libjava/posix-threads.cc

   1 // posix-threads.cc - interface between libjava and POSIX threads.
   2
   3 /* Copyright (C) 1998, 1999  Cygnus Solutions
   4
   5    This file is part of libgcj.
   6
   7 This software is copyrighted work licensed under the terms of the
   8 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   9 details.  */
  10
  11 // TO DO:
  12 // * Document signal handling limitations
  13
  14 #include <config.h>
  15
  16 // If we're using the Boehm GC, then we need to override some of the
  17 // thread primitives.  This is fairly gross.
  18 #ifdef HAVE_BOEHM_GC
  19 extern "C"
  20 {
  21 #include <boehm-config.h>
  22 #include <gc.h>
  23 };
  24 #endif /* HAVE_BOEHM_GC */
  25
  26 #include <stdlib.h>
  27 #include <time.h>
  28 #include <signal.h>
  29
  30 #include <cni.h>
  31 #include <jvm.h>
  32 #include <java/lang/Thread.h>
  33 #include <java/lang/System.h>
  34
  35 // This is used to implement thread startup.
  36 struct starter
  37 {
  38   _Jv_ThreadStartFunc *method;
  39   java::lang::Thread *object;
  40   _Jv_Thread_t *data;
  41 };
  42
  43 // This is the key used to map from the POSIX thread value back to the
  44 // Java object representing the thread.  The key is global to all
  45 // threads, so it is ok to make it a global here.
  46 pthread_key_t _Jv_ThreadKey;
  47
  48 // We keep a count of all non-daemon threads which are running.  When
  49 // this reaches zero, _Jv_ThreadWait returns.
  50 static pthread_mutex_t daemon_mutex;
  51 static pthread_cond_t daemon_cond;
  52 static int non_daemon_count;
  53
  54 // The signal to use when interrupting a thread.
  55 #ifdef LINUX_THREADS
  56   // LinuxThreads usurps both SIGUSR1 and SIGUSR2.
  57 #  define INTR SIGHUP
  58 #else /* LINUX_THREADS */
  59 #  define INTR SIGUSR2
  60 #endif /* LINUX_THREADS */
  61
  62 //
  63 // These are the flags that can appear in _Jv_Thread_t.
  64 //
  65
  66 // Thread started.
  67 #define FLAG_START   0x01
  68 // Thread is daemon.
  69 #define FLAG_DAEMON  0x02
  70
  71 \f
  72
  73 int
  74 _Jv_CondWait (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu,
  75               jlong millis, jint nanos)
  76 {
  77   int r;
  78   pthread_mutex_t *pmu;
  79 #ifdef HAVE_RECURSIVE_MUTEX
  80   pmu = mu;
  81 #else
  82   pmu = &mu->mutex2;
  83 #endif
  84   if (millis == 0 && nanos == 0)
  85     r = pthread_cond_wait (cv, pmu);
  86   else
  87     {
  88       struct timespec ts;
  89       unsigned long m = millis + java::lang::System::currentTimeMillis ();
  90
  91       ts.tv_sec = m / 1000;
  92       ts.tv_nsec = (m % 1000) * 1000 * 1000 + nanos;
  93
  94       r = pthread_cond_timedwait (cv, pmu, &ts);
  95     }
  96   return r;
  97 }
  98
  99 #ifndef RECURSIVE_MUTEX_IS_DEFAULT
 100
 101 void
 102 _Jv_MutexInit (_Jv_Mutex_t *mu)
 103 {
 104 #ifdef HAVE_RECURSIVE_MUTEX
 105   pthread_mutexattr_t *val = NULL;
 106
 107 #if defined (HAVE_PTHREAD_MUTEXATTR_SETTYPE)
 108   pthread_mutexattr_t attr;
 109
 110   // If this is slow, then allocate it statically and only initialize
 111   // it once.
