libjava/include/posix-threads.h

   1 // -*- c++ -*-
   2 // posix-threads.h - Defines for using POSIX threads.
   3
   4 /* Copyright (C) 1998, 1999, 2001, 2003  Free Software Foundation
   5
   6    This file is part of libgcj.
   7
   8 This software is copyrighted work licensed under the terms of the
   9 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
  10 details.  */
  11
  12 #ifndef __JV_POSIX_THREADS__
  13 #define __JV_POSIX_THREADS__
  14
  15 // NOTE: This file may only reference those pthread functions which
  16 // are known not to be overridden by the Boehm GC.  If in doubt, scan
  17 // boehm-gc/gc.h.  This is yucky but lets us avoid including gc.h
  18 // everywhere (which would be truly yucky).
  19
  20 #include <pthread.h>
  21 #include <sched.h>
  22
  23 //
  24 // Typedefs.
  25 //
  26
  27 typedef struct _Jv_Thread_t
  28 {
  29   // Flag values are defined in implementation.
  30   int flags;
  31
  32   // Actual thread id.
  33   pthread_t thread;
  34
  35   // Java Thread object.
  36   java::lang::Thread *thread_obj;
  37
  38   // Condition variable and corresponding mutex, used to implement the
  39   // interruptable wait/notify mechanism.
  40   pthread_cond_t wait_cond;
  41   pthread_mutex_t wait_mutex;
  42
  43   // Next thread for Condition Variable wait-list chain.
  44   _Jv_Thread_t *next;
  45
  46 } _Jv_Thread_t;
  47
  48 typedef void _Jv_ThreadStartFunc (java::lang::Thread *);
  49
  50
  51 // Condition Variables used to implement wait/notify/sleep/interrupt.
  52 typedef struct
  53 {
  54   // Linked list of Threads that are waiting to be notified.
  55   _Jv_Thread_t *first;
  56
  57 } _Jv_ConditionVariable_t;
  58
  59 typedef struct
  60 {
  61   // For compatibility, simplicity, and correctness, we do not use the native
  62   // pthreads recursive mutex implementation, but simulate them instead.
  63
  64   // Mutex the thread holds the entire time this mutex is held.
  65   pthread_mutex_t mutex;
  66
  67   // Thread holding this mutex.
  68   pthread_t owner;
  69
  70   // Number of times mutex is held (lock depth).  If 0, the lock is not held.
  71   int count;
  72 } _Jv_Mutex_t;
  73
  74 // This is a convenience function used only by the pthreads thread
  75 // implementation.  This is slow, but that's too bad -- we need to do
  76 // the checks for correctness.  It might be nice to be able to compile
  77 // this out.  Returns 0 if the lock is held by the current thread, and
  78 // 1 otherwise.
  79 inline int
  80 _Jv_PthreadCheckMonitor (_Jv_Mutex_t *mu)
  81 {
  82   pthread_t self = pthread_self();
  83   if (mu->owner == self)
  84     return 0;
  85   else return 1;
  86 }
  87
  88 //
  89 // Condition variables.
  90 //
  91
  92 int _Jv_CondWait (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu,
  93                   jlong millis, jint nanos);
  94
  95 int _Jv_CondNotify (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu);
  96
  97 int _Jv_CondNotifyAll (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu);
  98
  99 inline void
 100 _Jv_CondInit (_Jv_ConditionVariable_t *cv)
 101 {
 102   cv->first = 0;
 103 }
 104
 105 //
 106 // Mutexes.
