Move debugger initialization out of QQmlDebugServer and QQmlEngine

QQmlDebugConnector has to check the parameters before deciding if (and
what kind of) instance to create. It also has to add the services
itself as we don't want to tie a specific implementation of
QQmlDebugConnector to a specific set of services. Logic to load the
services from plugins will be added in a separate change. Integrating
the service initialization with the connector initialization enables us
to load the services before the server thread startsi, which will
simplify the thread synchronization.

QQmlConfigurableDebugService has to recheck for blockingMode once it
gets enabled as it cannot rely on being enabled right away anymore. It
should have done that already before as it's possible to disable and
re-enable services.

Change-Id: I9d161d78836bae10d688a90b4c2a32efed320412
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

8 files changed, 348 insertions, 163 deletions

diff --git a/src/qml/debugger/debugger.pri b/src/qml/debugger/debugger.pri
index d6fb02a122..cbb1646ff6 100644
--- a/src/qml/debugger/debugger.pri
+++ b/src/qml/debugger/debugger.pri
@@ -1,6 +1,8 @@
 contains(QT_CONFIG, no-qml-debug):DEFINES += QT_NO_QML_DEBUGGER
 
 SOURCES += \
+    $$PWD/qqmldebug.cpp \
+    $$PWD/qqmldebugconnector.cpp \
     $$PWD/qqmldebugservice.cpp \
     $$PWD/qqmlprofilerservice.cpp \
     $$PWD/qqmldebugserver.cpp \
diff --git a/src/qml/debugger/qqmlconfigurabledebugservice.cpp b/src/qml/debugger/qqmlconfigurabledebugservice.cpp
index 32dda87937..aa5e69b63d 100644
--- a/src/qml/debugger/qqmlconfigurabledebugservice.cpp
+++ b/src/qml/debugger/qqmlconfigurabledebugservice.cpp
@@ -39,11 +39,19 @@ QT_BEGIN_NAMESPACE
 
 QQmlConfigurableDebugService::QQmlConfigurableDebugService(const QString &name, float version,
                                                            QObject *parent) :
-    QQmlDebugService((*new QQmlConfigurableDebugServicePrivate(name, version)), parent) { init(); }
+    QQmlDebugService((*new QQmlConfigurableDebugServicePrivate(name, version)), parent)
+{
+    registerService();
+    init();
+}
 
 QQmlConfigurableDebugService::QQmlConfigurableDebugService(QQmlDebugServicePrivate &dd,
                                                            QObject *parent) :
-    QQmlDebugService(dd, parent) { init(); }
+    QQmlDebugService(dd, parent)
+{
+    registerService();
+    init();
+}
 
 QMutex *QQmlConfigurableDebugService::configMutex()
 {
@@ -56,7 +64,7 @@ void QQmlConfigurableDebugService::init()
     Q_D(QQmlConfigurableDebugService);
     QMutexLocker lock(&d->configMutex);
     // If we're not enabled or not blocking, don't wait for configuration
-    d->waitingForConfiguration = (registerService() == Enabled &&
+    d->waitingForConfiguration = (state() == Enabled &&
                                   QQmlDebugConnector::instance()->blockingMode());
 }
 
@@ -74,6 +82,8 @@ void QQmlConfigurableDebugService::stateChanged(QQmlDebugService::State newState
 {
     if (newState != Enabled)
         stopWaiting();
+    else
+        init();
 }
 
