Make the default size of QMutexPool a prime number

As pointed out by Olivier, this should allow for better distribution
in the array.

I also removed the unnecessary count member, since we can use
QVarLengthArray.count() instead.

2 files changed, 6 insertions, 7 deletions

diff --git a/src/corelib/thread/qmutexpool.cpp b/src/corelib/thread/qmutexpool.cpp
index 77a3cca..0d7c890 100644
--- a/src/corelib/thread/qmutexpool.cpp
+++ b/src/corelib/thread/qmutexpool.cpp
@@ -96,9 +96,9 @@ Q_GLOBAL_STATIC_WITH_ARGS(QMutexPool, globalMutexPool, (QMutex::Recursive))
     QMutexPool is destructed.
 */
 QMutexPool::QMutexPool(QMutex::RecursionMode recursionMode, int size)
-    : mutexes(size), count(size), recursionMode(recursionMode)
+    : mutexes(size), recursionMode(recursionMode)
 {
-    for (int index = 0; index < count; ++index) {
+    for (int index = 0; index < mutexes.count(); ++index) {
         mutexes[index] = 0;
     }
 }
@@ -109,7 +109,7 @@ QMutexPool::QMutexPool(QMutex::RecursionMode recursionMode, int size)
 */
 QMutexPool::~QMutexPool()
 {
-    for (int index = 0; index < count; ++index) {
+    for (int index = 0; index < mutexes.count(); ++index) {
         delete mutexes[index];
         mutexes[index] = 0;
     }
@@ -130,7 +130,7 @@ QMutexPool *QMutexPool::instance()
 QMutex *QMutexPool::get(const void *address)
 {
     Q_ASSERT_X(address != 0, "QMutexPool::get()", "'address' argument cannot be zero");
-    int index = int((quintptr(address) >> (sizeof(address) >> 1)) % count);
+    int index = int((quintptr(address) >> (sizeof(address) >> 1)) % mutexes.count());
 
     if (!mutexes[index]) {
         // mutex not created, create one
diff --git a/src/corelib/thread/qmutexpool_p.h b/src/corelib/thread/qmutexpool_p.h
index 4c1e32c..30a16d4 100644
--- a/src/corelib/thread/qmutexpool_p.h
+++ b/src/corelib/thread/qmutexpool_p.h
@@ -64,7 +64,7 @@ QT_BEGIN_NAMESPACE
 class Q_CORE_EXPORT QMutexPool
 {
 public:
-    explicit QMutexPool(QMutex::RecursionMode recursionMode = QMutex::NonRecursive, int size = 128);
+    explicit QMutexPool(QMutex::RecursionMode recursionMode = QMutex::NonRecursive, int size = 131);
     ~QMutexPool();
 
     QMutex *get(const void *address);
@@ -72,8 +72,7 @@ public:
     static QMutex *globalInstanceGet(const void *address);
 
 private:
-    QVarLengthArray<QAtomicPointer<QMutex>, 128> mutexes;
-    int count;
+    QVarLengthArray<QAtomicPointer<QMutex>, 131> mutexes;
     QMutex::RecursionMode recursionMode;
 };