 107 //
 108
 109 #ifdef LOCK_DEBUG
 110 # include <stdio.h>
 111 #endif
 112
 113 inline void
 114 _Jv_MutexInit (_Jv_Mutex_t *mu)
 115 {
 116 # ifdef LOCK_DEBUG /* Assumes Linuxthreads */
 117   pthread_mutexattr_t attr;
 118   pthread_mutexattr_init(&attr);
 119   pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK);
 120   pthread_mutex_init (&mu->mutex, &attr);
 121 # else
 122   pthread_mutex_init (&mu->mutex, 0);
 123 # endif
 124
 125   mu->count = 0;
 126   mu->owner = 0;
 127 }
 128
 129 inline int
 130 _Jv_MutexLock (_Jv_Mutex_t *mu)
 131 {
 132   pthread_t self = pthread_self ();
 133   if (mu->owner == self)
 134     {
 135       mu->count++;
 136     }
 137   else
 138     {
 139 #     ifdef LOCK_DEBUG
 140         int result = pthread_mutex_lock (&mu->mutex);
 141         if (0 != result)
 142           {
 143             fprintf(stderr, "Pthread_mutex_lock returned %d\n", result);
 144             for (;;) {}
 145           }
 146 #     else
 147         pthread_mutex_lock (&mu->mutex);
 148 #     endif
 149       mu->count = 1;
 150       mu->owner = self;
 151     }
 152   return 0;
 153 }
 154
 155 inline int
 156 _Jv_MutexUnlock (_Jv_Mutex_t *mu)
 157 {
 158   if (_Jv_PthreadCheckMonitor (mu))
 159     {
 160 #     ifdef LOCK_DEBUG
 161         fprintf(stderr, "_Jv_MutexUnlock: Not owner\n");
 162         for (;;) {}
 163 #     endif
 164       return 1;
 165     }
 166
 167   mu->count--;
 168
 169   if (mu->count == 0)
 170     {
 171       mu->owner = 0;
 172 #     ifdef LOCK_DEBUG
 173         int result = pthread_mutex_unlock (&mu->mutex);
 174         if (0 != result)
 175           {
 176             fprintf(stderr, "Pthread_mutex_unlock returned %d\n", result);
 177             for (;;) {}
 178           }
 179 #     else
 180         pthread_mutex_unlock (&mu->mutex);
 181 #     endif
 182     }
 183   return 0;
 184 }
 185
 186 #ifndef LINUX_THREADS
 187
 188 // pthread_mutex_destroy does nothing on Linux and it is a win to avoid
 189 // defining this macro.
 190
 191 #define _Jv_HaveMutexDestroy
 192
 193 inline void
 194 _Jv_MutexDestroy (_Jv_Mutex_t *mu)
 195 {
 196   pthread_mutex_destroy (&mu->mutex);
 197 }
 198
 199 #endif /* LINUX_THREADS */
 200
 201 //
 202 // Thread creation and manipulation.
 203 //
 204
 205 void _Jv_InitThreads (void);
 206
 207 _Jv_Thread_t *_Jv_ThreadInitData (java::lang::Thread *thread);
 208 void _Jv_ThreadDestroyData (_Jv_Thread_t *data);
 209
 210 inline java::lang::Thread *
 211 _Jv_ThreadCurrent (void)
 212 {
 213   extern pthread_key_t _Jv_ThreadKey;
 214   return (java::lang::Thread *) pthread_getspecific (_Jv_ThreadKey);
 215 }
 216
 217 #ifdef JV_HASH_SYNCHRONIZATION
 218 // Should be specialized to just load the "current thread" register
 219 // on platforms that support it.   Speed is of the essence.  The value
 220 // of the descriptor is not, so long as there is a one-to-one correspondence
 221 // to threads.
 222
 223
 224 #ifdef __ia64__
 225
 226 typedef size_t _Jv_ThreadId_t;
 227
 228 register size_t _Jv_self __asm__("r13");
 229         // For linux_threads this is really a pointer to its thread data
 230         // structure.  We treat it as opaque.  That should also work
 231         // on other operating systems that follow the ABI standard.
 232
 233 // This should become the prototype for machines that maintain a thread
 234 // pointer in a register.
 235 inline _Jv_ThreadId_t
 236 _Jv_ThreadSelf (void)
 237 {
 238   return _Jv_self;
 239 }
 240
 241 #define JV_SELF_DEFINED
 242
 243 #endif /* __ia64__ */
 244
 245 #ifdef __alpha__
 246
 247 #ifdef __FreeBSD__
 248 #include <machine/pal.h>
 249 #define PAL_rduniq PAL_rdunique
 250 #elif defined (__osf__)
 251 #include <machine/pal.h>
 252 #else
 253 #include <asm/pal.h>
 254 #endif
 255
 256 typedef unsigned long _Jv_ThreadId_t;
 257
 258 inline _Jv_ThreadId_t
 259 _Jv_ThreadSelf (void)
 260 {
 261   register unsigned long id __asm__("$0");
 262   __asm__ ("call_pal %1" : "=r"(id) : "i"(PAL_rduniq));
 263   return id;
 264 }
 265
 266 #define JV_SELF_DEFINED
 267
 268 #endif /* __alpha__ */
 269
 270 #if defined(SLOW_PTHREAD_SELF)
 271
 272 #include "sysdep/locks.h"
 273
 274 typedef pthread_t _Jv_ThreadId_t;
 275
 276 // E.g. on X86 Linux, pthread_self() is too slow for our purpose.
 277 // Instead we maintain a cache based on the current sp value.
 278 // This is similar to what's done for thread local allocation in the
 279 // GC, only far simpler.
