CppTools: Avoid unnecessary blocking of main thread

Among others, BaseEditorDocumentParser::projectPart() was a blocking
operation in case the parser was running. This led to noticeable GUI
freezes for the ClangCodeModel since the function was called from the
main thread.

Rework *EditorDocumentParser to clearly separate the configuration data
(input) from the actual object state. Querying/setting configuration or
(last) state does not block anymore. update() is supposed to get the
necessary configuration and the last state at the beginning and to set
the new state at end.

Change-Id: Ib4b534fa6ff373c3059826726b3f10ece95acc21
Reviewed-by: Erik Verbruggen <erik.verbruggen@theqtcompany.com>

1 files changed, 32 insertions, 47 deletions

diff --git a/src/plugins/cpptools/baseeditordocumentparser.cpp b/src/plugins/cpptools/baseeditordocumentparser.cpp
index d24e341b1f..31d08bd431 100644
--- a/src/plugins/cpptools/baseeditordocumentparser.cpp
+++ b/src/plugins/cpptools/baseeditordocumentparser.cpp
@@ -44,15 +44,19 @@ namespace CppTools {
     It's meant to be used in the C++ editor to get precise results by using
     the "best" project part for a file.
 
-    Derived classes are expected to implement update() by using the protected
-    mutex, determineProjectPart() and by respecting the options set by the client.
+    Derived classes are expected to implement update() this way:
+
+    \list
+        \li Get a copy of the configuration and the last state.
+        \li Acquire the protected m_updateIsRunning for the duration of update().
+        \li Work on the data and do whatever is necessary. At least, update
+            the project part with the help of determineProjectPart().
+        \li Ensure the new state is set before update() returns.
+    \endlist
 */
 
 BaseEditorDocumentParser::BaseEditorDocumentParser(const QString &filePath)
-    : m_mutex(QMutex::Recursive)
-    , m_filePath(filePath)
-    , m_usePrecompiledHeaders(false)
-    , m_editorDefinesChangedSinceLastUpdate(false)
+    : m_filePath(filePath)
 {
 }
 
@@ -65,44 +69,33 @@ QString BaseEditorDocumentParser::filePath() const
     return m_filePath;
 }
 
-ProjectPart::Ptr BaseEditorDocumentParser::projectPart() const
-{
-    QMutexLocker locker(&m_mutex);
-    return m_projectPart;
-}
-
-void BaseEditorDocumentParser::setProjectPart(ProjectPart::Ptr projectPart)
+BaseEditorDocumentParser::Configuration BaseEditorDocumentParser::configuration() const
 {
-    QMutexLocker locker(&m_mutex);
-    m_manuallySetProjectPart = projectPart;
+    QMutexLocker locker(&m_stateAndConfigurationMutex);
+    return m_configuration;
 }
 
-bool BaseEditorDocumentParser::usePrecompiledHeaders() const
+void BaseEditorDocumentParser::setConfiguration(const Configuration &configuration)
 {
-    QMutexLocker locker(&m_mutex);
-    return m_usePrecompiledHeaders;
+    QMutexLocker locker(&m_stateAndConfigurationMutex);
+    m_configuration = configuration;
 }
 
-void BaseEditorDocumentParser::setUsePrecompiledHeaders(bool usePrecompiledHeaders)
+BaseEditorDocumentParser::State BaseEditorDocumentParser::state() const
 {
-    QMutexLocker locker(&m_mutex);
-    m_usePrecompiledHeaders = usePrecompiledHeaders;
+    QMutexLocker locker(&m_stateAndConfigurationMutex);
+    return m_state;
 }
 
-QByteArray BaseEditorDocumentParser::editorDefines() const
+void BaseEditorDocumentParser::setState(const State &state)
 {
-    QMutexLocker locker(&m_mutex);
-    return m_editorDefines;
+    QMutexLocker locker(&m_stateAndConfigurationMutex);
+    m_state = state;
 }
 
-void BaseEditorDocumentParser::setEditorDefines(const QByteArray &editorDefines)
+ProjectPart::Ptr BaseEditorDocumentParser::projectPart() const
 {
-    QMutexLocker locker(&m_mutex);
-
-    if (editorDefines != m_editorDefines) {
-        m_editorDefines = editorDefines;
-        m_editorDefinesChangedSinceLastUpdate = true;
-    }
+    return state().projectPart;
 }
 
 BaseEditorDocumentParser *BaseEditorDocumentParser::get(const QString &filePath)
@@ -115,15 +108,17 @@ BaseEditorDocumentParser *BaseEditorDocumentParser::get(const QString &filePath)
     return 0;
 }
 
-ProjectPart::Ptr BaseEditorDocumentParser::determineProjectPart() const
+ProjectPart::Ptr BaseEditorDocumentParser::determineProjectPart(const QString &filePath,
+                                                                const Configuration &config,
+                                                                const State &state)
 {
-    if (m_manuallySetProjectPart)
-        return m_manuallySetProjectPart;
+    if (config.manuallySetProjectPart)
+        return config.manuallySetProjectPart;
 
-    ProjectPart::Ptr projectPart = m_projectPart;
+    ProjectPart::Ptr projectPart = state.projectPart;
 
     CppModelManager *cmm = CppModelManager::instance();
-    QList<ProjectPart::Ptr> projectParts = cmm->projectPart(m_filePath);
+    QList<ProjectPart::Ptr> projectParts = cmm->projectPart(filePath);
     if (projectParts.isEmpty()) {
         if (projectPart)
             // File is not directly part of any project, but we got one before. We will re-use it,
@@ -131,7 +126,7 @@ ProjectPart::Ptr BaseEditorDocumentParser::determineProjectPart() const
             return projectPart;
 
         // Fall-back step 1: Get some parts through the dependency table:
-        projectParts = cmm->projectPartFromDependencies(Utils::FileName::fromString(m_filePath));
+        projectParts = cmm->projectPartFromDependencies(Utils::FileName::fromString(filePath));
         if (projectParts.isEmpty())
             // Fall-back step 2: Use fall-back part from the model manager:
             projectPart = cmm->fallbackProjectPart();
@@ -146,14 +141,4 @@ ProjectPart::Ptr BaseEditorDocumentParser::determineProjectPart() const
     return projectPart;
 }
 
-bool BaseEditorDocumentParser::editorDefinesChanged() const
-{
-    return m_editorDefinesChangedSinceLastUpdate;
-}
-
-void BaseEditorDocumentParser::resetEditorDefinesChanged()
-{
-    m_editorDefinesChangedSinceLastUpdate = false;
-}
-
 } // namespace CppTools