 void QQmlConfigurableDebugService::engineAboutToBeAdded(QQmlEngine *engine)
diff --git a/src/qml/debugger/qqmldebug.cpp b/src/qml/debugger/qqmldebug.cpp
new file mode 100644
index 0000000000..83718921f1
--- /dev/null
+++ b/src/qml/debugger/qqmldebug.cpp
@@ -0,0 +1,120 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** 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 The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/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 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qqmldebug.h"
+#include "qqmldebugconnector_p.h"
+
+#include <private/qqmlengine_p.h>
+
+QT_BEGIN_NAMESPACE
+
+QQmlDebuggingEnabler::QQmlDebuggingEnabler(bool printWarning)
+{
+#ifndef QQML_NO_DEBUG_PROTOCOL
+    if (!QQmlEnginePrivate::qml_debugging_enabled
+            && printWarning) {
+        qDebug("QML debugging is enabled. Only use this in a safe environment.");
+    }
+    QQmlEnginePrivate::qml_debugging_enabled = true;
+#else
+    Q_UNUSED(printWarning);
+#endif
+}
+
+/*!
+ * \enum QQmlDebuggingEnabler::StartMode
+ *
+ * Defines the debug server's start behavior. You can interrupt QML engines starting while a debug
+ * client is connecting, in order to set breakpoints in or profile startup code.
+ *
+ * \value DoNotWaitForClient Run any QML engines as usual while the debug services are connecting.
+ * \value WaitForClient      If a QML engine starts while the debug services are connecting,
+ *                           interrupt it until they are done.
+ */
+
+/*!
+ * Enables debugging for QML engines created after calling this function. The debug server will
+ * listen on \a port at \a hostName and block the QML engine until it receives a connection if
+ * \a mode is \c WaitForClient. If \a mode is not specified it won't block and if \a hostName is not
+ * specified it will listen on all available interfaces. You can only start one debug server at a
+ * time. A debug server may have already been started if the -qmljsdebugger= command line argument
+ * was given. This method returns \c true if a new debug server was successfully started, or
+ * \c false otherwise.
+ */
+bool QQmlDebuggingEnabler::startTcpDebugServer(int port, StartMode mode, const QString &hostName)
+{
+#ifndef QQML_NO_DEBUG_PROTOCOL
+    QQmlDebugConnector::setPluginKey(QLatin1String("QQmlDebugServer"));
+    QQmlDebugConnector *connector = QQmlDebugConnector::instance();
+    if (connector) {
+        QVariantHash configuration;
+        configuration[QLatin1String("portFrom")] = configuration[QLatin1String("portTo")] = port;
+        configuration[QLatin1String("block")] = (mode == WaitForClient);
+        configuration[QLatin1String("hostAddress")] = hostName;
+        return connector->open(configuration);
+    }
+#else
+    Q_UNUSED(port);
+    Q_UNUSED(block);
+    Q_UNUSED(hostName);
+#endif
+    return false;
+}
+
+/*!
+ * Enables debugging for QML engines created after calling this function. The debug server will
+ * connect to a debugger waiting on a local socket at the given \a socketFileName and block the QML
+ * engine until the connection is established if \a mode is \c WaitForClient. If \a mode is not
+ * specified it will not block. You can only start one debug server at a time. A debug server may
+ * have already been started if the -qmljsdebugger= command line argument was given. This method
+ * returns \c true if a new debug server was successfully started, or \c false otherwise.
+ */
+bool QQmlDebuggingEnabler::connectToLocalDebugger(const QString &socketFileName, StartMode mode)
+{
+#ifndef QQML_NO_DEBUG_PROTOCOL
+    QQmlDebugConnector::setPluginKey(QLatin1String("QQmlDebugServer"));
+    QQmlDebugConnector *connector = QQmlDebugConnector::instance();
+    if (connector) {
+        QVariantHash configuration;
+        configuration[QLatin1String("fileName")] = socketFileName;
+        configuration[QLatin1String("block")] = (mode == WaitForClient);
