qquickworkerscript.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qtqmlworkerscriptglobal_p.h"
#include "qquickworkerscript_p.h"
#include <private/qqmlengine_p.h>
#include <private/qqmlexpression_p.h>
#include <private/qjsvalue_p.h>
 
#include <QtCore/qcoreevent.h>
#include <QtCore/qcoreapplication.h>
#include <QtCore/qdebug.h>
#include <QtQml/qjsengine.h>
#include <QtCore/qmutex.h>
#include <QtCore/qwaitcondition.h>
#include <QtCore/qfile.h>
#include <QtCore/qdatetime.h>
#include <QtQml/qqmlinfo.h>
#include <QtQml/qqmlfile.h>
#if QT_CONFIG(qml_network)
#include <QtNetwork/qnetworkaccessmanager.h>
#include "qqmlnetworkaccessmanagerfactory.h"
#endif
 
#include <private/qv4serialize_p.h>
 
#include <private/qv4value_p.h>
#include <private/qv4functionobject_p.h>
#include <private/qv4script_p.h>
#include <private/qv4scopedvalue_p.h>
#include <private/qv4jscall_p.h>
 
QT_BEGIN_NAMESPACE
 
class WorkerDataEvent : public QEvent
{
public:
    enum Type { WorkerData = QEvent::User };
 
    WorkerDataEvent(int workerId, const QByteArray &data);
    virtual ~WorkerDataEvent();
 
    int workerId() const;
    QByteArray data() const;
 
private:
    int m_id;
    QByteArray m_data;
};
 
class WorkerLoadEvent : public QEvent
{
public:
    enum Type { WorkerLoad = WorkerDataEvent::WorkerData + 1 };
 
    WorkerLoadEvent(int workerId, const QUrl &url);
 
    int workerId() const;
    QUrl url() const;
 
private:
    int m_id;
    QUrl m_url;
};
 
class WorkerRemoveEvent : public QEvent
{
public:
    enum Type { WorkerRemove = WorkerLoadEvent::WorkerLoad + 1 };
 
    WorkerRemoveEvent(int workerId);
 
    int workerId() const;
 
private:
    int m_id;
};
 
class WorkerErrorEvent : public QEvent
{
public:
    enum Type { WorkerError = WorkerRemoveEvent::WorkerRemove + 1 };
 
    WorkerErrorEvent(const QQmlError &error);
 
    QQmlError error() const;
 
private:
    QQmlError m_error;
};
 
struct WorkerScript : public QV4::ExecutionEngine::Deletable
{
    WorkerScript(QV4::ExecutionEngine *);
    ~WorkerScript() = default;
 
    QQuickWorkerScriptEnginePrivate *p = nullptr;
    QUrl source;
    QQuickWorkerScript *owner = nullptr;
#if QT_CONFIG(qml_network)
    QScopedPointer<QNetworkAccessManager> scriptLocalNAM;
#endif
};
 
V4_DEFINE_EXTENSION(WorkerScript, workerScriptExtension);
 
class QQuickWorkerScriptEnginePrivate : public QObject
{
    Q_OBJECT
public:
    enum WorkerEventTypes {
        WorkerDestroyEvent = QEvent::User + 100
    };
 
    QQuickWorkerScriptEnginePrivate(QQmlEngine *eng);
 
    QQmlEngine *qmlengine;
 
    QMutex m_lock;
    QWaitCondition m_wait;
 
    // ExecutionEngines are owned by the worker script and created and deleted
    // in the worker thread. QQuickWorkerScript instances, however, belong to
    // the main thread. They are only inserted as place holders when creating
    // the worker script.
    QHash<int, QBiPointer<QV4::ExecutionEngine, QQuickWorkerScript>> workers;
 
    int m_nextId;
 
    static QV4::ReturnedValue method_sendMessage(const QV4::FunctionObject *, const QV4::Value *thisObject, const QV4::Value *argv, int argc);
    QV4::ExecutionEngine *workerEngine(int id);
 
signals:
    void stopThread();
 
protected:
    bool event(QEvent *) override;
 
private:
    void processMessage(int, const QByteArray &);
    void processLoad(int, const QUrl &);
    void reportScriptException(WorkerScript *, const QQmlError &error);
};
 
QQuickWorkerScriptEnginePrivate::QQuickWorkerScriptEnginePrivate(QQmlEngine *engine)
: qmlengine(engine), m_nextId(0)
{
}
 
QV4::ReturnedValue QQuickWorkerScriptEnginePrivate::method_sendMessage(const QV4::FunctionObject *b,
                                                                       const QV4::Value *, const QV4::Value *argv, int argc)
{
    QV4::Scope scope(b);
    const WorkerScript *script = workerScriptExtension(scope.engine);
    Q_ASSERT(script);
 
