CppTools: Do not block GUI thread for completions

The GUI was blocked while waiting for the parsed document. Now the
blocking operation is executed in the completion thread.

Task-number: QTCREATORBUG-11037
Task-number: QTCREATORBUG-11433
Change-Id: Ia7c1b1b7eea0ba75010ff667ba05273c62c18491
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/cpptools/cppcompletionassist.cpp

@@ -28,10 +28,13 @@
 ****************************************************************************/
 
 #include "cppcompletionassist.h"
+
+#include "cppdoxygen.h"
 #include "cppmodelmanager.h"
+#include "cppmodelmanagerinterface.h"
+#include "cppsnapshotupdater.h"
 #include "cpptoolsconstants.h"
 #include "cpptoolseditorsupport.h"
-#include "cppdoxygen.h"
 
 #include <coreplugin/icore.h>
 #include <cppeditor/cppeditorconstants.h>
@@ -422,24 +425,9 @@ TextEditor::IAssistInterface *InternalCompletionAssistProvider::createAssistInte
         int position, TextEditor::AssistReason reason) const
 {
     Q_UNUSED(project);
-
-    CppModelManagerInterface *modelManager = CppModelManagerInterface::instance();
-
-    if (CppEditorSupport *supp = modelManager->cppEditorSupport(editor)) {
-        if (QSharedPointer<SnapshotUpdater> updater = supp->snapshotUpdater()) {
-            updater->update(modelManager->workingCopy());
-            return new CppTools::Internal::CppCompletionAssistInterface(
-                        document,
-                        position,
-                        editor->document()->filePath(),
-                        reason,
-                        updater->snapshot(),
-                        updater->includePaths(),
-                        updater->frameworkPaths());
-        }
-    }
-
-    return 0;
+    QTC_ASSERT(editor, return 0);
+    QTC_ASSERT(document, return 0);
+    return new CppTools::Internal::CppCompletionAssistInterface(editor, document, position, reason);
 }
 
 // -----------------
@@ -1930,3 +1918,20 @@ bool CppCompletionAssistProcessor::completeConstructorOrFunction(const QList<CPl
 
     return false;
 }
+
+void CppCompletionAssistInterface::getCppSpecifics() const
+{
+    if (m_gotCppSpecifics)
+        return;
+    m_gotCppSpecifics = true;
+
+    CppModelManagerInterface *modelManager = CppModelManagerInterface::instance();
+    if (CppEditorSupport *supp = modelManager->cppEditorSupport(m_editor)) {
+        if (QSharedPointer<SnapshotUpdater> updater = supp->snapshotUpdater()) {
+            updater->update(modelManager->workingCopy());
+            m_snapshot = updater->snapshot();
+            m_includePaths = updater->includePaths();
+            m_frameworkPaths = updater->frameworkPaths();
+        }
+    }
+}

src/plugins/cpptools/cppcompletionassist.h

@@ -39,6 +39,7 @@
 #  include <cplusplus/Symbol.h>
 #endif
 
+#include <texteditor/basetexteditor.h>
 #include <texteditor/codeassist/basicproposalitemlistmodel.h>
 #include <texteditor/codeassist/defaultassistinterface.h>
 #include <texteditor/codeassist/iassistprocessor.h>
@@ -170,6 +171,16 @@ private:
 class CppCompletionAssistInterface : public TextEditor::DefaultAssistInterface
 {
 public:
+    CppCompletionAssistInterface(TextEditor::BaseTextEditor *editor,
+                                 QTextDocument *textDocument,
+                                 int position,
+                                 TextEditor::AssistReason reason)
+        : TextEditor::DefaultAssistInterface(textDocument, position, editor->document()->filePath(),
+                                             reason)
+        , m_editor(editor)
+        , m_gotCppSpecifics(false)
+    {}
+
     CppCompletionAssistInterface(QTextDocument *textDocument,
                                  int position,
                                  const QString &fileName,
@@ -178,19 +189,25 @@ public:
                                  const QStringList &includePaths,
                                  const QStringList &frameworkPaths)
         : TextEditor::DefaultAssistInterface(textDocument, position, fileName, reason)
+        , m_editor(0)
+        , m_gotCppSpecifics(true)
         , m_snapshot(snapshot)
         , m_includePaths(includePaths)
         , m_frameworkPaths(frameworkPaths)
     {}
 
-    const CPlusPlus::Snapshot &snapshot() const { return m_snapshot; }
-    const QStringList &includePaths() const { return m_includePaths; }
-    const QStringList &frameworkPaths() const { return m_frameworkPaths; }
+    const CPlusPlus::Snapshot &snapshot() const { getCppSpecifics(); return m_snapshot; }
+    const QStringList &includePaths() const { getCppSpecifics(); return m_includePaths; }
+    const QStringList &frameworkPaths() const { getCppSpecifics(); return m_frameworkPaths; }
 
 private:
-    CPlusPlus::Snapshot m_snapshot;
-    QStringList m_includePaths;
-    QStringList m_frameworkPaths;
+    void getCppSpecifics() const;
+
+    TextEditor::BaseTextEditor *m_editor;
+    mutable bool m_gotCppSpecifics;
+    mutable CPlusPlus::Snapshot m_snapshot;
+    mutable QStringList m_includePaths;
+    mutable QStringList m_frameworkPaths;
 };
 
 } // Internal