+        return connector->open(configuration);
+    }
+#else
+    Q_UNUSED(fileName);
+    Q_UNUSED(block);
+#endif
+    return false;
+}
+
+QT_END_NAMESPACE
diff --git a/src/qml/debugger/qqmldebugconnector.cpp b/src/qml/debugger/qqmldebugconnector.cpp
new file mode 100644
index 0000000000..eb111f75d0
--- /dev/null
+++ b/src/qml/debugger/qqmldebugconnector.cpp
@@ -0,0 +1,120 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** 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 The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/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 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qqmldebugpluginmanager_p.h"
+#include "qqmldebugconnector_p.h"
+#include "qdebugmessageservice_p.h"
+#include "qqmlenginecontrolservice_p.h"
+#include "qqmlenginedebugservice_p.h"
+#include "qqmlinspectorservice_p.h"
+#include "qqmlprofilerservice_p.h"
+#include "qv4debugservice_p.h"
+#include <QtCore/QPluginLoader>
+#include <QtCore/QCoreApplication>
+#include <QtCore/QDir>
+#include <QtCore/QDebug>
+
+#include <private/qcoreapplication_p.h>
+#include <private/qqmlengine_p.h>
+
+QT_BEGIN_NAMESPACE
+
+extern QQmlDebugConnector *loadQQmlDebugConnector(const QString &key);
+
+struct QQmlDebugConnectorParams {
+    QString pluginKey;
+    QString arguments;
+    QQmlDebugConnector *instance;
+
+    QQmlDebugConnectorParams() : instance(0)
+    {
+        if (qApp) {
+            QCoreApplicationPrivate *appD =
+                    static_cast<QCoreApplicationPrivate*>(QObjectPrivate::get(qApp));
+            if (appD)
+                arguments = appD->qmljsDebugArgumentsString();
+        }
+    }
+};
+
+Q_GLOBAL_STATIC(QQmlDebugConnectorParams, qmlDebugConnectorParams)
+
+void QQmlDebugConnector::setPluginKey(const QString &key)
+{
+    QQmlDebugConnectorParams *params = qmlDebugConnectorParams();
+    if (params) {
+        if (params->instance)
+            qWarning() << "QML debugger: Cannot set plugin key after loading the plugin.";
+        else
+            params->pluginKey = key;
+    }
+}
+
+QQmlDebugConnector *QQmlDebugConnector::instance()
+{
+    QQmlDebugConnectorParams *params = qmlDebugConnectorParams();
+    if (!params)
+        return 0;
+
+    if (!QQmlEnginePrivate::qml_debugging_enabled) {
+        if (!params->arguments.isEmpty()) {
+            qWarning() << QString::fromLatin1(
+                              "QML Debugger: Ignoring \"-qmljsdebugger=%1\". Debugging has not "
+                              "been enabled.").arg(params->arguments);
+            params->arguments.clear();
+        }
+        return 0;
+    }
+
+    if (!params->instance) {
+        if (!params->pluginKey.isEmpty()) {
+            if (params->pluginKey != QLatin1String("QQmlDebugServer"))
+                return 0; // We cannot load anything else, yet
+        } else if (params->arguments.isEmpty()) {
+            return 0; // no explicit class name given and no command line arguments
+        }
+        params->instance = loadQQmlDebugConnector(QLatin1String("QQmlDebugServer"));
+        if (params->instance) {
+            QQmlEngineDebugService::instance();
+            QV4DebugService::instance();
+            QQmlProfilerService::instance();
+            QDebugMessageService::instance();
+            QQmlEngineControlService::instance();
+            QQmlInspectorService::instance();
+        }
+    }
+
+    return params->instance;
+}
+
+QT_END_NAMESPACE
diff --git a/src/qml/debugger/qqmldebugconnector_p.h b/src/qml/debugger/qqmldebugconnector_p.h
index 3fd2240a0d..e7b8b98c66 100644
--- a/src/qml/debugger/qqmldebugconnector_p.h
+++ b/src/qml/debugger/qqmldebugconnector_p.h
@@ -57,6 +57,7 @@ class Q_QML_PRIVATE_EXPORT QQmlDebugConnector : public QObject
 {
     Q_OBJECT
 public:
+    static void setPluginKey(const QString &key);
     static QQmlDebugConnector *instance();
 