    QV4::ScopedValue v(scope, argc > 0 ? argv[0] : QV4::Value::undefinedValue());
    QByteArray data = QV4::Serialize::serialize(v, scope.engine);
 
    QMutexLocker locker(&script->p->m_lock);
    if (script->owner)
        QCoreApplication::postEvent(script->owner, new WorkerDataEvent(0, data));
 
    return QV4::Encode::undefined();
}
 
bool QQuickWorkerScriptEnginePrivate::event(QEvent *event)
{
    if (event->type() == (QEvent::Type)WorkerDataEvent::WorkerData) {
        WorkerDataEvent *workerEvent = static_cast<WorkerDataEvent *>(event);
        processMessage(workerEvent->workerId(), workerEvent->data());
        return true;
    } else if (event->type() == (QEvent::Type)WorkerLoadEvent::WorkerLoad) {
        WorkerLoadEvent *workerEvent = static_cast<WorkerLoadEvent *>(event);
        processLoad(workerEvent->workerId(), workerEvent->url());
        return true;
    } else if (event->type() == (QEvent::Type)WorkerDestroyEvent) {
        emit stopThread();
        return true;
    } else if (event->type() == (QEvent::Type)WorkerRemoveEvent::WorkerRemove) {
        QMutexLocker locker(&m_lock);
        WorkerRemoveEvent *workerEvent = static_cast<WorkerRemoveEvent *>(event);
        auto itr = workers.find(workerEvent->workerId());
        if (itr != workers.end()) {
            if (itr->isT1())
                delete itr->asT1();
            workers.erase(itr);
        }
        return true;
    } else {
        return QObject::event(event);
    }
}
 
QV4::ExecutionEngine *QQuickWorkerScriptEnginePrivate::workerEngine(int id)
{
    const auto it = workers.find(id);
    if (it == workers.end())
        return nullptr;
    if (it->isT1())
        return it->asT1();
 
    QQuickWorkerScript *owner = it->asT2();
    auto *engine = new QV4::ExecutionEngine;
    WorkerScript *script = workerScriptExtension(engine);
    script->owner = owner;
    script->p = this;
    *it = engine;
    return engine;
}
 
void QQuickWorkerScriptEnginePrivate::processMessage(int id, const QByteArray &data)
{
    QV4::ExecutionEngine *engine = workerEngine(id);
    if (!engine)
        return;
 
    QV4::Scope scope(engine);
    QV4::ScopedString v(scope, engine->newString(QStringLiteral("WorkerScript")));
    QV4::ScopedObject worker(scope, engine->globalObject->get(v));
    QV4::ScopedFunctionObject onmessage(scope);
    if (worker)
        onmessage = worker->get((v = engine->newString(QStringLiteral("onMessage"))));
 
    if (!onmessage)
        return;
 
    QV4::ScopedValue value(scope, QV4::Serialize::deserialize(data, engine));
 
    QV4::JSCallArguments jsCallData(scope, 1);
    *jsCallData.thisObject = engine->global();
    jsCallData.args[0] = value;
    onmessage->call(jsCallData);
    if (scope.hasException()) {
        QQmlError error = scope.engine->catchExceptionAsQmlError();
        WorkerScript *script = workerScriptExtension(engine);
        reportScriptException(script, error);
    }
}
 
void QQuickWorkerScriptEnginePrivate::processLoad(int id, const QUrl &url)
{
    if (url.isRelative())
        return;
 
    QString fileName = QQmlFile::urlToLocalFileOrQrc(url);
 
    QV4::ExecutionEngine *engine = workerEngine(id);
    if (!engine)
        return;
 
    WorkerScript *script = workerScriptExtension(engine);
    script->source = url;
 
    if (fileName.endsWith(QLatin1String(".mjs"))) {
        auto module = engine->loadModule(url);
        if (module.compiled) {
            if (module.compiled->instantiate(engine))
                module.compiled->evaluate();
        } else if (module.native) {
            // Nothing to do. There is no global code in a native module.
        } else {
            engine->throwError(QStringLiteral("Could not load module file"));
        }
    } else {
        QString error;
        QV4::Scope scope(engine);
        QScopedPointer<QV4::Script> program;
        program.reset(QV4::Script::createFromFileOrCache(
                          engine, /*qmlContext*/nullptr, fileName, url, &error));
        if (program.isNull()) {
            if (!error.isEmpty())
                qWarning().nospace() << error;
            return;
        }
 
        if (!engine->hasException)
            program->run();
    }
 
    if (engine->hasException)
        reportScriptException(script, engine->catchExceptionAsQmlError());
}
 
void QQuickWorkerScriptEnginePrivate::reportScriptException(WorkerScript *script,
                                                                  const QQmlError &error)
{
    QMutexLocker locker(&script->p->m_lock);
    if (script->owner)
        QCoreApplication::postEvent(script->owner, new WorkerErrorEvent(error));
}
 
