Send response data only to target client.

Before, the response was sent to all clients in a broad-cast and had
to be filtered on the client-side. This required additional client
identification data to be added to all requests and responses.

Now, we keep track of the transport and transport-internal client and
only send the response to that client. This is very benefitial for
multi-client setups but also reduces traffic for single-client setups
and thus their performance.

Change-Id: Ia1ef5e031b0058222083d352a8aa28a7d566a6ca
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

12 files changed, 82 insertions, 86 deletions

diff --git a/src/imports/webchannel/qmlwebviewtransport.cpp b/src/imports/webchannel/qmlwebviewtransport.cpp
index 7fb9d16..3d4e2ed 100644
--- a/src/imports/webchannel/qmlwebviewtransport.cpp
+++ b/src/imports/webchannel/qmlwebviewtransport.cpp
@@ -74,7 +74,7 @@ QObject *QmlWebViewTransport::webViewExperimental() const
     return m_webViewExperimental;
 }
 
-void QmlWebViewTransport::sendMessage(const QString &message) const
+void QmlWebViewTransport::sendMessage(const QString &message, int /*clientId*/) const
 {
     if (!m_webViewExperimental) {
         qWarning("Cannot send message - did you forget to set the webViewExperimental property?");
@@ -83,16 +83,16 @@ void QmlWebViewTransport::sendMessage(const QString &message) const
     QMetaObject::invokeMethod(m_webViewExperimental, "postMessage", Q_ARG(QString, message));
 }
 
-void QmlWebViewTransport::sendMessage(const QByteArray &message) const
+void QmlWebViewTransport::sendMessage(const QByteArray &message, int clientId) const
 {
-    sendMessage(QString::fromUtf8(message));
+    sendMessage(QString::fromUtf8(message), clientId);
 }
 
 void QmlWebViewTransport::handleWebViewMessage(const QVariantMap &message)
 {
     if (m_handler) {
         const QString &data = message[QStringLiteral("data")].toString();
-        m_handler->handleMessage(data);
+        m_handler->handleMessage(data, this, -1);
         emit messageReceived(data);
     }
 }
diff --git a/src/imports/webchannel/qmlwebviewtransport.h b/src/imports/webchannel/qmlwebviewtransport.h
index 98dc504..bb1e27e 100644
--- a/src/imports/webchannel/qmlwebviewtransport.h
+++ b/src/imports/webchannel/qmlwebviewtransport.h
@@ -55,8 +55,8 @@ public:
     explicit QmlWebViewTransport(QObject *parent = 0);
     ~QmlWebViewTransport() Q_DECL_OVERRIDE;
 
-    void sendMessage(const QString &message) const Q_DECL_OVERRIDE;
-    void sendMessage(const QByteArray &message) const Q_DECL_OVERRIDE;
+    void sendMessage(const QString &message, int clientId) const Q_DECL_OVERRIDE;
+    void sendMessage(const QByteArray &message, int clientId) const Q_DECL_OVERRIDE;
     void setMessageHandler(QWebChannelMessageHandlerInterface *handler) Q_DECL_OVERRIDE;
 
     void setWebViewExperimental(QObject *webViewExperimental);
diff --git a/src/webchannel/qmetaobjectpublisher.cpp b/src/webchannel/qmetaobjectpublisher.cpp
index d06fe98..2914714 100644
--- a/src/webchannel/qmetaobjectpublisher.cpp
+++ b/src/webchannel/qmetaobjectpublisher.cpp
@@ -41,6 +41,7 @@
 
 #include "qmetaobjectpublisher_p.h"
 #include "qwebchannel.h"
+#include "qwebchannel_p.h"
 
 #include <QEvent>
 #include <QJsonDocument>
@@ -336,27 +337,27 @@ void QMetaObjectPublisher::sendPendingPropertyUpdates()
     setClientIsIdle(false);
 }
 
