Updated to fedora-glibc-20051020T0651
[glibc.git] / malloc / arena.c
blobabbca1f02e7b62795a01ab4a74f41910220cfa03
1 /* Malloc implementation for multiple threads without lock contention.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Wolfram Gloger <wg@malloc.de>, 2001.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public License as
8 published by the Free Software Foundation; either version 2.1 of the
9 License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; see the file COPYING.LIB. If not,
18 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
21 /* $Id$ */
23 #include <stdbool.h>
25 /* Compile-time constants. */
27 #define HEAP_MIN_SIZE (32*1024)
28 #ifndef HEAP_MAX_SIZE
29 #define HEAP_MAX_SIZE (1024*1024) /* must be a power of two */
30 #endif
32 /* HEAP_MIN_SIZE and HEAP_MAX_SIZE limit the size of mmap()ed heaps
33 that are dynamically created for multi-threaded programs. The
34 maximum size must be a power of two, for fast determination of
35 which heap belongs to a chunk. It should be much larger than the
36 mmap threshold, so that requests with a size just below that
37 threshold can be fulfilled without creating too many heaps. */
40 #ifndef THREAD_STATS
41 #define THREAD_STATS 0
42 #endif
44 /* If THREAD_STATS is non-zero, some statistics on mutex locking are
45 computed. */
47 /***************************************************************************/
49 #define top(ar_ptr) ((ar_ptr)->top)
51 /* A heap is a single contiguous memory region holding (coalesceable)
52 malloc_chunks. It is allocated with mmap() and always starts at an
53 address aligned to HEAP_MAX_SIZE. Not used unless compiling with
54 USE_ARENAS. */
56 typedef struct _heap_info {
57 mstate ar_ptr; /* Arena for this heap. */
58 struct _heap_info *prev; /* Previous heap. */
59 size_t size; /* Current size in bytes. */
60 size_t pad; /* Make sure the following data is properly aligned. */
61 } heap_info;
63 /* Thread specific data */
65 static tsd_key_t arena_key;
66 static mutex_t list_lock;
68 #if THREAD_STATS
69 static int stat_n_heaps;
70 #define THREAD_STAT(x) x
71 #else
72 #define THREAD_STAT(x) do ; while(0)
73 #endif
75 /* Mapped memory in non-main arenas (reliable only for NO_THREADS). */
76 static unsigned long arena_mem;
78 /* Already initialized? */
79 int __malloc_initialized = -1;
81 /**************************************************************************/
83 #if USE_ARENAS
85 /* arena_get() acquires an arena and locks the corresponding mutex.
86 First, try the one last locked successfully by this thread. (This
87 is the common case and handled with a macro for speed.) Then, loop
88 once over the circularly linked list of arenas. If no arena is
89 readily available, create a new one. In this latter case, `size'
90 is just a hint as to how much memory will be required immediately
91 in the new arena. */
93 #define arena_get(ptr, size) do { \
94 Void_t *vptr = NULL; \
95 ptr = (mstate)tsd_getspecific(arena_key, vptr); \
96 if(ptr && !mutex_trylock(&ptr->mutex)) { \
97 THREAD_STAT(++(ptr->stat_lock_direct)); \
98 } else \
99 ptr = arena_get2(ptr, (size)); \
100 } while(0)
102 /* find the heap and corresponding arena for a given ptr */
104 #define heap_for_ptr(ptr) \
105 ((heap_info *)((unsigned long)(ptr) & ~(HEAP_MAX_SIZE-1)))
106 #define arena_for_chunk(ptr) \
107 (chunk_non_main_arena(ptr) ? heap_for_ptr(ptr)->ar_ptr : &main_arena)
109 #else /* !USE_ARENAS */
