semaphore.h

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2019, Google Inc.
 *
 * 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 */