Get monotonic time working on Mac OS X for corelib programs.

Mac OS X does not provide POSIX monotonic timers. Instead it does
provide a Mach call to get the absolute time (a.k.a., number of CPU
ticks) for the next timer event. This gets us around the bug in
select(2) on Mac, that it doesn't wakeup when the times been changed.

Of course, if you used the GUI event dispatcher, which is based on
CFRunLoopTimers, this is not an issue, but if you really just need
corelib, it's a bear to bring in the other stuff.

Thanks to the nice guys at Parallels for the basics of the patch!

Task-number: 237384
Reviewed-by: Bradley T. Hughes

1 files changed, 21 insertions, 2 deletions

diff --git a/src/corelib/kernel/qeventdispatcher_unix.cpp b/src/corelib/kernel/qeventdispatcher_unix.cpp
index 0eeea04b88..9deb78ff38 100644
--- a/src/corelib/kernel/qeventdispatcher_unix.cpp
+++ b/src/corelib/kernel/qeventdispatcher_unix.cpp
@@ -59,6 +59,10 @@
 #  include <sys/times.h>
 #endif
 
+#ifdef Q_OS_MAC
+#include <mach/mach_time.h>
+#endif
+
 QT_BEGIN_NAMESPACE
 
 Q_CORE_EXPORT bool qt_disable_lowpriority_timers=false;
@@ -259,7 +263,7 @@ int QEventDispatcherUNIXPrivate::doSelect(QEventLoop::ProcessEventsFlags flags,
 
 QTimerInfoList::QTimerInfoList()
 {
-#if (_POSIX_MONOTONIC_CLOCK-0 <= 0)
+#if (_POSIX_MONOTONIC_CLOCK-0 <= 0) && !defined(Q_OS_MAC)
     useMonotonicTimers = false;
 
 #  if (_POSIX_MONOTONIC_CLOCK == 0)
@@ -287,6 +291,9 @@ QTimerInfoList::QTimerInfoList()
         msPerTick = 0;
     }
 #else
+#  if defined(Q_OS_MAC)
+    useMonotonicTimers = true;
+#  endif
     // using monotonic timers unconditionally
     getTime(currentTime);
 #endif
@@ -335,7 +342,19 @@ bool QTimerInfoList::timeChanged(timeval *delta)
 
 void QTimerInfoList::getTime(timeval &t)
 {
-#if !defined(QT_NO_CLOCK_MONOTONIC) && !defined(QT_BOOTSTRAPPED)
+#if defined(Q_OS_MAC)
+    {
+        static mach_timebase_info_data_t info = {0,0};
+        if (info.denom == 0)
+            mach_timebase_info(&info);
+
+        uint64_t cpu_time = mach_absolute_time();
+        uint64_t nsecs = cpu_time * (info.numer / info.denom);
+        t.tv_sec = nsecs * 1e-9;
+        t.tv_usec = nsecs * 1e-3 - (t.tv_sec * 1e6);
+        return;
+    }
+#elif !defined(QT_NO_CLOCK_MONOTONIC) && !defined(QT_BOOTSTRAPPED)
     if (useMonotonicTimers) {
         timespec ts;
         clock_gettime(CLOCK_MONOTONIC, &ts);