111 /* There is only one arena, main_arena. */
113 #if THREAD_STATS
114 #define arena_get(ar_ptr, sz) do { \
115 ar_ptr = &main_arena; \
116 if(!mutex_trylock(&ar_ptr->mutex)) \
117 ++(ar_ptr->stat_lock_direct); \
118 else { \
119 (void)mutex_lock(&ar_ptr->mutex); \
120 ++(ar_ptr->stat_lock_wait); \
122 } while(0)
123 #else
124 #define arena_get(ar_ptr, sz) do { \
125 ar_ptr = &main_arena; \
126 (void)mutex_lock(&ar_ptr->mutex); \
127 } while(0)
128 #endif
129 #define arena_for_chunk(ptr) (&main_arena)
131 #endif /* USE_ARENAS */
133 /**************************************************************************/
135 #ifndef NO_THREADS
137 /* atfork support. */
139 static __malloc_ptr_t (*save_malloc_hook) (size_t __size,
140 __const __malloc_ptr_t);
141 # if !defined _LIBC || !defined USE_TLS || (defined SHARED && !USE___THREAD)
142 static __malloc_ptr_t (*save_memalign_hook) (size_t __align, size_t __size,
143 __const __malloc_ptr_t);
144 # endif
145 static void (*save_free_hook) (__malloc_ptr_t __ptr,
146 __const __malloc_ptr_t);
147 static Void_t* save_arena;
149 /* Magic value for the thread-specific arena pointer when
150 malloc_atfork() is in use. */
152 #define ATFORK_ARENA_PTR ((Void_t*)-1)
154 /* The following hooks are used while the `atfork' handling mechanism
155 is active. */
157 static Void_t*
158 malloc_atfork(size_t sz, const Void_t *caller)
160 Void_t *vptr = NULL;
161 Void_t *victim;
163 tsd_getspecific(arena_key, vptr);
164 if(vptr == ATFORK_ARENA_PTR) {
165 /* We are the only thread that may allocate at all. */
166 if(save_malloc_hook != malloc_check) {
167 return _int_malloc(&main_arena, sz);
168 } else {
169 if(top_check()<0)
170 return 0;
171 victim = _int_malloc(&main_arena, sz+1);
172 return mem2mem_check(victim, sz);
174 } else {
175 /* Suspend the thread until the `atfork' handlers have completed.
176 By that time, the hooks will have been reset as well, so that
177 mALLOc() can be used again. */
178 (void)mutex_lock(&list_lock);
179 (void)mutex_unlock(&list_lock);
180 return public_mALLOc(sz);
184 static void
185 free_atfork(Void_t* mem, const Void_t *caller)
187 Void_t *vptr = NULL;
188 mstate ar_ptr;
189 mchunkptr p; /* chunk corresponding to mem */
191 if (mem == 0) /* free(0) has no effect */
192 return;
194 p = mem2chunk(mem); /* do not bother to replicate free_check here */
196 #if HAVE_MMAP
197 if (chunk_is_mmapped(p)) /* release mmapped memory. */
199 munmap_chunk(p);
200 return;
202 #endif
204 ar_ptr = arena_for_chunk(p);
205 tsd_getspecific(arena_key, vptr);
206 if(vptr != ATFORK_ARENA_PTR)
207 (void)mutex_lock(&ar_ptr->mutex);
208 _int_free(ar_ptr, mem);
209 if(vptr != ATFORK_ARENA_PTR)
210 (void)mutex_unlock(&ar_ptr->mutex);
214 /* Counter for number of times the list is locked by the same thread. */
215 static unsigned int atfork_recursive_cntr;
217 /* The following two functions are registered via thread_atfork() to
218 make sure that the mutexes remain in a consistent state in the
219 fork()ed version of a thread. Also adapt the malloc and free hooks
220 temporarily, because the `atfork' handler mechanism may use
221 malloc/free internally (e.g. in LinuxThreads). */
223 static void
224 ptmalloc_lock_all (void)
226 mstate ar_ptr;
228 if(__malloc_initialized < 1)
229 return;
230 if (mutex_trylock(&list_lock))
232 Void_t *my_arena;
233 tsd_getspecific(arena_key, my_arena);
234 if (my_arena == ATFORK_ARENA_PTR)
235 /* This is the same thread which already locks the global list.
