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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 = 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