLACE:
#ifdef MALLOC_FILL
        if (opt_junk && size < oldsize)
                memset((void *)((uintptr_t)ptr + size), 0x5a, oldsize - size);
        else if (opt_zero && size > oldsize)
                memset((void *)((uintptr_t)ptr + oldsize), 0, size - oldsize);
#endif
        return (ptr);
}

static inline void *
iralloc(void *ptr, size_t size)
{
        size_t oldsize;

        assert(ptr != NULL);
        assert(size != 0);

        oldsize = isalloc(ptr);

        if (size <= arena_maxclass)
                return (arena_ralloc(ptr, size, oldsize));
        else
                return (huge_ralloc(ptr, size, oldsize));
}

static bool
arena_new(arena_t *arena)
{
        unsigned i;
        arena_bin_t *bin;
        size_t pow2_size, prev_run_size;

        if (malloc_spin_init(&arena->lock))
                return (true);

#ifdef MALLOC_STATS
        memset(&arena->stats, 0, sizeof(arena_stats_t));
#endif

        /* Initialize chunks. */
        RB_INIT(&arena->chunks);
        arena->spare = NULL;

        arena->ndirty = 0;

        RB_INIT(&arena->runs_avail_szad);
        RB_INIT(&arena->runs_avail_ad);
        RB_INIT(&arena->runs_alloced_ad);

#ifdef MALLOC_BALANCE
        arena->contention = 0;
#endif
#ifdef MALLOC_LAZY_FREE
        if (opt_lazy_free_2pow >= 0) {
                arena->free_cache = (void **) base_calloc(1, sizeof(void *)
                    * (1U << opt_lazy_free_2pow));
                if (arena->free_cache == NULL)
                        return (true);
        } else
                arena->free_cache = NULL;
#endif

        /* Initialize bins. */
        prev_run_size = pagesize;

        /* (2^n)-spaced tiny bins. */
        for (i = 0; i < ntbins; i++) {
                bin = &arena->bins[i];
                bin->runcur = NULL;
                RB_INIT(&bin->runs);

                bin->reg_size = (1U << (TINY_MIN_2POW + i));

                prev_run_size = arena_bin_run_size_calc(bin, prev_run_size);

#ifdef MALLOC_STATS
                memset(&bin->stats, 0, sizeof(malloc_bin_stats_t));
#endif
        }

        /* Quantum-spaced bins. */
        for (; i < ntbins + nqbins; i++) {
                bin = &arena->bins[i];
                bin->runcur = NULL;
                RB_INIT(&bin->runs);

                bin->reg_size = quantum * (i - ntbins + 1);

                pow2_size = pow2_ceil(quantum * (i - ntbins + 1));
                prev_run_size = arena_bin_run_size_calc(bin, prev_run_size);

#ifdef MALLOC_STATS
                memset(&bin->stats, 0, sizeof(malloc_bin_stats_t));
#endif
        }

        /* (2^n)-spaced sub-page bins. */
        for (; i < ntbins + nqbins + nsbins; i++) {
                bin = &arena->bins[i];
                bin->runcur = NULL;
                RB_INIT(&bin->runs);

                bin->reg_size = (small_max << (i - (ntbins + nqbins) + 1));

                prev_run_size = arena_bin_run_size_calc(bin, prev_run_size);

#ifdef MALLOC_STATS
                memset(&bin->stats, 0, sizeof(malloc_bin_stats_t));
#endif
        }

#ifdef MALLOC_DEBUG
        arena->magic = ARENA_MAGIC;
#endif

        return (false);
}

/* Create a new arena and insert it into the arenas array at index ind. */
static arena_t *
arenas_extend(unsigned ind)
{
        arena_t *ret;

        /* Allocate enough space for trailing bins. */
        ret = (arena_t *)base_alloc(sizeof(arena_t)
            + (sizeof(arena_bin_t) * (ntbins + nqbins + nsbins - 1)));
        if (ret != NULL && arena_new(ret) == false) {
                arenas[ind] = ret;
                return (ret);
        }
        /* Only reached if there is an OOM error. */

        /*
         * OOM here is quite inconvenient to propagate, since dealing with it
         * would require a check for failure in the fast path.  Instead, punt
         * by using arenas[0].  In practice, this is an extremely unlikely
         * failure.
         */
        _malloc_message(_getprogname(),
            ": (malloc) Error initializing arena\n", "", "");
        if (opt_abort)
                abort();

        return (arenas[0]);
}

/*
 * End arena.
 */
/******************************************************************************/
/*
 * Begin general internal functions.
 */

static void *
huge_malloc(size_t size, bool zero)
{
        void *ret;
        size_t csize;
        extent_node_t *node;

        /* Allocate one or more contiguous chunks for this request. */

        csize = CHUNK_CEILING(size);
        if (csize == 0) {
                /* size is large enough to cause size_t wrap-around. */
                return (NULL);
        }

        /* Allocate an extent node with which to track the chunk. */
        node = base_node_alloc();
        if (node == NULL)
                return (NULL);

        ret = chunk_alloc(csize, zero);
        if (ret == NULL) {
                base_node_dealloc(node);
                return (NULL);
        }

        /* Insert node into huge. */
        node->addr = ret;
        node->size = csize;

        malloc_mutex_lock(&huge_mtx);
        RB_INSERT(extent_tree_ad_s, &huge, node);
#ifdef MALLOC_STATS
        huge_nmalloc++;
        huge_allocated += csize;
#endif
        malloc_mutex_unlock(&huge_mtx);

#ifdef MALLOC_FILL
        if (zero == false) {
                if (opt_junk)
                        memset(ret, 0xa5, csize);
                else if (opt_zero)
                        memset(ret, 0, csize);
        }
#endif

        return (ret);
}

/* Only handles large allocations that require more than chunk alignment. */
static void *
huge_palloc(size_t alignment, size_t size)
{
        void *ret;
        size_t alloc_size, chunk_size, offset;
        extent_node_t *node;

        /*
         * This allocation requires alignment that is even larger than chunk
         * alignment.  This means that huge_malloc() isn't good enough.
         *
         * Allocate almost twice as many chunks as are demanded by the size or
         * alignment, in order to assure the alignment can be achieved, then
         * unmap leading and trailing chunks.
         */
        assert(alignment >= chunksize);

        chunk_size = CHUNK_CEILING(size);

        if (size >= alignment)
                alloc_size = chunk_size + alignment - chunksize;
        else
                alloc_size = (alignment << 1) - chunksize;