236 Just bump the counter. */
237 goto out;
239 /* This thread has to wait its turn. */
240 (void)mutex_lock(&list_lock);
242 for(ar_ptr = &main_arena;;) {
243 (void)mutex_lock(&ar_ptr->mutex);
244 ar_ptr = ar_ptr->next;
245 if(ar_ptr == &main_arena) break;
247 save_malloc_hook = __malloc_hook;
248 save_free_hook = __free_hook;
249 __malloc_hook = malloc_atfork;
250 __free_hook = free_atfork;
251 /* Only the current thread may perform malloc/free calls now. */
252 tsd_getspecific(arena_key, save_arena);
253 tsd_setspecific(arena_key, ATFORK_ARENA_PTR);
254 out:
255 ++atfork_recursive_cntr;
258 static void
259 ptmalloc_unlock_all (void)
261 mstate ar_ptr;
263 if(__malloc_initialized < 1)
264 return;
265 if (--atfork_recursive_cntr != 0)
266 return;
267 tsd_setspecific(arena_key, save_arena);
268 __malloc_hook = save_malloc_hook;
269 __free_hook = save_free_hook;
270 for(ar_ptr = &main_arena;;) {
271 (void)mutex_unlock(&ar_ptr->mutex);
272 ar_ptr = ar_ptr->next;
273 if(ar_ptr == &main_arena) break;
275 (void)mutex_unlock(&list_lock);
278 #ifdef __linux__
280 /* In NPTL, unlocking a mutex in the child process after a
281 fork() is currently unsafe, whereas re-initializing it is safe and
282 does not leak resources. Therefore, a special atfork handler is
283 installed for the child. */
285 static void
286 ptmalloc_unlock_all2 (void)
288 mstate ar_ptr;
290 if(__malloc_initialized < 1)
291 return;
292 #if defined _LIBC || defined MALLOC_HOOKS
293 tsd_setspecific(arena_key, save_arena);
294 __malloc_hook = save_malloc_hook;
295 __free_hook = save_free_hook;
296 #endif
297 for(ar_ptr = &main_arena;;) {
298 mutex_init(&ar_ptr->mutex);
299 ar_ptr = ar_ptr->next;
300 if(ar_ptr == &main_arena) break;
302 mutex_init(&list_lock);
303 atfork_recursive_cntr = 0;
306 #else
308 #define ptmalloc_unlock_all2 ptmalloc_unlock_all
310 #endif
312 #endif /* !defined NO_THREADS */
314 /* Initialization routine. */
315 #ifdef _LIBC
316 #include <string.h>
317 extern char **_environ;
319 static char *
320 internal_function
321 next_env_entry (char ***position)
323 char **current = *position;
324 char *result = NULL;
326 while (*current != NULL)
328 if (__builtin_expect ((*current)[0] == 'M', 0)
329 && (*current)[1] == 'A'
330 && (*current)[2] == 'L'
331 && (*current)[3] == 'L'
332 && (*current)[4] == 'O'
333 && (*current)[5] == 'C'
334 && (*current)[6] == '_')
336 result = &(*current)[7];
338 /* Save current position for next visit. */
339 *position = ++current;
341 break;
344 ++current;
347 return result;
349 #endif /* _LIBC */
351 /* Set up basic state so that _int_malloc et al can work. */
352 static void
353 ptmalloc_init_minimal (void)
355 #if DEFAULT_TOP_PAD != 0
356 mp_.top_pad = DEFAULT_TOP_PAD;
357 #endif
358 mp_.n_mmaps_max = DEFAULT_MMAP_MAX;