 280 // This code should probably go away when Linux/X86 starts using a
 281 // segment register to hold the thread id.
 282 # define LOG_THREAD_SPACING 12
 283                         // If two thread pointer values are closer than
 284                         // 1 << LOG_THREAD_SPACING, we assume they belong
 285                         // to the same thread.
 286 # define SELF_CACHE_SIZE 1024
 287 # define SC_INDEX(sp) (((unsigned long)(sp) >> 19) & (SELF_CACHE_SIZE-1))
 288                         // Mapping from sp value to cache index.
 289                         // Note that this is not in any real sense a hash
 290                         // function, since we need to be able to clear
 291                         // all possibly matching slots on thread startup.
 292                         // Thus all entries that might correspond to
 293                         // a given thread are intentionally contiguous.
 294                         // Works well with anything that allocates at least
 295                         // 512KB stacks.
 296 # define SC_CLEAR_MIN (-16)     // When starting a new thread, we clear
 297 # define SC_CLEAR_MAX 0         // all self cache entries between
 298                                 // SC_INDEX(sp)+SC_CLEAR_MIN and
 299                                 // SC_INDEX(sp)+SC_CLEAR_MAX to ensure
 300                                 // we never see stale values.  The
 301                                 // current values assume a downward
 302                                 // growing stack of size <= 7.5 MB.
 303 # define BAD_HIGH_SP_VALUE ((size_t)(-1))
 304
 305 extern volatile
 306 struct self_cache_entry {
 307   size_t high_sp_bits;  // sp value >> LOG_THREAD_SPACING
 308   pthread_t self;       // Corresponding thread
 309 } _Jv_self_cache[];
 310
 311 void _Jv_Self_Cache_Init();
 312
 313 _Jv_ThreadId_t
 314 _Jv_ThreadSelf_out_of_line(volatile self_cache_entry *sce,
 315                            size_t high_sp_bits);
 316
 317 inline _Jv_ThreadId_t
 318 _Jv_ThreadSelf (void)
 319 {
 320   int dummy;
 321   size_t sp = (size_t)(&dummy);
 322   unsigned h = SC_INDEX(sp);
 323   volatile self_cache_entry *sce = _Jv_self_cache + h;
 324   pthread_t candidate_self = sce -> self;  // Read must precede following one.
 325   read_barrier();
 326   if (sce -> high_sp_bits == sp >> LOG_THREAD_SPACING)
 327     {
 328       // The sce -> self value we read must be valid.  An intervening
 329       // cache replacement by another thread would have first replaced
 330       // high_sp_bits by something else, and it can't possibly change
 331       // back without our intervention.
 332       return candidate_self;
 333     }
 334   else
 335     return _Jv_ThreadSelf_out_of_line(sce, sp >> LOG_THREAD_SPACING);
 336 }
 337
 338 #define JV_SELF_DEFINED
 339
 340 #endif /* SLOW_PTHREAD_SELF */
 341
 342 #ifndef JV_SELF_DEFINED /* If all else fails, call pthread_self directly */
 343
 344 typedef pthread_t _Jv_ThreadId_t;
 345
 346 inline _Jv_ThreadId_t
 347 _Jv_ThreadSelf (void)
 348 {
 349   return pthread_self();
 350 }
 351
 352 #endif /* !JV_SELF_DEFINED */
 353
 354 #endif /* JV_HASH_SYNCHRONIZATION */
 355
 356 inline _Jv_Thread_t *
 357 _Jv_ThreadCurrentData (void)
 358 {
 359   extern pthread_key_t _Jv_ThreadDataKey;
 360   return (_Jv_Thread_t *) pthread_getspecific (_Jv_ThreadDataKey);
 361 }
 362
 363 inline void
 364 _Jv_ThreadYield (void)
 365 {
 366 #ifdef HAVE_SCHED_YIELD
 367   sched_yield ();
 368 #endif /* HAVE_SCHED_YIELD */
 369 }
 370
 371 void _Jv_ThreadRegister (_Jv_Thread_t *data);
 372 void _Jv_ThreadUnRegister ();
 373
 374 void _Jv_ThreadSetPriority (_Jv_Thread_t *data, jint prio);
 375
 376 void _Jv_ThreadStart (java::lang::Thread *thread, _Jv_Thread_t *data,
 377                       _Jv_ThreadStartFunc *meth);
 378
 379 void _Jv_ThreadWait (void);
 380
 381 void _Jv_ThreadInterrupt (_Jv_Thread_t *data);
 382
 383 #endif /* __JV_POSIX_THREADS__ */