        /* Allocate an extent node with which to track the chunk. */
        node = base_node_alloc();
        if (node == NULL)
                return (NULL);

        ret = chunk_alloc(alloc_size, false);
        if (ret == NULL) {
                base_node_dealloc(node);
                return (NULL);
        }

        offset = (uintptr_t)ret & (alignment - 1);
        assert((offset & chunksize_mask) == 0);
        assert(offset < alloc_size);
        if (offset == 0) {
                /* Trim trailing space. */
                chunk_dealloc((void *)((uintptr_t)ret + chunk_size), alloc_size
                    - chunk_size);
        } else {
                size_t trailsize;

                /* Trim leading space. */
                chunk_dealloc(ret, alignment - offset);

                ret = (void *)((uintptr_t)ret + (alignment - offset));

                trailsize = alloc_size - (alignment - offset) - chunk_size;
                if (trailsize != 0) {
                    /* Trim trailing space. */
                    assert(trailsize < alloc_size);
                    chunk_dealloc((void *)((uintptr_t)ret + chunk_size),
                        trailsize);
                }
        }

        /* Insert node into huge. */
        node->addr = ret;
        node->size = chunk_size;

        malloc_mutex_lock(&huge_mtx);
        RB_INSERT(extent_tree_ad_s, &huge, node);
#ifdef MALLOC_STATS
        huge_nmalloc++;
        huge_allocated += chunk_size;
#endif
        malloc_mutex_unlock(&huge_mtx);

#ifdef MALLOC_FILL
        if (opt_junk)
                memset(ret, 0xa5, chunk_size);
        else if (opt_zero)
                memset(ret, 0, chunk_size);
#endif

        return (ret);
}

static void *
huge_ralloc(void *ptr, size_t size, size_t oldsize)
{
        void *ret;
        size_t copysize;

        /* Avoid moving the allocation if the size class would not change. */
        if (oldsize > arena_maxclass &&
            CHUNK_CEILING(size) == CHUNK_CEILING(oldsize)) {
#ifdef MALLOC_FILL
                if (opt_junk && size < oldsize) {
                        memset((void *)((uintptr_t)ptr + size), 0x5a, oldsize
                            - size);
                } else if (opt_zero && size > oldsize) {
                        memset((void *)((uintptr_t)ptr + oldsize), 0, size
                            - oldsize);
                }
#endif
                return (ptr);
        }

        /*
         * If we get here, then size and oldsize are different enough that we
         * need to use a different size class.  In that case, fall back to
         * allocating new space and copying.
         */
        ret = huge_malloc(size, false);
        if (ret == NULL)
                return (NULL);

        copysize = (size < oldsize) ? size : oldsize;
#ifdef VM_COPY_MIN
        if (copysize >= VM_COPY_MIN)
                pages_copy(ret, ptr, copysize);
        else
#endif
                memcpy(ret, ptr, copysize);
        idalloc(ptr);
        return (ret);
}

static void
huge_dalloc(void *ptr)
{
        extent_node_t *node, key;

        malloc_mutex_lock(&huge_mtx);

        /* Extract from tree of huge allocations. */
        key.addr = ptr;
        node = RB_FIND(extent_tree_ad_s, &huge, &key);
        assert(node != NULL);
        assert(node->addr == ptr);
        RB_REMOVE(extent_tree_ad_s, &huge, node);

#ifdef MALLOC_STATS
        huge_ndalloc++;
        huge_allocated -= node->size;
#endif

        malloc_mutex_unlock(&huge_mtx);

        /* Unmap chunk. */
#ifdef MALLOC_DSS
#ifdef MALLOC_FILL
        if (opt_dss && opt_junk)
                memset(node->addr, 0x5a, node->size);
#endif
#endif
        chunk_dealloc(node->addr, node->size);

        base_node_dealloc(node);
}

#ifdef BSD
static inline unsigned
malloc_ncpus(void)
{
        unsigned ret;
        int mib[2];
        size_t len;

        mib[0] = CTL_HW;
        mib[1] = HW_NCPU;
        len = sizeof(ret);
        if (sysctl(mib, 2, &ret, &len, (void *) 0, 0) == -1) {
                /* Error. */
                return (1);
        }

        return (ret);
}
#elif (defined(LINUX_HOST))
#include <fcntl.h>

static inline unsigned
malloc_ncpus(void)
{
        unsigned ret;
        int fd, nread, column;
        char buf[1];
        static const char matchstr[] = "processor\t:";

        /*
         * sysconf(3) would be the preferred method for determining the number
         * of CPUs, but it uses malloc internally, which causes untennable
         * recursion during malloc initialization.
         */
        fd = open("/proc/cpuinfo", O_RDONLY);
        if (fd == -1)
                return (1); /* Error. */
        /*
         * Count the number of occurrences of matchstr at the beginnings of
         * lines.  This treats hyperthreaded CPUs as multiple processors.
         */
        column = 0;
        ret = 0;
        while (true) {
                nread = read(fd, &buf, sizeof(buf));
                if (nread <= 0)
                        break; /* EOF or error. */

                if (buf[0] == '\n')
                        column = 0;
                else if (column != -1) {
                        if (buf[0] == matchstr[column]) {
                                column++;
                                if (column == sizeof(matchstr) - 1) {
                                        column = -1;
                                        ret++;
                                }
                        } else
                                column = -1;
                }
        }
        if (ret == 0)
                ret = 1; /* Something went wrong in the parser. */
        close(fd);

        return (ret);
}
#elif (defined(DARWIN))
#include <mach/mach_init.h>
#include <mach/mach_host.h>

static inline unsigned
malloc_ncpus(void)
{
        kern_return_t error;
        natural_t n;
        processor_info_array_t pinfo;
        mach_msg_type_number_t pinfocnt;

        error = host_processor_info(mach_host_self(), PROCESSOR_BASIC_INFO,
                                    &n, &pinfo, &pinfocnt);
        if (error != KERN_SUCCESS)
                return (1); /* Error. */
        else
                return (n);
}
#elif (defined(HAVE_KSTAT))
#include <kstat.h>

static inline unsigned
malloc_ncpus(void)
{
        unsigned ret;
        kstat_ctl_t *ctl;
        kstat_t *kstat;
        kstat_named_t *named;
        unsigned i;

        if ((ctl = kstat_open()) == NULL)
                return (1); /* Error. */

        if ((kstat = kstat_lookup(ctl, "unix", -1, "system_misc")) == NULL)
                return (1); /* Error. */

        if (kstat_read(ctl, kstat, NULL) == -1)
                return (1); /* Error. */

        named = KSTAT_NAMED_PTR(kstat);

