Add a debug service for controlling qml engines

Like this we can control the starting and stopping of qml engines from
the client without having to extend each of the other debug services.

Change-Id: I5f1c077b6cfa0e628c32e8bcdea2ec053e310509
Reviewed-by: Kai Koehne <kai.koehne@digia.com>

4 files changed, 249 insertions, 2 deletions

diff --git a/src/qml/debugger/debugger.pri b/src/qml/debugger/debugger.pri
index 2116c7292b..e9f1d6f5fe 100644
--- a/src/qml/debugger/debugger.pri
+++ b/src/qml/debugger/debugger.pri
@@ -7,7 +7,8 @@ SOURCES += \
     $$PWD/qqmlenginedebugservice.cpp \
     $$PWD/qdebugmessageservice.cpp \
     $$PWD/qv4debugservice.cpp \
-    $$PWD/qqmlconfigurabledebugservice.cpp
+    $$PWD/qqmlconfigurabledebugservice.cpp \
+    $$PWD/qqmlenginecontrolservice.cpp
 
 HEADERS += \
     $$PWD/qqmldebugservice_p.h \
@@ -24,4 +25,5 @@ HEADERS += \
     $$PWD/qdebugmessageservice_p.h \
     $$PWD/qv4debugservice_p.h \
     $$PWD/qqmlconfigurabledebugservice_p.h \
-    $$PWD/qqmlconfigurabledebugservice_p_p.h
+    $$PWD/qqmlconfigurabledebugservice_p_p.h \
+    $$PWD/qqmlenginecontrolservice_p.h
diff --git a/src/qml/debugger/qqmlenginecontrolservice.cpp b/src/qml/debugger/qqmlenginecontrolservice.cpp
new file mode 100644
index 0000000000..90815912ad
--- /dev/null
+++ b/src/qml/debugger/qqmlenginecontrolservice.cpp
@@ -0,0 +1,145 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QQmlEngine>
+#include "qqmldebug.h"
+#include "qqmlenginecontrolservice_p.h"
+
+QT_BEGIN_NAMESPACE
+
+Q_GLOBAL_STATIC(QQmlEngineControlService, qmlEngineControlService)
+
+QQmlEngineControlService::QQmlEngineControlService() :
+    QQmlDebugService(QStringLiteral("EngineControl"), 1)
+{
+    QMutexLocker lock(&dataMutex);
+    registerService();
+}
+
+QQmlEngineControlService *QQmlEngineControlService::instance()
+{
+    return qmlEngineControlService();
+}
+
+void QQmlEngineControlService::messageReceived(const QByteArray &message)
+{
+    QMutexLocker lock(&dataMutex);
+    QQmlDebugStream d(message);
+    int command;
+    int engineId;
+    d >> command >> engineId;
+    QQmlEngine *engine = qobject_cast<QQmlEngine *>(objectForId(engineId));
+    if (command == StartWaitingEngine && startingEngines.contains(engine)) {
+        startingEngines.removeOne(engine);
+        emit attachedToEngine(engine);
+    } else if (command == StopWaitingEngine && stoppingEngines.contains(engine)) {
+        stoppingEngines.removeOne(engine);
+        emit detachedFromEngine(engine);
+    }
+}
+
+void QQmlEngineControlService::engineAboutToBeAdded(QQmlEngine *engine)
+{
+    QMutexLocker lock(&dataMutex);
+    if (state() == Enabled) {
+        Q_ASSERT(!stoppingEngines.contains(engine));
+        Q_ASSERT(!startingEngines.contains(engine));
+        startingEngines.append(engine);
+        sendMessage(EngineAboutToBeAdded, engine);
+    } else {
+        emit attachedToEngine(engine);
+    }
+}
+
+void QQmlEngineControlService::engineAboutToBeRemoved(QQmlEngine *engine)
+{
+    QMutexLocker lock(&dataMutex);
+    if (state() == Enabled) {
+        Q_ASSERT(!stoppingEngines.contains(engine));
+        Q_ASSERT(!startingEngines.contains(engine));
+        stoppingEngines.append(engine);
+        sendMessage(EngineAboutToBeRemoved, engine);
+    } else {
+        emit detachedFromEngine(engine);
+    }
+}
+
+void QQmlEngineControlService::engineAdded(QQmlEngine *engine)
+{
+    if (state() == Enabled) {
