// thread/kaldi-semaphore.h

// 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.

#ifndef KALDI_THREAD_KALDI_SEMAPHORE_H_

#define KALDI_THREAD_KALDI_SEMAPHORE_H_ 1

#include <pthread.h>

namespace kaldi {

class Semaphore {

public:

Semaphore(int32 initValue = 0);

~Semaphore();

bool TryWait(); ///< Returns true if Wait() goes through

void Wait(); ///< decrease the counter

void Signal(); ///< increase the counter

/**

* returns the counter value,

* zero means no resources, the Wait() will block

*/

int32 GetValue() {

return counter_;

}

private:

int32 counter_; ///< the semaphore counter, 0 means block on Wait()

pthread_mutex_t mutex_;

pthread_cond_t cond_;

KALDI_DISALLOW_COPY_AND_ASSIGN(Semaphore);

};

} //namespace

#endif // KALDI_THREAD_KALDI_SEMAPHORE_H_