        for (i = 0; i < kstat->ks_ndata; i++) {
                if (strcmp(named[i].name, "ncpus") == 0) {
                        /* Figure out which one of these to actually use. */
                        switch(named[i].data_type) {
                        case KSTAT_DATA_INT32:
                                ret = named[i].value.i32;
                                break;
                        case KSTAT_DATA_UINT32:
                                ret = named[i].value.ui32;
                                break;
                        case KSTAT_DATA_INT64:
                                ret = named[i].value.i64;
                                break;
                        case KSTAT_DATA_UINT64:
                                ret = named[i].value.ui64;
                                break;
                        default:
                                return (1); /* Error. */
                        }
                }
        }

        kstat_close(ctl); /* Don't bother checking for an error. */

        return (ret);
}
#else
static inline unsigned
malloc_ncpus(void)
{

        /*
         * We lack a way to determine the number of CPUs on this platform, so
         * assume 1 CPU.
         */
        return (1);
}
#endif

static void
malloc_print_stats(void)
{

        if (opt_print_stats) {
                char s[UMAX2S_BUFSIZE];
                _malloc_message("___ Begin malloc statistics ___\n", "", "",
                    "");
                _malloc_message("Assertions ",
#ifdef NDEBUG
                    "disabled",
#else
                    "enabled",
#endif
                    "\n", "");
                _malloc_message("Boolean MALLOC_OPTIONS: ",
                    opt_abort ? "A" : "a", "", "");
#ifdef MALLOC_DSS
                _malloc_message(opt_dss ? "D" : "d", "", "", "");
#endif
#ifdef MALLOC_FILL
                _malloc_message(opt_junk ? "J" : "j", "", "", "");
#endif
#ifdef MALLOC_DSS
                _malloc_message(opt_mmap ? "M" : "m", "", "", "");
#endif
                _malloc_message("P", "", "", "");
#ifdef MALLOC_UTRACE
                _malloc_message(opt_utrace ? "U" : "u", "", "", "");
#endif
#ifdef MALLOC_SYSV
                _malloc_message(opt_sysv ? "V" : "v", "", "", "");
#endif
#ifdef MALLOC_XMALLOC
                _malloc_message(opt_xmalloc ? "X" : "x", "", "", "");
#endif
#ifdef MALLOC_FILL
                _malloc_message(opt_zero ? "Z" : "z", "", "", "");
#endif
                _malloc_message("\n", "", "", "");

                _malloc_message("CPUs: ", umax2s(ncpus, s), "\n", "");
                _malloc_message("Max arenas: ", umax2s(narenas, s), "\n", "");
#ifdef MALLOC_LAZY_FREE
                if (opt_lazy_free_2pow >= 0) {
                        _malloc_message("Lazy free slots: ",
                            umax2s(1U << opt_lazy_free_2pow, s), "\n", "");
                } else
                        _malloc_message("Lazy free slots: 0\n", "", "", "");
#endif
#ifdef MALLOC_BALANCE
                _malloc_message("Arena balance threshold: ",
                    umax2s(opt_balance_threshold, s), "\n", "");
#endif
                _malloc_message("Pointer size: ", umax2s(sizeof(void *), s),
                    "\n", "");
                _malloc_message("Quantum size: ", umax2s(quantum, s), "\n", "");
                _malloc_message("Max small size: ", umax2s(small_max, s), "\n",
                    "");
                _malloc_message("Max dirty pages per arena: ",
                    umax2s(opt_dirty_max, s), "\n", "");

                _malloc_message("Chunk size: ", umax2s(chunksize, s), "", "");
                _malloc_message(" (2^", umax2s(opt_chunk_2pow, s), ")\n", "");

#ifdef MALLOC_STATS
                {
                        size_t allocated, mapped;
#ifdef MALLOC_BALANCE
                        uint64_t nbalance = 0;
#endif
                        unsigned i;
                        arena_t *arena;

                        /* Calculate and print allocated/mapped stats. */

                        /* arenas. */
                        for (i = 0, allocated = 0; i < narenas; i++) {
                                if (arenas[i] != NULL) {
                                        malloc_spin_lock(&arenas[i]->lock);
                                        allocated +=
                                            arenas[i]->stats.allocated_small;
                                        allocated +=
                                            arenas[i]->stats.allocated_large;
#ifdef MALLOC_BALANCE
                                        nbalance += arenas[i]->stats.nbalance;
#endif
                                        malloc_spin_unlock(&arenas[i]->lock);
                                }
                        }

                        /* huge/base. */
                        malloc_mutex_lock(&huge_mtx);
                        allocated += huge_allocated;
                        mapped = stats_chunks.curchunks * chunksize;
                        malloc_mutex_unlock(&huge_mtx);

                        malloc_mutex_lock(&base_mtx);
                        mapped += base_mapped;
                        malloc_mutex_unlock(&base_mtx);

#ifdef WIN32
                        malloc_printf("Allocated: %lu, mapped: %lu\n",
                            allocated, mapped);
#else
                        malloc_printf("Allocated: %zu, mapped: %zu\n",
                            allocated, mapped);
#endif

#ifdef MALLOC_BALANCE
                        malloc_printf("Arena balance reassignments: %llu\n",
                            nbalance);
#endif

                        /* Print chunk stats. */
                        {
                                chunk_stats_t chunks_stats;

                                malloc_mutex_lock(&huge_mtx);
                                chunks_stats = stats_chunks;
                                malloc_mutex_unlock(&huge_mtx);

                                malloc_printf("chunks: nchunks   "
                                    "highchunks    curchunks\n");
                                malloc_printf("  %13llu%13lu%13lu\n",
                                    chunks_stats.nchunks,
                                    chunks_stats.highchunks,
                                    chunks_stats.curchunks);
                        }

                        /* Print chunk stats. */
                        malloc_printf(
                            "huge: nmalloc      ndalloc    allocated\n");
#ifdef WIN32
                        malloc_printf(" %12llu %12llu %12lu\n",
                            huge_nmalloc, huge_ndalloc, huge_allocated);
#else
                        malloc_printf(" %12llu %12llu %12zu\n",
                            huge_nmalloc, huge_ndalloc, huge_allocated);
#endif
                        /* Print stats for each arena. */
                        for (i = 0; i < narenas; i++) {
                                arena = arenas[i];
                                if (arena != NULL) {
                                        malloc_printf(
                                            "\narenas[%u]:\n", i);
                                        malloc_spin_lock(&arena->lock);
                                        stats_print(arena);
                                        malloc_spin_unlock(&arena->lock);
                                }
                        }
                }
#endif /* #ifdef MALLOC_STATS */
                _malloc_message("--- End malloc statistics ---\n", "", "", "");
        }
}

