Assistant: Don't query the database for unneeded data

If we only need registered documentations of a specific namespace we can
restrict the SQL query accordingly, so that we don't have to iterate
through all the results afterwards.

Change-Id: I124cf16ed95e1010b8a05d8cb723c2a1f03120d4
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

3 files changed, 14 insertions, 5 deletions

diff --git a/src/assistant/help/qhelpcollectionhandler.cpp b/src/assistant/help/qhelpcollectionhandler.cpp
index 163eefed1..5935295e6 100644
--- a/src/assistant/help/qhelpcollectionhandler.cpp
+++ b/src/assistant/help/qhelpcollectionhandler.cpp
@@ -355,12 +355,21 @@ bool QHelpCollectionHandler::addCustomFilter(const QString &filterName,
     return true;
 }
 
-QHelpCollectionHandler::DocInfoList QHelpCollectionHandler::registeredDocumentations() const
+QHelpCollectionHandler::DocInfoList QHelpCollectionHandler::registeredDocumentations(
+        const QString &namespaceName) const
 {
     DocInfoList list;
     if (m_dbOpened) {
-        m_query.exec(QLatin1String("SELECT a.Name, a.FilePath, b.Name "
-            "FROM NamespaceTable a, FolderTable b WHERE a.Id=b.NamespaceId"));
+        static const QLatin1String baseQuery("SELECT a.Name, a.FilePath, b.Name "
+                                             "FROM NamespaceTable a, FolderTable b "
+                                             "WHERE a.Id=b.NamespaceId");
+        if (namespaceName.isEmpty()) {
+            m_query.prepare(baseQuery);
+        } else {
+            m_query.prepare(baseQuery + QLatin1String(" AND a.Name=? LIMIT 1"));
+            m_query.bindValue(0, namespaceName);
+        }
+        m_query.exec();
 
         while (m_query.next()) {
             DocInfo info;
diff --git a/src/assistant/help/qhelpcollectionhandler_p.h b/src/assistant/help/qhelpcollectionhandler_p.h
index b2b249715..2b1b57718 100644
--- a/src/assistant/help/qhelpcollectionhandler_p.h
+++ b/src/assistant/help/qhelpcollectionhandler_p.h
@@ -88,7 +88,7 @@ public:
     bool addCustomFilter(const QString &filterName,
         const QStringList &attributes);
 
-    DocInfoList registeredDocumentations() const;
+    DocInfoList registeredDocumentations(const QString &namespaceName = QString()) const;
     bool registerDocumentation(const QString &fileName);
     bool unregisterDocumentation(const QString &namespaceName);
 
diff --git a/src/assistant/help/qhelpenginecore.cpp b/src/assistant/help/qhelpenginecore.cpp
index b3396f2fe..e351c07d1 100644
--- a/src/assistant/help/qhelpenginecore.cpp
+++ b/src/assistant/help/qhelpenginecore.cpp
@@ -351,7 +351,7 @@ QString QHelpEngineCore::documentationFileName(const QString &namespaceName)
 {
     if (d->setup()) {
         const QHelpCollectionHandler::DocInfoList &docList =
-            d->collectionHandler->registeredDocumentations();
+            d->collectionHandler->registeredDocumentations(namespaceName);
         for (const QHelpCollectionHandler::DocInfo &info : docList) {
             if (info.namespaceName == namespaceName) {
                 if (QDir::isAbsolutePath(info.fileName))