2 * Copyright (C) 2011 The Android Open Source Project
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
23 #include "base/logging.h"
24 #include "mutex-inl.h"
26 #include "scoped_thread_state_change.h"
27 #include "thread-inl.h"
32 Mutex* Locks::abort_lock_ = nullptr;
33 Mutex* Locks::allocated_thread_ids_lock_ = nullptr;
34 Mutex* Locks::breakpoint_lock_ = nullptr;
35 ReaderWriterMutex* Locks::classlinker_classes_lock_ = nullptr;
36 ReaderWriterMutex* Locks::heap_bitmap_lock_ = nullptr;
37 Mutex* Locks::logging_lock_ = nullptr;
38 Mutex* Locks::mem_maps_lock_ = nullptr;
39 Mutex* Locks::modify_ldt_lock_ = nullptr;
40 ReaderWriterMutex* Locks::mutator_lock_ = nullptr;
41 Mutex* Locks::runtime_shutdown_lock_ = nullptr;
42 Mutex* Locks::thread_list_lock_ = nullptr;
43 Mutex* Locks::thread_suspend_count_lock_ = nullptr;
44 Mutex* Locks::trace_lock_ = nullptr;
45 Mutex* Locks::profiler_lock_ = nullptr;
46 Mutex* Locks::unexpected_signal_lock_ = nullptr;
47 Mutex* Locks::intern_table_lock_ = nullptr;
50 // A guard for all_mutexes_ that's not a mutex (Mutexes must CAS to acquire and busy wait).
51 Atomic<const BaseMutex*> all_mutexes_guard;
52 // All created mutexes guarded by all_mutexes_guard_.
53 std::set<BaseMutex*>* all_mutexes;
54 AllMutexData() : all_mutexes(NULL) {}
56 static struct AllMutexData gAllMutexData[kAllMutexDataSize];
59 static bool ComputeRelativeTimeSpec(timespec* result_ts, const timespec& lhs, const timespec& rhs) {
60 const int32_t one_sec = 1000 * 1000 * 1000; // one second in nanoseconds.
61 result_ts->tv_sec = lhs.tv_sec - rhs.tv_sec;
62 result_ts->tv_nsec = lhs.tv_nsec - rhs.tv_nsec;
63 if (result_ts->tv_nsec < 0) {
65 result_ts->tv_nsec += one_sec;
66 } else if (result_ts->tv_nsec > one_sec) {
68 result_ts->tv_nsec -= one_sec;
70 return result_ts->tv_sec < 0;
74 class ScopedAllMutexesLock {
76 explicit ScopedAllMutexesLock(const BaseMutex* mutex) : mutex_(mutex) {
77 while (!gAllMutexData->all_mutexes_guard.CompareExchangeWeakAcquire(0, mutex)) {
81 ~ScopedAllMutexesLock() {
82 while (!gAllMutexData->all_mutexes_guard.CompareExchangeWeakRelease(mutex_, 0)) {
87 const BaseMutex* const mutex_;
90 BaseMutex::BaseMutex(const char* name, LockLevel level) : level_(level), name_(name) {
91 if (kLogLockContentions) {
92 ScopedAllMutexesLock mu(this);
93 std::set<BaseMutex*>** all_mutexes_ptr = &gAllMutexData->all_mutexes;
94 if (*all_mutexes_ptr == NULL) {
95 // We leak the global set of all mutexes to avoid ordering issues in global variable
96 // construction/destruction.
97 *all_mutexes_ptr = new std::set<BaseMutex*>();
99 (*all_mutexes_ptr)->insert(this);
103 BaseMutex::~BaseMutex() {
104 if (kLogLockContentions) {
105 ScopedAllMutexesLock mu(this);
106 gAllMutexData->all_mutexes->erase(this);
110 void BaseMutex::DumpAll(std::ostream& os) {
111 if (kLogLockContentions) {
112 os << "Mutex logging:\n";
113 ScopedAllMutexesLock mu(reinterpret_cast<const BaseMutex*>(-1));
114 std::set<BaseMutex*>* all_mutexes = gAllMutexData->all_mutexes;
115 if (all_mutexes == NULL) {
116 // No mutexes have been created yet during at startup.
