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       jlong m = millis + java::lang::System::currentTimeMillis ();
  90       ts.tv_sec = m / 1000;
  91       ts.tv_nsec = ((m % 1000) * 1000000) + nanos;
  92
  93       r = pthread_cond_timedwait (cv, pmu, &ts);
  94     }
  95   return r;
  96 }
  97
  98 #ifndef RECURSIVE_MUTEX_IS_DEFAULT
  99
 100 void
 101 _Jv_MutexInit (_Jv_Mutex_t *mu)
 102 {
 103 #ifdef HAVE_RECURSIVE_MUTEX
 104   pthread_mutexattr_t *val = NULL;
 105
 106 #if defined (HAVE_PTHREAD_MUTEXATTR_SETTYPE)
 107   pthread_mutexattr_t attr;
 108
 109   // If this is slow, then allocate it statically and only initialize
 110   // it once.
 111   pthread_mutexattr_init (&attr);
 112   pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
 113   val = &attr;
 114 #elif defined (HAVE_PTHREAD_MUTEXATTR_SETKIND_NP)
 115   pthread_mutexattr_t attr;
 116   pthread_mutexattr_init (&attr);
 117   pthread_mutexattr_setkind_np (&attr, PTHREAD_MUTEX_RECURSIVE_NP);
 118   val = &attr;
 119 #endif
 120
 121   pthread_mutex_init (mu, val);
 122
 123 #if defined (HAVE_PTHREAD_MUTEXATTR_SETTYPE) || defined (HAVE_PTHREAD_MUTEXATTR_SETKIND_NP)
 124   pthread_mutexattr_destroy (&attr);
 125 #endif
 126
 127 #else /* HAVE_RECURSIVE_MUTEX */
 128
 129   // No recursive mutex, so simulate one.
 130   pthread_mutex_init (&mu->mutex, NULL);
 131   pthread_mutex_init (&mu->mutex2, NULL);
 132   pthread_cond_init (&mu->cond, 0);
 133   mu->count = 0;
 134
 135 #endif /* HAVE_RECURSIVE_MUTEX */
 136 }
 137
 138 #endif /* not RECURSIVE_MUTEX_IS_DEFAULT */
 139
 140 #if ! defined (LINUX_THREADS) && ! defined (HAVE_RECURSIVE_MUTEX)
 141
 142 void
 143 _Jv_MutexDestroy (_Jv_Mutex_t *mu)
 144 {
 145   pthread_mutex_destroy (&mu->mutex);
 146   pthread_mutex_destroy (&mu->mutex2);
 147   pthread_cond_destroy (&mu->cond);
 148 }
 149
 150 int
 151 _Jv_MutexLock (_Jv_Mutex_t *mu)
 152 {
 153   if (pthread_mutex_lock (&mu->mutex))
 154     return -1;
 155   while (1)
 156     {
 157       if (mu->count == 0)
 158         {
 159           // Grab the lock.
 160           mu->thread = pthread_self ();
 161           mu->count = 1;
 162           pthread_mutex_lock (&mu->mutex2);
 163           break;
 164         }
 165       else if (pthread_self () == mu->thread)
 166         {
 167           // Already have the lock.
 168           mu->count += 1;
 169           break;
 170         }
 171       else
 172         {
 173           // Try to acquire the lock.
 174           pthread_cond_wait (&mu->cond, &mu->mutex);
 175         }
 176     }
 177   pthread_mutex_unlock (&mu->mutex);
 178   return 0;
 179 }
 180
 181 int
 182 _Jv_MutexUnlock (_Jv_Mutex_t *mu)
 183 {
 184   if (pthread_mutex_lock (&mu->mutex))
 185     return -1;
 186   int r = 0;
 187   if (mu->count == 0 || pthread_self () != mu->thread)
 188     r = -1;
 189   else
 190     {
 191       mu->count -= 1;
 192       if (! mu->count)
 193         {
 194           pthread_mutex_unlock (&mu->mutex2);
 195           pthread_cond_signal (&mu->cond);
 196         }
 197     }
 198   pthread_mutex_unlock (&mu->mutex);
 199   return r;
 200 }
 201
 202 #endif /* not LINUX_THREADS and not HAVE_RECURSIVE_MUTEX */
 203
 204 static void
 205 handle_intr (int)
 206 {
 207   // Do nothing.
 208 }
 209
 210 void
 211 _Jv_InitThreads (void)
 212 {
 213   pthread_key_create (&_Jv_ThreadKey, NULL);
 214   pthread_mutex_init (&daemon_mutex, NULL);
 215   pthread_cond_init (&daemon_cond, 0);
 216   non_daemon_count = 0;
 217
 218   // Arrange for the interrupt signal to interrupt system calls.