 112   pthread_mutexattr_init (&attr);
 113   pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
 114   val = &attr;
 115 #elif defined (HAVE_PTHREAD_MUTEXATTR_SETKIND_NP)
 116   pthread_mutexattr_t attr;
 117   pthread_mutexattr_init (&attr);
 118   pthread_mutexattr_setkind_np (&attr, PTHREAD_MUTEX_RECURSIVE_NP);
 119   val = &attr;
 120 #endif
 121
 122   pthread_mutex_init (mu, val);
 123
 124 #if defined (HAVE_PTHREAD_MUTEXATTR_SETTYPE) || defined (HAVE_PTHREAD_MUTEXATTR_SETKIND_NP)
 125   pthread_mutexattr_destroy (&attr);
 126 #endif
 127
 128 #else /* HAVE_RECURSIVE_MUTEX */
 129
 130   // No recursive mutex, so simulate one.
 131   pthread_mutex_init (&mu->mutex, NULL);
 132   pthread_mutex_init (&mu->mutex2, NULL);
 133   pthread_cond_init (&mu->cond, 0);
 134   mu->count = 0;
 135
 136 #endif /* HAVE_RECURSIVE_MUTEX */
 137 }
 138
 139 #endif /* not RECURSIVE_MUTEX_IS_DEFAULT */
 140
 141 #if ! defined (LINUX_THREADS) && ! defined (HAVE_RECURSIVE_MUTEX)
 142
 143 void
 144 _Jv_MutexDestroy (_Jv_Mutex_t *mu)
 145 {
 146   pthread_mutex_destroy (&mu->mutex);
 147   pthread_mutex_destroy (&mu->mutex2);
 148   pthread_cond_destroy (&mu->cond);
 149 }
 150
 151 int
 152 _Jv_MutexLock (_Jv_Mutex_t *mu)
 153 {
 154   if (pthread_mutex_lock (&mu->mutex))
 155     return -1;
 156   while (1)
 157     {
 158       if (mu->count == 0)
 159         {
 160           // Grab the lock.
 161           mu->thread = pthread_self ();
 162           mu->count = 1;
 163           pthread_mutex_lock (&mu->mutex2);
 164           break;
 165         }
 166       else if (pthread_self () == mu->thread)
 167         {
 168           // Already have the lock.
 169           mu->count += 1;
 170           break;
 171         }
 172       else
 173         {
 174           // Try to acquire the lock.
 175           pthread_cond_wait (&mu->cond, &mu->mutex);
 176         }
 177     }
 178   pthread_mutex_unlock (&mu->mutex);
 179   return 0;
 180 }
 181
 182 int
 183 _Jv_MutexUnlock (_Jv_Mutex_t *mu)
 184 {
 185   if (pthread_mutex_lock (&mu->mutex))
 186     return -1;
 187   int r = 0;
 188   if (mu->count == 0 || pthread_self () != mu->thread)
 189     r = -1;
 190   else
 191     {
 192       mu->count -= 1;
 193       if (! mu->count)
 194         {
 195           pthread_mutex_unlock (&mu->mutex2);
 196           pthread_cond_signal (&mu->cond);
 197         }
 198     }
 199   pthread_mutex_unlock (&mu->mutex);
 200   return r;
 201 }
 202
 203 #endif /* not LINUX_THREADS and not HAVE_RECURSIVE_MUTEX */
 204
 205 static void
 206 handle_intr (int)
 207 {
 208   // Do nothing.
 209 }
 210
 211 void
 212 _Jv_InitThreads (void)
 213 {
 214   pthread_key_create (&_Jv_ThreadKey, NULL);
 215   pthread_mutex_init (&daemon_mutex, NULL);
 216   pthread_cond_init (&daemon_cond, 0);
 217   non_daemon_count = 0;
 218
 219   // Arrange for the interrupt signal to interrupt system calls.
 220   struct sigaction act;
 221   act.sa_handler = handle_intr;
 222   sigemptyset (&act.sa_mask);
 223   act.sa_flags = 0;
 224   sigaction (INTR, &act, NULL);
 225
 226   // Arrange for SIGINT to be blocked to all threads.  It is only
 227   // deliverable to the master thread.
 228   sigset_t mask;
 229   sigemptyset (&mask);
 230   sigaddset (&mask, SIGINT);
 231   pthread_sigmask (SIG_BLOCK, &mask, NULL);
 232 }
 233
 234 void
 235 _Jv_ThreadInitData (_Jv_Thread_t **data, java::lang::Thread *)
 236 {
 237   _Jv_Thread_t *info = new _Jv_Thread_t;
 238
 239   info->flags = 0;
 240   info->exception = NULL;
 241
 242   // FIXME register a finalizer for INFO here.