119 typedef std::set<BaseMutex*>::const_iterator It;
120 os << "(Contended)\n";
121 for (It it = all_mutexes->begin(); it != all_mutexes->end(); ++it) {
122 BaseMutex* mutex = *it;
123 if (mutex->HasEverContended()) {
128 os << "(Never contented)\n";
129 for (It it = all_mutexes->begin(); it != all_mutexes->end(); ++it) {
130 BaseMutex* mutex = *it;
131 if (!mutex->HasEverContended()) {
139 void BaseMutex::CheckSafeToWait(Thread* self) {
141 CheckUnattachedThread(level_);
145 CHECK(self->GetHeldMutex(level_) == this || level_ == kMonitorLock)
146 << "Waiting on unacquired mutex: " << name_;
147 bool bad_mutexes_held = false;
148 for (int i = kLockLevelCount - 1; i >= 0; --i) {
150 BaseMutex* held_mutex = self->GetHeldMutex(static_cast<LockLevel>(i));
151 if (held_mutex != NULL) {
152 LOG(ERROR) << "Holding \"" << held_mutex->name_ << "\" "
153 << "(level " << LockLevel(i) << ") while performing wait on "
154 << "\"" << name_ << "\" (level " << level_ << ")";
155 bad_mutexes_held = true;
159 CHECK(!bad_mutexes_held);
163 inline void BaseMutex::ContentionLogData::AddToWaitTime(uint64_t value) {
164 if (kLogLockContentions) {
165 // Atomically add value to wait_time.
166 uint64_t new_val, old_val;
167 volatile int64_t* addr = reinterpret_cast<volatile int64_t*>(&wait_time);
168 volatile const int64_t* caddr = const_cast<volatile const int64_t*>(addr);
170 old_val = static_cast<uint64_t>(QuasiAtomic::Read64(caddr));
171 new_val = old_val + value;
172 } while (!QuasiAtomic::Cas64(static_cast<int64_t>(old_val), static_cast<int64_t>(new_val), addr));
176 void BaseMutex::RecordContention(uint64_t blocked_tid,
178 uint64_t nano_time_blocked) {
179 if (kLogLockContentions) {
180 ContentionLogData* data = contention_log_data_;
181 ++(data->contention_count);
182 data->AddToWaitTime(nano_time_blocked);
183 ContentionLogEntry* log = data->contention_log;
184 // This code is intentionally racy as it is only used for diagnostics.
185 uint32_t slot = data->cur_content_log_entry.LoadRelaxed();
186 if (log[slot].blocked_tid == blocked_tid &&
187 log[slot].owner_tid == blocked_tid) {
192 slot = data->cur_content_log_entry.LoadRelaxed();
193 new_slot = (slot + 1) % kContentionLogSize;
194 } while (!data->cur_content_log_entry.CompareExchangeWeakRelaxed(slot, new_slot));
195 log[new_slot].blocked_tid = blocked_tid;
196 log[new_slot].owner_tid = owner_tid;
197 log[new_slot].count.StoreRelaxed(1);
202 void BaseMutex::DumpContention(std::ostream& os) const {
203 if (kLogLockContentions) {
204 const ContentionLogData* data = contention_log_data_;
205 const ContentionLogEntry* log = data->contention_log;
206 uint64_t wait_time = data->wait_time;
207 uint32_t contention_count = data->contention_count.LoadRelaxed();
208 if (contention_count == 0) {
209 os << "never contended";
211 os << "contended " << contention_count
212 << " total wait of contender " << PrettyDuration(wait_time)
213 << " average " << PrettyDuration(wait_time / contention_count);
214 SafeMap<uint64_t, size_t> most_common_blocker;
215 SafeMap<uint64_t, size_t> most_common_blocked;
216 for (size_t i = 0; i < kContentionLogSize; ++i) {
217 uint64_t blocked_tid = log[i].blocked_tid;
218 uint64_t owner_tid = log[i].owner_tid;
219 uint32_t count = log[i].count.LoadRelaxed();
221 auto it = most_common_blocked.find(blocked_tid);
222 if (it != most_common_blocked.end()) {
223 most_common_blocked.Overwrite(blocked_tid, it->second + count);
225 most_common_blocked.Put(blocked_tid, count);
227 it = most_common_blocker.find(owner_tid);
228 if (it != most_common_blocker.end()) {
229 most_common_blocker.Overwrite(owner_tid, it->second + count);
231 most_common_blocker.Put(owner_tid, count);
235 uint64_t max_tid = 0;
236 size_t max_tid_count = 0;
237 for (const auto& pair : most_common_blocked) {
238 if (pair.second > max_tid_count) {
239 max_tid = pair.first;
240 max_tid_count = pair.second;
244 os << " sample shows most blocked tid=" << max_tid;
248 for (const auto& pair : most_common_blocker) {
249 if (pair.second > max_tid_count) {
250 max_tid = pair.first;
251 max_tid_count = pair.second;
255 os << " sample shows tid=" << max_tid << " owning during this time";
262 Mutex::Mutex(const char* name, LockLevel level, bool recursive)
263 : BaseMutex(name, level), recursive_(recursive), recursion_count_(0) {
265 DCHECK_EQ(0, state_.LoadRelaxed());
266 DCHECK_EQ(0, num_contenders_.LoadRelaxed());
268 CHECK_MUTEX_CALL(pthread_mutex_init, (&mutex_, nullptr));
270 exclusive_owner_ = 0;
275 if (state_.LoadRelaxed() != 0) {
276 Runtime* runtime = Runtime::Current();
277 bool shutting_down = runtime == nullptr || runtime->IsShuttingDown(Thread::Current());
278 LOG(shutting_down ? WARNING : FATAL) << "destroying mutex with owner: " << exclusive_owner_;
280 CHECK_EQ(exclusive_owner_, 0U) << "unexpectedly found an owner on unlocked mutex " << name_;
281 CHECK_EQ(num_contenders_.LoadSequentiallyConsistent(), 0)
282 << "unexpectedly found a contender on mutex " << name_;
285 // We can't use CHECK_MUTEX_CALL here because on shutdown a suspended daemon thread
286 // may still be using locks.