-bool QMetaObjectPublisher::invokeMethod(QObject *const object, const int methodIndex,
-                                                const QJsonArray &args, const QJsonValue &id)
+QByteArray QMetaObjectPublisher::invokeMethod(QObject *const object, const int methodIndex,
+                                              const QJsonArray &args, const QJsonValue &id)
 {
     const QMetaMethod &method = object->metaObject()->method(methodIndex);
 
     if (method.name() == QByteArrayLiteral("deleteLater")) {
         // invoke `deleteLater` on wrapped QObject indirectly
         deleteWrappedObject(object);
-        return true;
+        return QByteArray();
     } else if (!method.isValid()) {
         qWarning() << "Cannot invoke unknown method of index" << methodIndex << "on object" << object << '.';
-        return false;
+        return QByteArray();
     } else if (method.access() != QMetaMethod::Public) {
         qWarning() << "Cannot invoke non-public method" << method.name() << "on object" << object << '.';
-        return false;
+        return QByteArray();
     } else if (method.methodType() != QMetaMethod::Method && method.methodType() != QMetaMethod::Slot) {
         qWarning() << "Cannot invoke non-public method" << method.name() << "on object" << object << '.';
-        return false;
+        return QByteArray();
     } else if (args.size() > 10) {
         qWarning() << "Cannot invoke method" << method.name() << "on object" << object << "with more than 10 arguments, as that is not supported by QMetaMethod::invoke.";
-        return false;
+        return QByteArray();
     } else if (args.size() > method.parameterCount()) {
         qWarning() << "Ignoring additional arguments while invoking method" << method.name() << "on object" << object << ':'
                    << args.size() << "arguments given, but method only takes" << method.parameterCount() << '.';
@@ -388,9 +389,7 @@ bool QMetaObjectPublisher::invokeMethod(QObject *const object, const int methodI
                   arguments[5], arguments[6], arguments[7], arguments[8], arguments[9]);
 
     // and send the return value to the client
-    webChannel->respond(id, wrapResult(returnValue));
-
-    return true;
+    return generateJSONMessage(id, wrapResult(returnValue), true);
 }
 
 void QMetaObjectPublisher::signalEmitted(const QObject *object, const int signalIndex, const QVariantList &arguments)
@@ -486,70 +485,74 @@ void QMetaObjectPublisher::deleteWrappedObject(QObject *object) const
     object->deleteLater();
 }
 
-bool QMetaObjectPublisher::handleRequest(const QJsonObject &message)
+QByteArray QMetaObjectPublisher::handleRequest(const QJsonObject &message)
 {
     if (!message.contains(KEY_DATA)) {
-        return false;
+        return QByteArray();
     }
 
     const QJsonObject &payload = message.value(KEY_DATA).toObject();
     if (!payload.contains(KEY_TYPE)) {
-        return false;
+        return QByteArray();
     }
 
     const Type type = toType(payload.value(KEY_TYPE));
     if (type == TypeIdle) {
         setClientIsIdle(true);
-        return true;
+        return QByteArray();
     } else if (type == TypeInit) {
         if (!blockUpdates) {
             initializeClients();
         } else {
             pendingInit = true;
         }
-        return true;
+        return QByteArray();
     } else if (type == TypeDebug) {
         static QTextStream out(stdout);
         out << "DEBUG: " << payload.value(KEY_MESSAGE).toString() << endl;
-        return true;
+        return QByteArray();
     } else if (payload.contains(KEY_OBJECT)) {
         const QString &objectName = payload.value(KEY_OBJECT).toString();
         QObject *object = registeredObjects.value(objectName);
         if (!object) {
             qWarning() << "Unknown object encountered" << objectName;
-            return false;
+            return QByteArray();
         }
 
