// thread/kaldi-semaphore.cc

// Copyright 2012 Karel Vesely (Brno University of Technology)

// See ../../COPYING for clarification regarding multiple authors

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED

// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,

// MERCHANTABLITY OR NON-INFRINGEMENT.

// See the Apache 2 License for the specific language governing permissions and

// limitations under the License.

#include "base/kaldi-error.h"

#include "thread/kaldi-semaphore.h"

namespace kaldi {

Semaphore::Semaphore(int32 initValue) {

counter_ = initValue;

if (pthread_mutex_init(&mutex_, NULL) != 0) {

KALDI_ERR << "Cannot initialize pthread mutex";

}

if (pthread_cond_init(&cond_, NULL) != 0) {

KALDI_ERR << "Cannot initialize pthread conditional variable";

}

}

Semaphore::~Semaphore() {

if (pthread_mutex_destroy(&mutex_) != 0) {

KALDI_ERR << "Cannot destroy pthread mutex";

}

if (pthread_cond_destroy(&cond_) != 0) {

KALDI_ERR << "Cannot destroy pthread conditional variable";

}

}

bool Semaphore::TryWait() {

int32 ret = 0;

bool try_wait_succeeded = false;

ret |= pthread_mutex_lock(&mutex_);

if (counter_ > 0) {

counter_--;

try_wait_succeeded = true;

}

ret |= pthread_mutex_unlock(&mutex_);

if (ret != 0) {

KALDI_ERR << "Error in pthreads";

}

return try_wait_succeeded;

}

void Semaphore::Wait() {

int32 ret = 0;

ret |= pthread_mutex_lock(&mutex_);

while (counter_ <= 0) {

ret |= pthread_cond_wait(&cond_, &mutex_);

}

counter_--;

ret |= pthread_mutex_unlock(&mutex_);

if (ret != 0) {

KALDI_ERR << "Error in pthreads";

}

}

void Semaphore::Signal() {

int32 ret = 0;

ret |= pthread_mutex_lock(&mutex_);

counter_++;

ret |= pthread_cond_signal(&cond_);

ret |= pthread_mutex_unlock(&mutex_);

if (ret != 0) {

KALDI_ERR << "Error in pthreads";

}

}

} // namespace kaldi