ClassView: Move delaying of update into the main thread

Minimize the communication with parser's thread.
Don't call getParseDocumentTree() multiple times
when subsequent request for the same document comes
before the timeout.
Don't queue again already queued documentUpdated()
signal (it's emitted form non-gui thread).
Prepare for moving the calls to SessionManager out of the
parser's thread.

Task-number: QTCREATORBUG-25317
Change-Id: I5d4898b5addbb589d415e00c66de5cba7b96d512
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

1 files changed, 73 insertions, 43 deletions

diff --git a/src/plugins/classview/classviewmanager.cpp b/src/plugins/classview/classviewmanager.cpp
index e51cef78b9..7724fbc493 100644
--- a/src/plugins/classview/classviewmanager.cpp
+++ b/src/plugins/classview/classviewmanager.cpp
@@ -41,6 +41,7 @@
 #include <texteditor/texteditor.h>
 
 #include <QThread>
+#include <QTimer>
 
 using namespace Core;
 using namespace Utils;
@@ -92,51 +93,37 @@ public:
     QThread m_parserThread;
     ParserTreeItem::ConstPtr m_root;
 
+    QTimer m_timer;
+    QHash<QString, CPlusPlus::Document::Ptr> m_awaitingDocuments;
+
     //! Internal manager state. \sa Manager::state
     bool state = false;
 
     //! there is some massive operation ongoing so temporary we should wait
     bool disableCodeParser = false;
-};
 
-///////////////////////////////// Manager //////////////////////////////////
-
-Manager::Manager(QObject *parent)
-    : QObject(parent),
-    d(new ManagerPrivate())
-{
-    d->m_parser = new Parser();
-    d->m_parser->moveToThread(&d->m_parserThread);
-    connect(&d->m_parserThread, &QThread::finished, d->m_parser, &QObject::deleteLater);
-    managerInstance = this;
-
-    // register - to be able send between signal/slots
-    qRegisterMetaType<QSharedPointer<QStandardItem> >("QSharedPointer<QStandardItem>");
-
-    initialize();
-
-    // start a separate thread for the parser
-    d->m_parserThread.start();
-}
+    void cancelScheduledUpdate();
+    void resetParser();
+    ParserTreeItem::ConstPtr findItemByRoot(const QStandardItem *item, bool skipRoot = false) const;
+};
 
-Manager::~Manager()
+void ManagerPrivate::cancelScheduledUpdate()
 {
-    d->m_parserThread.quit();
-    d->m_parserThread.wait();
-    delete d;
-    managerInstance = nullptr;
+    m_timer.stop();
+    m_awaitingDocuments.clear();
 }
 
-Manager *Manager::instance()
+void ManagerPrivate::resetParser()
 {
-    return managerInstance;
+    cancelScheduledUpdate();
+    QMetaObject::invokeMethod(m_parser, &Parser::resetDataToCurrentState, Qt::QueuedConnection);
 }
 
 /*!
     Returns the internal tree item for \a item. \a skipRoot skips the root
     item.
 */
-ParserTreeItem::ConstPtr Manager::findItemByRoot(const QStandardItem *item, bool skipRoot) const
+ParserTreeItem::ConstPtr ManagerPrivate::findItemByRoot(const QStandardItem *item, bool skipRoot) const
 {
     if (!item)
         return ParserTreeItem::ConstPtr();
@@ -152,7 +139,7 @@ ParserTreeItem::ConstPtr Manager::findItemByRoot(const QStandardItem *item, bool
     if (skipRoot && uiList.count() > 0)
         uiList.removeLast();
 
-    ParserTreeItem::ConstPtr internal = d->m_root;
+    ParserTreeItem::ConstPtr internal = m_root;
     while (uiList.count() > 0) {
         cur = uiList.last();
         uiList.removeLast();
@@ -165,12 +152,45 @@ ParserTreeItem::ConstPtr Manager::findItemByRoot(const QStandardItem *item, bool
     return internal;
 }
 