         if (type == TypeInvokeMethod) {
             return invokeMethod(object, payload.value(KEY_METHOD).toInt(-1), payload.value(KEY_ARGS).toArray(), message.value(KEY_ID));
         } else if (type == TypeConnectToSignal) {
             signalHandler.connectTo(object, payload.value(KEY_SIGNAL).toInt(-1));
-            return true;
+            return QByteArray();
         } else if (type == TypeDisconnectFromSignal) {
             signalHandler.disconnectFrom(object, payload.value(KEY_SIGNAL).toInt(-1));
-            return true;
+            return QByteArray();
         } else if (type == TypeSetProperty) {
             const int propertyIdx = payload.value(KEY_PROPERTY).toInt(-1);
             QMetaProperty property = object->metaObject()->property(propertyIdx);
             if (!property.isValid()) {
                 qWarning() << "Cannot set unknown property" << payload.value(KEY_PROPERTY) << "of object" << objectName;
-                return false;
+                return QByteArray();
             } else if (!object->metaObject()->property(propertyIdx).write(object, payload.value(KEY_VALUE).toVariant())) {
                 qWarning() << "Could not write value " << payload.value(KEY_VALUE)
                            << "to property" << property.name() << "of object" << objectName;
-                return false;
+                return QByteArray();
             }
-            return true;
+            return QByteArray();
         }
     }
-    return false;
+    return QByteArray();
 }
 
-void QMetaObjectPublisher::handleMessage(const QString &message)
+void QMetaObjectPublisher::handleMessage(const QString &message, QWebChannelTransportInterface *transport, int clientId)
 {
     const QJsonDocument doc = QJsonDocument::fromJson(message.toUtf8());
-    if (doc.isObject()) {
-        handleRequest(doc.object());
+    if (!doc.isObject()) {
+        return;
+    }
+    const QByteArray &response = handleRequest(doc.object());
+    if (!response.isEmpty()) {
+        transport->sendMessage(response, clientId);
     }
 }
 
diff --git a/src/webchannel/qmetaobjectpublisher_p.h b/src/webchannel/qmetaobjectpublisher_p.h
index 3047548..4413df4 100644
--- a/src/webchannel/qmetaobjectpublisher_p.h
+++ b/src/webchannel/qmetaobjectpublisher_p.h
@@ -81,7 +81,7 @@ public:
      *
      * @return true if the request was handled, false otherwise.
      */
-    bool handleRequest(const QJsonObject &message);
+    QByteArray handleRequest(const QJsonObject &message);
 
     /**
      * Serialize the QMetaObject of @p object and return it in JSON form.
@@ -124,10 +124,10 @@ public:
     /**
      * Invoke the method of index @p methodIndex on @p object with the arguments @p args.
      *
-     * The return value of the method invocation is then transmitted to the calling client
-     * via a webchannel response to the message identified by @p id.
+     * The return value of the method invocation is then serialized and a response message
+     * is returned.
      */
-    bool invokeMethod(QObject *const object, const int methodIndex, const QJsonArray &args, const QJsonValue &id);
+    QByteArray invokeMethod(QObject *const object, const int methodIndex, const QJsonArray &args, const QJsonValue &id);
 
     /**
      * Callback of the signalHandler which forwards the signal invocation to the webchannel clients.
@@ -164,7 +164,7 @@ public:
     /**
      * Parse the message as JSON and if it succeeds, call handleRequest with the obtained JSON object.
      */
-    void handleMessage(const QString &message) Q_DECL_OVERRIDE;
+    void handleMessage(const QString &message, QWebChannelTransportInterface* transport, int clientId) Q_DECL_OVERRIDE;
 
 signals:
     void blockUpdatesChanged(bool block);
diff --git a/src/webchannel/qwebchannel.cpp b/src/webchannel/qwebchannel.cpp
index 5e8e320..75d1a4b 100644
--- a/src/webchannel/qwebchannel.cpp
+++ b/src/webchannel/qwebchannel.cpp
@@ -50,13 +50,8 @@
 