359 mp_.mmap_threshold = DEFAULT_MMAP_THRESHOLD;
360 mp_.trim_threshold = DEFAULT_TRIM_THRESHOLD;
361 mp_.pagesize = malloc_getpagesize;
365 #ifdef _LIBC
366 # ifdef SHARED
367 static void *
368 __failing_morecore (ptrdiff_t d)
370 return (void *) MORECORE_FAILURE;
373 extern struct dl_open_hook *_dl_open_hook;
374 libc_hidden_proto (_dl_open_hook);
375 # endif
377 # if defined SHARED && defined USE_TLS && !USE___THREAD
378 /* This is called by __pthread_initialize_minimal when it needs to use
379 malloc to set up the TLS state. We cannot do the full work of
380 ptmalloc_init (below) until __pthread_initialize_minimal has finished,
381 so it has to switch to using the special startup-time hooks while doing
382 those allocations. */
383 void
384 __libc_malloc_pthread_startup (bool first_time)
386 if (first_time)
388 ptmalloc_init_minimal ();
389 save_malloc_hook = __malloc_hook;
390 save_memalign_hook = __memalign_hook;
391 save_free_hook = __free_hook;
392 __malloc_hook = malloc_starter;
393 __memalign_hook = memalign_starter;
394 __free_hook = free_starter;
396 else
398 __malloc_hook = save_malloc_hook;
399 __memalign_hook = save_memalign_hook;
400 __free_hook = save_free_hook;
403 # endif
404 #endif
406 static void
407 ptmalloc_init (void)
409 #if __STD_C
410 const char* s;
411 #else
412 char* s;
413 #endif
414 int secure = 0;
416 if(__malloc_initialized >= 0) return;
417 __malloc_initialized = 0;
419 #ifdef _LIBC
420 # if defined SHARED && defined USE_TLS && !USE___THREAD
421 /* ptmalloc_init_minimal may already have been called via
422 __libc_malloc_pthread_startup, above. */
423 if (mp_.pagesize == 0)
424 # endif
425 #endif
426 ptmalloc_init_minimal();
428 #ifndef NO_THREADS
429 # if defined _LIBC && defined USE_TLS
430 /* We know __pthread_initialize_minimal has already been called,
431 and that is enough. */
432 # define NO_STARTER
433 # endif
434 # ifndef NO_STARTER
435 /* With some threads implementations, creating thread-specific data
436 or initializing a mutex may call malloc() itself. Provide a
437 simple starter version (realloc() won't work). */
438 save_malloc_hook = __malloc_hook;
439 save_memalign_hook = __memalign_hook;
440 save_free_hook = __free_hook;
441 __malloc_hook = malloc_starter;
442 __memalign_hook = memalign_starter;
443 __free_hook = free_starter;
444 # ifdef _LIBC
445 /* Initialize the pthreads interface. */
446 if (__pthread_initialize != NULL)
447 __pthread_initialize();
448 # endif /* !defined _LIBC */
449 # endif /* !defined NO_STARTER */
450 #endif /* !defined NO_THREADS */
451 mutex_init(&main_arena.mutex);
452 main_arena.next = &main_arena;
454 #if defined _LIBC && defined SHARED
455 /* In case this libc copy is in a non-default namespace, never use brk.
