QmlProfiler: Send loaded events in batches of about 1024

This significantly reduces the number of signals necessary when
loading traces. The overhead of queueing those signals across threads
was responsible for up to 80% of the time required to load a trace.

Change-Id: I461a2ef9944b0be102a29f8ed6b2b3f2f59f3c0f
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/qmlprofiler/qmlprofilerdatamodel.cpp

@@ -154,6 +154,15 @@ void QmlProfilerDataModel::addEvent(const QmlEvent &event)
     d->eventStream << event;
 }
 
+void QmlProfilerDataModel::addEvents(const QVector<QmlEvent> &events)
+{
+    Q_D(QmlProfilerDataModel);
+    for (const QmlEvent &event : events) {
+        d->modelManager->dispatch(event, d->eventTypes[event.typeIndex()]);
+        d->eventStream << event;
+    }
+}
+
 void QmlProfilerDataModel::clear()
 {
     Q_D(QmlProfilerDataModel);

src/plugins/qmlprofiler/qmlprofilerdatamodel.h

@@ -52,6 +52,7 @@ public:
     void clear();
     bool isEmpty() const;
     void addEvent(const QmlEvent &event);
+    void addEvents(const QVector<QmlEvent> &events);
     void replayEvents(qint64 startTime, qint64 endTime,
                       QmlProfilerModelManager::EventLoader loader) const;
     void finalize();

src/plugins/qmlprofiler/qmlprofilermodelmanager.cpp

@@ -378,8 +378,8 @@ void QmlProfilerModelManager::load(const QString &filename)
     connect(reader, &QmlProfilerFileReader::notesLoaded,
             d->notesModel, &QmlProfilerNotesModel::setNotes);
 
-    connect(reader, &QmlProfilerFileReader::qmlEventLoaded,
-            d->model, &QmlProfilerDataModel::addEvent);
+    connect(reader, &QmlProfilerFileReader::qmlEventsLoaded,
+            d->model, &QmlProfilerDataModel::addEvents);
 
     connect(reader, &QmlProfilerFileReader::success, this, [this, reader]() {
         d->traceTime->setTime(reader->traceStart(), reader->traceEnd());

src/plugins/qmlprofiler/qmlprofilertracefile.cpp

@@ -123,7 +123,7 @@ QmlProfilerFileReader::QmlProfilerFileReader(QObject *parent) :
     m_loadedFeatures(0)
 {
     static int meta[] = {
-        qRegisterMetaType<QmlEvent>(),
+        qRegisterMetaType<QVector<QmlEvent> >(),
         qRegisterMetaType<QVector<QmlEventType> >(),
         qRegisterMetaType<QVector<QmlNote> >()
     };
@@ -248,7 +248,9 @@ bool QmlProfilerFileReader::loadQzt(QIODevice *device)
     emit notesLoaded(m_notes);
     updateProgress(device);
 
-    QmlEvent event;
+    const int eventBufferLength = 1024;
+    QVector<QmlEvent> eventBuffer(eventBufferLength);
+    int eventBufferIndex = 0;
     while (!stream.atEnd()) {
         stream >> data;
         buffer.setData(qUncompress(data));
@@ -256,6 +258,7 @@ bool QmlProfilerFileReader::loadQzt(QIODevice *device)
         while (!buffer.atEnd()) {
             if (isCanceled())
                 return false;
+            QmlEvent &event = eventBuffer[eventBufferIndex];
             bufferStream >> event;
             if (bufferStream.status() == QDataStream::Ok) {
                 if (event.typeIndex() >= m_eventTypes.length()) {
@@ -263,7 +266,6 @@ bool QmlProfilerFileReader::loadQzt(QIODevice *device)
                     return false;
                 }
                 m_loadedFeatures |= (1ULL << m_eventTypes[event.typeIndex()].feature());
-                emit qmlEventLoaded(event);
             } else if (bufferStream.status() == QDataStream::ReadPastEnd) {
                 break; // Apparently EOF is a character so we end up here after the last event.
             } else if (bufferStream.status() == QDataStream::ReadCorruptData) {
@@ -272,10 +274,16 @@ bool QmlProfilerFileReader::loadQzt(QIODevice *device)
             } else {
                 Q_UNREACHABLE();
             }
+            if (++eventBufferIndex == eventBufferLength) {
+                emit qmlEventsLoaded(eventBuffer);
+                eventBufferIndex = 0;
+            }
         }
         buffer.close();
         updateProgress(device);
     }
+    eventBuffer.resize(eventBufferIndex);
+    emit qmlEventsLoaded(eventBuffer);
     emit success();
     return true;
 }
@@ -499,8 +507,7 @@ void QmlProfilerFileReader::loadEvents(QXmlStreamReader &stream)
                 std::sort(events.begin(), events.end(), [](const QmlEvent &a, const QmlEvent &b) {
                     return a.timestamp() < b.timestamp();
                 });
-                foreach (const QmlEvent &event, events)
-                    emit qmlEventLoaded(event);
+                emit qmlEventsLoaded(events);
                 return;
             }
             break;

src/plugins/qmlprofiler/qmlprofilertracefile.h

@@ -62,7 +62,7 @@ public:
 signals:
     void typesLoaded(const QVector<QmlProfiler::QmlEventType> &types);
     void notesLoaded(const QVector<QmlProfiler::QmlNote> &notes);
-    void qmlEventLoaded(const QmlProfiler::QmlEvent &event);
+    void qmlEventsLoaded(const QVector<QmlProfiler::QmlEvent> &event);
     void error(const QString &error);
     void success();