cache results of feature search

looking up the same files in the same locations over and over again
is a rather significant waste. in particular, looking up the CONFIG
flags that don't correspond with features has a measurable impact on qt
creator's project loading time.

Task-number: QTCREATORBUG-9154
Change-Id: Ibae3d8b7797e706a6416a7d45c77734ab1281b51
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
(cherry picked from qtcreator/fa27cd79e05aed4ebd16d5648480cc7d48fefd43)
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

1 files changed, 19 insertions, 1 deletions

diff --git a/qmake/library/qmakeevaluator.h b/qmake/library/qmakeevaluator.h
index 09617ba019..91433302d0 100644
--- a/qmake/library/qmakeevaluator.h
+++ b/qmake/library/qmakeevaluator.h
@@ -55,9 +55,13 @@
 #include <qstack.h>
 #include <qstring.h>
 #include <qstringlist.h>
+#include <qshareddata.h>
 #ifndef QT_BOOTSTRAPPED
 # include <qprocess.h>
 #endif
+#ifdef PROEVALUATOR_THREAD_SAFE
+# include <qmutex.h>
+#endif
 
 QT_BEGIN_NAMESPACE
 
@@ -83,6 +87,20 @@ public:
     virtual void doneWithEval(ProFile *parent) = 0;
 };
 
+typedef QPair<QString, QString> QMakeFeatureKey; // key, parent
+typedef QHash<QMakeFeatureKey, QString> QMakeFeatureHash;
+
+class QMAKE_EXPORT QMakeFeatureRoots : public QSharedData
+{
+public:
+    QMakeFeatureRoots(const QStringList &_paths) : paths(_paths) {}
+    const QStringList paths;
+    mutable QMakeFeatureHash cache;
+#ifdef PROEVALUATOR_THREAD_SAFE
+    mutable QMutex mutex;
+#endif
+};
+
 // We use a QLinkedList based stack instead of a QVector based one (QStack), so that
 // the addresses of value maps stay constant. The qmake generators rely on that.
 class QMAKE_EXPORT ProValueMapStack : public QLinkedList<ProValueMap>
@@ -284,7 +302,7 @@ public:
     QStringList m_qmakepath;
     QStringList m_qmakefeatures;
     QStringList m_mkspecPaths;
-    QStringList m_featureRoots;
+    QExplicitlySharedDataPointer<QMakeFeatureRoots> m_featureRoots;
     ProString m_dirSep;
     ProFunctionDefs m_functionDefs;
     ProStringList m_returnValue;