456 Likewise if dlopened from statically linked program. */
457 Dl_info di;
458 struct link_map *l;
460 if (_dl_open_hook != NULL
461 || (_dl_addr (ptmalloc_init, &di, &l, NULL) != 0
462 && l->l_ns != LM_ID_BASE))
463 __morecore = __failing_morecore;
464 #endif
466 mutex_init(&list_lock);
467 tsd_key_create(&arena_key, NULL);
468 tsd_setspecific(arena_key, (Void_t *)&main_arena);
469 thread_atfork(ptmalloc_lock_all, ptmalloc_unlock_all, ptmalloc_unlock_all2);
470 #ifndef NO_THREADS
471 # ifndef NO_STARTER
472 __malloc_hook = save_malloc_hook;
473 __memalign_hook = save_memalign_hook;
474 __free_hook = save_free_hook;
475 # else
476 # undef NO_STARTER
477 # endif
478 #endif
479 #ifdef _LIBC
480 secure = __libc_enable_secure;
481 s = NULL;
482 if (__builtin_expect (_environ != NULL, 1))
484 char **runp = _environ;
485 char *envline;
487 while (__builtin_expect ((envline = next_env_entry (&runp)) != NULL,
490 size_t len = strcspn (envline, "=");
492 if (envline[len] != '=')
493 /* This is a "MALLOC_" variable at the end of the string
494 without a '=' character. Ignore it since otherwise we
495 will access invalid memory below. */
496 continue;
498 switch (len)
500 case 6:
501 if (memcmp (envline, "CHECK_", 6) == 0)
502 s = &envline[7];
503 break;
504 case 8:
505 if (! secure)
507 if (memcmp (envline, "TOP_PAD_", 8) == 0)
508 mALLOPt(M_TOP_PAD, atoi(&envline[9]));
509 else if (memcmp (envline, "PERTURB_", 8) == 0)
510 mALLOPt(M_PERTURB, atoi(&envline[9]));
512 break;
513 case 9:
514 if (! secure && memcmp (envline, "MMAP_MAX_", 9) == 0)
515 mALLOPt(M_MMAP_MAX, atoi(&envline[10]));
516 break;
517 case 15:
518 if (! secure)
520 if (memcmp (envline, "TRIM_THRESHOLD_", 15) == 0)
521 mALLOPt(M_TRIM_THRESHOLD, atoi(&envline[16]));
522 else if (memcmp (envline, "MMAP_THRESHOLD_", 15) == 0)
523 mALLOPt(M_MMAP_THRESHOLD, atoi(&envline[16]));
525 break;
526 default:
527 break;
531 #else
532 if (! secure)
534 if((s = getenv("MALLOC_TRIM_THRESHOLD_")))
535 mALLOPt(M_TRIM_THRESHOLD, atoi(s));
536 if((s = getenv("MALLOC_TOP_PAD_")))
537 mALLOPt(M_TOP_PAD, atoi(s));
538 if((s = getenv("MALLOC_PERTURB_")))
539 mALLOPt(M_PERTURB, atoi(s));
540 if((s = getenv("MALLOC_MMAP_THRESHOLD_")))
541 mALLOPt(M_MMAP_THRESHOLD, atoi(s));
542 if((s = getenv("MALLOC_MMAP_MAX_")))
543 mALLOPt(M_MMAP_MAX, atoi(s));
545 s = getenv("MALLOC_CHECK_");
546 #endif
547 if(s) {
548 if(s[0]) mALLOPt(M_CHECK_ACTION, (int)(s[0] - '0'));
549 if (check_action != 0)
550 __malloc_check_init();
552 if(__malloc_initialize_hook != NULL)
553 (*__malloc_initialize_hook)();
554 __malloc_initialized = 1;
557 /* There are platforms (e.g. Hurd) with a link-time hook mechanism. */
558 #ifdef thread_atfork_static
559 thread_atfork_static(ptmalloc_lock_all, ptmalloc_unlock_all, \
560 ptmalloc_unlock_all2)
561 #endif
565 /* Managing heaps and arenas (for concurrent threads) */
567 #if USE_ARENAS
569 #if MALLOC_DEBUG > 1
571 /* Print the complete contents of a single heap to stderr. */
573 static void
574 #if __STD_C
575 dump_heap(heap_info *heap)
576 #else
577 dump_heap(heap) heap_info *heap;
578 #endif
580 char *ptr;
581 mchunkptr p;
583 fprintf(stderr, "Heap %p, size %10lx:\n", heap, (long)heap->size);
584 ptr = (heap->ar_ptr != (mstate)(heap+1)) ?
