blockingqueue.h

/*
 *  Copyright (C) 2006  Helmut Grohne
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifndef LIBMUTH_BLOCKINGQUEUE_H
#define LIBMUTH_BLOCKINGQUEUE_H

#include "blockingqueue_decls.h"
#include "lock.h"
#include "condition.h"

template<class C> inline BlockingQueue<C>::BlockingQueue() : notempty(lock) {
}

template<class C> inline bool BlockingQueue<C>::isempty() const {
        /* We need to lock the queue before asking it whether it is empty. */
        WITHACQUIRED(this->lock);
        return this->queue.empty();
}

template<class C> inline void BlockingQueue<C>::put(const C &item) {
        /* The queue has to be locked for all operations. */
        WITHACQUIRED(this->lock);
        /* Check whether the queue is empty. We only need to notify other
         * threads if this is the case. */
        const bool wasempty(this->queue.empty());
        this->queue.push(item);
        if(wasempty)
                this->notempty.notify();
}

template<class C> inline C BlockingQueue<C>::get() {
        WITHACQUIRED(this->lock);
        /* If the queue is empty wait. Waiting means unlocking it and locking
         * it when another thread has invoked .notify() and .release()d the
         * lock. */
        while(this->queue.empty())
                this->notempty.wait();
        /* Get and remove the first element. */
        C t(this->queue.front());
        this->queue.pop();
        return t;
}

#endif

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