WorkerDataEvent::WorkerDataEvent(int workerId, const QByteArray &data)
: QEvent((QEvent::Type)WorkerData), m_id(workerId), m_data(data)
{
}
 
WorkerDataEvent::~WorkerDataEvent()
{
}
 
int WorkerDataEvent::workerId() const
{
    return m_id;
}
 
QByteArray WorkerDataEvent::data() const
{
    return m_data;
}
 
WorkerLoadEvent::WorkerLoadEvent(int workerId, const QUrl &url)
: QEvent((QEvent::Type)WorkerLoad), m_id(workerId), m_url(url)
{
}
 
int WorkerLoadEvent::workerId() const
{
    return m_id;
}
 
QUrl WorkerLoadEvent::url() const
{
    return m_url;
}
 
WorkerRemoveEvent::WorkerRemoveEvent(int workerId)
: QEvent((QEvent::Type)WorkerRemove), m_id(workerId)
{
}
 
int WorkerRemoveEvent::workerId() const
{
    return m_id;
}
 
WorkerErrorEvent::WorkerErrorEvent(const QQmlError &error)
: QEvent((QEvent::Type)WorkerError), m_error(error)
{
}
 
QQmlError WorkerErrorEvent::error() const
{
    return m_error;
}
 
QQuickWorkerScriptEngine::QQuickWorkerScriptEngine(QQmlEngine *parent)
: QThread(parent), d(new QQuickWorkerScriptEnginePrivate(parent))
{
    d->m_lock.lock();
    connect(d, SIGNAL(stopThread()), this, SLOT(quit()), Qt::DirectConnection);
    start(QThread::LowestPriority);
    d->m_wait.wait(&d->m_lock);
    d->moveToThread(this);
    d->m_lock.unlock();
}
 
QQuickWorkerScriptEngine::~QQuickWorkerScriptEngine()
{
    d->m_lock.lock();
    QCoreApplication::postEvent(d, new QEvent((QEvent::Type)QQuickWorkerScriptEnginePrivate::WorkerDestroyEvent));
    d->m_lock.unlock();
 
    //We have to force to cleanup the main thread's event queue here
    //to make sure the main GUI release all pending locks/wait conditions which
    //some worker script/agent are waiting for (QQmlListModelWorkerAgent::sync() for example).
    while (!isFinished()) {
        // We can't simply wait here, because the worker thread will not terminate
        // until the main thread processes the last data event it generates
        QCoreApplication::processEvents();
        yieldCurrentThread();
    }
 
    delete d;
}
 
 
WorkerScript::WorkerScript(QV4::ExecutionEngine *engine)
{
    engine->initQmlGlobalObject();
 
    QV4::Scope scope(engine);
    QV4::ScopedObject api(scope, engine->newObject());
    QV4::ScopedString sendMessageName(scope, engine->newString(QStringLiteral("sendMessage")));
    QV4::ScopedFunctionObject sendMessage(
                scope, QV4::FunctionObject::createBuiltinFunction(
                    engine, sendMessageName,
                    QQuickWorkerScriptEnginePrivate::method_sendMessage, 1));
    api->put(sendMessageName, sendMessage);
    QV4::ScopedString workerScriptName(scope, engine->newString(QStringLiteral("WorkerScript")));
    engine->globalObject->put(workerScriptName, api);
 
#if QT_CONFIG(qml_network)
    engine->networkAccessManager = [](QV4::ExecutionEngine *engine) {
        WorkerScript *workerScript = workerScriptExtension(engine);
        if (workerScript->scriptLocalNAM)
            return workerScript->scriptLocalNAM.get();
        if (auto *namFactory = workerScript->p->qmlengine->networkAccessManagerFactory())
            workerScript->scriptLocalNAM.reset(namFactory->create(workerScript->p));
        else
            workerScript->scriptLocalNAM.reset(new QNetworkAccessManager(workerScript->p));
        return workerScript->scriptLocalNAM.get();
    };
#endif // qml_network
}
 
int QQuickWorkerScriptEngine::registerWorkerScript(QQuickWorkerScript *owner)
{
    const int id = d->m_nextId++;
 
    d->m_lock.lock();
    d->workers.insert(id, owner);
    d->m_lock.unlock();
 
    return id;
}
 
void QQuickWorkerScriptEngine::removeWorkerScript(int id)
{
    const auto it = d->workers.find(id);
    if (it == d->workers.end())
        return;
 