     virtual bool blockingMode() const = 0;
@@ -70,6 +71,7 @@ public:
     virtual bool removeService(QQmlDebugService *service) = 0;
 
     virtual void sendMessages(QQmlDebugService *service, const QList<QByteArray> &messages) = 0;
+    virtual bool open(const QVariantHash &configuration = QVariantHash()) = 0;
 };
 
 QT_END_NAMESPACE
diff --git a/src/qml/debugger/qqmldebugserver.cpp b/src/qml/debugger/qqmldebugserver.cpp
index 5160aecaee..4d5e3f5605 100644
--- a/src/qml/debugger/qqmldebugserver.cpp
+++ b/src/qml/debugger/qqmldebugserver.cpp
@@ -35,10 +35,6 @@
 #include "qqmldebugserverconnection_p.h"
 #include "qqmldebugservice_p.h"
 #include "qqmldebugservice_p_p.h"
-#include "qqmlenginedebugservice_p.h"
-#include "qv4debugservice_p.h"
-#include "qdebugmessageservice_p.h"
-#include "qqmlprofilerservice_p.h"
 
 #include <private/qqmlengine_p.h>
 #include <private/qqmlglobal_p.h>
@@ -103,11 +99,14 @@ public:
     bool addService(QQmlDebugService *service);
     bool removeService(QQmlDebugService *service);
 
+    bool open(const QVariantHash &configuration);
+
     void receiveMessage(const QByteArray &message);
     void sendMessages(QQmlDebugService *service, const QList<QByteArray> &messages);
 
     template<class Action>
-    static bool enable(Action action);
+    bool enable(Action action);
+    bool enableFromArguments();
 
 private slots:
     void wakeEngine(QQmlEngine *engine);
@@ -119,8 +118,8 @@ private:
     friend struct StartTcpServerAction;
     friend struct ConnectToLocalAction;
     friend class QQmlDebugServerThread;
-    friend class QQmlDebugConnector;
     friend struct QQmlDebugServerInstanceWrapper;
+    friend QQmlDebugConnector *loadQQmlDebugConnector(const QString &key);
 
     class EngineCondition {
     public:
@@ -209,6 +208,42 @@ private:
     QString m_fileName;
 };
 
+struct StartTcpServerAction {
+    int portFrom;
+    int portTo;
+    bool block;
+    QString hostAddress;
+
+    StartTcpServerAction(int portFrom, int portTo, bool block, const QString &hostAddress) :
+        portFrom(portFrom), portTo(portTo), block(block), hostAddress(hostAddress) {}
+
+    bool operator()(QQmlDebugServerImpl *d)
+    {
+        if (!d->init(QLatin1String("qmldbg_tcp"), block))
+            return false;
+        d->m_thread->setPortRange(portFrom, portTo == -1 ? portFrom : portTo, block, hostAddress);
+        d->m_thread->start();
+        return true;
+    }
+};
+
+struct ConnectToLocalAction {
+    QString fileName;
+    bool block;
+
+    ConnectToLocalAction(const QString &fileName, bool block) :
+        fileName(fileName), block(block) {}
+
+    bool operator()(QQmlDebugServerImpl *d)
+    {
+        if (!d->init(QLatin1String("qmldbg_local"), block))
+            return false;
+        d->m_thread->setFileName(fileName, block);
+        d->m_thread->start();
+        return true;
+    }
+};
+
 void QQmlDebugServerImpl::advertisePlugins()
 {
     if (!m_gotHello)
@@ -357,15 +392,11 @@ bool QQmlDebugServerImpl::blockingMode() const
     return m_blockingMode;
 }
 
-QQmlDebugConnector *QQmlDebugConnector::instance()
+QQmlDebugConnector *loadQQmlDebugConnector(const QString &key)
 {
-    QQmlDebugServerInstanceWrapper *wrapper = debugServerInstance();
-    if (wrapper && wrapper->m_instance.m_thread) {
-        QQmlDebugServerImpl *ret = &(wrapper->m_instance);
-        QMutexLocker locker(&ret->m_helloMutex);
-        if (ret->m_blockingMode && !ret->m_gotHello)
-            ret->m_helloCondition.wait(&ret->m_helloMutex);
-        return ret;
+    if (key == QLatin1String("QQmlDebugServer")) {
+        QQmlDebugServerInstanceWrapper *wrapper = debugServerInstance();
+        return wrapper ? &(wrapper->m_instance) : 0;
     } else {
         return 0;
     }
@@ -380,8 +411,6 @@ static void cleanupOnShutdown()
 
