C++: release more futures.

The CPPEditorWidget retained two futures, as did the attached future
watchers retained them too. Together, each future and the watcher held
on to a complete snapshot that would only get released when another
future was set. This could result into retaining old snapshots in
editors that were invisible/unused for long.

Change-Id: I1133e857c620437b4a69b9dad468f6bd458304b8
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

4 files changed, 72 insertions, 70 deletions

diff --git a/src/plugins/cppeditor/cppeditor.cpp b/src/plugins/cppeditor/cppeditor.cpp
index e71f4cb845..47a1b58854 100644
--- a/src/plugins/cppeditor/cppeditor.cpp
+++ b/src/plugins/cppeditor/cppeditor.cpp
@@ -549,19 +549,14 @@ void CPPEditorWidget::ctor()
                 this, SLOT(onDocumentUpdated()));
         connect(editorSupport, SIGNAL(semanticInfoUpdated(CppTools::SemanticInfo)),
                 this, SLOT(updateSemanticInfo(CppTools::SemanticInfo)));
-        connect(editorSupport, SIGNAL(highlighterStarted(QFuture<TextEditor::HighlightingResult>*,uint)),
-                this, SLOT(highlighterStarted(QFuture<TextEditor::HighlightingResult>*,uint)));
+        connect(editorSupport, SIGNAL(highlighterStarted(QFuture<TextEditor::HighlightingResult>,uint)),
+                this, SLOT(highlighterStarted(QFuture<TextEditor::HighlightingResult>,uint)));
     }
 
     m_highlightRevision = 0;
-    connect(&m_highlightWatcher, SIGNAL(resultsReadyAt(int,int)),
-            SLOT(highlightSymbolUsages(int,int)));
-    connect(&m_highlightWatcher, SIGNAL(finished()),
-            SLOT(finishHighlightSymbolUsages()));
 
     m_referencesRevision = 0;
     m_referencesCursorPosition = 0;
-    connect(&m_referencesWatcher, SIGNAL(finished()), SLOT(markSymbolsNow()));
 
     connect(this, SIGNAL(refactorMarkerClicked(TextEditor::RefactorMarker)),
             this, SLOT(onRefactorMarkerClicked(TextEditor::RefactorMarker)));
@@ -854,40 +849,39 @@ void CPPEditorWidget::renameUsages()
 
 void CPPEditorWidget::markSymbolsNow()
 {
-    if (m_references.isCanceled())
-        return;
-    else if (m_referencesCursorPosition != position())
-        return;
-    else if (m_referencesRevision != editorRevision())
-        return;
-
-    const SemanticInfo info = m_lastSemanticInfo;
-    TranslationUnit *unit = info.doc->translationUnit();
-    const QList<int> result = m_references.result();
+    QTC_ASSERT(m_referencesWatcher, return);
+    if (!m_referencesWatcher->isCanceled()
+            && m_referencesCursorPosition == position()
+            && m_referencesRevision == editorRevision()) {
+        const SemanticInfo info = m_lastSemanticInfo;
+        TranslationUnit *unit = info.doc->translationUnit();
+        const QList<int> result = m_referencesWatcher->result();
 
-    QList<QTextEdit::ExtraSelection> selections;
+        QList<QTextEdit::ExtraSelection> selections;
 
-    foreach (int index, result) {
-        unsigned line, column;
-        unit->getTokenPosition(index, &line, &column);
+        foreach (int index, result) {
+            unsigned line, column;
+            unit->getTokenPosition(index, &line, &column);
 
-        if (column)
-            --column;  // adjust the column position.
+            if (column)
+                --column;  // adjust the column position.
 
-        const int len = unit->tokenAt(index).f.length;
+            const int len = unit->tokenAt(index).f.length;
 
-        QTextCursor cursor(document()->findBlockByNumber(line - 1));
-        cursor.setPosition(cursor.position() + column);
-        cursor.setPosition(cursor.position() + len, QTextCursor::KeepAnchor);
+            QTextCursor cursor(document()->findBlockByNumber(line - 1));
+            cursor.setPosition(cursor.position() + column);
+            cursor.setPosition(cursor.position() + len, QTextCursor::KeepAnchor);
 
-        QTextEdit::ExtraSelection sel;
-        sel.format = baseTextDocument()->fontSettings().toTextCharFormat(TextEditor::C_OCCURRENCES);
-        sel.cursor = cursor;
-        selections.append(sel);
+            QTextEdit::ExtraSelection sel;
+            sel.format = baseTextDocument()->fontSettings()
+                         .toTextCharFormat(TextEditor::C_OCCURRENCES);
+            sel.cursor = cursor;
+            selections.append(sel);
+        }
 