/*
 * FreeBSD's pthreads implementation calls malloc(3), so the malloc
 * implementation has to take pains to avoid infinite recursion during
 * initialization.
 */
#if (defined(WIN32) || defined(DARWIN))
#define malloc_init() false
#else
static inline bool
malloc_init(void)
{
        if (malloc_initialized == false)
                return (malloc_init_hard());

        return (false);
}
#endif

#ifndef WIN32
static
#endif
bool
malloc_init_hard(void)
{
        unsigned i;
        char buf[PATH_MAX + 1];
        const char *opts;
        long result;
#ifndef WIN32
        int linklen;
#endif

#ifndef WIN32
        malloc_mutex_lock(&init_lock);
#endif

        if (malloc_initialized) {
                /*
                 * Another thread initialized the allocator before this one
                 * acquired init_lock.
                 */
#ifndef WIN32
                malloc_mutex_unlock(&init_lock);
#endif
                return (false);
        }

#ifdef WIN32
        /* get a thread local storage index */
        tlsIndex = TlsAlloc();
#endif

        /* Get page size and number of CPUs */
#ifdef WIN32
        {
                SYSTEM_INFO info;

                GetSystemInfo(&info);
                result = info.dwPageSize;

                pagesize = (unsigned) result;

                ncpus = info.dwNumberOfProcessors;
        }
#else
        ncpus = malloc_ncpus();

        result = sysconf(_SC_PAGESIZE);
        assert(result != -1);

        pagesize = (unsigned) result;
#endif

        /*
         * We assume that pagesize is a power of 2 when calculating
         * pagesize_mask and pagesize_2pow.
         */
        assert(((result - 1) & result) == 0);
        pagesize_mask = result - 1;
        pagesize_2pow = ffs((int)result) - 1;

#ifdef MALLOC_LAZY_FREE
                if (ncpus == 1)
                        opt_lazy_free_2pow = -1;
#endif

        for (i = 0; i < 3; i++) {
                unsigned j;

                /* Get runtime configuration. */
                switch (i) {
                case 0:
#ifndef WIN32
                        if ((linklen = readlink("/etc/malloc.conf", buf,
                                                sizeof(buf) - 1)) != -1) {
                                /*
                                 * Use the contents of the "/etc/malloc.conf"
                                 * symbolic link's name.
                                 */
                                buf[linklen] = '\0';
                                opts = buf;
                        } else
#endif
                        {
                                /* No configuration specified. */
                                buf[0] = '\0';
                                opts = buf;
                        }
                        break;
                case 1:
/*                      if (issetugid() == 0 && (opts = */
/*                          getenv("MALLOC_OPTIONS")) != NULL) { */
/*                              /\* */
/*                               * Do nothing; opts is already initialized to */
/*                               * the value of the MALLOC_OPTIONS environment */
/*                               * variable. */
/*                               *\/ */
/*                      } else { */
                                /* No configuration specified. */
                                buf[0] = '\0';
                                opts = buf;
/*                      } */
                        break;
                case 2:
                        if (_malloc_options != NULL) {
                                /*
                                 * Use options that were compiled into the
                                 * program.
                                 */
                                opts = _malloc_options;
                        } else {
                                /* No configuration specified. */
                                buf[0] = '\0';
                                opts = buf;
                        }
                        break;
                default:
                        /* NOTREACHED */
                        buf[0] = '\0';
                        opts = buf;
                        assert(false);
                }

                for (j = 0; opts[j] != '\0'; j++) {
                        unsigned k, nreps;
                        bool nseen;

                        /* Parse repetition count, if any. */
                        for (nreps = 0, nseen = false;; j++, nseen = true) {
                                switch (opts[j]) {
                                        case '0': case '1': case '2': case '3':
                                        case '4': case '5': case '6': case '7':
                                        case '8': case '9':
                                                nreps *= 10;
                                                nreps += opts[j] - '0';
                                                break;
                                        default:
                                                goto MALLOC_OUT;
                                }
                        }
MALLOC_OUT:
                        if (nseen == false)
                                nreps = 1;

                        for (k = 0; k < nreps; k++) {
                                switch (opts[j]) {
                                case 'a':
                                        opt_abort = false;
                                        break;
                                case 'A':
                                        opt_abort = true;
                                        break;
                                case 'b':
#ifdef MALLOC_BALANCE
                                        opt_balance_threshold >>= 1;
#endif
                                        break;
                                case 'B':
#ifdef MALLOC_BALANCE
                                        if (opt_balance_threshold == 0)
                                                opt_balance_threshold = 1;
                                        else if ((opt_balance_threshold << 1)
                                            > opt_balance_threshold)
                                                opt_balance_threshold <<= 1;
#endif
                                        break;
                                case 'd':
#ifdef MALLOC_DSS
                                        opt_dss = false;
#endif
                                        break;
                                case 'D':
#ifdef MALLOC_DSS
                                        opt_dss = true;
#endif
                                        break;
                                case 'f':
                                        opt_dirty_max >>= 1;
                                        break;
                                case 'F':
                                        if (opt_dirty_max == 0)
                                                opt_dirty_max = 1;
                                        else if ((opt_dirty_max << 1) != 0)
                                                opt_dirty_max <<= 1;
                                        break;
#ifdef MALLOC_FILL
                                case 'j':
                                        opt_junk = false;
                                        break;
                                case 'J':
                                        opt_junk = true;
                                        break;
#endif
                                case 'k':
                                        /*
                                         * Chunks always require at least one
                                         * header page, so chunks can never be
                                         * smaller than two pages.
                                         */
                                        if (opt_chunk_2pow > pagesize_2pow + 1)
                                                opt_chunk_2pow--;
                                        break;
                                case 'K':
                                        if (opt_chunk_2pow + 1 <
                                            (sizeof(size_t) << 3))
                                                opt_chunk_2pow++;
                                        break;
                                case 'l':
#ifdef MALLOC_LAZY_FREE
                                        if (opt_lazy_free_2pow >= 0)
                                                opt_lazy_free_2pow--;
#endif
                                        break;
                                case 'L':
#ifdef MALLOC_LAZY_FREE
                                        if (ncpus > 1)
                                                opt_lazy_free_2pow++;
#endif
                                        break;
                                case 'm':
#ifdef MALLOC_DSS
                                        opt_mmap = false;
#endif
                                        break;
                                case 'M':
#ifdef MALLOC_DSS
                                        opt_mmap = true;
#endif
                                        break;
                                case 'n':
                                        opt_narenas_lshift--;
                                        break;
                                case 'N':
                                        opt_narenas_lshift++;
                                        break;
                                case 'p':
                                        opt_print_stats = false;
                                        break;
                                case 'P':
                                        opt_print_stats = true;
                                        break;
                                case 'q':
                                        if (opt_quantum_2pow > QUANTUM_2POW_MIN)
                                                opt_quantum_2pow--;
                                        break;
                                case 'Q':
                                        if (opt_quantum_2pow < pagesize_2pow -
                                            1)
                                                opt_quantum_2pow++;
                                        break;
                                case 's':
                                        if (opt_small_max_2pow >
                                            QUANTUM_2POW_MIN)
                                                opt_small_max_2pow--;
                                        break;
                                case 'S':
                                        if (opt_small_max_2pow < pagesize_2pow
                                            - 1)
                                                opt_small_max_2pow++;
                                        break;
#ifdef MALLOC_UTRACE
                                case 'u':
                                        opt_utrace = false;
                                        break;
                                case 'U':
                                        opt_utrace = true;
                                        break;
#endif
#ifdef MALLOC_SYSV
                                case 'v':
                                        opt_sysv = false;
                                        break;
                                case 'V':
                                        opt_sysv = true;
                                        break;
#endif
#ifdef MALLOC_XMALLOC
                                case 'x':
                                        opt_xmalloc = false;
                                        break;
                                case 'X':
                                        opt_xmalloc = true;
                                        break;
#endif
#ifdef MALLOC_FILL
                                case 'z':
                                        opt_zero = false;
                                        break;
                                case 'Z':
                                        opt_zero = true;
                                        break;
#endif
                                default: {
                                        char cbuf[2];