 bool QQmlDebugServerImpl::init(const QString &pluginName, bool block)
 {
-    if (!QQmlEnginePrivate::qml_debugging_enabled)
-        return false;
     if (m_thread)
         return false;
     static bool postRoutineAdded = false;
@@ -414,9 +443,30 @@ QQmlDebugServerImpl::QQmlDebugServerImpl() :
     qRegisterMetaType<QList<QByteArray> >("QList<QByteArray>");
     // used in changeServiceState
     qRegisterMetaType<QQmlDebugService::State>("QQmlDebugService::State");
+}
 
+bool QQmlDebugServerImpl::open(const QVariantHash &configuration = QVariantHash())
+{
+    if (configuration.isEmpty()) {
+        return enableFromArguments();
+    } if (configuration.contains(QLatin1String("portFrom"))) {
+        return enable(StartTcpServerAction(
+                             configuration[QLatin1String("portFrom")].toInt(),
+                             configuration[QLatin1String("portTo")].toInt(),
+                             configuration[QLatin1String("block")].toBool(),
+                             configuration[QLatin1String("hostAddress")].toString()));
+    } else if (configuration.contains(QLatin1String("fileName"))) {
+        return enable(ConnectToLocalAction(configuration[QLatin1String("fileName")].toString(),
+                      configuration[QLatin1String("block")].toBool()));
+    }
+
+    return false;
+}
+
+bool QQmlDebugServerImpl::enableFromArguments()
+{
     if (qApp == 0)
-        return;
+        return false;
     QCoreApplicationPrivate *appD = static_cast<QCoreApplicationPrivate*>(QObjectPrivate::get(qApp));
 #ifndef QT_NO_QML_DEBUGGER
     // ### remove port definition when protocol is changed
@@ -429,15 +479,6 @@ QQmlDebugServerImpl::QQmlDebugServerImpl() :
 
     // format: qmljsdebugger=port:<port_from>[,port_to],host:<ip address>][,block]
     if (!appD->qmljsDebugArgumentsString().isEmpty()) {
-        if (!QQmlEnginePrivate::qml_debugging_enabled) {
-            qWarning() << QString(QLatin1String(
-                              "QML Debugger: Ignoring \"-qmljsdebugger=%1\". "
-                              "Debugging has not been enabled.")).arg(
-                              appD->qmljsDebugArgumentsString());
-            return;
-        }
-
-        QString pluginName;
         QStringList lstjsDebugArguments = appD->qmljsDebugArgumentsString()
                                                                 .split(QLatin1Char(','));
         QStringList::const_iterator argsItEnd = lstjsDebugArguments.cend();
@@ -445,7 +486,6 @@ QQmlDebugServerImpl::QQmlDebugServerImpl() :
         for (; argsIt != argsItEnd; ++argsIt) {
             const QString strArgument = *argsIt;
             if (strArgument.startsWith(QLatin1String("port:"))) {
-                pluginName = QLatin1String("qmldbg_tcp");
                 portFrom = strArgument.mid(5).toInt(&ok);
                 portTo = portFrom;
                 QStringList::const_iterator argsNext = argsIt + 1;
@@ -461,7 +501,6 @@ QQmlDebugServerImpl::QQmlDebugServerImpl() :
             } else if (strArgument == QLatin1String("block")) {
                 block = true;
             } else if (strArgument.startsWith(QLatin1String("file:"))) {
-                pluginName = QLatin1String("qmldbg_local");
                 fileName = strArgument.mid(5);
                 ok = !fileName.isEmpty();
             } else {
@@ -472,13 +511,10 @@ QQmlDebugServerImpl::QQmlDebugServerImpl() :
         }
 
