Store the copy of the index inside the help collection file

This avoids having to open all .qch files at startup, which is slow
and can lead to contention on open file handles.

This change is backward compatible. The old help lib
won't use the new tables. The new help lib will
generate the new tables on first run or regenerate them
when it detects they are not anymore in sync.

Store also the timestamp info about the qch files and compare
it upon every startup. If it doesn't match then new tables' data
is regenerated. The case when running new Creator,
then running old Creator and reconfiguring doc set and then
running new Creator again should work properly.

Task-number: QTCREATORBUG-18242
Change-Id: I7f656935ae2383b866b27e256eec23dab588efc5
Reviewed-by: Kai Koehne <kai.koehne@qt.io>

1 files changed, 15 insertions, 3 deletions

diff --git a/src/assistant/help/qhelpengine.cpp b/src/assistant/help/qhelpengine.cpp
index 41ded85ee..966c33354 100644
--- a/src/assistant/help/qhelpengine.cpp
+++ b/src/assistant/help/qhelpengine.cpp
@@ -48,6 +48,7 @@
 #include <QtCore/QDir>
 #include <QtCore/QFile>
 #include <QtCore/QPluginLoader>
+#include <QtCore/QTimer>
 #include <QtWidgets/QApplication>
 #include <QtSql/QSqlQuery>
 
@@ -64,15 +65,26 @@ void QHelpEnginePrivate::init(const QString &collectionFile,
         indexModel = new QHelpIndexModel(this);
 
     connect(helpEngineCore, &QHelpEngineCore::setupFinished,
-            this, &QHelpEnginePrivate::applyCurrentFilter);
+            this, &QHelpEnginePrivate::scheduleApplyCurrentFilter);
     connect(helpEngineCore, &QHelpEngineCore::currentFilterChanged,
-            this, &QHelpEnginePrivate::applyCurrentFilter);
+            this, &QHelpEnginePrivate::scheduleApplyCurrentFilter);
 }
 
-void QHelpEnginePrivate::applyCurrentFilter()
+void QHelpEnginePrivate::scheduleApplyCurrentFilter()
 {
     if (!error.isEmpty())
         return;
+
+    if (m_isApplyCurrentFilterScheduled)
+        return;
+
+    m_isApplyCurrentFilterScheduled = true;
+    QTimer::singleShot(0, this, &QHelpEnginePrivate::applyCurrentFilter);
+}
+
+void QHelpEnginePrivate::applyCurrentFilter()
+{
+    m_isApplyCurrentFilterScheduled = false;
     contentModel->createContents(currentFilter);
     indexModel->createIndex(currentFilter);
 }