585 (char*)(heap + 1) : (char*)(heap + 1) + sizeof(struct malloc_state);
586 p = (mchunkptr)(((unsigned long)ptr + MALLOC_ALIGN_MASK) &
587 ~MALLOC_ALIGN_MASK);
588 for(;;) {
589 fprintf(stderr, "chunk %p size %10lx", p, (long)p->size);
590 if(p == top(heap->ar_ptr)) {
591 fprintf(stderr, " (top)\n");
592 break;
593 } else if(p->size == (0|PREV_INUSE)) {
594 fprintf(stderr, " (fence)\n");
595 break;
597 fprintf(stderr, "\n");
598 p = next_chunk(p);
602 #endif /* MALLOC_DEBUG > 1 */
604 /* If consecutive mmap (0, HEAP_MAX_SIZE << 1, ...) calls return decreasing
605 addresses as opposed to increasing, new_heap would badly fragment the
606 address space. In that case remember the second HEAP_MAX_SIZE part
607 aligned to HEAP_MAX_SIZE from last mmap (0, HEAP_MAX_SIZE << 1, ...)
608 call (if it is already aligned) and try to reuse it next time. We need
609 no locking for it, as kernel ensures the atomicity for us - worst case
610 we'll call mmap (addr, HEAP_MAX_SIZE, ...) for some value of addr in
611 multiple threads, but only one will succeed. */
612 static char *aligned_heap_area;
614 /* Create a new heap. size is automatically rounded up to a multiple
615 of the page size. */
617 static heap_info *
618 internal_function
619 #if __STD_C
620 new_heap(size_t size, size_t top_pad)
621 #else
622 new_heap(size, top_pad) size_t size, top_pad;
623 #endif
625 size_t page_mask = malloc_getpagesize - 1;
626 char *p1, *p2;
627 unsigned long ul;
628 heap_info *h;
630 if(size+top_pad < HEAP_MIN_SIZE)
631 size = HEAP_MIN_SIZE;
632 else if(size+top_pad <= HEAP_MAX_SIZE)
633 size += top_pad;
634 else if(size > HEAP_MAX_SIZE)
635 return 0;
636 else
637 size = HEAP_MAX_SIZE;
638 size = (size + page_mask) & ~page_mask;
640 /* A memory region aligned to a multiple of HEAP_MAX_SIZE is needed.
641 No swap space needs to be reserved for the following large
642 mapping (on Linux, this is the case for all non-writable mappings
643 anyway). */
644 p2 = MAP_FAILED;
645 if(aligned_heap_area) {
646 p2 = (char *)MMAP(aligned_heap_area, HEAP_MAX_SIZE, PROT_NONE,
647 MAP_PRIVATE|MAP_NORESERVE);
648 aligned_heap_area = NULL;
649 if (p2 != MAP_FAILED && ((unsigned long)p2 & (HEAP_MAX_SIZE-1))) {
650 munmap(p2, HEAP_MAX_SIZE);
651 p2 = MAP_FAILED;
654 if(p2 == MAP_FAILED) {
655 p1 = (char *)MMAP(0, HEAP_MAX_SIZE<<1, PROT_NONE,
656 MAP_PRIVATE|MAP_NORESERVE);
657 if(p1 != MAP_FAILED) {
658 p2 = (char *)(((unsigned long)p1 + (HEAP_MAX_SIZE-1))
659 & ~(HEAP_MAX_SIZE-1));
660 ul = p2 - p1;
661 if (ul)
662 munmap(p1, ul);
663 else
664 aligned_heap_area = p2 + HEAP_MAX_SIZE;
665 munmap(p2 + HEAP_MAX_SIZE, HEAP_MAX_SIZE - ul);
666 } else {
667 /* Try to take the chance that an allocation of only HEAP_MAX_SIZE
668 is already aligned. */
669 p2 = (char *)MMAP(0, HEAP_MAX_SIZE, PROT_NONE, MAP_PRIVATE|MAP_NORESERVE);
670 if(p2 == MAP_FAILED)
671 return 0;
672 if((unsigned long)p2 & (HEAP_MAX_SIZE-1)) {
673 munmap(p2, HEAP_MAX_SIZE);
674 return 0;
678 if(mprotect(p2, size, PROT_READ|PROT_WRITE) != 0) {
679 munmap(p2, HEAP_MAX_SIZE);
680 return 0;
682 h = (heap_info *)p2;
683 h->size = size;
