1 // posix-threads.cc - interface between libjava and POSIX threads.
3 /* Copyright (C) 1998, 1999, 2000, 2001, 2004, 2006 Free Software Foundation
5 This file is part of libgcj.
7 This software is copyrighted work licensed under the terms of the
8 Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
12 // * Document signal handling limitations
17 #include "posix-threads.h"
19 // If we're using the Boehm GC, then we need to override some of the
20 // thread primitives. This is fairly gross.
23 #endif /* HAVE_BOEHM_GC */
31 #include <unistd.h> // To test for _POSIX_THREAD_PRIORITY_SCHEDULING
36 #include <java/lang/Thread.h>
37 #include <java/lang/System.h>
38 #include <java/lang/Long.h>
39 #include <java/lang/OutOfMemoryError.h>
40 #include <java/lang/InternalError.h>
42 // This is used to implement thread startup.
45 _Jv_ThreadStartFunc *method;
49 // This is the key used to map from the POSIX thread value back to the
50 // Java object representing the thread. The key is global to all
51 // threads, so it is ok to make it a global here.
52 pthread_key_t _Jv_ThreadKey;
54 // This is the key used to map from the POSIX thread value back to the
55 // _Jv_Thread_t* representing the thread.
56 pthread_key_t _Jv_ThreadDataKey;
58 // We keep a count of all non-daemon threads which are running. When
59 // this reaches zero, _Jv_ThreadWait returns.
60 static pthread_mutex_t daemon_mutex;
61 static pthread_cond_t daemon_cond;
62 static int non_daemon_count;
64 // The signal to use when interrupting a thread.
65 #if defined(LINUX_THREADS) || defined(FREEBSD_THREADS)
66 // LinuxThreads (prior to glibc 2.1) usurps both SIGUSR1 and SIGUSR2.
67 // GC on FreeBSD uses both SIGUSR1 and SIGUSR2.
69 #else /* LINUX_THREADS */
71 #endif /* LINUX_THREADS */
74 // These are the flags that can appear in _Jv_Thread_t.
78 #define FLAG_START 0x01
80 #define FLAG_DAEMON 0x02
85 _Jv_MutexLock (_Jv_Mutex_t *mu)
87 pthread_t self = pthread_self ();
88 if (mu->owner == self)
94 JvSetThreadState holder (_Jv_ThreadCurrent(), JV_BLOCKED);
97 int result = pthread_mutex_lock (&mu->mutex);
100 fprintf(stderr, "Pthread_mutex_lock returned %d\n", result);
104 pthread_mutex_lock (&mu->mutex);
112 // Wait for the condition variable "CV" to be notified.
114 // 0: the condition was notified, or the timeout expired.
115 // _JV_NOT_OWNER: the thread does not own the mutex "MU".
116 // _JV_INTERRUPTED: the thread was interrupted. Its interrupted flag is set.
118 _Jv_CondWait (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu,
119 jlong millis, jint nanos)
121 pthread_t self = pthread_self();
122 if (mu->owner != self)
123 return _JV_NOT_OWNER;
127 JvThreadState new_state = JV_WAITING;
128 if (millis > 0 || nanos > 0)
130 // Calculate the abstime corresponding to the timeout.
131 unsigned long long seconds;
134 // For better accuracy, should use pthread_condattr_setclock
135 // and clock_gettime.
136 #ifdef HAVE_GETTIMEOFDAY
138 gettimeofday (&tv, NULL);
142 unsigned long long startTime = java::lang::System::currentTimeMillis();
143 seconds = startTime / 1000;
144 /* Assume we're about half-way through this millisecond. */
145 usec = (startTime % 1000) * 1000 + 500;
147 /* These next two statements cannot overflow. */
148 usec += nanos / 1000;
149 usec += (millis % 1000) * 1000;
150 /* These two statements could overflow only if tv.tv_sec was
152 seconds += millis / 1000;
153 seconds += usec / 1000000;
156 if (ts.tv_sec < 0 || (unsigned long long)ts.tv_sec != seconds)
158 // We treat a timeout that won't fit into a struct timespec
159 // as a wait forever.
163 /* This next statement also cannot overflow. */
164 ts.tv_nsec = (usec % 1000000) * 1000 + (nanos % 1000);
167 _Jv_Thread_t *current = _Jv_ThreadCurrentData ();
168 java::lang::Thread *current_obj = _Jv_ThreadCurrent ();
170 pthread_mutex_lock (¤t->wait_mutex);
172 // Now that we hold the wait mutex, check if this thread has been
173 // interrupted already.