                                        cbuf[0] = opts[j];
                                        cbuf[1] = '\0';
                                        _malloc_message(_getprogname(),
                                            ": (malloc) Unsupported character "
                                            "in malloc options: '", cbuf,
                                            "'\n");
                                }
                                }
                        }
                }
        }

#ifdef MALLOC_DSS
        /* Make sure that there is some method for acquiring memory. */
        if (opt_dss == false && opt_mmap == false)
                opt_mmap = true;
#endif

        /* Take care to call atexit() only once. */
        if (opt_print_stats) {
#ifndef WIN32
                /* Print statistics at exit. */
                atexit(malloc_print_stats);
#endif
        }

        /* Set variables according to the value of opt_small_max_2pow. */
        if (opt_small_max_2pow < opt_quantum_2pow)
                opt_small_max_2pow = opt_quantum_2pow;
        small_max = (1U << opt_small_max_2pow);

        /* Set bin-related variables. */
        bin_maxclass = (pagesize >> 1);
        assert(opt_quantum_2pow >= TINY_MIN_2POW);
        ntbins = opt_quantum_2pow - TINY_MIN_2POW;
        assert(ntbins <= opt_quantum_2pow);
        nqbins = (small_max >> opt_quantum_2pow);
        nsbins = pagesize_2pow - opt_small_max_2pow - 1;

        /* Set variables according to the value of opt_quantum_2pow. */
        quantum = (1U << opt_quantum_2pow);
        quantum_mask = quantum - 1;
        if (ntbins > 0)
                small_min = (quantum >> 1) + 1;
        else
                small_min = 1;
        assert(small_min <= quantum);

        /* Set variables according to the value of opt_chunk_2pow. */
        chunksize = (1LU << opt_chunk_2pow);
        chunksize_mask = chunksize - 1;
        chunk_npages = (chunksize >> pagesize_2pow);
        {
                size_t header_size;

                /*
                 * Compute the header size such that it is large
                 * enough to contain the page map and enough nodes for the
                 * worst case: one node per non-header page plus one extra for
                 * situations where we briefly have one more node allocated
                 * than we will need.
                 */
                header_size = sizeof(arena_chunk_t) +
                    (sizeof(arena_chunk_map_t) * (chunk_npages - 1)) +
                    (sizeof(extent_node_t) * chunk_npages);
                arena_chunk_header_npages = (header_size >> pagesize_2pow) +
                    ((header_size & pagesize_mask) != 0);
        }
        arena_maxclass = chunksize - (arena_chunk_header_npages <<
            pagesize_2pow);
#ifdef MALLOC_LAZY_FREE
        /*
         * Make sure that allocating the free_cache does not exceed the limits
         * of what base_alloc() can handle.
         */
        while ((sizeof(void *) << opt_lazy_free_2pow) > chunksize)
                opt_lazy_free_2pow--;
#endif

        UTRACE(0, 0, 0);

#ifdef MALLOC_STATS
        memset(&stats_chunks, 0, sizeof(chunk_stats_t));
#endif

        /* Various sanity checks that regard configuration. */
        assert(quantum >= sizeof(void *));
        assert(quantum <= pagesize);
        assert(chunksize >= pagesize);
        assert(quantum * 4 <= chunksize);

        /* Initialize chunks data. */
        malloc_mutex_init(&huge_mtx);
        RB_INIT(&huge);
#ifdef MALLOC_DSS
        malloc_mutex_init(&dss_mtx);
        dss_base = sbrk(0);
        dss_prev = dss_base;
        dss_max = dss_base;
        RB_INIT(&dss_chunks_szad);
        RB_INIT(&dss_chunks_ad);
#endif
#ifdef MALLOC_STATS
        huge_nmalloc = 0;
        huge_ndalloc = 0;
        huge_allocated = 0;
#endif

        /* Initialize base allocation data structures. */
#ifdef MALLOC_STATS
        base_mapped = 0;
#endif
#ifdef MALLOC_DSS
        /*
         * Allocate a base chunk here, since it doesn't actually have to be
         * chunk-aligned.  Doing this before allocating any other chunks allows
         * the use of space that would otherwise be wasted.
         */
        if (opt_dss)
                base_pages_alloc(0);
#endif
        base_nodes = NULL;
        malloc_mutex_init(&base_mtx);

        if (ncpus > 1) {
                /*
                 * For SMP systems, create four times as many arenas as there
                 * are CPUs by default.
                 */
                opt_narenas_lshift += 2;
        }