+        setExtraSelections(CodeSemanticsSelection, selections);
     }
-
-    setExtraSelections(CodeSemanticsSelection, selections);
+    m_referencesWatcher.reset();
 }
 
 static QList<int> lazyFindReferences(Scope *scope, QString code, Document::Ptr doc,
@@ -951,12 +945,15 @@ void CPPEditorWidget::markSymbols(const QTextCursor &tc, const SemanticInfo &inf
         CanonicalSymbol cs(this, info);
         QString expression;
         if (Scope *scope = cs.getScopeAndExpression(this, info, tc, &expression)) {
-            m_references.cancel();
+            if (m_referencesWatcher)
+                m_referencesWatcher->cancel();
+            m_referencesWatcher.reset(new QFutureWatcher<QList<int> >);
+            connect(m_referencesWatcher.data(), SIGNAL(finished()), SLOT(markSymbolsNow()));
+
             m_referencesRevision = info.revision;
             m_referencesCursorPosition = position();
-            m_references = QtConcurrent::run(&lazyFindReferences, scope, expression, info.doc,
-                                             info.snapshot);
-            m_referencesWatcher.setFuture(m_references);
+            m_referencesWatcher->setFuture(QtConcurrent::run(&lazyFindReferences, scope, expression,
+                                                             info.doc, info.snapshot));
         } else {
             const QList<QTextEdit::ExtraSelection> selections = extraSelections(CodeSemanticsSelection);
 
@@ -1164,8 +1161,10 @@ void CPPEditorWidget::updateOutlineToolTip()
 
 void CPPEditorWidget::updateUses()
 {
-    if (editorRevision() != m_highlightRevision)
-        m_highlighter.cancel();
+    if (m_highlightWatcher) {
+        m_highlightWatcher->cancel();
+        m_highlightWatcher.reset();
+    }
 
     // Block premature semantic info calculation when editor is created.
     if (m_modelManager && m_modelManager->cppEditorSupport(editor())->initialized())
@@ -1185,32 +1184,29 @@ void CPPEditorWidget::highlightSymbolUsages(int from, int to)
     if (editorRevision() != m_highlightRevision)
         return; // outdated
 
-    else if (m_highlighter.isCanceled())
+    else if (!m_highlightWatcher || m_highlightWatcher->isCanceled())
         return; // aborted
 
     TextEditor::SyntaxHighlighter *highlighter = baseTextDocument()->syntaxHighlighter();
     QTC_ASSERT(highlighter, return);
 
     TextEditor::SemanticHighlighter::incrementalApplyExtraAdditionalFormats(
-                highlighter, m_highlighter, from, to, m_semanticHighlightFormatMap);
+                highlighter, m_highlightWatcher->future(), from, to, m_semanticHighlightFormatMap);
 }
 
 void CPPEditorWidget::finishHighlightSymbolUsages()
 {
-    if (editorRevision() != m_highlightRevision)
-        return; // outdated
-
-    if (m_highlighter.isCanceled())
-        return; // aborted
-
-    else if (m_lastSemanticInfo.doc.isNull())
-        return;
-
-    TextEditor::SyntaxHighlighter *highlighter = baseTextDocument()->syntaxHighlighter();
-    QTC_ASSERT(highlighter, return);
-
-    TextEditor::SemanticHighlighter::clearExtraAdditionalFormatsUntilEnd(
-                highlighter, m_highlighter);
+    QTC_ASSERT(m_highlightWatcher, return);
+    if (!m_highlightWatcher->isCanceled()
+            && editorRevision() == m_highlightRevision
+            && !m_lastSemanticInfo.doc.isNull()) {
+        TextEditor::SyntaxHighlighter *highlighter = baseTextDocument()->syntaxHighlighter();
+        QTC_CHECK(highlighter);
+        if (highlighter)
+            TextEditor::SemanticHighlighter::clearExtraAdditionalFormatsUntilEnd(highlighter,
+                m_highlightWatcher->future());
+    }
+    m_highlightWatcher.reset();
 }
 
 void CPPEditorWidget::switchDeclarationDefinition(bool inNextSplit)
@@ -1612,12 +1608,18 @@ void CPPEditorWidget::semanticRehighlight(bool force)
         m_modelManager->cppEditorSupport(editor())->recalculateSemanticInfoDetached(force);
 }
 
-void CPPEditorWidget::highlighterStarted(QFuture<TextEditor::HighlightingResult> *highlighter,
+void CPPEditorWidget::highlighterStarted(QFuture<TextEditor::HighlightingResult> highlighter,
                                          unsigned revision)
 {
-    m_highlighter = *highlighter;
     m_highlightRevision = revision;
-    m_highlightWatcher.setFuture(m_highlighter);
+
+    m_highlightWatcher.reset(new QFutureWatcher<TextEditor::HighlightingResult>);
+    connect(m_highlightWatcher.data(), SIGNAL(resultsReadyAt(int,int)),
+            SLOT(highlightSymbolUsages(int,int)));
+    connect(m_highlightWatcher.data(), SIGNAL(finished()),
+            SLOT(finishHighlightSymbolUsages()));
+
+    m_highlightWatcher->setFuture(highlighter);
 }
 
 void CPPEditorWidget::updateSemanticInfo(const SemanticInfo &semanticInfo)
diff --git a/src/plugins/cppeditor/cppeditor.h b/src/plugins/cppeditor/cppeditor.h
index b6103acd26..4b9b01f8ff 100644
--- a/src/plugins/cppeditor/cppeditor.h
+++ b/src/plugins/cppeditor/cppeditor.h
@@ -144,10 +144,10 @@ public:
 