287 int rc = pthread_mutex_destroy(&mutex_);
290 // TODO: should we just not log at all if shutting down? this could be the logging mutex!
291 MutexLock mu(Thread::Current(), *Locks::runtime_shutdown_lock_);
292 Runtime* runtime = Runtime::Current();
293 bool shutting_down = (runtime == NULL) || runtime->IsShuttingDownLocked();
294 PLOG(shutting_down ? WARNING : FATAL) << "pthread_mutex_destroy failed for " << name_;
299 void Mutex::ExclusiveLock(Thread* self) {
300 DCHECK(self == NULL || self == Thread::Current());
301 if (kDebugLocking && !recursive_) {
304 if (!recursive_ || !IsExclusiveHeld(self)) {
308 int32_t cur_state = state_.LoadRelaxed();
309 if (LIKELY(cur_state == 0)) {
310 // Change state from 0 to 1 and impose load/store ordering appropriate for lock acquisition.
311 done = state_.CompareExchangeWeakAcquire(0 /* cur_state */, 1 /* new state */);
313 // Failed to acquire, hang up.
314 ScopedContentionRecorder scr(this, SafeGetTid(self), GetExclusiveOwnerTid());
316 if (futex(state_.Address(), FUTEX_WAIT, 1, NULL, NULL, 0) != 0) {
317 // EAGAIN and EINTR both indicate a spurious failure, try again from the beginning.
318 // We don't use TEMP_FAILURE_RETRY so we can intentionally retry to acquire the lock.
319 if ((errno != EAGAIN) && (errno != EINTR)) {
320 PLOG(FATAL) << "futex wait failed for " << name_;
326 DCHECK_EQ(state_.LoadRelaxed(), 1);
328 CHECK_MUTEX_CALL(pthread_mutex_lock, (&mutex_));
330 DCHECK_EQ(exclusive_owner_, 0U);
331 exclusive_owner_ = SafeGetTid(self);
332 RegisterAsLocked(self);
336 CHECK(recursion_count_ == 1 || recursive_) << "Unexpected recursion count on mutex: "
337 << name_ << " " << recursion_count_;
342 bool Mutex::ExclusiveTryLock(Thread* self) {
343 DCHECK(self == NULL || self == Thread::Current());
344 if (kDebugLocking && !recursive_) {
347 if (!recursive_ || !IsExclusiveHeld(self)) {
351 int32_t cur_state = state_.LoadRelaxed();
352 if (cur_state == 0) {
353 // Change state from 0 to 1 and impose load/store ordering appropriate for lock acquisition.
354 done = state_.CompareExchangeWeakAcquire(0 /* cur_state */, 1 /* new state */);
359 DCHECK_EQ(state_.LoadRelaxed(), 1);
361 int result = pthread_mutex_trylock(&mutex_);
362 if (result == EBUSY) {
367 PLOG(FATAL) << "pthread_mutex_trylock failed for " << name_;
370 DCHECK_EQ(exclusive_owner_, 0U);
371 exclusive_owner_ = SafeGetTid(self);
372 RegisterAsLocked(self);
376 CHECK(recursion_count_ == 1 || recursive_) << "Unexpected recursion count on mutex: "
377 << name_ << " " << recursion_count_;
383 void Mutex::ExclusiveUnlock(Thread* self) {
384 DCHECK(self == NULL || self == Thread::Current());
386 DCHECK_NE(exclusive_owner_, 0U);
388 if (!recursive_ || recursion_count_ == 0) {
390 CHECK(recursion_count_ == 0 || recursive_) << "Unexpected recursion count on mutex: "
391 << name_ << " " << recursion_count_;
393 RegisterAsUnlocked(self);
397 int32_t cur_state = state_.LoadRelaxed();
398 if (LIKELY(cur_state == 1)) {
399 // We're no longer the owner.
