source: xplcommon/src/xplcommon/posix/CondVar.h@ 34:ad3194cb9bef

// Copyright (c) 2013 by István Váradi

// This file is part of libxplcommon, a common utility library for
// development related to X-Plane

// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:

// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// The views and conclusions contained in the software and documentation are those
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#ifndef XPLCOMMON_POSIX_CONDVAR_H
#define XPLCOMMON_POSIX_CONDVAR_H
//------------------------------------------------------------------------------

#include "Mutex.h"

//------------------------------------------------------------------------------

namespace xplcommon { namespace posix {

//------------------------------------------------------------------------------

/**
 * A condition variable for POSIX threads.
 */
class CondVar
{
private:
    /**
     * Fill the given timespec with the absolute time corresponding to
     * the given relative timeout.
     */
    static void getAbsTime(struct ::timespec& abstime, int timeout);

    /**
     * The pthreads structure.
     */
    pthread_cond_t cond;

public:
    /**
     * Construct the condition variable.
     */
    CondVar();

    /**
     * Destroy the condition variable.
     */
    ~CondVar();

    /**
     * Wait for the condition variable.
     *
     * @param mutex the mutex to unlock and re-lock.
     * @param timeout the number of milliseconds to wait at most. If
     * negative, the function will wait indefinitely.
     *
     * @return true, if the condition variable was signalled, false
     * if a timeout occured
     */
    bool wait(Mutex& mutex, int timeout = -1);

    /**
     * Signal the condition variable to wake up one thread.
     */
    void signal();

    /**
     * Signal all threads waiting on the condition variable.
     */
    void broadcast();
};

//------------------------------------------------------------------------------
// Inline definitions
//------------------------------------------------------------------------------

inline CondVar::CondVar()
{
    pthread_cond_init(&cond, 0);
}

//------------------------------------------------------------------------------

inline CondVar::~CondVar()
{
    pthread_cond_destroy(&cond);
}

//------------------------------------------------------------------------------

inline bool CondVar::wait(Mutex& mutex, int timeout)
{
    if (timeout<0) {
        pthread_cond_wait(&cond, &mutex.mutex);
        return true;
    } else {
        struct ::timespec abstime;
        getAbsTime(abstime, timeout);
        return pthread_cond_timedwait(&cond, &mutex.mutex, &abstime)==0;
    }
}

//------------------------------------------------------------------------------

inline void CondVar::signal()
{
    pthread_cond_signal(&cond);
}

//------------------------------------------------------------------------------

inline void CondVar::broadcast()
{
    pthread_cond_broadcast(&cond);
}

//------------------------------------------------------------------------------

} /* namespace xplcommon::posix */ } /* namespace xplcommon */

//------------------------------------------------------------------------------
#endif // XPLCOMMON_POSIX_CONDVAR_H

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