     FollowSymbolUnderCursor *followSymbolUnderCursorDelegate(); // exposed for tests
 
-Q_SIGNALS:
+signals:
     void outlineModelIndexChanged(const QModelIndex &index);
 
-public Q_SLOTS:
+public slots:
     void setSortedOutline(bool sort);
     void switchDeclarationDefinition(bool inNextSplit);
     void renameSymbolUnderCursor();
@@ -156,7 +156,7 @@ public Q_SLOTS:
     void showPreProcessorWidget();
     void renameUsagesNow(const QString &replacement = QString());
     void semanticRehighlight(bool force = false);
-    void highlighterStarted(QFuture<TextEditor::HighlightingResult> *highlighter,
+    void highlighterStarted(QFuture<TextEditor::HighlightingResult> highlighter,
                             unsigned revision);
 
 protected:
@@ -169,10 +169,10 @@ protected:
 
     const CPlusPlus::Macro *findCanonicalMacro(const QTextCursor &cursor,
                                                CPlusPlus::Document::Ptr doc) const;
-protected Q_SLOTS:
+protected slots:
     void slotCodeStyleSettingsChanged(const QVariant &);
 
-private Q_SLOTS:
+private slots:
     void jumpToOutlineElement(int index);
     void updateOutlineNow();
     void updateOutlineIndex();
@@ -254,12 +254,10 @@ private:
     QList<TextEditor::QuickFixOperation::Ptr> m_quickFixes;
     bool m_objcEnabled;
 
-    QFuture<TextEditor::HighlightingResult> m_highlighter;
-    QFutureWatcher<TextEditor::HighlightingResult> m_highlightWatcher;
+    QScopedPointer<QFutureWatcher<TextEditor::HighlightingResult> > m_highlightWatcher;
     unsigned m_highlightRevision; // the editor revision that requested the highlight
 
-    QFuture<QList<int> > m_references;
-    QFutureWatcher<QList<int> > m_referencesWatcher;
+    QScopedPointer<QFutureWatcher<QList<int> > > m_referencesWatcher;
     unsigned m_referencesRevision;
     int m_referencesCursorPosition;
 
diff --git a/src/plugins/cpptools/cpptoolseditorsupport.cpp b/src/plugins/cpptools/cpptoolseditorsupport.cpp
index 2638a127ce..6a31f98f85 100644
--- a/src/plugins/cpptools/cpptoolseditorsupport.cpp
+++ b/src/plugins/cpptools/cpptoolseditorsupport.cpp
@@ -390,7 +390,7 @@ void CppEditorSupport::startHighlighting()
 
         m_highlighter = m_highlightingSupport->highlightingFuture(doc, snapshot);
         m_lastHighlightRevision = revision;
-        emit highlighterStarted(&m_highlighter, m_lastHighlightRevision);
+        emit highlighterStarted(m_highlighter, m_lastHighlightRevision);
     } else {
         const unsigned revision = currentSource(false).revision;
         if (m_lastHighlightRevision == revision)
@@ -400,7 +400,7 @@ void CppEditorSupport::startHighlighting()
         static const Document::Ptr dummyDoc;
         static const Snapshot dummySnapshot;
         m_highlighter = m_highlightingSupport->highlightingFuture(dummyDoc, dummySnapshot);
-        emit highlighterStarted(&m_highlighter, m_lastHighlightRevision);
+        emit highlighterStarted(m_highlighter, m_lastHighlightRevision);
     }
 }
 
@@ -500,6 +500,8 @@ void CppEditorSupport::onCurrentEditorChanged()
 
 void CppEditorSupport::releaseResources()
 {
+    m_highlighter.cancel();
+    m_highlighter = QFuture<TextEditor::HighlightingResult>();
     snapshotUpdater()->releaseSnapshot();
     QMutexLocker semanticLocker(&m_lastSemanticInfoLock);
     m_lastSemanticInfo = SemanticInfo();
diff --git a/src/plugins/cpptools/cpptoolseditorsupport.h b/src/plugins/cpptools/cpptoolseditorsupport.h
index f9ba876256..1d6179e5d8 100644
--- a/src/plugins/cpptools/cpptoolseditorsupport.h
+++ b/src/plugins/cpptools/cpptoolseditorsupport.h
@@ -132,7 +132,7 @@ signals:
     void documentUpdated();
     void diagnosticsChanged();
     void semanticInfoUpdated(CppTools::SemanticInfo);
-    void highlighterStarted(QFuture<TextEditor::HighlightingResult> *, unsigned revision);
+    void highlighterStarted(QFuture<TextEditor::HighlightingResult>, unsigned revision);
 
 private slots:
     void onMimeTypeChanged();