semaphore.h

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2019, Google Inc.
 *
 * semaphore.h - General-purpose counting semaphore
 */
 
#pragma once
 
#include <libcamera/base/private.h>
 
#include <libcamera/base/mutex.h>
 
namespace libcamera {
 
class Semaphore
{
public:
    Semaphore(unsigned int n = 0);
 
    unsigned int available() LIBCAMERA_TSA_EXCLUDES(mutex_);
    void acquire(unsigned int n = 1) LIBCAMERA_TSA_EXCLUDES(mutex_);
    bool tryAcquire(unsigned int n = 1) LIBCAMERA_TSA_EXCLUDES(mutex_);
    void release(unsigned int n = 1) LIBCAMERA_TSA_EXCLUDES(mutex_);
 
private:
    Mutex mutex_;
    ConditionVariable cv_;
    unsigned int available_ LIBCAMERA_TSA_GUARDED_BY(mutex_);
};
 
} /* namespace libcamera */