 QT_BEGIN_NAMESPACE
 
-void QWebChannelPrivate::sendJSONMessage(const QJsonValue &id, const QJsonValue &data, bool response) const
+QByteArray generateJSONMessage(const QJsonValue &id, const QJsonValue &data, bool response)
 {
-    if (transports.isEmpty()) {
-        qWarning("QWebChannel is not connected to any transports, cannot send messages.");
-        return;
-    }
-
     QJsonObject obj;
     if (response) {
         obj[QStringLiteral("response")] = true;
@@ -66,11 +61,7 @@ void QWebChannelPrivate::sendJSONMessage(const QJsonValue &id, const QJsonValue
         obj[QStringLiteral("data")] = data;
     }
     QJsonDocument doc(obj);
-    const QByteArray &message = doc.toJson(QJsonDocument::Compact);
-
-    foreach (QWebChannelTransportInterface *transport, transports) {
-        transport->sendMessage(message);
-    }
+    return doc.toJson(QJsonDocument::Compact);
 }
 
 QWebChannel::QWebChannel(QObject *parent)
@@ -136,14 +127,17 @@ void QWebChannel::disconnectFrom(QWebChannelTransportInterface *transport)
     }
 }
 
-void QWebChannel::respond(const QJsonValue &messageId, const QJsonValue &data) const
-{
-    d->sendJSONMessage(messageId, data, true);
-}
-
 void QWebChannel::sendMessage(const QJsonValue &id, const QJsonValue &data) const
 {
-    d->sendJSONMessage(id, data, false);
+    if (d->transports.isEmpty()) {
+        qWarning("QWebChannel is not connected to any transports, cannot send messages.");
+        return;
+    }
+
+    const QByteArray &message = generateJSONMessage(id, data, false);
+    foreach (QWebChannelTransportInterface *transport, d->transports) {
+        transport->sendMessage(message);
+    }
 }
 
 QT_END_NAMESPACE
diff --git a/src/webchannel/qwebchannel.h b/src/webchannel/qwebchannel.h
index 9139a15..ec3f72b 100644
--- a/src/webchannel/qwebchannel.h
+++ b/src/webchannel/qwebchannel.h
@@ -97,7 +97,6 @@ signals:
 
 public slots:
     void sendMessage(const QJsonValue &id, const QJsonValue &data = QJsonValue()) const;
-    void respond(const QJsonValue &messageId, const QJsonValue &data = QJsonValue()) const;
 
 private:
     QScopedPointer<QWebChannelPrivate> d;
diff --git a/src/webchannel/qwebchannel.js b/src/webchannel/qwebchannel.js
index 33f4cf5..9529c0b 100644
--- a/src/webchannel/qwebchannel.js
+++ b/src/webchannel/qwebchannel.js
@@ -57,13 +57,6 @@ var QWebChannelMessageTypes = {
 var QWebChannel = function(baseUrlOrSocket, initCallback, rawChannel)
 {
     var channel = this;
-    // support multiple channels listening to the same socket
-    // the responses to channel.exec must be distinguishable
-    // see: http://stackoverflow.com/a/2117523/35250
-    this.id = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
-        var r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8);
-        return v.toString(16);
-    });
     this.send = function(data)
     {
         if (typeof(data) !== "string") {
@@ -82,10 +75,8 @@ var QWebChannel = function(baseUrlOrSocket, initCallback, rawChannel)
             jsonData.data = {};
         }
         if (jsonData.response) {
-            if (jsonData.id[0] === channel.id) {
-                channel.execCallbacks[jsonData.id[1]](jsonData.data);
-                delete channel.execCallbacks[jsonData.id];
-            }
+            channel.execCallbacks[jsonData.id](jsonData.data);
+            delete channel.execCallbacks[jsonData.id];
         } else if (channel.subscriptions[jsonData.id]) {
             channel.subscriptions[jsonData.id].forEach(function(callback) {
                 (callback)(jsonData.data); }
@@ -153,7 +144,7 @@ var QWebChannel = function(baseUrlOrSocket, initCallback, rawChannel)
         }
         var id = channel.execId++;
         channel.execCallbacks[id] = callback;
-        channel.send({"id": [channel.id, id], "data": data});
+        channel.send({"id": id, "data": data});
     };
 
     this.objectMap = {};
diff --git a/src/webchannel/qwebchannel_p.h b/src/webchannel/qwebchannel_p.h
index 954134e..b81640e 100644
--- a/src/webchannel/qwebchannel_p.h
+++ b/src/webchannel/qwebchannel_p.h
@@ -53,12 +53,12 @@ class QJsonValue;
 class QWebChannelTransportInterface;
 class QMetaObjectPublisher;
 
