condition_variable_posix.cc

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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/optional.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"

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 !defined(OS_MACOSX) && !defined(OS_NACL) && \

      !(defined(OS_ANDROID) && 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 defined(OS_MACOSX)

  // 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() {

  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) {

  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 = usecs / Time::kMicrosecondsPerSecond;

  relative_time.tv_nsec =

      (usecs % Time::kMicrosecondsPerSecond) * Time::kNanosecondsPerMicrosecond;

#if DCHECK_IS_ON()

  user_lock_->CheckHeldAndUnmark();

#endif

#if defined(OS_MACOSX)

  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 defined(OS_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(OS_ANDROID) && 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  // OS_ANDROID && HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC

#endif  // OS_MACOSX

  // 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