        /* Determine how many arenas to use. */
        narenas = ncpus;
        if (opt_narenas_lshift > 0) {
                if ((narenas << opt_narenas_lshift) > narenas)
                        narenas <<= opt_narenas_lshift;
                /*
                 * Make sure not to exceed the limits of what base_alloc() can
                 * handle.
                 */
                if (narenas * sizeof(arena_t *) > chunksize)
                        narenas = chunksize / sizeof(arena_t *);
        } else if (opt_narenas_lshift < 0) {
                if ((narenas >> -opt_narenas_lshift) < narenas)
                        narenas >>= -opt_narenas_lshift;
                /* Make sure there is at least one arena. */
                if (narenas == 0)
                        narenas = 1;
        }
#ifdef MALLOC_BALANCE
        assert(narenas != 0);
        for (narenas_2pow = 0;
             (narenas >> (narenas_2pow + 1)) != 0;
             narenas_2pow++);
#endif

#ifdef NO_TLS
        if (narenas > 1) {
                static const unsigned primes[] = {1, 3, 5, 7, 11, 13, 17, 19,
                    23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83,
                    89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149,
                    151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211,
                    223, 227, 229, 233, 239, 241, 251, 257, 263};
                unsigned nprimes, parenas;

                /*
                 * Pick a prime number of hash arenas that is more than narenas
                 * so that direct hashing of pthread_self() pointers tends to
                 * spread allocations evenly among the arenas.
                 */
                assert((narenas & 1) == 0); /* narenas must be even. */
                nprimes = (sizeof(primes) >> SIZEOF_INT_2POW);
                parenas = primes[nprimes - 1]; /* In case not enough primes. */
                for (i = 1; i < nprimes; i++) {
                        if (primes[i] > narenas) {
                                parenas = primes[i];
                                break;
                        }
                }
                narenas = parenas;
        }
#endif

#ifndef NO_TLS
#  ifndef MALLOC_BALANCE
        next_arena = 0;
#  endif
#endif

        /* Allocate and initialize arenas. */
        arenas = (arena_t **)base_alloc(sizeof(arena_t *) * narenas);
        if (arenas == NULL) {
#ifndef WIN32
                malloc_mutex_unlock(&init_lock);
#endif
                return (true);
        }
        /*
         * Zero the array.  In practice, this should always be pre-zeroed,
         * since it was just mmap()ed, but let's be sure.
         */
        memset(arenas, 0, sizeof(arena_t *) * narenas);

        /*
         * Initialize one arena here.  The rest are lazily created in
         * choose_arena_hard().
         */
        arenas_extend(0);
        if (arenas[0] == NULL) {
#ifndef WIN32
                malloc_mutex_unlock(&init_lock);
#endif
                return (true);
        }
#ifndef NO_TLS
        /*
         * Assign the initial arena to the initial thread, in order to avoid
         * spurious creation of an extra arena if the application switches to
         * threaded mode.
         */
#ifdef WIN32
        TlsSetValue(tlsIndex, arenas[0]);
#else
        arenas_map = arenas[0];
#endif
#endif

        /*
         * Seed here for the initial thread, since choose_arena_hard() is only
         * called for other threads.  The seed values don't really matter.
         */
#ifdef MALLOC_LAZY_FREE
        SPRN(lazy_free, 42);
#endif
#ifdef MALLOC_BALANCE
        SPRN(balance, 42);
#endif

        malloc_spin_init(&arenas_lock);

        malloc_initialized = true;
#ifndef WIN32
        malloc_mutex_unlock(&init_lock);
#endif
        return (false);
}

/* XXX Why not just expose malloc_print_stats()? */
#ifdef WIN32
void
malloc_shutdown()
{

        malloc_print_stats();
}
#endif

/*
 * End general internal functions.
 */
/******************************************************************************/
/*
 * Begin malloc(3)-compatible functions.
 */

DSOEXPORT
#ifdef DARWIN
inline void *
moz_malloc(size_t size)
#else
void *
malloc(size_t size)
#endif
{
        void *ret;

        if (malloc_init()) {
                ret = NULL;
                goto RETURN;
        }

        if (size == 0) {
#ifdef MALLOC_SYSV
                if (opt_sysv == false)
#endif
                        size = 1;
#ifdef MALLOC_SYSV
                else {
                        ret = NULL;
                        goto RETURN;
                }
#endif
        }

        ret = imalloc(size);

RETURN:
        if (ret == NULL) {
#ifdef MALLOC_XMALLOC
                if (opt_xmalloc) {
                        _malloc_message(_getprogname(),
                            ": (malloc) Error in malloc(): out of memory\n", "",
                            "");
                        abort();
                }
#endif
                errno = ENOMEM;
        }

        UTRACE(0, size, ret);
        return (ret);
}

DSOEXPORT
#ifdef DARWIN
inline int
moz_posix_memalign(void **memptr, size_t alignment, size_t size)
#else
int
posix_memalign(void **memptr, size_t alignment, size_t size)
#endif
{
        int ret;
        void *result;

        if (malloc_init())
                result = NULL;
        else {
                /* Make sure that alignment is a large enough power of 2. */
                if (((alignment - 1) & alignment) != 0
                    || alignment < sizeof(void *)) {
#ifdef MALLOC_XMALLOC
                        if (opt_xmalloc) {
                                _malloc_message(_getprogname(),
                                    ": (malloc) Error in posix_memalign(): "
                                    "invalid alignment\n", "", "");
                                abort();
                        }
#endif
                        result = NULL;
                        ret = EINVAL;
                        goto RETURN;
                }

                result = ipalloc(alignment, size);
        }

        if (result == NULL) {
#ifdef MALLOC_XMALLOC
                if (opt_xmalloc) {
                        _malloc_message(_getprogname(),
                        ": (malloc) Error in posix_memalign(): out of memory\n",
                        "", "");
                        abort();
                }
#endif
                ret = ENOMEM;
                goto RETURN;
        }

        *memptr = result;
        ret = 0;

RETURN:
        UTRACE(0, size, result);
        return (ret);
}

DSOEXPORT
#ifdef DARWIN
inline void *
moz_memalign(size_t alignment, size_t size)
#else
void *
memalign(size_t alignment, size_t size)
#endif
{
        void *ret;

#ifdef DARWIN
        if (moz_posix_memalign(&ret, alignment, size) != 0)
#else
        if (posix_memalign(&ret, alignment, size) != 0)
#endif
                return (NULL);

        return ret;
}

DSOEXPORT
#ifdef DARWIN
inline void *
moz_valloc(size_t size)
#else
void *
valloc(size_t size)
#endif
{
#ifdef DARWIN
        return (moz_memalign(pagesize, size));
#else
        return (memalign(pagesize, size));
#endif
}