400 exclusive_owner_ = 0;
401 // Change state to 0 and impose load/store ordering appropriate for lock release.
402 // Note, the relaxed loads below musn't reorder before the CompareExchange.
403 // TODO: the ordering here is non-trivial as state is split across 3 fields, fix by placing
404 // a status bit into the state on contention.
405 done = state_.CompareExchangeWeakSequentiallyConsistent(cur_state, 0 /* new state */);
406 if (LIKELY(done)) { // Spurious fail?
408 if (UNLIKELY(num_contenders_.LoadRelaxed() > 0)) {
409 futex(state_.Address(), FUTEX_WAKE, 1, NULL, NULL, 0);
413 // Logging acquires the logging lock, avoid infinite recursion in that case.
414 if (this != Locks::logging_lock_) {
415 LOG(FATAL) << "Unexpected state_ in unlock " << cur_state << " for " << name_;
417 LogMessageData data(__FILE__, __LINE__, INTERNAL_FATAL, -1);
418 LogMessage::LogLine(data, StringPrintf("Unexpected state_ %d in unlock for %s",
419 cur_state, name_).c_str());
425 exclusive_owner_ = 0;
426 CHECK_MUTEX_CALL(pthread_mutex_unlock, (&mutex_));
431 void Mutex::Dump(std::ostream& os) const {
432 os << (recursive_ ? "recursive " : "non-recursive ")
434 << " level=" << static_cast<int>(level_)
435 << " rec=" << recursion_count_
436 << " owner=" << GetExclusiveOwnerTid() << " ";
440 std::ostream& operator<<(std::ostream& os, const Mutex& mu) {
445 ReaderWriterMutex::ReaderWriterMutex(const char* name, LockLevel level)
446 : BaseMutex(name, level)
448 , state_(0), num_pending_readers_(0), num_pending_writers_(0)
450 { // NOLINT(whitespace/braces)
452 CHECK_MUTEX_CALL(pthread_rwlock_init, (&rwlock_, nullptr));
454 exclusive_owner_ = 0;
457 ReaderWriterMutex::~ReaderWriterMutex() {
459 CHECK_EQ(state_.LoadRelaxed(), 0);
460 CHECK_EQ(exclusive_owner_, 0U);
461 CHECK_EQ(num_pending_readers_.LoadRelaxed(), 0);
462 CHECK_EQ(num_pending_writers_.LoadRelaxed(), 0);
464 // We can't use CHECK_MUTEX_CALL here because on shutdown a suspended daemon thread
465 // may still be using locks.
466 int rc = pthread_rwlock_destroy(&rwlock_);
469 // TODO: should we just not log at all if shutting down? this could be the logging mutex!
470 MutexLock mu(Thread::Current(), *Locks::runtime_shutdown_lock_);
471 Runtime* runtime = Runtime::Current();
472 bool shutting_down = runtime == NULL || runtime->IsShuttingDownLocked();
473 PLOG(shutting_down ? WARNING : FATAL) << "pthread_rwlock_destroy failed for " << name_;
478 void ReaderWriterMutex::ExclusiveLock(Thread* self) {
479 DCHECK(self == NULL || self == Thread::Current());
480 AssertNotExclusiveHeld(self);
484 int32_t cur_state = state_.LoadRelaxed();
485 if (LIKELY(cur_state == 0)) {
486 // Change state from 0 to -1 and impose load/store ordering appropriate for lock acquisition.
487 done = state_.CompareExchangeWeakAcquire(0 /* cur_state*/, -1 /* new state */);
489 // Failed to acquire, hang up.
490 ScopedContentionRecorder scr(this, SafeGetTid(self), GetExclusiveOwnerTid());
491 ++num_pending_writers_;
492 if (futex(state_.Address(), FUTEX_WAIT, cur_state, NULL, NULL, 0) != 0) {
493 // EAGAIN and EINTR both indicate a spurious failure, try again from the beginning.
494 // We don't use TEMP_FAILURE_RETRY so we can intentionally retry to acquire the lock.