+Q_WEBCHANNEL_EXPORT QByteArray generateJSONMessage(const QJsonValue &id, const QJsonValue &data, bool response);
+
 struct Q_WEBCHANNEL_EXPORT QWebChannelPrivate
 {
     QVector<QWebChannelTransportInterface*> transports;
     QMetaObjectPublisher *publisher;
-
-    void sendJSONMessage(const QJsonValue &id, const QJsonValue &data, bool response) const;
 };
 
 QT_END_NAMESPACE
diff --git a/src/webchannel/qwebchanneltransportinterface.h b/src/webchannel/qwebchanneltransportinterface.h
index 9044c68..c532732 100644
--- a/src/webchannel/qwebchanneltransportinterface.h
+++ b/src/webchannel/qwebchanneltransportinterface.h
@@ -48,6 +48,7 @@
 
 QT_BEGIN_NAMESPACE
 
+class QWebChannelTransportInterface;
 class Q_WEBCHANNEL_EXPORT QWebChannelMessageHandlerInterface
 {
 public:
@@ -56,7 +57,7 @@ public:
     /**
      * Handle a text message from a web channel client.
      */
-    virtual void handleMessage(const QString &message) = 0;
+    virtual void handleMessage(const QString &message, QWebChannelTransportInterface* transport, int clientId) = 0;
 };
 
 #define QWebChannelMessageHandlerInterface_iid "org.qt-project.Qt.QWebChannelMessageHandlerInterface"
@@ -71,12 +72,12 @@ public:
     /**
      * Send a text message to all web channel clients.
      */
-    virtual void sendMessage(const QString &message) const = 0;
+    virtual void sendMessage(const QString &message, int clientId = -1) const = 0;
 
     /**
      * Send a binary message to all web channel clients.
      */
-    virtual void sendMessage(const QByteArray &message) const = 0;
+    virtual void sendMessage(const QByteArray &message, int clientId = -1) const = 0;
 
     /**
      * Sets the message handler that will be called on incoming messages from web channel clients.
diff --git a/src/webchannel/qwebsockettransport.cpp b/src/webchannel/qwebsockettransport.cpp
index 9a432fe..8c25a9b 100644
--- a/src/webchannel/qwebsockettransport.cpp
+++ b/src/webchannel/qwebsockettransport.cpp
@@ -50,9 +50,10 @@ QT_USE_NAMESPACE
 
 //BEGIN QWebSocketTransportPrivate
 
-QWebSocketTransportPrivate::QWebSocketTransportPrivate(QObject *parent)
+QWebSocketTransportPrivate::QWebSocketTransportPrivate(QWebSocketTransport *transport, QObject *parent)
     : QWebSocketServer(QStringLiteral("QWebChannel Server"), NonSecureMode, parent)
     , m_messageHandler(Q_NULLPTR)
+    , m_transport(transport)
     , m_useSecret(true)
     , m_starting(false)
 {
@@ -76,10 +77,14 @@ void QWebSocketTransportPrivate::initLater()
     m_starting = true;
 }
 
-void QWebSocketTransportPrivate::sendMessage(const QString &message)
+void QWebSocketTransportPrivate::sendMessage(const QString &message, int clientId)
 {
-    foreach (QWebSocket *client, m_clients) {
-        client->sendTextMessage(message);
+    if (clientId == -1) {
+        foreach (QWebSocket *client, m_clients) {
+            client->sendTextMessage(message);
+        }
+    } else {
+        m_clients.at(clientId)->sendTextMessage(message);
     }
 }
 