+        QMutexLocker lock(&dataMutex);
+        Q_ASSERT(!startingEngines.contains(engine));
+        Q_ASSERT(!stoppingEngines.contains(engine));
+        sendMessage(EngineAdded, engine);
+    }
+}
+
+void QQmlEngineControlService::engineRemoved(QQmlEngine *engine)
+{
+    if (state() == Enabled) {
+        QMutexLocker lock(&dataMutex);
+        Q_ASSERT(!startingEngines.contains(engine));
+        Q_ASSERT(!stoppingEngines.contains(engine));
+        sendMessage(EngineRemoved, engine);
+    }
+}
+
+void QQmlEngineControlService::sendMessage(QQmlEngineControlService::MessageType type, QQmlEngine *engine)
+{
+    QByteArray message;
+    QQmlDebugStream d(&message, QIODevice::WriteOnly);
+    d << type << idForObject(engine);
+    QQmlDebugService::sendMessage(message);
+}
+
+void QQmlEngineControlService::stateChanged(State)
+{
+    // We flush everything for any kind of state change, to avoid complicated timing issues.
+    QMutexLocker lock(&dataMutex);
+    foreach (QQmlEngine *engine, startingEngines)
+        emit attachedToEngine(engine);
+    startingEngines.clear();
+    foreach (QQmlEngine *engine, stoppingEngines)
+        emit detachedFromEngine(engine);
+    stoppingEngines.clear();
+}
+
+QT_END_NAMESPACE
diff --git a/src/qml/debugger/qqmlenginecontrolservice_p.h b/src/qml/debugger/qqmlenginecontrolservice_p.h
new file mode 100644
index 0000000000..150d36d9cf
--- /dev/null
+++ b/src/qml/debugger/qqmlenginecontrolservice_p.h
@@ -0,0 +1,98 @@
+/****************************************************************************
+**
+** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QQMLENGINECONTROLSERVICE_H
+#define QQMLENGINECONTROLSERVICE_H
+
+#include <QMutex>
+#include "qqmldebugservice_p.h"
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+QT_BEGIN_NAMESPACE
+
+class QQmlEngineControlService : public QQmlDebugService
+{
+public:
+    enum MessageType {
+        EngineAboutToBeAdded,
+        EngineAdded,
+        EngineAboutToBeRemoved,
+        EngineRemoved
+    };
+
+    enum CommandType {
+        StartWaitingEngine,
+        StopWaitingEngine
+    };
+
+    QQmlEngineControlService();
+
+    static QQmlEngineControlService *instance();
+
+protected:
+    QMutex dataMutex;
+    QList<QQmlEngine *> startingEngines;
+    QList<QQmlEngine *> stoppingEngines;
+
+    void messageReceived(const QByteArray &);
+    void engineAboutToBeAdded(QQmlEngine *);
+    void engineAboutToBeRemoved(QQmlEngine *);
+    void engineAdded(QQmlEngine *);
+    void engineRemoved(QQmlEngine *);
+
+    void sendMessage(MessageType type, QQmlEngine *engine);
+
+    void stateChanged(State);
+};
+
+QT_END_NAMESPACE
+
+#endif // QQMLENGINECONTROLSERVICE_H
diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index 0529e41007..8e61ba61cc 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -66,6 +66,7 @@
 #include <private/qqmlprofilerservice_p.h>
 #include <private/qv4debugservice_p.h>
 #include <private/qdebugmessageservice_p.h>
+#include <private/qqmlenginecontrolservice_p.h>
 #include "qqmlincubator.h"
 #include "qqmlabstracturlinterceptor.h"
 #include <private/qv4profilerservice_p.h>
@@ -819,6 +820,7 @@ void QQmlEnginePrivate::init()
         QV4ProfilerService::instance();
         QQmlProfilerService::instance();
         QDebugMessageService::instance();
+        QQmlEngineControlService::instance();
         QQmlDebugServer::instance()->addEngine(q);
     }
 }