         if (ok) {
-            if (init(pluginName, block)) {
-                if (!fileName.isEmpty())
-                    m_thread->setFileName(fileName, block);
-                else
-                    m_thread->setPortRange(portFrom, portTo, block, hostAddress);
-                m_thread->start();
-            }
+            if (!fileName.isEmpty())
+                return enable(ConnectToLocalAction(fileName, block));
+            else
+                return enable(StartTcpServerAction(portFrom, portTo, block, hostAddress));
         } else {
             qWarning() << QString(QLatin1String(
                               "QML Debugger: Ignoring \"-qmljsdebugger=%1\". "
@@ -494,6 +530,7 @@ QQmlDebugServerImpl::QQmlDebugServerImpl() :
                      appD->qmljsDebugArgumentsString());
     }
 #endif
+    return false;
 }
 
 void QQmlDebugServerImpl::receiveMessage(const QByteArray &message)
@@ -688,7 +725,7 @@ void QQmlDebugServerImpl::removeEngine(QQmlEngine *engine)
 bool QQmlDebugServerImpl::addService(QQmlDebugService *service)
 {
     // to be executed outside of debugger thread
-    Q_ASSERT(QThread::currentThread() != thread());
+    Q_ASSERT(!m_thread || QThread::currentThread() != thread());
 
     connect(service, SIGNAL(attachedToEngine(QQmlEngine*)),
             this, SLOT(wakeEngine(QQmlEngine*)), Qt::QueuedConnection);
@@ -711,7 +748,7 @@ bool QQmlDebugServerImpl::addService(QQmlDebugService *service)
 bool QQmlDebugServerImpl::removeService(QQmlDebugService *service)
 {
     // to be executed outside of debugger thread
-    Q_ASSERT(QThread::currentThread() != thread());
+    Q_ASSERT(!m_thread || QThread::currentThread() != thread());
 
     QWriteLocker lock(&m_pluginsLock);
     QQmlDebugService::State newState = QQmlDebugService::NotConnected;
@@ -745,58 +782,21 @@ void QQmlDebugServerImpl::sendMessages(QQmlDebugService *service, const QList<QB
                               Q_ARG(QList<QByteArray>, prefixedMessages));
 }
 
-struct StartTcpServerAction {
-    int portFrom;
-    int portTo;
-    bool block;
-    QString hostAddress;
-
-    StartTcpServerAction(int portFrom, int portTo, bool block, const QString &hostAddress) :
-        portFrom(portFrom), portTo(portTo), block(block), hostAddress(hostAddress) {}
-
-    bool operator()(QQmlDebugServerImpl *d)
-    {
-        if (!d->init(QLatin1String("qmldbg_tcp"), block))
-            return false;
-        d->m_thread->setPortRange(portFrom, portTo == -1 ? portFrom : portTo, block, hostAddress);
-        d->m_thread->start();
-        return true;
-    }
-};
-
-struct ConnectToLocalAction {
-    QString fileName;
-    bool block;
-
-    ConnectToLocalAction(const QString &fileName, bool block) :
-        fileName(fileName), block(block) {}
-
-    bool operator()(QQmlDebugServerImpl *d)
-    {
-        if (!d->init(QLatin1String("qmldbg_local"), block))
-            return false;
-        d->m_thread->setFileName(fileName, block);
-        d->m_thread->start();
-        return true;
-    }
-};
-
 template<class Action>
 bool QQmlDebugServerImpl::enable(Action action)
 {
 #ifndef QT_NO_QML_DEBUGGER
-    QQmlDebugServerInstanceWrapper *wrapper = debugServerInstance();
-    if (!wrapper)
-        return false;
-    QQmlDebugServerImpl *d = &wrapper->m_instance;
-    if (d->m_thread)
+    if (m_thread)
         return false;
-    if (!action(d))
+    if (!action(this))
         return false;
-    while (!d->m_connection) {
-        if (!d->m_thread)
+    while (!m_connection) {
+        if (!m_thread)
             return false;
     }
+    QMutexLocker locker(&m_helloMutex);
+    if (m_blockingMode && !m_gotHello)
+        m_helloCondition.wait(&m_helloMutex);
     return true;
 #else
     Q_UNUSED(action);
@@ -804,58 +804,6 @@ bool QQmlDebugServerImpl::enable(Action action)
 #endif
 }
 