DSOEXPORT
#ifdef DARWIN
inline void *
moz_calloc(size_t num, size_t size)
#else
void *
calloc(size_t num, size_t size)
#endif
{
        void *ret;
        size_t num_size;

        if (malloc_init()) {
                num_size = 0;
                ret = NULL;
                goto RETURN;
        }

        num_size = num * size;
        if (num_size == 0) {
#ifdef MALLOC_SYSV
                if ((opt_sysv == false) && ((num == 0) || (size == 0)))
#endif
                        num_size = 1;
#ifdef MALLOC_SYSV
                else {
                        ret = NULL;
                        goto RETURN;
                }
#endif
        /*
         * Try to avoid division here.  We know that it isn't possible to
         * overflow during multiplication if neither operand uses any of the
         * most significant half of the bits in a size_t.
         */
        } else if (((num | size) & (SIZE_T_MAX << (sizeof(size_t) << 2)))
            && (num_size / size != num)) {
                /* size_t overflow. */
                ret = NULL;
                goto RETURN;
        }

        ret = icalloc(num_size);

RETURN:
        if (ret == NULL) {
#ifdef MALLOC_XMALLOC
                if (opt_xmalloc) {
                        _malloc_message(_getprogname(),
                            ": (malloc) Error in calloc(): out of memory\n", "",
                            "");
                        abort();
                }
#endif
                errno = ENOMEM;
        }

        UTRACE(0, num_size, ret);
        return (ret);
}

DSOEXPORT
#ifdef DARWIN
inline void *
moz_realloc(void *ptr, size_t size)
#else
void *
realloc(void *ptr, size_t size)
#endif
{
        void *ret;

        if (size == 0) {
#ifdef MALLOC_SYSV
                if (opt_sysv == false)
#endif
                        size = 1;
#ifdef MALLOC_SYSV
                else {
                        if (ptr != NULL)
                                idalloc(ptr);
                        ret = NULL;
                        goto RETURN;
                }
#endif
        }

        if (ptr != NULL) {
                assert(malloc_initialized);

                ret = iralloc(ptr, size);

                if (ret == NULL) {
#ifdef MALLOC_XMALLOC
                        if (opt_xmalloc) {
                                _malloc_message(_getprogname(),
                                    ": (malloc) Error in realloc(): out of "
                                    "memory\n", "", "");
                                abort();
                        }
#endif
                        errno = ENOMEM;
                }
        } else {
                if (malloc_init())
                        ret = NULL;
                else
                        ret = imalloc(size);

                if (ret == NULL) {
#ifdef MALLOC_XMALLOC
                        if (opt_xmalloc) {
                                _malloc_message(_getprogname(),
                                    ": (malloc) Error in realloc(): out of "
                                    "memory\n", "", "");
                                abort();
                        }
#endif
                        errno = ENOMEM;
                }
        }

#ifdef MALLOC_SYSV
RETURN:
#endif
        UTRACE(ptr, size, ret);
        return (ret);
}

DSOEXPORT
#ifdef DARWIN
inline void
moz_free(void *ptr)
#else
void
free(void *ptr)
#endif
{

        UTRACE(ptr, 0, 0);
        if (ptr != NULL) {
                assert(malloc_initialized);

                idalloc(ptr);
        }
}

/*
 * This is a work in progress, which doesn't even get used.
 */
#ifdef USE_STATS_MEMORY
/* Utility to update mallinfo for malloc_stats() and mallinfo() */

static void
malloc_update_mallinfo(arena_t *arena, struct mallinfo *mi)
{
  int i, navail;
  size_t avail;
  avail = chunksize * narenas;

#if 0
  malloc_printf("allocated:   %u %u %u\n",
                arena->stats.allocated_small + arena->stats.allocated_large,
                arena->stats.nmalloc_small + arena->stats.nmalloc_large,
                arena->stats.ndalloc_small + arena->stats.ndalloc_large);
  
  malloc_printf("available:   %u\n", avail);
#endif
  
/*   stats_print(arena); */
  malloc_spin_lock(&arena->lock);

  /* clear unused fields */
  mi->arena = mi->ordblks = mi->smblks = mi->usmblks = mi->fsmblks = 0;
  mi->uordblks = arena->stats.allocated_small + arena->stats.allocated_large;
  mi->fordblks = arena->stats.mapped - mi->uordblks;
  
  mi->hblks = mi->hblkhd = 0;
  mi->keepcost = arena->stats.mapped;
  malloc_spin_unlock(&arena->lock);
}

#ifndef DARWIN
DSOEXPORT
struct mallinfo
mallinfo()
{
    struct mallinfo mi;

    /* Calculate and print allocated/mapped stats. */
    malloc_update_mallinfo(choose_arena(), &mi);
    return mi;
}
# endif
#endif

/*
 * End malloc(3)-compatible functions.
 */
/******************************************************************************/
/*
 * Begin non-standard functions.
 */

DSOEXPORT
#ifdef DARWIN
inline size_t
moz_malloc_usable_size(const void *ptr)
#else
size_t
malloc_usable_size(const void *ptr)
#endif
{

        assert(ptr != NULL);

        return (isalloc(ptr));
}

#ifdef WIN32
void*
_recalloc(void *ptr, size_t count, size_t size)
{
        size_t oldsize = (ptr != NULL) ? isalloc(ptr) : 0;
        size_t newsize = count * size;

        /*
         * In order for all trailing bytes to be zeroed, the caller needs to
         * use calloc(), followed by recalloc().  However, the current calloc()
         * implementation only zeros the bytes requested, so if recalloc() is
         * to work 100% correctly, calloc() will need to change to zero
         * trailing bytes.
         */

        ptr = realloc(ptr, newsize);
        if (ptr != NULL && oldsize < newsize) {
                memset((void *)((uintptr_t)ptr + oldsize), 0, newsize -
                    oldsize);
        }

        return ptr;
}

/*
 * This impl of _expand doesn't ever actually expand or shrink blocks: it
 * simply replies that you may continue using a shrunk block.
 */
void*
_expand(void *ptr, size_t newsize)
{
        if (isalloc(ptr) >= newsize)
                return ptr;

        return NULL;
}

size_t
_msize(const void *ptr)
{

        return malloc_usable_size(ptr);
}
#endif


/*
 * End non-standard functions.
 */
/******************************************************************************/
/*
 * Begin library-private functions, used by threading libraries for protection
 * of malloc during fork().  These functions are only called if the program is
 * running in threaded mode, so there is no need to check whether the program
 * is threaded here.
 */

void
_malloc_prefork(void)
{
        unsigned i;

