From 007252adb9008a05940972a4332bce5d00512570 Mon Sep 17 00:00:00 2001
From: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Date: Sat, 26 Apr 2014 16:32:06 +0200
Subject: QRegularExpression: lock a mutex only if there's actual work to do

We can do the (atomic) test of studyData before locking the mutex
protecting the entire function body.

Change-Id: I3006e3a0028608f21668ddaebe8a799aed56362f
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/tools/qregularexpression.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'src/corelib/tools')

diff --git a/src/corelib/tools/qregularexpression.cpp b/src/corelib/tools/qregularexpression.cpp
index 316681e652..2cd76b389d 100644
--- a/src/corelib/tools/qregularexpression.cpp
+++ b/src/corelib/tools/qregularexpression.cpp
@@ -1137,11 +1137,11 @@ void QRegularExpressionPrivate::optimizePattern(OptimizePatternOption option)
 {
     Q_ASSERT(compiledPattern);
 
-    QMutexLocker lock(&mutex);
-
     if (studyData.load()) // already optimized
         return;
 
+    QMutexLocker lock(&mutex);
+
     if ((option == LazyOptimizeOption) && (++usedCount != qt_qregularexpression_optimize_after_use_count))
         return;
 
-- 
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