 219   struct sigaction act;
 220   act.sa_handler = handle_intr;
 221   sigemptyset (&act.sa_mask);
 222   act.sa_flags = 0;
 223   sigaction (INTR, &act, NULL);
 224
 225   // Arrange for SIGINT to be blocked to all threads.  It is only
 226   // deliverable to the master thread.
 227   sigset_t mask;
 228   sigemptyset (&mask);
 229   sigaddset (&mask, SIGINT);
 230   pthread_sigmask (SIG_BLOCK, &mask, NULL);
 231 }
 232
 233 void
 234 _Jv_ThreadInitData (_Jv_Thread_t **data, java::lang::Thread *)
 235 {
 236   _Jv_Thread_t *info = new _Jv_Thread_t;
 237
 238   info->flags = 0;
 239   info->exception = NULL;
 240
 241   // FIXME register a finalizer for INFO here.
 242   // FIXME also must mark INFO somehow.
 243
 244   *data = info;
 245 }
 246
 247 void
 248 _Jv_ThreadSetPriority (_Jv_Thread_t *data, jint prio)
 249 {
 250   if (data->flags & FLAG_START)
 251     {
 252       struct sched_param param;
 253
 254       param.sched_priority = prio;
 255       pthread_setschedparam (data->thread, SCHED_RR, &param);
 256     }
 257 }
 258
 259
 260 // This is called as a cleanup handler when a thread is exiting.  We
 261 // use it to throw the requested exception.  It's entirely possible
 262 // that this approach is doomed to failure, in which case we'll need
 263 // to adopt some alternate.  For instance, use a signal to implement
 264 // _Jv_ThreadCancel.
 265 static void
 266 throw_cleanup (void *data)
 267 {
 268   _Jv_Thread_t *td = (_Jv_Thread_t *) data;
 269   _Jv_Throw ((java::lang::Throwable *) td->exception);
 270 }
 271
 272 void
 273 _Jv_ThreadCancel (_Jv_Thread_t *data, void *error)
 274 {
 275   data->exception = error;
 276   pthread_cancel (data->thread);
 277 }
 278
 279 // This function is called when a thread is started.  We don't arrange
 280 // to call the `run' method directly, because this function must
 281 // return a value.
 282 static void *
 283 really_start (void *x)
 284 {
 285   struct starter *info = (struct starter *) x;
 286
 287   pthread_cleanup_push (throw_cleanup, info->data);
 288   pthread_setspecific (_Jv_ThreadKey, info->object);
 289   info->method (info->object);
 290   pthread_cleanup_pop (0);
 291
 292   if (! (info->data->flags & FLAG_DAEMON))
 293     {
 294       pthread_mutex_lock (&daemon_mutex);
 295       --non_daemon_count;
 296       if (! non_daemon_count)
 297         pthread_cond_signal (&daemon_cond);
 298       pthread_mutex_unlock (&daemon_mutex);
 299     }
 300
 301   return NULL;
 302 }
 303
 304 void
 305 _Jv_ThreadStart (java::lang::Thread *thread, _Jv_Thread_t *data,
 306                  _Jv_ThreadStartFunc *meth)
 307 {
 308   struct sched_param param;
 309   pthread_attr_t attr;
 310   struct starter *info;
 311
 312   if (data->flags & FLAG_START)
 313     return;
 314   data->flags |= FLAG_START;
 315
 316   param.sched_priority = thread->getPriority();
 317
 318   pthread_attr_init (&attr);
 319   pthread_attr_setschedparam (&attr, &param);
 320
 321   // FIXME: handle marking the info object for GC.
 322   info = (struct starter *) _Jv_AllocBytes (sizeof (struct starter));
 323   info->method = meth;
 324   info->object = thread;
 325   info->data = data;
 326
 327   if (! thread->isDaemon())
 328     {
 329       pthread_mutex_lock (&daemon_mutex);
 330       ++non_daemon_count;
 331       pthread_mutex_unlock (&daemon_mutex);
 332     }
 333   else
 334     data->flags |= FLAG_DAEMON;
 335   pthread_create (&data->thread, &attr, really_start, (void *) info);
 336
 337   pthread_attr_destroy (&attr);
 338 }
 339
 340 void
 341 _Jv_ThreadWait (void)
 342 {
 343   // Arrange for SIGINT to be delivered to the master thread.
 344   sigset_t mask;
 345   sigemptyset (&mask);
 346   sigaddset (&mask, SIGINT);
 347   pthread_sigmask (SIG_UNBLOCK, &mask, NULL);
 348
 349   pthread_mutex_lock (&daemon_mutex);
 350   if (non_daemon_count)
 351     pthread_cond_wait (&daemon_cond, &daemon_mutex);
 352   pthread_mutex_unlock (&daemon_mutex);
 353 }
 354
 355 void
 356 _Jv_ThreadInterrupt (_Jv_Thread_t *data)
 357 {
 358   pthread_kill (data->thread, INTR);
 359 }