684 THREAD_STAT(stat_n_heaps++);
685 return h;
688 /* Grow or shrink a heap. size is automatically rounded up to a
689 multiple of the page size if it is positive. */
691 static int
692 #if __STD_C
693 grow_heap(heap_info *h, long diff)
694 #else
695 grow_heap(h, diff) heap_info *h; long diff;
696 #endif
698 size_t page_mask = malloc_getpagesize - 1;
699 long new_size;
701 if(diff >= 0) {
702 diff = (diff + page_mask) & ~page_mask;
703 new_size = (long)h->size + diff;
704 if(new_size > HEAP_MAX_SIZE)
705 return -1;
706 if(mprotect((char *)h + h->size, diff, PROT_READ|PROT_WRITE) != 0)
707 return -2;
708 } else {
709 new_size = (long)h->size + diff;
710 if(new_size < (long)sizeof(*h))
711 return -1;
712 /* Try to re-map the extra heap space freshly to save memory, and
713 make it inaccessible. */
714 if((char *)MMAP((char *)h + new_size, -diff, PROT_NONE,
715 MAP_PRIVATE|MAP_FIXED) == (char *) MAP_FAILED)
716 return -2;
717 /*fprintf(stderr, "shrink %p %08lx\n", h, new_size);*/
719 h->size = new_size;
720 return 0;
723 /* Delete a heap. */
725 #define delete_heap(heap) \
726 do { \
727 if ((char *)(heap) + HEAP_MAX_SIZE == aligned_heap_area) \
728 aligned_heap_area = NULL; \
729 munmap((char*)(heap), HEAP_MAX_SIZE); \
730 } while (0)
732 static int
733 internal_function
734 #if __STD_C
735 heap_trim(heap_info *heap, size_t pad)
736 #else
737 heap_trim(heap, pad) heap_info *heap; size_t pad;
738 #endif
740 mstate ar_ptr = heap->ar_ptr;
741 unsigned long pagesz = mp_.pagesize;
742 mchunkptr top_chunk = top(ar_ptr), p, bck, fwd;
743 heap_info *prev_heap;
744 long new_size, top_size, extra;
746 /* Can this heap go away completely? */
747 while(top_chunk == chunk_at_offset(heap, sizeof(*heap))) {
748 prev_heap = heap->prev;
749 p = chunk_at_offset(prev_heap, prev_heap->size - (MINSIZE-2*SIZE_SZ));
750 assert(p->size == (0|PREV_INUSE)); /* must be fencepost */
751 p = prev_chunk(p);
752 new_size = chunksize(p) + (MINSIZE-2*SIZE_SZ);
753 assert(new_size>0 && new_size<(long)(2*MINSIZE));
754 if(!prev_inuse(p))
755 new_size += p->prev_size;
756 assert(new_size>0 && new_size<HEAP_MAX_SIZE);
757 if(new_size + (HEAP_MAX_SIZE - prev_heap->size) < pad + MINSIZE + pagesz)
758 break;
759 ar_ptr->system_mem -= heap->size;
760 arena_mem -= heap->size;
761 delete_heap(heap);
762 heap = prev_heap;
763 if(!prev_inuse(p)) { /* consolidate backward */
764 p = prev_chunk(p);
765 unlink(p, bck, fwd);
767 assert(((unsigned long)((char*)p + new_size) & (pagesz-1)) == 0);
768 assert( ((char*)p + new_size) == ((char*)heap + heap->size) );
769 top(ar_ptr) = top_chunk = p;
770 set_head(top_chunk, new_size | PREV_INUSE);
771 /*check_chunk(ar_ptr, top_chunk);*/
773 top_size = chunksize(top_chunk);
774 extra = ((top_size - pad - MINSIZE + (pagesz-1))/pagesz - 1) * pagesz;
775 if(extra < (long)pagesz)
776 return 0;
777 /* Try to shrink. */
778 if(grow_heap(heap, -extra) != 0)
779 return 0;
780 ar_ptr->system_mem -= extra;
781 arena_mem -= extra;
783 /* Success. Adjust top accordingly. */
784 set_head(top_chunk, (top_size - extra) | PREV_INUSE);
785 /*check_chunk(ar_ptr, top_chunk);*/