495 if ((errno != EAGAIN) && (errno != EINTR)) {
496 PLOG(FATAL) << "futex wait failed for " << name_;
499 --num_pending_writers_;
502 DCHECK_EQ(state_.LoadRelaxed(), -1);
504 CHECK_MUTEX_CALL(pthread_rwlock_wrlock, (&rwlock_));
506 DCHECK_EQ(exclusive_owner_, 0U);
507 exclusive_owner_ = SafeGetTid(self);
508 RegisterAsLocked(self);
509 AssertExclusiveHeld(self);
512 void ReaderWriterMutex::ExclusiveUnlock(Thread* self) {
513 DCHECK(self == NULL || self == Thread::Current());
514 AssertExclusiveHeld(self);
515 RegisterAsUnlocked(self);
516 DCHECK_NE(exclusive_owner_, 0U);
520 int32_t cur_state = state_.LoadRelaxed();
521 if (LIKELY(cur_state == -1)) {
522 // We're no longer the owner.
523 exclusive_owner_ = 0;
524 // Change state from -1 to 0 and impose load/store ordering appropriate for lock release.
525 // Note, the relaxed loads below musn't reorder before the CompareExchange.
526 // TODO: the ordering here is non-trivial as state is split across 3 fields, fix by placing
527 // a status bit into the state on contention.
528 done = state_.CompareExchangeWeakSequentiallyConsistent(-1 /* cur_state*/, 0 /* new state */);
529 if (LIKELY(done)) { // Weak CAS may fail spuriously.
531 if (UNLIKELY(num_pending_readers_.LoadRelaxed() > 0 ||
532 num_pending_writers_.LoadRelaxed() > 0)) {
533 futex(state_.Address(), FUTEX_WAKE, -1, NULL, NULL, 0);
537 LOG(FATAL) << "Unexpected state_:" << cur_state << " for " << name_;
541 exclusive_owner_ = 0;
542 CHECK_MUTEX_CALL(pthread_rwlock_unlock, (&rwlock_));
546 #if HAVE_TIMED_RWLOCK
547 bool ReaderWriterMutex::ExclusiveLockWithTimeout(Thread* self, int64_t ms, int32_t ns) {
548 DCHECK(self == NULL || self == Thread::Current());
552 InitTimeSpec(true, CLOCK_REALTIME, ms, ns, &end_abs_ts);
554 int32_t cur_state = state_.LoadRelaxed();
555 if (cur_state == 0) {
556 // Change state from 0 to -1 and impose load/store ordering appropriate for lock acquisition.
557 done = state_.CompareExchangeWeakAcquire(0 /* cur_state */, -1 /* new state */);
559 // Failed to acquire, hang up.
561 InitTimeSpec(true, CLOCK_REALTIME, 0, 0, &now_abs_ts);
563 if (ComputeRelativeTimeSpec(&rel_ts, end_abs_ts, now_abs_ts)) {
564 return false; // Timed out.
566 ScopedContentionRecorder scr(this, SafeGetTid(self), GetExclusiveOwnerTid());
567 ++num_pending_writers_;
568 if (futex(state_.Address(), FUTEX_WAIT, cur_state, &rel_ts, NULL, 0) != 0) {
569 if (errno == ETIMEDOUT) {
570 --num_pending_writers_;
571 return false; // Timed out.
572 } else if ((errno != EAGAIN) && (errno != EINTR)) {
573 // EAGAIN and EINTR both indicate a spurious failure,
574 // recompute the relative time out from now and try again.
575 // We don't use TEMP_FAILURE_RETRY so we can recompute rel_ts;
576 PLOG(FATAL) << "timed futex wait failed for " << name_;
579 --num_pending_writers_;
584 InitTimeSpec(true, CLOCK_REALTIME, ms, ns, &ts);
585 int result = pthread_rwlock_timedwrlock(&rwlock_, &ts);
586 if (result == ETIMEDOUT) {
591 PLOG(FATAL) << "pthread_rwlock_timedwrlock failed for " << name_;
594 exclusive_owner_ = SafeGetTid(self);
595 RegisterAsLocked(self);
596 AssertSharedHeld(self);
601 bool ReaderWriterMutex::SharedTryLock(Thread* self) {
602 DCHECK(self == NULL || self == Thread::Current());
606 int32_t cur_state = state_.LoadRelaxed();
607 if (cur_state >= 0) {
608 // Add as an extra reader and impose load/store ordering appropriate for lock acquisition.
609 done = state_.CompareExchangeWeakAcquire(cur_state, cur_state + 1);
611 // Owner holds it exclusively.