+///////////////////////////////// Manager //////////////////////////////////
+
+Manager::Manager(QObject *parent)
+    : QObject(parent),
+    d(new ManagerPrivate())
+{
+    d->m_parser = new Parser();
+    d->m_parser->moveToThread(&d->m_parserThread);
+    connect(&d->m_parserThread, &QThread::finished, d->m_parser, &QObject::deleteLater);
+    managerInstance = this;
+
+    // register - to be able send between signal/slots
+    qRegisterMetaType<QSharedPointer<QStandardItem> >("QSharedPointer<QStandardItem>");
+
+    initialize();
+
+    // start a separate thread for the parser
+    d->m_parserThread.start();
+}
+
+Manager::~Manager()
+{
+    d->m_parserThread.quit();
+    d->m_parserThread.wait();
+    delete d;
+    managerInstance = nullptr;
+}
+
+Manager *Manager::instance()
+{
+    return managerInstance;
+}
+
 /*!
     Checks \a item for lazy data population of a QStandardItemModel.
 */
 bool Manager::canFetchMore(QStandardItem *item, bool skipRoot) const
 {
-    ParserTreeItem::ConstPtr ptr = findItemByRoot(item, skipRoot);
+    ParserTreeItem::ConstPtr ptr = d->findItemByRoot(item, skipRoot);
     if (ptr.isNull())
         return false;
     return ptr->canFetchMore(item);
@@ -182,7 +202,7 @@ bool Manager::canFetchMore(QStandardItem *item, bool skipRoot) const
 */
 void Manager::fetchMore(QStandardItem *item, bool skipRoot)
 {
-    ParserTreeItem::ConstPtr ptr = findItemByRoot(item, skipRoot);
+    ParserTreeItem::ConstPtr ptr = d->findItemByRoot(item, skipRoot);
     if (ptr.isNull())
         return;
     ptr->fetchMore(item);
@@ -190,7 +210,7 @@ void Manager::fetchMore(QStandardItem *item, bool skipRoot)
 
 bool Manager::hasChildren(QStandardItem *item) const
 {
-    ParserTreeItem::ConstPtr ptr = findItemByRoot(item);
+    ParserTreeItem::ConstPtr ptr = d->findItemByRoot(item);
     if (ptr.isNull())
         return false;
     return ptr->childCount();
@@ -199,6 +219,7 @@ bool Manager::hasChildren(QStandardItem *item) const
 void Manager::initialize()
 {
     using ProjectExplorer::SessionManager;
+    d->m_timer.setSingleShot(true);
 
     // connections to enable/disable navi widget factory
     SessionManager *sessionManager = SessionManager::instance();
@@ -215,6 +236,7 @@ void Manager::initialize()
 
         // disable tree updates to speed up
         d->disableCodeParser = true;
+        d->cancelScheduledUpdate();
     });
     connect(ProgressManager::instance(), &ProgressManager::allTasksFinished,
             this, [this](Id type) {
@@ -229,7 +251,7 @@ void Manager::initialize()
             return;
 
         // request to update a tree to the current state
-        resetParser();
+        d->resetParser();
     });
 
     connect(d->m_parser, &Parser::treeRegenerated,
@@ -258,10 +280,23 @@ void Manager::initialize()
         if (d->disableCodeParser)
             return;
 
-        QMetaObject::invokeMethod(d->m_parser, [this, doc]() {
-            d->m_parser->parseDocument(doc); }, Qt::QueuedConnection);
-    }, Qt::QueuedConnection);
-    //
+        if (doc.data() == nullptr)
+            return;
+
+        d->m_awaitingDocuments.insert(doc->fileName(), doc);
+        d->m_timer.start(400); // Accumulate multiple requests into one, restarts the timer
+    });
+
+    connect(&d->m_timer, &QTimer::timeout, this, [this]() {
+        const QList<CPlusPlus::Document::Ptr> docsToBeUpdated = d->m_awaitingDocuments.values();
+        d->cancelScheduledUpdate();
+        if (!state() || d->disableCodeParser) // enabling any of them will trigger the total update
+            return;
+        QMetaObject::invokeMethod(d->m_parser, [this, docsToBeUpdated]() {
+            d->m_parser->updateDocuments(docsToBeUpdated);
+        }, Qt::QueuedConnection);
+    });
+
     connect(codeModelManager, &CppTools::CppModelManager::aboutToRemoveFiles,
             d->m_parser, &Parser::removeFiles, Qt::QueuedConnection);
 }
@@ -295,12 +330,7 @@ void Manager::setState(bool state)
     d->state = state;
 
     if (state) // enabled - request a current snapshots etc?..
-        resetParser();
-}
-
-void Manager::resetParser()
-{
-    QMetaObject::invokeMethod(d->m_parser, &Parser::resetDataToCurrentState, Qt::QueuedConnection);
+        d->resetParser();
 }
 
 /*!