workerthread.cpp

/********************************************************************************
 *  FARSA Experiments Library                                                   *
 *  Copyright (C) 2007-2012                                                     *
 *  Gianluca Massera <emmegian@yahoo.it>                                        *
 *  Stefano Nolfi <stefano.nolfi@istc.cnr.it>                                   *
 *  Tomassino Ferrauto <tomassino.ferrauto@istc.cnr.it>                         *
 *                                                                              *
 *  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA  *
 ********************************************************************************/

#include "workerthread.h"

namespace farsa {

WorkerThread::WorkerThread( QObject* parent ) :
    QThread(parent),
    operations(),
    mutex(),
    waitForOperationsToDo(),
    operation(NULL),
    quitRequested(false),
    exceptions() {
}

WorkerThread::~WorkerThread() {
    foreach (BaseException *e, exceptions) {
        delete e;
    }
}

void WorkerThread::addOperation( ThreadOperation* newOperation ) {
    mutex.lock();
    operations.enqueue( newOperation );
    mutex.unlock();
    if ( operations.size() == 1 ) {
        // wake the run thread because now there is something to do
        waitForOperationsToDo.wakeAll();
    }
}

void WorkerThread::stopCurrentOperation() {
    mutex.lock();
    if ( operation ) {
        operation->stop();
    }
    mutex.unlock();
}

void WorkerThread::run() {
    forever {
        mutex.lock();
        // We have to check quitRequested here (not only after waitForOperationsToDo.wait()) because quit() can
        // be called before run() starts. In that case quitRequested is already true, but we lost the "signal"
        // that should wake us when on the wait condition and so we would sleep indefinitely
        if ( quitRequested ) {
            mutex.unlock();
            return;
        }
        if ( operations.size() == 0 ) {
            // wait the adding of an operation
            waitForOperationsToDo.wait( &mutex );
        }
        if ( quitRequested ) {
            mutex.unlock();
            return;
        }
        operation = operations.dequeue();
        mutex.unlock();
        try {
            operation->run();
        } catch (BaseException& e) {
            BaseException* cloned = e.clone();
            exceptions.append(cloned);

            emit exceptionDuringOperation(cloned);
        } catch (...) {
            UnknownException* e = new UnknownException();
            exceptions.append(e);

            emit exceptionDuringOperation(e);
        }
        mutex.lock();
        delete operation;
        operation = NULL;
        mutex.unlock();
        if ( quitRequested ) {
            return;
        }
    }
}

void WorkerThread::quit() {
    mutex.lock();
    quitRequested = true;
    mutex.unlock();
    stopCurrentOperation();
    waitForOperationsToDo.wakeAll();
    wait();
}

} // end namespace farsa