616 int result = pthread_rwlock_tryrdlock(&rwlock_);
617 if (result == EBUSY) {
622 PLOG(FATAL) << "pthread_mutex_trylock failed for " << name_;
625 RegisterAsLocked(self);
626 AssertSharedHeld(self);
630 bool ReaderWriterMutex::IsSharedHeld(const Thread* self) const {
631 DCHECK(self == NULL || self == Thread::Current());
633 if (UNLIKELY(self == NULL)) { // Handle unattached threads.
634 result = IsExclusiveHeld(self); // TODO: a better best effort here.
636 result = (self->GetHeldMutex(level_) == this);
641 void ReaderWriterMutex::Dump(std::ostream& os) const {
643 << " level=" << static_cast<int>(level_)
644 << " owner=" << GetExclusiveOwnerTid() << " ";
648 std::ostream& operator<<(std::ostream& os, const ReaderWriterMutex& mu) {
653 ConditionVariable::ConditionVariable(const char* name, Mutex& guard)
654 : name_(name), guard_(guard) {
656 DCHECK_EQ(0, sequence_.LoadRelaxed());
659 pthread_condattr_t cond_attrs;
660 CHECK_MUTEX_CALL(pthread_condattr_init, (&cond_attrs));
661 #if !defined(__APPLE__)
662 // Apple doesn't have CLOCK_MONOTONIC or pthread_condattr_setclock.
663 CHECK_MUTEX_CALL(pthread_condattr_setclock(&cond_attrs, CLOCK_MONOTONIC));
665 CHECK_MUTEX_CALL(pthread_cond_init, (&cond_, &cond_attrs));
669 ConditionVariable::~ConditionVariable() {
671 if (num_waiters_!= 0) {
672 Runtime* runtime = Runtime::Current();
673 bool shutting_down = runtime == nullptr || runtime->IsShuttingDown(Thread::Current());
674 LOG(shutting_down ? WARNING : FATAL) << "ConditionVariable::~ConditionVariable for " << name_
675 << " called with " << num_waiters_ << " waiters.";
678 // We can't use CHECK_MUTEX_CALL here because on shutdown a suspended daemon thread
679 // may still be using condition variables.
680 int rc = pthread_cond_destroy(&cond_);
683 MutexLock mu(Thread::Current(), *Locks::runtime_shutdown_lock_);
684 Runtime* runtime = Runtime::Current();
685 bool shutting_down = (runtime == NULL) || runtime->IsShuttingDownLocked();
686 PLOG(shutting_down ? WARNING : FATAL) << "pthread_cond_destroy failed for " << name_;
691 void ConditionVariable::Broadcast(Thread* self) {
692 DCHECK(self == NULL || self == Thread::Current());
693 // TODO: enable below, there's a race in thread creation that causes false failures currently.
694 // guard_.AssertExclusiveHeld(self);
695 DCHECK_EQ(guard_.GetExclusiveOwnerTid(), SafeGetTid(self));
697 if (num_waiters_ > 0) {
698 sequence_++; // Indicate the broadcast occurred.
701 int32_t cur_sequence = sequence_.LoadRelaxed();
702 // Requeue waiters onto mutex. The waiter holds the contender count on the mutex high ensuring
703 // mutex unlocks will awaken the requeued waiter thread.
704 done = futex(sequence_.Address(), FUTEX_CMP_REQUEUE, 0,
705 reinterpret_cast<const timespec*>(std::numeric_limits<int32_t>::max()),
706 guard_.state_.Address(), cur_sequence) != -1;
708 if (errno != EAGAIN) {
709 PLOG(FATAL) << "futex cmp requeue failed for " << name_;
715 CHECK_MUTEX_CALL(pthread_cond_broadcast, (&cond_));
719 void ConditionVariable::Signal(Thread* self) {
720 DCHECK(self == NULL || self == Thread::Current());
721 guard_.AssertExclusiveHeld(self);
723 if (num_waiters_ > 0) {
724 sequence_++; // Indicate a signal occurred.
725 // Futex wake 1 waiter who will then come and in contend on mutex. It'd be nice to requeue them
726 // to avoid this, however, requeueing can only move all waiters.
727 int num_woken = futex(sequence_.Address(), FUTEX_WAKE, 1, NULL, NULL, 0);
728 // Check something was woken or else we changed sequence_ before they had chance to wait.
729 CHECK((num_woken == 0) || (num_woken == 1));
732 CHECK_MUTEX_CALL(pthread_cond_signal, (&cond_));
736 void ConditionVariable::Wait(Thread* self) {
737 guard_.CheckSafeToWait(self);
738 WaitHoldingLocks(self);
741 void ConditionVariable::WaitHoldingLocks(Thread* self) {
742 DCHECK(self == NULL || self == Thread::Current());
743 guard_.AssertExclusiveHeld(self);
744 unsigned int old_recursion_count = guard_.recursion_count_;
747 // Ensure the Mutex is contended so that requeued threads are awoken.