786 return 1;
789 /* Create a new arena with initial size "size". */
791 static mstate
792 _int_new_arena(size_t size)
794 mstate a;
795 heap_info *h;
796 char *ptr;
797 unsigned long misalign;
799 h = new_heap(size + (sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT),
800 mp_.top_pad);
801 if(!h) {
802 /* Maybe size is too large to fit in a single heap. So, just try
803 to create a minimally-sized arena and let _int_malloc() attempt
804 to deal with the large request via mmap_chunk(). */
805 h = new_heap(sizeof(*h) + sizeof(*a) + MALLOC_ALIGNMENT, mp_.top_pad);
806 if(!h)
807 return 0;
809 a = h->ar_ptr = (mstate)(h+1);
810 malloc_init_state(a);
811 /*a->next = NULL;*/
812 a->system_mem = a->max_system_mem = h->size;
813 arena_mem += h->size;
814 #ifdef NO_THREADS
815 if((unsigned long)(mp_.mmapped_mem + arena_mem + main_arena.system_mem) >
816 mp_.max_total_mem)
817 mp_.max_total_mem = mp_.mmapped_mem + arena_mem + main_arena.system_mem;
818 #endif
820 /* Set up the top chunk, with proper alignment. */
821 ptr = (char *)(a + 1);
822 misalign = (unsigned long)chunk2mem(ptr) & MALLOC_ALIGN_MASK;
823 if (misalign > 0)
824 ptr += MALLOC_ALIGNMENT - misalign;
825 top(a) = (mchunkptr)ptr;
826 set_head(top(a), (((char*)h + h->size) - ptr) | PREV_INUSE);
828 return a;
831 static mstate
832 internal_function
833 #if __STD_C
834 arena_get2(mstate a_tsd, size_t size)
835 #else
836 arena_get2(a_tsd, size) mstate a_tsd; size_t size;
837 #endif
839 mstate a;
841 if(!a_tsd)
842 a = a_tsd = &main_arena;
843 else {
844 a = a_tsd->next;
845 if(!a) {
846 /* This can only happen while initializing the new arena. */
847 (void)mutex_lock(&main_arena.mutex);
848 THREAD_STAT(++(main_arena.stat_lock_wait));
849 return &main_arena;
853 /* Check the global, circularly linked list for available arenas. */
854 bool retried = false;
855 repeat:
856 do {
857 if(!mutex_trylock(&a->mutex)) {
858 if (retried)
859 (void)mutex_unlock(&list_lock);
860 THREAD_STAT(++(a->stat_lock_loop));
861 tsd_setspecific(arena_key, (Void_t *)a);
862 return a;
864 a = a->next;
865 } while(a != a_tsd);
867 /* If not even the list_lock can be obtained, try again. This can
868 happen during `atfork', or for example on systems where thread
869 creation makes it temporarily impossible to obtain _any_
870 locks. */
871 if(!retried && mutex_trylock(&list_lock)) {
872 /* We will block to not run in a busy loop. */
873 (void)mutex_lock(&list_lock);
875 /* Since we blocked there might be an arena available now. */
876 retried = true;
877 a = a_tsd;
878 goto repeat;
881 /* Nothing immediately available, so generate a new arena. */
882 a = _int_new_arena(size);
883 if(a)
885 tsd_setspecific(arena_key, (Void_t *)a);
886 mutex_init(&a->mutex);
887 mutex_lock(&a->mutex); /* remember result */
889 /* Add the new arena to the global list. */
890 a->next = main_arena.next;
891 atomic_write_barrier ();
892 main_arena.next = a;
894 THREAD_STAT(++(a->stat_lock_loop));
896 (void)mutex_unlock(&list_lock);
898 return a;
901 #endif /* USE_ARENAS */
904 * Local variables:
905 * c-basic-offset: 2
906 * End: