/****************************************************************************+
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**+
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).+
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** All rights reserved.+
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** Contact: Nokia Corporation (qt-info@nokia.com)+
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**+
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** This file is part of the QtCore module of the Qt Toolkit.+
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**+
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** $QT_BEGIN_LICENSE:LGPL$+
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** No Commercial Usage+
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** This file contains pre-release code and may not be distributed.+
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** You may use this file in accordance with the terms and conditions+
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** contained in the Technology Preview License Agreement accompanying+
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** this package.+
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**+
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** GNU Lesser General Public License Usage+
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** Alternatively, this file may be used under the terms of the GNU Lesser+
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** General Public License version 2.1 as published by the Free Software+
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** Foundation and appearing in the file LICENSE.LGPL included in the+
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** packaging of this file.  Please review the following information to+
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** ensure the GNU Lesser General Public License version 2.1 requirements+
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.+
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**+
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** In addition, as a special exception, Nokia gives you certain additional+
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** rights.  These rights are described in the Nokia Qt LGPL Exception+
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.+
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**+
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** If you have questions regarding the use of this file, please contact+
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** Nokia at qt-info@nokia.com.+
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**+
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**+
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**+
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**+
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**+
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**+
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**+
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**+
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** $QT_END_LICENSE$+
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**+
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****************************************************************************/+
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+
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#include "qtconcurrentthreadengine.h"+
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+
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#ifndef QT_NO_CONCURRENT+
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+
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QT_BEGIN_NAMESPACE+
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+
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namespace QtConcurrent {+
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+
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ThreadEngineBarrier::ThreadEngineBarrier()+
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:count(0) { }+
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+
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void ThreadEngineBarrier::acquire()+
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{+
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    forever {+
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        int localCount = int(count);+
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        if (localCount < 0) {+
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            if (count.testAndSetOrdered(localCount, localCount -1))+
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                return;+
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        } else {+
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            if (count.testAndSetOrdered(localCount, localCount + 1))+
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                return;+
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        }+
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    }+
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}+
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+
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int ThreadEngineBarrier::release()+
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{+
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    forever {+
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        int localCount = int(count);+
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        if (localCount == -1) {+
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            if (count.testAndSetOrdered(-1, 0)) {+
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                semaphore.release();+
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                return 0;+
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            }+
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        } else if (localCount < 0) {+
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            if (count.testAndSetOrdered(localCount, localCount + 1))+
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                return qAbs(localCount + 1);+
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        } else {+
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            if (count.testAndSetOrdered(localCount, localCount - 1))+
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                return localCount - 1;+
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        }+
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    }+
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}+
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+
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// Wait until all threads have been released+
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void ThreadEngineBarrier::wait()+
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{+
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    forever {+
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        int localCount = int(count);+
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        if (localCount == 0)+
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            return;+
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+
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        Q_ASSERT(localCount > 0); // multiple waiters are not allowed.+
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        if (count.testAndSetOrdered(localCount, -localCount)) {+
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            semaphore.acquire();+
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            return;+
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        }+
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    }+
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}+
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+
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int ThreadEngineBarrier::currentCount()+
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{+
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    return int(count);+
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}+
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+
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// releases a thread, unless this is the last thread.+
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// returns true if the thread was released.+
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bool ThreadEngineBarrier::releaseUnlessLast()+
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{+
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    forever {+
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        int localCount = int(count);+
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        if (qAbs(localCount) == 1) {+
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            return false;+
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        } else if (localCount < 0) {+
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            if (count.testAndSetOrdered(localCount, localCount + 1))+
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                return true;+
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        } else {+
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            if (count.testAndSetOrdered(localCount, localCount - 1))+
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                return true;+
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        }+
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    }+
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}+
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+
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ThreadEngineBase::ThreadEngineBase()+
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:futureInterface(0), threadPool(QThreadPool::globalInstance())+
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{+
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    setAutoDelete(false);+
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}+
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+
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ThreadEngineBase::~ThreadEngineBase() {}+
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+
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void ThreadEngineBase::startSingleThreaded()+
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{+
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    start();+
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    while (threadFunction() != ThreadFinished)+
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        ;+
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    finish();+
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}+
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+
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void ThreadEngineBase::startBlocking()+
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{+
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    start();+
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    barrier.acquire();+
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    startThreads();+
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+
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    bool throttled = false;+
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#ifndef QT_NO_EXCEPTIONS+
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    try {+
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#endif+
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        while (threadFunction() == ThrottleThread) {+
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            if (threadThrottleExit()) {+
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                throttled = true;+
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                break;+
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            }+
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        }+
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#ifndef QT_NO_EXCEPTIONS+
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    } catch (QtConcurrent::Exception &e) {+
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        handleException(e);+
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    } catch (...) {+
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        handleException(QtConcurrent::UnhandledException());+
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    }+
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#endif+
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+
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    if (throttled == false) {+
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        barrier.release();+
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    }+
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+
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    barrier.wait();+
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    finish();+
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    exceptionStore.throwPossibleException();+
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}+
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+
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void ThreadEngineBase::startThread()+
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{+
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    startThreadInternal();+
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}+
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+
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void ThreadEngineBase::acquireBarrierSemaphore()+
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{+
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    barrier.acquire();+
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}+
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+
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bool ThreadEngineBase::isCanceled()+
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{+
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    if (futureInterface)+
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        return futureInterface->isCanceled();+
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    else+
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        return false;+
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}+
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+
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void ThreadEngineBase::waitForResume()+
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{+
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    if (futureInterface)+
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        futureInterface->waitForResume();+
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}+
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+
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bool ThreadEngineBase::isProgressReportingEnabled()+
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{+
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    // If we don't have a QFuture, there is no-one to report the progress to.+
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    return (futureInterface != 0);+
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}+
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+
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void ThreadEngineBase::setProgressValue(int progress)+
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{+
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    if (futureInterface)+
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        futureInterface->setProgressValue(progress);+
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}+
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+
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void ThreadEngineBase::setProgressRange(int minimum, int maximum)+
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{+
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    if (futureInterface)+
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        futureInterface->setProgressRange(minimum, maximum);+
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}+
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+
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bool ThreadEngineBase::startThreadInternal()+
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{+
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    if (this->isCanceled())+
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        return false;+
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+
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    barrier.acquire();+
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    if (!threadPool->tryStart(this)) {+
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        barrier.release();+
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        return false;+
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    }+
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    return true;+
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}+
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+
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void ThreadEngineBase::startThreads()+
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{+
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    while (shouldStartThread() && startThreadInternal())+
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        ;+
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}+
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+
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void ThreadEngineBase::threadExit()+
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{+
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    const bool asynchronous = futureInterface != 0;+
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    const int lastThread = (barrier.release() == 0);+
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+
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    if (lastThread && asynchronous)+
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        this->asynchronousFinish();+
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}+
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+
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// Called by a worker thread that wants to be throttled. If the current number+
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// of running threads is larger than one the thread is allowed to exit and+
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// this function returns one.+
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bool ThreadEngineBase::threadThrottleExit()+
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{+
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    return barrier.releaseUnlessLast();+
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}+
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+
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void ThreadEngineBase::run() // implements QRunnable.+
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{+
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    if (this->isCanceled()) {+
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        threadExit();+
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        return;+
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    }+
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+
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    startThreads();+
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+
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#ifndef QT_NO_EXCEPTIONS+
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    try {+
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#endif+
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        while (threadFunction() == ThrottleThread) {+
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            // threadFunction returning ThrottleThread means it that the user+
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            // struct wants to be throttled by making a worker thread exit.+
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            // Respect that request unless this is the only worker thread left+
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            // running, in which case it has to keep going.+
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            if (threadThrottleExit())+
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                return;+
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        }+
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+
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#ifndef QT_NO_EXCEPTIONS+
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    } catch (QtConcurrent::Exception &e) {+
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        handleException(e);+
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    } catch (...) {+
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        handleException(QtConcurrent::UnhandledException());+
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    }+
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#endif+
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    threadExit();+
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}+
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+
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#ifndef QT_NO_EXCEPTIONS+
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+
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void ThreadEngineBase::handleException(const QtConcurrent::Exception &exception)+
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{+
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    if (futureInterface)+
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        futureInterface->reportException(exception);+
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    else+
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        exceptionStore.setException(exception);+
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}+
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#endif+
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+
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+
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} // namepsace QtConcurrent+
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+
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QT_END_NAMESPACE+
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+
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#endif // QT_NO_CONCURRENT+
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