    if (it->isT1()) {
        QV4::ExecutionEngine *engine = it->asT1();
        workerScriptExtension(engine)->owner = nullptr;
    }
    QCoreApplication::postEvent(d, new WorkerRemoveEvent(id));
}
 
void QQuickWorkerScriptEngine::executeUrl(int id, const QUrl &url)
{
    QCoreApplication::postEvent(d, new WorkerLoadEvent(id, url));
}
 
void QQuickWorkerScriptEngine::sendMessage(int id, const QByteArray &data)
{
    QCoreApplication::postEvent(d, new WorkerDataEvent(id, data));
}
 
void QQuickWorkerScriptEngine::run()
{
    d->m_lock.lock();
    d->m_wait.wakeAll();
    d->m_lock.unlock();
 
    exec();
 
    for (auto it = d->workers.begin(), end = d->workers.end(); it != end; ++it) {
        if (it->isT1())
            delete it->asT1();
    }
 
    d->workers.clear();
}
 
 
QQuickWorkerScript::QQuickWorkerScript(QObject *parent)
: QObject(parent), m_engine(nullptr), m_scriptId(-1), m_componentComplete(true)
{
}
 
QQuickWorkerScript::~QQuickWorkerScript()
{
    if (m_scriptId != -1) m_engine->removeWorkerScript(m_scriptId);
}
 
QUrl QQuickWorkerScript::source() const
{
    return m_source;
}
 
void QQuickWorkerScript::setSource(const QUrl &source)
{
    if (m_source == source)
        return;
 
    m_source = source;
 
    if (engine()) {
        const QQmlContext *context = qmlContext(this);
        m_engine->executeUrl(m_scriptId, context ? context->resolvedUrl(m_source) : m_source);
    }
 
    emit sourceChanged();
}
 
bool QQuickWorkerScript::ready() const
{
    return m_engine != nullptr;
}
 
void QQuickWorkerScript::sendMessage(QQmlV4Function *args)
{
    if (!engine()) {
        qWarning("QQuickWorkerScript: Attempt to send message before WorkerScript establishment");
        return;
    }
 
    QV4::Scope scope(args->v4engine());
    QV4::ScopedValue argument(scope, QV4::Value::undefinedValue());
    if (args->length() != 0)
        argument = (*args)[0];
 
    m_engine->sendMessage(m_scriptId, QV4::Serialize::serialize(argument, scope.engine));
}
 
void QQuickWorkerScript::classBegin()
{
    m_componentComplete = false;
}
 
QQuickWorkerScriptEngine *QQuickWorkerScript::engine()
{
    if (m_engine) return m_engine;
    if (m_componentComplete) {
        const QQmlContext *context = qmlContext(this);
        QQmlEngine *engine = context ? context->engine() : nullptr;
        if (!engine) {
            qWarning("QQuickWorkerScript: engine() called without qmlEngine() set");
            return nullptr;
        }
 
        QQmlEnginePrivate *enginePrivate = QQmlEnginePrivate::get(engine);
        if (enginePrivate->workerScriptEngine == nullptr)
            enginePrivate->workerScriptEngine = new QQuickWorkerScriptEngine(engine);
        m_engine = qobject_cast<QQuickWorkerScriptEngine *>(enginePrivate->workerScriptEngine);
        Q_ASSERT(m_engine);
        m_scriptId = m_engine->registerWorkerScript(this);
 
        if (m_source.isValid())
            m_engine->executeUrl(m_scriptId, context->resolvedUrl(m_source));
 
        emit readyChanged();
 
        return m_engine;
    }
    return nullptr;
}
 
void QQuickWorkerScript::componentComplete()
{
    m_componentComplete = true;
    engine(); // Get it started now.
}
 
bool QQuickWorkerScript::event(QEvent *event)
{
    if (event->type() == (QEvent::Type)WorkerDataEvent::WorkerData) {
        if (QQmlEngine *engine = qmlEngine(this)) {
            QV4::ExecutionEngine *v4 = engine->handle();
            WorkerDataEvent *workerEvent = static_cast<WorkerDataEvent *>(event);
            emit message(QJSValuePrivate::fromReturnedValue(
                             QV4::Serialize::deserialize(workerEvent->data(), v4)));
        }
        return true;
    } else if (event->type() == (QEvent::Type)WorkerErrorEvent::WorkerError) {
        WorkerErrorEvent *workerEvent = static_cast<WorkerErrorEvent *>(event);
        QQmlEnginePrivate::warning(qmlEngine(this), workerEvent->error());
        return true;
    } else {
        return QObject::event(event);
    }
}
 
QT_END_NAMESPACE
 
#include <qquickworkerscript.moc>
 
#include "moc_qquickworkerscript_p.cpp"