 243   // FIXME also must mark INFO somehow.
 244
 245   *data = info;
 246 }
 247
 248 void
 249 _Jv_ThreadSetPriority (_Jv_Thread_t *data, jint prio)
 250 {
 251   if (data->flags & FLAG_START)
 252     {
 253       struct sched_param param;
 254
 255       param.sched_priority = prio;
 256       pthread_setschedparam (data->thread, SCHED_RR, &param);
 257     }
 258 }
 259
 260
 261 // This is called as a cleanup handler when a thread is exiting.  We
 262 // use it to throw the requested exception.  It's entirely possible
 263 // that this approach is doomed to failure, in which case we'll need
 264 // to adopt some alternate.  For instance, use a signal to implement
 265 // _Jv_ThreadCancel.
 266 static void
 267 throw_cleanup (void *data)
 268 {
 269   _Jv_Thread_t *td = (_Jv_Thread_t *) data;
 270   _Jv_Throw ((java::lang::Throwable *) td->exception);
 271 }
 272
 273 void
 274 _Jv_ThreadCancel (_Jv_Thread_t *data, void *error)
 275 {
 276   data->exception = error;
 277   pthread_cancel (data->thread);
 278 }
 279
 280 // This function is called when a thread is started.  We don't arrange
 281 // to call the `run' method directly, because this function must
 282 // return a value.
 283 static void *
 284 really_start (void *x)
 285 {
 286   struct starter *info = (struct starter *) x;
 287
 288   pthread_cleanup_push (throw_cleanup, info->data);
 289   pthread_setspecific (_Jv_ThreadKey, info->object);
 290   info->method (info->object);
 291   pthread_cleanup_pop (0);
 292
 293   if (! (info->data->flags & FLAG_DAEMON))
 294     {
 295       pthread_mutex_lock (&daemon_mutex);
 296       --non_daemon_count;
 297       if (! non_daemon_count)
 298         pthread_cond_signal (&daemon_cond);
 299       pthread_mutex_unlock (&daemon_mutex);
 300     }
 301
 302   return NULL;
 303 }
 304
 305 void
 306 _Jv_ThreadStart (java::lang::Thread *thread, _Jv_Thread_t *data,
 307                  _Jv_ThreadStartFunc *meth)
 308 {
 309   struct sched_param param;
 310   pthread_attr_t attr;
 311   struct starter *info;
 312
 313   if (data->flags & FLAG_START)
 314     return;
 315   data->flags |= FLAG_START;
 316
 317   param.sched_priority = thread->getPriority();
 318
 319   pthread_attr_init (&attr);
 320   pthread_attr_setschedparam (&attr, &param);
 321
 322   // FIXME: handle marking the info object for GC.
 323   info = (struct starter *) _Jv_AllocBytes (sizeof (struct starter));
 324   info->method = meth;
 325   info->object = thread;
 326   info->data = data;
 327
 328   if (! thread->isDaemon())
 329     {
 330       pthread_mutex_lock (&daemon_mutex);
 331       ++non_daemon_count;
 332       pthread_mutex_unlock (&daemon_mutex);
 333     }
 334   else
 335     data->flags |= FLAG_DAEMON;
 336   pthread_create (&data->thread, &attr, really_start, (void *) info);
 337
 338   pthread_attr_destroy (&attr);
 339 }
 340
 341 void
 342 _Jv_ThreadWait (void)
 343 {
 344   // Arrange for SIGINT to be delivered to the master thread.
 345   sigset_t mask;
 346   sigemptyset (&mask);
 347   sigaddset (&mask, SIGINT);
 348   pthread_sigmask (SIG_UNBLOCK, &mask, NULL);
 349
 350   pthread_mutex_lock (&daemon_mutex);
 351   if (non_daemon_count)
 352     pthread_cond_wait (&daemon_cond, &daemon_mutex);
 353   pthread_mutex_unlock (&daemon_mutex);
 354 }
 355
 356 void
 357 _Jv_ThreadInterrupt (_Jv_Thread_t *data)
 358 {
 359   pthread_kill (data->thread, INTR);
 360 }