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- // Copyright (c) 2011 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "base/synchronization/condition_variable.h"
- #include <errno.h>
- #include <stdint.h>
- #include <sys/time.h>
- #include "base/synchronization/lock.h"
- #include "base/threading/scoped_blocking_call.h"
- #include "base/threading/thread_restrictions.h"
- #include "base/time/time.h"
- #include "build/build_config.h"
- #include "third_party/abseil-cpp/absl/types/optional.h"
- #if BUILDFLAG(IS_ANDROID) && __ANDROID_API__ < 21
- #define HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC 1
- #endif
- namespace base {
- ConditionVariable::ConditionVariable(Lock* user_lock)
- : user_mutex_(user_lock->lock_.native_handle())
- #if DCHECK_IS_ON()
- , user_lock_(user_lock)
- #endif
- {
- int rv = 0;
- // http://crbug.com/293736
- // NaCl doesn't support monotonic clock based absolute deadlines.
- // On older Android platform versions, it's supported through the
- // non-standard pthread_cond_timedwait_monotonic_np. Newer platform
- // versions have pthread_condattr_setclock.
- // Mac can use relative time deadlines.
- #if !BUILDFLAG(IS_APPLE) && !BUILDFLAG(IS_NACL) && \
- !defined(HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC)
- pthread_condattr_t attrs;
- rv = pthread_condattr_init(&attrs);
- DCHECK_EQ(0, rv);
- pthread_condattr_setclock(&attrs, CLOCK_MONOTONIC);
- rv = pthread_cond_init(&condition_, &attrs);
- pthread_condattr_destroy(&attrs);
- #else
- rv = pthread_cond_init(&condition_, NULL);
- #endif
- DCHECK_EQ(0, rv);
- }
- ConditionVariable::~ConditionVariable() {
- #if BUILDFLAG(IS_APPLE)
- // This hack is necessary to avoid a fatal pthreads subsystem bug in the
- // Darwin kernel. http://crbug.com/517681.
- {
- base::Lock lock;
- base::AutoLock l(lock);
- struct timespec ts;
- ts.tv_sec = 0;
- ts.tv_nsec = 1;
- pthread_cond_timedwait_relative_np(&condition_, lock.lock_.native_handle(),
- &ts);
- }
- #endif
- int rv = pthread_cond_destroy(&condition_);
- DCHECK_EQ(0, rv);
- }
- void ConditionVariable::Wait() {
- absl::optional<internal::ScopedBlockingCallWithBaseSyncPrimitives>
- scoped_blocking_call;
- if (waiting_is_blocking_)
- scoped_blocking_call.emplace(FROM_HERE, BlockingType::MAY_BLOCK);
- #if DCHECK_IS_ON()
- user_lock_->CheckHeldAndUnmark();
- #endif
- int rv = pthread_cond_wait(&condition_, user_mutex_);
- DCHECK_EQ(0, rv);
- #if DCHECK_IS_ON()
- user_lock_->CheckUnheldAndMark();
- #endif
- }
- void ConditionVariable::TimedWait(const TimeDelta& max_time) {
- absl::optional<internal::ScopedBlockingCallWithBaseSyncPrimitives>
- scoped_blocking_call;
- if (waiting_is_blocking_)
- scoped_blocking_call.emplace(FROM_HERE, BlockingType::MAY_BLOCK);
- int64_t usecs = max_time.InMicroseconds();
- struct timespec relative_time;
- relative_time.tv_sec =
- static_cast<time_t>(usecs / Time::kMicrosecondsPerSecond);
- relative_time.tv_nsec =
- (usecs % Time::kMicrosecondsPerSecond) * Time::kNanosecondsPerMicrosecond;
- #if DCHECK_IS_ON()
- user_lock_->CheckHeldAndUnmark();
- #endif
- #if BUILDFLAG(IS_APPLE)
- int rv = pthread_cond_timedwait_relative_np(
- &condition_, user_mutex_, &relative_time);
- #else
- // The timeout argument to pthread_cond_timedwait is in absolute time.
- struct timespec absolute_time;
- #if BUILDFLAG(IS_NACL)
- // See comment in constructor for why this is different in NaCl.
- struct timeval now;
- gettimeofday(&now, NULL);
- absolute_time.tv_sec = now.tv_sec;
- absolute_time.tv_nsec = now.tv_usec * Time::kNanosecondsPerMicrosecond;
- #else
- struct timespec now;
- clock_gettime(CLOCK_MONOTONIC, &now);
- absolute_time.tv_sec = now.tv_sec;
- absolute_time.tv_nsec = now.tv_nsec;
- #endif
- absolute_time.tv_sec += relative_time.tv_sec;
- absolute_time.tv_nsec += relative_time.tv_nsec;
- absolute_time.tv_sec += absolute_time.tv_nsec / Time::kNanosecondsPerSecond;
- absolute_time.tv_nsec %= Time::kNanosecondsPerSecond;
- DCHECK_GE(absolute_time.tv_sec, now.tv_sec); // Overflow paranoia
- #if defined(HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC)
- int rv = pthread_cond_timedwait_monotonic_np(
- &condition_, user_mutex_, &absolute_time);
- #else
- int rv = pthread_cond_timedwait(&condition_, user_mutex_, &absolute_time);
- #endif // HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC
- #endif // BUILDFLAG(IS_APPLE)
- // On failure, we only expect the CV to timeout. Any other error value means
- // that we've unexpectedly woken up.
- DCHECK(rv == 0 || rv == ETIMEDOUT);
- #if DCHECK_IS_ON()
- user_lock_->CheckUnheldAndMark();
- #endif
- }
- void ConditionVariable::Broadcast() {
- int rv = pthread_cond_broadcast(&condition_);
- DCHECK_EQ(0, rv);
- }
- void ConditionVariable::Signal() {
- int rv = pthread_cond_signal(&condition_);
- DCHECK_EQ(0, rv);
- }
- } // namespace base
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