Inline the common case when there is no contention.

QMutex locking could be used in performence critical code (such
as QObject and co.) where the cost of a function call is
not neglectible. This would slow down the common case where
there is only one thread and no contention.

Since we need to keep the old symbol for binary compatibilty, introduce
new *Inline function.

Reviewed-by: Brad

1 files changed, 60 insertions, 11 deletions

diff --git a/src/corelib/thread/qmutex.h b/src/corelib/thread/qmutex.h
index 509f300..710b794 100644
--- a/src/corelib/thread/qmutex.h
+++ b/src/corelib/thread/qmutex.h
@@ -43,6 +43,7 @@
 #define QMUTEX_H
 
 #include <QtCore/qglobal.h>
+#include <QtCore/qatomic.h>
 #include <new>
 
 QT_BEGIN_HEADER
@@ -53,7 +54,8 @@ QT_MODULE(Core)
 
 #ifndef QT_NO_THREAD
 
-class QMutexPrivate;
+class QAtomicInt;
+class QMutexData;
 
 class Q_CORE_EXPORT QMutex
 {
@@ -66,10 +68,13 @@ public:
     explicit QMutex(RecursionMode mode = NonRecursive);
     ~QMutex();
 
-    void lock();
-    bool tryLock();
+    void lock();     //### Qt5: make inline;
+    inline void lockInline();
+    bool tryLock();  //### Qt5: make inline;
     bool tryLock(int timeout);
-    void unlock();
+    inline bool tryLockInline();
+    void unlock();     //### Qt5: make inline;
+    inline void unlockInline();
 
 #if defined(QT3_SUPPORT)
     inline QT3_SUPPORT bool locked()
@@ -86,9 +91,11 @@ public:
 #endif
 
 private:
+    void lockInternal();
+    void unlockInternal();
     Q_DISABLE_COPY(QMutex)
 
-    QMutexPrivate *d;
+    QMutexData *d;
 };
 
 class Q_CORE_EXPORT QMutexLocker
@@ -99,7 +106,7 @@ public:
         Q_ASSERT_X((reinterpret_cast<quintptr>(m) & quintptr(1u)) == quintptr(0),
                    "QMutexLocker", "QMutex pointer is misaligned");
         if (m) {
-            m->lock();
+            m->lockInline();
             val = reinterpret_cast<quintptr>(m) | quintptr(1u);
         } else {
             val = 0;
@@ -111,7 +118,7 @@ public:
     {
         if ((val & quintptr(1u)) == quintptr(1u)) {
             val &= ~quintptr(1u);
-            mutex()->unlock();
+            mutex()->unlockInline();
         }
     }
 
@@ -119,7 +126,7 @@ public:
     {
         if (val) {
             if ((val & quintptr(1u)) == quintptr(0u)) {
-                mutex()->lock();
+                mutex()->lockInline();
                 val |= quintptr(1u);
             }
         }
@@ -145,6 +152,46 @@ private:
     quintptr val;
 };
 
+class QMutexData
+{
+    public:
+        QAtomicInt contenders;
+        const uint recursive : 1;
+        uint reserved : 31;
+    protected:
+        QMutexData(QMutex::RecursionMode mode);
+        ~QMutexData();
+};
+
+inline void QMutex::unlockInline()
+{
+    if (d->recursive) {
+        unlock();
+    } else if (!d->contenders.testAndSetRelease(1, 0)) {
+        unlockInternal();
+    }
+}
+
+inline bool QMutex::tryLockInline()
+{
+    if (d->recursive) {
+        return tryLock();
+    } else {
+        return d->contenders.testAndSetAcquire(0, 1);
+    }
+}
+
+inline void QMutex::lockInline()
+{
+    if (d->recursive) {
+        lock();
+    } else if(!tryLockInline()) {
+        lockInternal();
+    }
+}
+
+
+
 #else // QT_NO_THREAD
 
 
@@ -157,9 +204,11 @@ public:
     inline ~QMutex() {}
 
     static inline void lock() {}
-    static inline bool tryLock() { return true; }
-    static inline bool tryLock(int timeout) { Q_UNUSED(timeout); return true; }
-    static void unlock() {}
+    static inline void lockInline() {}
+    static inline bool tryLock(int timeout = 0) { Q_UNUSED(timeout); return true; }
+    static inline bool tryLockInline() { return true; }
+    static inline void unlock() {}
+    static inline void unlockInline() {}
 
 #if defined(QT3_SUPPORT)
     static inline QT3_SUPPORT bool locked() { return false; }