-/*!
- * \enum QQmlDebuggingEnabler::StartMode
- *
- * Defines the debug server's start behavior. You can interrupt QML engines starting while a debug
- * client is connecting, in order to set breakpoints in or profile startup code.
- *
- * \value DoNotWaitForClient Run any QML engines as usual while the debug services are connecting.
- * \value WaitForClient      If a QML engine starts while the debug services are connecting,
- *                           interrupt it until they are done.
- */
-
-/*!
- * Enables debugging for QML engines created after calling this function. The debug server will
- * listen on \a port at \a hostName and block the QML engine until it receives a connection if
- * \a mode is \c WaitForClient. If \a mode is not specified it won't block and if \a hostName is not
- * specified it will listen on all available interfaces. You can only start one debug server at a
- * time. A debug server may have already been started if the -qmljsdebugger= command line argument
- * was given. This method returns \c true if a new debug server was successfully started, or
- * \c false otherwise.
- */
-bool QQmlDebuggingEnabler::startTcpDebugServer(int port, StartMode mode, const QString &hostName)
-{
-#ifndef QQML_NO_DEBUG_PROTOCOL
-    return QQmlDebugServerImpl::enable(StartTcpServerAction(port, port, mode == WaitForClient,
-                                                            hostName));
-#else
-    Q_UNUSED(port);
-    Q_UNUSED(block);
-    Q_UNUSED(hostName);
-    return false;
-#endif
-}
-
-/*!
- * Enables debugging for QML engines created after calling this function. The debug server will
- * connect to a debugger waiting on a local socket at the given \a socketFileName and block the QML
- * engine until the connection is established if \a mode is \c WaitForClient. If \a mode is not
- * specified it will not block. You can only start one debug server at a time. A debug server may
- * have already been started if the -qmljsdebugger= command line argument was given. This method
- * returns \c true if a new debug server was successfully started, or \c false otherwise.
- */
-bool QQmlDebuggingEnabler::connectToLocalDebugger(const QString &socketFileName, StartMode mode)
-{
-#ifndef QQML_NO_DEBUG_PROTOCOL
-    return QQmlDebugServerImpl::enable(ConnectToLocalAction(socketFileName, mode == WaitForClient));
-#else
-    Q_UNUSED(fileName);
-    Q_UNUSED(block);
-    return false;
-#endif
-}
-
 void QQmlDebugServerImpl::wakeEngine(QQmlEngine *engine)
 {
     // to be executed in debugger thread
diff --git a/src/qml/debugger/qqmlprofilerservice.cpp b/src/qml/debugger/qqmlprofilerservice.cpp
index 4a4f70b894..4062f2f33c 100644
--- a/src/qml/debugger/qqmlprofilerservice.cpp
+++ b/src/qml/debugger/qqmlprofilerservice.cpp
@@ -106,19 +106,22 @@ QQmlProfilerService *QQmlProfilerService::instance()
 
 void QQmlProfilerService::engineAboutToBeAdded(QQmlEngine *engine)
 {
-    Q_ASSERT_X(QThread::currentThread() != thread(), Q_FUNC_INFO, "QML profilers have to be added from the engine thread");
+    Q_ASSERT_X(QThread::currentThread() == engine->thread(), Q_FUNC_INFO,
+               "QML profilers have to be added from the engine thread");
 
