// Copyright 2013 the V8 project 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 "src/base/platform/semaphore.h"

#if V8_OS_DARWIN

#include <dispatch/dispatch.h>

#elif V8_OS_WIN

#include <windows.h>

#endif

#include <errno.h>

#include "src/base/logging.h"

#include "src/base/platform/elapsed-timer.h"

#include "src/base/platform/time.h"

namespace v8 {

namespace base {

#if V8_OS_DARWIN

Semaphore::Semaphore(int count) {

native_handle_ = dispatch_semaphore_create(count);

DCHECK(native_handle_);

}

Semaphore::~Semaphore() { dispatch_release(native_handle_); }

void Semaphore::Signal() { dispatch_semaphore_signal(native_handle_); }

void Semaphore::Wait() {

dispatch_semaphore_wait(native_handle_, DISPATCH_TIME_FOREVER);

}

bool Semaphore::WaitFor(const TimeDelta& rel_time) {

dispatch_time_t timeout =

dispatch_time(DISPATCH_TIME_NOW, rel_time.InNanoseconds());

return dispatch_semaphore_wait(native_handle_, timeout) == 0;

}

#elif V8_OS_POSIX

Semaphore::Semaphore(int count) {

DCHECK_GE(count, 0);

int result = sem_init(&native_handle_, 0, count);

DCHECK_EQ(0, result);

USE(result);

}

Semaphore::~Semaphore() {

int result = sem_destroy(&native_handle_);

DCHECK_EQ(0, result);

USE(result);

}

void Semaphore::Signal() {

int result = sem_post(&native_handle_);

// This check may fail with <libc-2.21, which we use on the try bots, if the

// semaphore is destroyed while sem_post is still executed. A work around is

// to extend the lifetime of the semaphore.

if (result != 0) {

FATAL("Error when signaling semaphore, errno: %d", errno);

}

}

void Semaphore::Wait() {

while (true) {

int result = sem_wait(&native_handle_);

if (result == 0) return; // Semaphore was signalled.

// Signal caused spurious wakeup.

DCHECK_EQ(-1, result);

DCHECK_EQ(EINTR, errno);

}

}

bool Semaphore::WaitFor(const TimeDelta& rel_time) {

// Compute the time for end of timeout.

const Time time = Time::NowFromSystemTime() + rel_time;

const struct timespec ts = time.ToTimespec();

// Wait for semaphore signalled or timeout.

while (true) {

int result = sem_timedwait(&native_handle_, &ts);

if (result == 0) return true; // Semaphore was signalled.

#if V8_LIBC_GLIBC && !V8_GLIBC_PREREQ(2, 4)

if (result > 0) {

// sem_timedwait in glibc prior to 2.3.4 returns the errno instead of -1.

errno = result;

result = -1;

}

#endif

if (result == -1 && errno == ETIMEDOUT) {

// Timed out while waiting for semaphore.

return false;

}

// Signal caused spurious wakeup.

DCHECK_EQ(-1, result);

DCHECK_EQ(EINTR, errno);

}

}

#elif V8_OS_WIN

Semaphore::Semaphore(int count) {

DCHECK_GE(count, 0);

native_handle_ = ::CreateSemaphoreA(nullptr, count, 0x7FFFFFFF, nullptr);

DCHECK_NOT_NULL(native_handle_);

}

Semaphore::~Semaphore() {

BOOL result = CloseHandle(native_handle_);

DCHECK(result);

USE(result);

}

void Semaphore::Signal() {

LONG dummy;

BOOL result = ReleaseSemaphore(native_handle_, 1, &dummy);

DCHECK(result);

USE(result);

}

void Semaphore::Wait() {

DWORD result = WaitForSingleObject(native_handle_, INFINITE);

DCHECK(result == WAIT_OBJECT_0);

USE(result);

}

bool Semaphore::WaitFor(const TimeDelta& rel_time) {

TimeTicks now = TimeTicks::Now();

TimeTicks end = now + rel_time;

while (true) {

int64_t msec = (end - now).InMilliseconds();

if (msec >= static_cast<int64_t>(INFINITE)) {

DWORD result = WaitForSingleObject(native_handle_, INFINITE - 1);

if (result == WAIT_OBJECT_0) {

return true;

}

DCHECK(result == WAIT_TIMEOUT);

now = TimeTicks::Now();

} else {

DWORD result = WaitForSingleObject(

native_handle_, (msec < 0) ? 0 : static_cast<DWORD>(msec));

if (result == WAIT_TIMEOUT) {

return false;

}

DCHECK(result == WAIT_OBJECT_0);

return true;

}

}

}

#elif V8_OS_STARBOARD

Semaphore::Semaphore(int count) : native_handle_(count) { DCHECK_GE(count, 0); }

Semaphore::~Semaphore() {}

void Semaphore::Signal() { native_handle_.Put(); }

void Semaphore::Wait() { native_handle_.Take(); }

bool Semaphore::WaitFor(const TimeDelta& rel_time) {

int64_t microseconds = rel_time.InMicroseconds();

return native_handle_.TakeWait(microseconds);

}

#endif // V8_OS_DARWIN

} // namespace base

} // namespace v8