@@ -132,7 +137,8 @@ void QWebSocketTransportPrivate::socketError()
 void QWebSocketTransportPrivate::messageReceived(const QString &message)
 {
     if (m_messageHandler) {
-        m_messageHandler->handleMessage(message);
+        QWebSocket *client = qobject_cast<QWebSocket*>(sender());
+        m_messageHandler->handleMessage(message, m_transport, m_clients.indexOf(client));
     }
     emit textDataReceived(message);
 }
@@ -153,7 +159,7 @@ void QWebSocketTransportPrivate::clientDisconnected()
 
 QWebSocketTransport::QWebSocketTransport(QObject *parent)
     : QObject(parent)
-    , d(new QWebSocketTransportPrivate)
+    , d(new QWebSocketTransportPrivate(this))
 {
     connect(d.data(), SIGNAL(textDataReceived(QString)),
             SIGNAL(messageReceived(QString)));
@@ -172,14 +178,14 @@ QWebSocketTransport::~QWebSocketTransport()
 
 }
 
-void QWebSocketTransport::sendMessage(const QByteArray &message) const
+void QWebSocketTransport::sendMessage(const QByteArray &message, int clientId) const
 {
-    d->sendMessage(QString::fromUtf8(message));
+    d->sendMessage(QString::fromUtf8(message), clientId);
 }
 
-void QWebSocketTransport::sendMessage(const QString &message) const
+void QWebSocketTransport::sendMessage(const QString &message, int clientId) const
 {
-    d->sendMessage(message);
+    d->sendMessage(message, clientId);
 }
 
 void QWebSocketTransport::setMessageHandler(QWebChannelMessageHandlerInterface *handler)
diff --git a/src/webchannel/qwebsockettransport.h b/src/webchannel/qwebsockettransport.h
index 6b1cb13..b3e484f 100644
--- a/src/webchannel/qwebsockettransport.h
+++ b/src/webchannel/qwebsockettransport.h
@@ -57,8 +57,8 @@ public:
     explicit QWebSocketTransport(QObject *parent = 0);
     ~QWebSocketTransport() Q_DECL_OVERRIDE;
 
-    void sendMessage(const QByteArray &message) const Q_DECL_OVERRIDE;
-    void sendMessage(const QString &message) const Q_DECL_OVERRIDE;
+    void sendMessage(const QByteArray &message, int clientId = -1) const Q_DECL_OVERRIDE;
+    void sendMessage(const QString &message, int clientId = -1) const Q_DECL_OVERRIDE;
     void setMessageHandler(QWebChannelMessageHandlerInterface *handler) Q_DECL_OVERRIDE;
 
     QString baseUrl() const;
diff --git a/src/webchannel/qwebsockettransport_p.h b/src/webchannel/qwebsockettransport_p.h
index 1a95787..95a431d 100644
--- a/src/webchannel/qwebsockettransport_p.h
+++ b/src/webchannel/qwebsockettransport_p.h
@@ -48,6 +48,7 @@
 
 QT_BEGIN_NAMESPACE
 
+class QWebSocketTransport;
 class QWebSocketTransportPrivate : public QWebSocketServer
 {
     Q_OBJECT
@@ -55,15 +56,16 @@ public:
     QString m_secret;
     QString m_baseUrl;
     QWebChannelMessageHandlerInterface *m_messageHandler;
+    QWebSocketTransport *m_transport;
 
     bool m_useSecret;
     bool m_starting;
 
-    explicit QWebSocketTransportPrivate(QObject *parent = 0);
+    explicit QWebSocketTransportPrivate(QWebSocketTransport* transport, QObject *parent = 0);
     virtual ~QWebSocketTransportPrivate();
 
     void initLater();
-    void sendMessage(const QString &message);
+    void sendMessage(const QString &message, int clientId);
 
 signals:
     void failed(const QString &reason);