     QMutexLocker lock(configMutex());
     QQmlProfilerAdapter *qmlAdapter = new QQmlProfilerAdapter(this, QQmlEnginePrivate::get(engine));
     QV4ProfilerAdapter *v4Adapter = new QV4ProfilerAdapter(this, QV8Engine::getV4(engine->handle()));
     addEngineProfiler(qmlAdapter, engine);
     addEngineProfiler(v4Adapter, engine);
+
     QQmlConfigurableDebugService::engineAboutToBeAdded(engine);
 }
 
 void QQmlProfilerService::engineAdded(QQmlEngine *engine)
 {
-    Q_ASSERT_X(QThread::currentThread() != thread(), Q_FUNC_INFO, "QML profilers have to be added from the engine thread");
+    Q_ASSERT_X(QThread::currentThread() == engine->thread(), Q_FUNC_INFO,
+               "QML profilers have to be added from the engine thread");
 
     QMutexLocker lock(configMutex());
     foreach (QQmlAbstractProfilerAdapter *profiler, m_engineProfilers.values(engine))
@@ -127,7 +130,8 @@ void QQmlProfilerService::engineAdded(QQmlEngine *engine)
 
 void QQmlProfilerService::engineAboutToBeRemoved(QQmlEngine *engine)
 {
-    Q_ASSERT_X(QThread::currentThread() != thread(), Q_FUNC_INFO, "QML profilers have to be removed from the engine thread");
+    Q_ASSERT_X(QThread::currentThread() == engine->thread(), Q_FUNC_INFO,
+               "QML profilers have to be removed from the engine thread");
 
     QMutexLocker lock(configMutex());
     bool isRunning = false;
@@ -146,7 +150,8 @@ void QQmlProfilerService::engineAboutToBeRemoved(QQmlEngine *engine)
 
 void QQmlProfilerService::engineRemoved(QQmlEngine *engine)
 {
-    Q_ASSERT_X(QThread::currentThread() != thread(), Q_FUNC_INFO, "QML profilers have to be removed from the engine thread");
+    Q_ASSERT_X(QThread::currentThread() == engine->thread(), Q_FUNC_INFO,
+               "QML profilers have to be removed from the engine thread");
 
     QMutexLocker lock(configMutex());
     foreach (QQmlAbstractProfilerAdapter *profiler, m_engineProfilers.values(engine)) {
diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index 34015c17da..1ed102f0c9 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -42,7 +42,6 @@
 #include "qqmlexpression.h"
 #include "qqmlcomponent.h"
 #include "qqmlvme_p.h"
-#include <private/qqmlenginedebugservice_p.h>
 #include "qqmlstringconverters_p.h"
 #include "qqmlxmlhttprequest_p.h"
 #include "qqmlscriptstring.h"
@@ -55,10 +54,6 @@
 #include "qqmltypenamecache_p.h"
 #include "qqmlnotifier_p.h"
 #include <private/qqmldebugconnector_p.h>
-#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/qqmlboundsignal_p.h>
@@ -863,11 +858,7 @@ void QQmlEnginePrivate::init()
 
     if (QCoreApplication::instance()->thread() == q->thread() && QQmlDebugConnector::instance()) {
         isDebugging = true;
-        QQmlEngineDebugService::instance();
-        QV4DebugService::instance();
-        QQmlProfilerService::instance();
-        QDebugMessageService::instance();
-        QQmlEngineControlService::instance();
+        QQmlDebugConnector::instance()->open();
         QQmlDebugConnector::instance()->addEngine(q);
     }
 }
@@ -1487,19 +1478,6 @@ Q_QML_EXPORT QObject *qmlAttachedPropertiesObject(int *idCache, const QObject *o
 
 #endif // QT_DEPRECATED_SINCE(5, 1)
 
-QQmlDebuggingEnabler::QQmlDebuggingEnabler(bool printWarning)
-{
-#ifndef QQML_NO_DEBUG_PROTOCOL
-    if (!QQmlEnginePrivate::qml_debugging_enabled
-            && printWarning) {
-        qDebug("QML debugging is enabled. Only use this in a safe environment.");
-    }
-    QQmlEnginePrivate::qml_debugging_enabled = true;
-#else
-    Q_UNUSED(printWarning);
-#endif
-}
-
 class QQmlDataExtended {
 public:
     QQmlDataExtended();