174 if (current_obj->interrupt_flag)
176 pthread_mutex_unlock (¤t->wait_mutex);
177 return _JV_INTERRUPTED;
180 // Set the thread's state.
181 JvSetThreadState holder (current_obj, new_state);
183 // Add this thread to the cv's wait set.
184 current->next = NULL;
186 if (cv->first == NULL)
189 for (_Jv_Thread_t *t = cv->first;; t = t->next)
198 // Record the current lock depth, so it can be restored when we re-aquire it.
199 int count = mu->count;
201 // Release the monitor mutex.
204 pthread_mutex_unlock (&mu->mutex);
207 bool done_sleeping = false;
209 while (! done_sleeping)
211 if (millis == 0 && nanos == 0)
212 r = pthread_cond_wait (¤t->wait_cond, ¤t->wait_mutex);
214 r = pthread_cond_timedwait (¤t->wait_cond, ¤t->wait_mutex,
217 // In older glibc's (prior to 2.1.3), the cond_wait functions may
218 // spuriously wake up on a signal. Catch that here.
220 done_sleeping = true;
223 // Check for an interrupt *before* releasing the wait mutex.
224 jboolean interrupted = current_obj->interrupt_flag;
226 pthread_mutex_unlock (¤t->wait_mutex);
228 // Reaquire the monitor mutex, and restore the lock count.
229 pthread_mutex_lock (&mu->mutex);
233 // If we were interrupted, or if a timeout occurred, remove ourself from
234 // the cv wait list now. (If we were notified normally, notify() will have
235 // already taken care of this)
236 if (r == ETIMEDOUT || interrupted)
238 _Jv_Thread_t *prev = NULL;
239 for (_Jv_Thread_t *t = cv->first; t != NULL; t = t->next)
244 prev->next = t->next;
253 return _JV_INTERRUPTED;
260 _Jv_CondNotify (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu)
262 if (_Jv_MutexCheckMonitor (mu))
263 return _JV_NOT_OWNER;
265 _Jv_Thread_t *target;
266 _Jv_Thread_t *prev = NULL;
268 for (target = cv->first; target != NULL; target = target->next)
270 pthread_mutex_lock (&target->wait_mutex);
272 if (target->thread_obj->interrupt_flag)
274 // Don't notify a thread that has already been interrupted.
275 pthread_mutex_unlock (&target->wait_mutex);
280 pthread_cond_signal (&target->wait_cond);
281 pthread_mutex_unlock (&target->wait_mutex);
283 // Two concurrent notify() calls must not be delivered to the same
284 // thread, so remove the target thread from the cv wait list now.
286 cv->first = target->next;
288 prev->next = target->next;
299 _Jv_CondNotifyAll (_Jv_ConditionVariable_t *cv, _Jv_Mutex_t *mu)
301 if (_Jv_MutexCheckMonitor (mu))
302 return _JV_NOT_OWNER;
304 _Jv_Thread_t *target;
305 _Jv_Thread_t *prev = NULL;
307 for (target = cv->first; target != NULL; target = target->next)
309 pthread_mutex_lock (&target->wait_mutex);
310 pthread_cond_signal (&target->wait_cond);
311 pthread_mutex_unlock (&target->wait_mutex);
326 _Jv_ThreadInterrupt (_Jv_Thread_t *data)
328 pthread_mutex_lock (&data->wait_mutex);
330 // Set the thread's interrupted flag *after* aquiring its wait_mutex. This
331 // ensures that there are no races with the interrupt flag being set after
332 // the waiting thread checks it and before pthread_cond_wait is entered.
333 data->thread_obj->interrupt_flag = true;
335 // Interrupt blocking system calls using a signal.
336 pthread_kill (data->thread, INTR);
338 pthread_cond_signal (&data->wait_cond);
340 pthread_mutex_unlock (&data->wait_mutex);
344 * Releases the block on a thread created by _Jv_ThreadPark(). This
345 * method can also be used to terminate a blockage caused by a prior
346 * call to park. This operation is unsafe, as the thread must be
347 * guaranteed to be live.
349 * @param thread the thread to unblock.
352 ParkHelper::unpark ()
354 using namespace ::java::lang;
355 volatile obj_addr_t *ptr = &permit;
357 /* If this thread is in state RUNNING, give it a permit and return
360 (ptr, Thread::THREAD_PARK_RUNNING, Thread::THREAD_PARK_PERMIT))
363 /* If this thread is parked, put it into state RUNNING and send it a
366 (ptr, Thread::THREAD_PARK_PARKED, Thread::THREAD_PARK_RUNNING))
368 pthread_mutex_lock (&mutex);
369 pthread_cond_signal (&cond);
370 pthread_mutex_unlock (&mutex);
375 * Sets our state to dead.