748 guard_.num_contenders_++;
749 guard_.recursion_count_ = 1;
750 int32_t cur_sequence = sequence_.LoadRelaxed();
751 guard_.ExclusiveUnlock(self);
752 if (futex(sequence_.Address(), FUTEX_WAIT, cur_sequence, NULL, NULL, 0) != 0) {
753 // Futex failed, check it is an expected error.
754 // EAGAIN == EWOULDBLK, so we let the caller try again.
755 // EINTR implies a signal was sent to this thread.
756 if ((errno != EINTR) && (errno != EAGAIN)) {
757 PLOG(FATAL) << "futex wait failed for " << name_;
760 guard_.ExclusiveLock(self);
761 CHECK_GE(num_waiters_, 0);
763 // We awoke and so no longer require awakes from the guard_'s unlock.
764 CHECK_GE(guard_.num_contenders_.LoadRelaxed(), 0);
765 guard_.num_contenders_--;
767 uint64_t old_owner = guard_.exclusive_owner_;
768 guard_.exclusive_owner_ = 0;
769 guard_.recursion_count_ = 0;
770 CHECK_MUTEX_CALL(pthread_cond_wait, (&cond_, &guard_.mutex_));
771 guard_.exclusive_owner_ = old_owner;
773 guard_.recursion_count_ = old_recursion_count;
776 void ConditionVariable::TimedWait(Thread* self, int64_t ms, int32_t ns) {
777 DCHECK(self == NULL || self == Thread::Current());
778 guard_.AssertExclusiveHeld(self);
779 guard_.CheckSafeToWait(self);
780 unsigned int old_recursion_count = guard_.recursion_count_;
783 InitTimeSpec(false, CLOCK_REALTIME, ms, ns, &rel_ts);
785 // Ensure the Mutex is contended so that requeued threads are awoken.
786 guard_.num_contenders_++;
787 guard_.recursion_count_ = 1;
788 int32_t cur_sequence = sequence_.LoadRelaxed();
789 guard_.ExclusiveUnlock(self);
790 if (futex(sequence_.Address(), FUTEX_WAIT, cur_sequence, &rel_ts, NULL, 0) != 0) {
791 if (errno == ETIMEDOUT) {
792 // Timed out we're done.
793 } else if ((errno == EAGAIN) || (errno == EINTR)) {
794 // A signal or ConditionVariable::Signal/Broadcast has come in.
796 PLOG(FATAL) << "timed futex wait failed for " << name_;
799 guard_.ExclusiveLock(self);
800 CHECK_GE(num_waiters_, 0);
802 // We awoke and so no longer require awakes from the guard_'s unlock.
803 CHECK_GE(guard_.num_contenders_.LoadRelaxed(), 0);
804 guard_.num_contenders_--;
806 #if !defined(__APPLE__)
807 int clock = CLOCK_MONOTONIC;
809 int clock = CLOCK_REALTIME;
811 uint64_t old_owner = guard_.exclusive_owner_;
812 guard_.exclusive_owner_ = 0;
813 guard_.recursion_count_ = 0;
815 InitTimeSpec(true, clock, ms, ns, &ts);
816 int rc = TEMP_FAILURE_RETRY(pthread_cond_timedwait(&cond_, &guard_.mutex_, &ts));
817 if (rc != 0 && rc != ETIMEDOUT) {
819 PLOG(FATAL) << "TimedWait failed for " << name_;
821 guard_.exclusive_owner_ = old_owner;
823 guard_.recursion_count_ = old_recursion_count;
827 if (logging_lock_ != nullptr) {
828 // Already initialized.
829 if (kRuntimeISA == kX86 || kRuntimeISA == kX86_64) {
830 DCHECK(modify_ldt_lock_ != nullptr);
832 DCHECK(modify_ldt_lock_ == nullptr);
834 DCHECK(abort_lock_ != nullptr);
835 DCHECK(allocated_thread_ids_lock_ != nullptr);
836 DCHECK(breakpoint_lock_ != nullptr);
837 DCHECK(classlinker_classes_lock_ != nullptr);
838 DCHECK(heap_bitmap_lock_ != nullptr);
839 DCHECK(logging_lock_ != nullptr);
840 DCHECK(mutator_lock_ != nullptr);
841 DCHECK(thread_list_lock_ != nullptr);
842 DCHECK(thread_suspend_count_lock_ != nullptr);
843 DCHECK(trace_lock_ != nullptr);
844 DCHECK(profiler_lock_ != nullptr);
845 DCHECK(unexpected_signal_lock_ != nullptr);
846 DCHECK(intern_table_lock_ != nullptr);
848 // Create global locks in level order from highest lock level to lowest.
