Replace the handcoded math and change the timer buckets again.

Reduce from 8 to 6 buckets and increase the step between each
bucket. This way, the second bucket is now of 224 timers, which should
be enough for 99.9% of the applications.

Also change the hardcoded math to calculations using enum values. This
helps in changing the timer buckets again in the future.

Also fix the last bucket not to have a timer ID of 16777216, as that
is not valid.

Reviewed-by: Olivier Goffart

1 files changed, 40 insertions, 11 deletions

diff --git a/src/corelib/kernel/qabstracteventdispatcher.cpp b/src/corelib/kernel/qabstracteventdispatcher.cpp
index 06b76c9..2949cd0 100644
--- a/src/corelib/kernel/qabstracteventdispatcher.cpp
+++ b/src/corelib/kernel/qabstracteventdispatcher.cpp
@@ -52,28 +52,48 @@ QT_BEGIN_NAMESPACE
 static const int TimerIdMask = 0x00ffffff;
 static const int TimerSerialMask = ~TimerIdMask & ~0x80000000;
 static const int TimerSerialCounter = TimerIdMask + 1;
-static const int MaxTimerId = TimerSerialCounter - 1;
-
-enum { NumberOfBuckets = 8, FirstBucketSize = 32 };
-
-static const int BucketSize[NumberOfBuckets] =
-    { 32, 64, 512, 4096, 32768, 262144, 2097152, 16777216 - 2364000 };
-static const int BucketOffset[NumberOfBuckets] =
-    { 0,  32,  96,  608,  4704,  37448,  266848,  2364000 };
+static const int MaxTimerId = TimerIdMask;
 
 static int FirstBucket[] = {
      1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16,
     17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32
 };
 
-static QBasicAtomicPointer<int> timerIds[NumberOfBuckets] =
+enum {
+    FirstBucketOffset  = 0,
+    SecondBucketOffset = sizeof(FirstBucket) / sizeof(FirstBucket[0]),
+    ThirdBucketOffset  = 0x100,
+    FourthBucketOffset = 0x1000,
+    FifthBucketOffset  = 0x10000,
+    SixthBucketOffset  = 0x100000
+};
+
+enum {
+    FirstBucketSize  = SecondBucketOffset,
+    SecondBucketSize = ThirdBucketOffset - SecondBucketOffset,
+    ThirdBucketSize  = FourthBucketOffset - ThirdBucketOffset,
+    FourthBucketSize = FifthBucketOffset - FourthBucketOffset,
+    FifthBucketSize  = SixthBucketOffset - FifthBucketOffset,
+    SixthBucketSize  = MaxTimerId - SixthBucketOffset
+};
+
+static const int BucketSize[] = {
+    FirstBucketSize, SecondBucketSize, ThirdBucketSize,
+    FourthBucketSize, FifthBucketSize, SixthBucketSize
+};
+enum { NumberOfBuckets = sizeof(BucketSize) / sizeof(BucketSize[0]) };
+
+static const int BucketOffset[] = {
+    FirstBucketOffset, SecondBucketOffset, ThirdBucketOffset,
+    FourthBucketOffset, FifthBucketOffset, SixthBucketOffset
+};
+
+static QBasicAtomicPointer<int> timerIds[] =
     { Q_BASIC_ATOMIC_INITIALIZER(FirstBucket),
       Q_BASIC_ATOMIC_INITIALIZER(0),
       Q_BASIC_ATOMIC_INITIALIZER(0),
       Q_BASIC_ATOMIC_INITIALIZER(0),
       Q_BASIC_ATOMIC_INITIALIZER(0),
-      Q_BASIC_ATOMIC_INITIALIZER(0),
-      Q_BASIC_ATOMIC_INITIALIZER(0),
       Q_BASIC_ATOMIC_INITIALIZER(0) };
 
 static void timerIdsDestructorFunction()
@@ -92,8 +112,17 @@ static inline int prepareNewValueWithSerialNumber(int oldId, int newId)
     return (newId & TimerIdMask) | ((oldId + TimerSerialCounter) & TimerSerialMask);
 }
 
+namespace {
+    template<bool> struct QStaticAssertType;
+    template<> struct QStaticAssertType<true> { enum { Value = 1 }; };
+}
+#define q_static_assert(expr)     (void)QStaticAssertType<expr>::Value
+
 static inline int bucketOffset(int timerId)
 {
+    q_static_assert(sizeof BucketSize == sizeof BucketOffset);
+    q_static_assert(sizeof(timerIds) / sizeof(timerIds[0]) == NumberOfBuckets);
+
     for (int i = 0; i < NumberOfBuckets; ++i) {
         if (timerId < BucketSize[i])
             return i;