378 ParkHelper::deactivate ()
380 permit = ::java::lang::Thread::THREAD_PARK_DEAD;
384 * Blocks the thread until a matching _Jv_ThreadUnpark() occurs, the
385 * thread is interrupted or the optional timeout expires. If an
386 * unpark call has already occurred, this also counts. A timeout
387 * value of zero is defined as no timeout. When isAbsolute is true,
388 * the timeout is in milliseconds relative to the epoch. Otherwise,
389 * the value is the number of nanoseconds which must occur before
390 * timeout. This call may also return spuriously (i.e. for no
393 * @param isAbsolute true if the timeout is specified in milliseconds from
395 * @param time either the number of nanoseconds to wait, or a time in
396 * milliseconds from the epoch to wait for.
399 ParkHelper::park (jboolean isAbsolute, jlong time)
401 using namespace ::java::lang;
402 volatile obj_addr_t *ptr = &permit;
404 /* If we have a permit, return immediately. */
406 (ptr, Thread::THREAD_PARK_PERMIT, Thread::THREAD_PARK_RUNNING))
410 jlong millis = 0, nanos = 0;
421 millis = java::lang::System::currentTimeMillis();
425 if (millis > 0 || nanos > 0)
427 // Calculate the abstime corresponding to the timeout.
428 // Everything is in milliseconds.
430 // We use `unsigned long long' rather than jlong because our
431 // caller may pass up to Long.MAX_VALUE millis. This would
432 // overflow the range of a timespec.
434 unsigned long long m = (unsigned long long)millis;
435 unsigned long long seconds = m / 1000;
438 if (ts.tv_sec < 0 || (unsigned long long)ts.tv_sec != seconds)
440 // We treat a timeout that won't fit into a struct timespec
441 // as a wait forever.
447 ts.tv_nsec = m * 1000000 + (unsigned long long)nanos;
453 (ptr, Thread::THREAD_PARK_RUNNING, Thread::THREAD_PARK_PARKED))
455 pthread_mutex_lock (&mutex);
456 if (millis == 0 && nanos == 0)
457 pthread_cond_wait (&cond, &mutex);
459 pthread_cond_timedwait (&cond, &mutex, &ts);
460 pthread_mutex_unlock (&mutex);
462 /* If we were unparked by some other thread, this will already
463 be in state THREAD_PARK_RUNNING. If we timed out, we have to
466 (ptr, Thread::THREAD_PARK_PARKED, Thread::THREAD_PARK_RUNNING);
481 sigaddset (&mask, SIGCHLD);
482 int c = pthread_sigmask (SIG_BLOCK, &mask, NULL);
484 JvFail (strerror (c));
492 sigaddset (&mask, SIGCHLD);
493 int c = pthread_sigmask (SIG_UNBLOCK, &mask, NULL);
495 JvFail (strerror (c));
499 _Jv_InitThreads (void)
501 pthread_key_create (&_Jv_ThreadKey, NULL);
502 pthread_key_create (&_Jv_ThreadDataKey, NULL);
503 pthread_mutex_init (&daemon_mutex, NULL);
504 pthread_cond_init (&daemon_cond, 0);
505 non_daemon_count = 0;
507 // Arrange for the interrupt signal to interrupt system calls.
508 struct sigaction act;
509 act.sa_handler = handle_intr;
510 sigemptyset (&act.sa_mask);
512 sigaction (INTR, &act, NULL);
514 // Block SIGCHLD here to ensure that any non-Java threads inherit the new
518 // Check/set the thread stack size.
519 size_t min_ss = 32 * 1024;
521 if (sizeof (void *) == 8)
522 // Bigger default on 64-bit systems.