        /* Acquire all mutexes in a safe order. */

        malloc_spin_lock(&arenas_lock);
        for (i = 0; i < narenas; i++) {
                if (arenas[i] != NULL)
                        malloc_spin_lock(&arenas[i]->lock);
        }
        malloc_spin_unlock(&arenas_lock);

        malloc_mutex_lock(&base_mtx);

        malloc_mutex_lock(&huge_mtx);

#ifdef MALLOC_DSS
        malloc_mutex_lock(&dss_mtx);
#endif
}

void
_malloc_postfork(void)
{
        unsigned i;

        /* Release all mutexes, now that fork() has completed. */

#ifdef MALLOC_DSS
        malloc_mutex_unlock(&dss_mtx);
#endif

        malloc_mutex_unlock(&huge_mtx);

        malloc_mutex_unlock(&base_mtx);

        malloc_spin_lock(&arenas_lock);
        for (i = 0; i < narenas; i++) {
                if (arenas[i] != NULL)
                        malloc_spin_unlock(&arenas[i]->lock);
        }
        malloc_spin_unlock(&arenas_lock);
}

/*
 * End library-private functions.
 */
/******************************************************************************/


#ifdef DARWIN
static malloc_zone_t zone;
static struct malloc_introspection_t zone_introspect;

static size_t
zone_size(malloc_zone_t *zone, void *ptr)
{
        size_t ret = 0;
        arena_chunk_t *chunk;

        /*
         * There appear to be places within Darwin (such as setenv(3)) that
         * cause calls to this function with pointers that *no* zone owns.  If
         * we knew that all pointers were owned by *some* zone, we could split
         * our zone into two parts, and use one as the default allocator and
         * the other as the default deallocator/reallocator.  Since that will
         * not work in practice, we must check all pointers to assure that they
         * reside within a mapped chunk before determining size.
         */

        chunk = (arena_chunk_t *)CHUNK_ADDR2BASE(ptr);
        if (chunk != ptr) {
                arena_t *arena;
                unsigned i;
                arena_t *arenas_snapshot[narenas];

                /*
                 * Make a copy of the arenas vector while holding arenas_lock in
                 * order to assure that all elements are up to date in this
                 * processor's cache.  Do this outside the following loop in
                 * order to reduce lock acquisitions.
                 */
                malloc_spin_lock(&arenas_lock);
                memcpy(&arenas_snapshot, arenas, sizeof(arena_t *) * narenas);
                malloc_spin_unlock(&arenas_lock);

                /* Region. */
                for (i = 0; i < narenas; i++) {
                        arena = arenas_snapshot[i];

                        if (arena != NULL) {
                                bool own;

                                /* Make sure ptr is within a chunk. */
                                malloc_spin_lock(&arena->lock);
                                if (RB_FIND(arena_chunk_tree_s, &arena->chunks,
                                    chunk) == chunk)
                                        own = true;
                                else
                                        own = false;
                                malloc_spin_unlock(&arena->lock);

                                if (own) {
                                        ret = arena_salloc(ptr);
                                        goto RETURN;
                                }
                        }
                }
        } else {
                extent_node_t *node;
                extent_node_t key;

                /* Chunk. */
                key.addr = (void *)chunk;
                malloc_mutex_lock(&huge_mtx);
                node = RB_FIND(extent_tree_ad_s, &huge, &key);
                if (node != NULL)
                        ret = node->size;
                else
                        ret = 0;
                malloc_mutex_unlock(&huge_mtx);
        }

RETURN:
        return (ret);
}

static void *
zone_malloc(malloc_zone_t *zone, size_t size)
{

        return (moz_malloc(size));
}

static void *
zone_calloc(malloc_zone_t *zone, size_t num, size_t size)
{

        return (moz_calloc(num, size));
}

static void *
zone_valloc(malloc_zone_t *zone, size_t size)
{
        void *ret = NULL; /* Assignment avoids useless compiler warning. */

        moz_posix_memalign(&ret, pagesize, size);

        return (ret);
}

static void
zone_free(malloc_zone_t *zone, void *ptr)
{

        moz_free(ptr);
}

static void *
zone_realloc(malloc_zone_t *zone, void *ptr, size_t size)
{

        return (moz_realloc(ptr, size));
}

static void *
zone_destroy(malloc_zone_t *zone)
{

        /* This function should never be called. */
        assert(false);
        return (NULL);
}

static size_t
zone_good_size(malloc_zone_t *zone, size_t size)
{
        size_t ret;
        void *p;

        /*
         * Actually create an object of the appropriate size, then find out
         * how large it could have been without moving up to the next size
         * class.
         */
        p = moz_malloc(size);
        if (p != NULL) {
                ret = isalloc(p);
                moz_free(p);
        } else
                ret = size;

        return (ret);
}

static void
zone_force_lock(malloc_zone_t *zone)
{

        _malloc_prefork();
}

static void
zone_force_unlock(malloc_zone_t *zone)
{

        _malloc_postfork();
}

static malloc_zone_t *
create_zone(void)
{

        assert(malloc_initialized);

        zone.size = (void *)zone_size;
        zone.malloc = (void *)zone_malloc;
        zone.calloc = (void *)zone_calloc;
        zone.valloc = (void *)zone_valloc;
        zone.free = (void *)zone_free;
        zone.realloc = (void *)zone_realloc;
        zone.destroy = (void *)zone_destroy;
        zone.zone_name = "jemalloc_zone";
        zone.batch_malloc = NULL;
        zone.batch_free = NULL;
        zone.introspect = &zone_introspect;

        zone_introspect.enumerator = NULL;
        zone_introspect.good_size = (void *)zone_good_size;
        zone_introspect.check = NULL;
        zone_introspect.print = NULL;
        zone_introspect.log = NULL;
        zone_introspect.force_lock = (void *)zone_force_lock;
        zone_introspect.force_unlock = (void *)zone_force_unlock;
        zone_introspect.statistics = NULL;

        return (&zone);
}

__attribute__((constructor))
void
jemalloc_darwin_init(void)
{
        extern unsigned malloc_num_zones;
        extern malloc_zone_t **malloc_zones;

        if (malloc_init_hard())
                abort();

        /*
         * The following code is *not* thread-safe, so it's critical that
         * initialization be manually triggered.
         */

        /* Register the custom zones. */
        malloc_zone_register(create_zone());
        assert(malloc_zones[malloc_num_zones - 1] == &zone);

        /*
         * Shift malloc_zones around so that zone is first, which makes it the
         * default zone.
         */
        assert(malloc_num_zones > 1);
        memmove(&malloc_zones[1], &malloc_zones[0],
                sizeof(malloc_zone_t *) * (malloc_num_zones - 1));
        malloc_zones[0] = &zone;
}
#endif