849 LockLevel current_lock_level = kMutatorLock;
850 DCHECK(mutator_lock_ == nullptr);
851 mutator_lock_ = new ReaderWriterMutex("mutator lock", current_lock_level);
853 #define UPDATE_CURRENT_LOCK_LEVEL(new_level) \
854 DCHECK_LT(new_level, current_lock_level); \
855 current_lock_level = new_level;
857 UPDATE_CURRENT_LOCK_LEVEL(kHeapBitmapLock);
858 DCHECK(heap_bitmap_lock_ == nullptr);
859 heap_bitmap_lock_ = new ReaderWriterMutex("heap bitmap lock", current_lock_level);
861 UPDATE_CURRENT_LOCK_LEVEL(kRuntimeShutdownLock);
862 DCHECK(runtime_shutdown_lock_ == nullptr);
863 runtime_shutdown_lock_ = new Mutex("runtime shutdown lock", current_lock_level);
865 UPDATE_CURRENT_LOCK_LEVEL(kProfilerLock);
866 DCHECK(profiler_lock_ == nullptr);
867 profiler_lock_ = new Mutex("profiler lock", current_lock_level);
869 UPDATE_CURRENT_LOCK_LEVEL(kTraceLock);
870 DCHECK(trace_lock_ == nullptr);
871 trace_lock_ = new Mutex("trace lock", current_lock_level);
873 UPDATE_CURRENT_LOCK_LEVEL(kThreadListLock);
874 DCHECK(thread_list_lock_ == nullptr);
875 thread_list_lock_ = new Mutex("thread list lock", current_lock_level);
877 UPDATE_CURRENT_LOCK_LEVEL(kBreakpointLock);
878 DCHECK(breakpoint_lock_ == nullptr);
879 breakpoint_lock_ = new Mutex("breakpoint lock", current_lock_level);
881 UPDATE_CURRENT_LOCK_LEVEL(kClassLinkerClassesLock);
882 DCHECK(classlinker_classes_lock_ == nullptr);
883 classlinker_classes_lock_ = new ReaderWriterMutex("ClassLinker classes lock",
886 UPDATE_CURRENT_LOCK_LEVEL(kAllocatedThreadIdsLock);
887 DCHECK(allocated_thread_ids_lock_ == nullptr);
888 allocated_thread_ids_lock_ = new Mutex("allocated thread ids lock", current_lock_level);
890 if (kRuntimeISA == kX86 || kRuntimeISA == kX86_64) {
891 UPDATE_CURRENT_LOCK_LEVEL(kModifyLdtLock);
892 DCHECK(modify_ldt_lock_ == nullptr);
893 modify_ldt_lock_ = new Mutex("modify_ldt lock", current_lock_level);
896 UPDATE_CURRENT_LOCK_LEVEL(kInternTableLock);
897 DCHECK(intern_table_lock_ == nullptr);
898 intern_table_lock_ = new Mutex("InternTable lock", current_lock_level);
901 UPDATE_CURRENT_LOCK_LEVEL(kAbortLock);
902 DCHECK(abort_lock_ == nullptr);
903 abort_lock_ = new Mutex("abort lock", current_lock_level, true);
905 UPDATE_CURRENT_LOCK_LEVEL(kThreadSuspendCountLock);
906 DCHECK(thread_suspend_count_lock_ == nullptr);
907 thread_suspend_count_lock_ = new Mutex("thread suspend count lock", current_lock_level);
909 UPDATE_CURRENT_LOCK_LEVEL(kUnexpectedSignalLock);
910 DCHECK(unexpected_signal_lock_ == nullptr);
911 unexpected_signal_lock_ = new Mutex("unexpected signal lock", current_lock_level, true);
913 UPDATE_CURRENT_LOCK_LEVEL(kMemMapsLock);
914 DCHECK(mem_maps_lock_ == nullptr);
915 mem_maps_lock_ = new Mutex("mem maps lock", current_lock_level);
917 UPDATE_CURRENT_LOCK_LEVEL(kLoggingLock);
918 DCHECK(logging_lock_ == nullptr);
919 logging_lock_ = new Mutex("logging lock", current_lock_level, true);
921 #undef UPDATE_CURRENT_LOCK_LEVEL