525 #ifdef PTHREAD_STACK_MIN
526 if (min_ss < PTHREAD_STACK_MIN)
527 min_ss = PTHREAD_STACK_MIN;
530 if (gcj::stack_size > 0 && gcj::stack_size < min_ss)
531 gcj::stack_size = min_ss;
535 _Jv_ThreadInitData (java::lang::Thread *obj)
537 _Jv_Thread_t *data = (_Jv_Thread_t *) _Jv_Malloc (sizeof (_Jv_Thread_t));
539 data->thread_obj = obj;
541 pthread_mutex_init (&data->wait_mutex, NULL);
542 pthread_cond_init (&data->wait_cond, NULL);
548 _Jv_ThreadDestroyData (_Jv_Thread_t *data)
550 pthread_mutex_destroy (&data->wait_mutex);
551 pthread_cond_destroy (&data->wait_cond);
552 _Jv_Free ((void *)data);
556 _Jv_ThreadSetPriority (_Jv_Thread_t *data, jint prio)
558 #ifdef _POSIX_THREAD_PRIORITY_SCHEDULING
559 if (data->flags & FLAG_START)
561 struct sched_param param;
563 param.sched_priority = prio;
564 pthread_setschedparam (data->thread, SCHED_OTHER, ¶m);
570 _Jv_ThreadRegister (_Jv_Thread_t *data)
572 pthread_setspecific (_Jv_ThreadKey, data->thread_obj);
573 pthread_setspecific (_Jv_ThreadDataKey, data);
575 // glibc 2.1.3 doesn't set the value of `thread' until after start_routine
576 // is called. Since it may need to be accessed from the new thread, work
577 // around the potential race here by explicitly setting it again.
578 data->thread = pthread_self ();
580 # ifdef SLOW_PTHREAD_SELF
581 // Clear all self cache slots that might be needed by this thread.
583 int low_index = SC_INDEX(&dummy) + SC_CLEAR_MIN;
584 int high_index = SC_INDEX(&dummy) + SC_CLEAR_MAX;
585 for (int i = low_index; i <= high_index; ++i)
587 int current_index = i;
588 if (current_index < 0)
589 current_index += SELF_CACHE_SIZE;
590 if (current_index >= SELF_CACHE_SIZE)
591 current_index -= SELF_CACHE_SIZE;
592 _Jv_self_cache[current_index].high_sp_bits = BAD_HIGH_SP_VALUE;
595 // Block SIGCHLD which is used in natPosixProcess.cc.
600 _Jv_ThreadUnRegister ()
602 pthread_setspecific (_Jv_ThreadKey, NULL);
603 pthread_setspecific (_Jv_ThreadDataKey, NULL);
606 // This function is called when a thread is started. We don't arrange
607 // to call the `run' method directly, because this function must
610 really_start (void *x)
612 struct starter *info = (struct starter *) x;
614 _Jv_ThreadRegister (info->data);
616 info->method (info->data->thread_obj);
618 if (! (info->data->flags & FLAG_DAEMON))
620 pthread_mutex_lock (&daemon_mutex);
622 if (! non_daemon_count)
623 pthread_cond_signal (&daemon_cond);
624 pthread_mutex_unlock (&daemon_mutex);
631 _Jv_ThreadStart (java::lang::Thread *thread, _Jv_Thread_t *data,
632 _Jv_ThreadStartFunc *meth)
634 struct sched_param param;
636 struct starter *info;
638 if (data->flags & FLAG_START)
640 data->flags |= FLAG_START;
642 // Block SIGCHLD which is used in natPosixProcess.cc.
643 // The current mask is inherited by the child thread.
646 param.sched_priority = thread->getPriority();
648 pthread_attr_init (&attr);
649 pthread_attr_setschedparam (&attr, ¶m);
650 pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
652 // Set stack size if -Xss option was given.
653 if (gcj::stack_size > 0)
655 int e = pthread_attr_setstacksize (&attr, gcj::stack_size);
657 JvFail (strerror (e));
660 info = (struct starter *) _Jv_AllocBytes (sizeof (struct starter));
664 if (! thread->isDaemon())
666 pthread_mutex_lock (&daemon_mutex);
668 pthread_mutex_unlock (&daemon_mutex);
671 data->flags |= FLAG_DAEMON;
672 int r = pthread_create (&data->thread, &attr, really_start, (void *) info);
674 pthread_attr_destroy (&attr);
678 const char* msg = "Cannot create additional threads";
679 throw new java::lang::OutOfMemoryError (JvNewStringUTF (msg));
684 _Jv_ThreadWait (void)
686 pthread_mutex_lock (&daemon_mutex);
687 if (non_daemon_count)
688 pthread_cond_wait (&daemon_cond, &daemon_mutex);
689 pthread_mutex_unlock (&daemon_mutex);
692 #if defined(SLOW_PTHREAD_SELF)
694 #include "sysdep/locks.h"
696 // Support for pthread_self() lookup cache.
697 volatile self_cache_entry _Jv_self_cache[SELF_CACHE_SIZE];
700 _Jv_ThreadSelf_out_of_line(volatile self_cache_entry *sce, size_t high_sp_bits)
702 pthread_t self = pthread_self();
703 sce -> high_sp_bits = high_sp_bits;
709 #endif /* SLOW_PTHREAD_SELF */