QTimerInfoList: change timerWait() to return std::optional<ms>

QEventDispatcherGlib: it used the out-parameter timespec to set a
timeout in milliseconds, making timerWait() return milliseconds is more
straightforward. Also timerWait() returns the time rounded to
milliseconds, so the code in QEventDispatcherGlib that rounded up the
timespec::tv_nsec part was no-op, tv_nsec was always 0 IIUC.

In QEventDispatcherGlib, guard against overflow with qt_saturate.

Change-Id: Ie6f78374d00cbe8a6adf7b50ed67c8c86ab4d29d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 7 insertions, 6 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm b/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm
index 41caac281b..a594259d99 100644
--- a/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm
+++ b/src/plugins/platforms/cocoa/qcocoaeventdispatcher.mm
@@ -115,6 +115,7 @@ void QCocoaEventDispatcherPrivate::maybeStartCFRunLoopTimer()
         return;
     }
 
+    using DoubleSeconds = std::chrono::duration<double, std::ratio<1>>;
     if (!runLoopTimerRef) {
         // start the CFRunLoopTimer
         CFAbsoluteTime ttf = CFAbsoluteTimeGetCurrent();
@@ -122,10 +123,10 @@ void QCocoaEventDispatcherPrivate::maybeStartCFRunLoopTimer()
         CFTimeInterval oneyear = CFTimeInterval(3600. * 24. * 365.);
 
         // Q: when should the CFRunLoopTimer fire for the first time?
-        struct timespec tv;
-        if (timerInfoList.timerWait(tv)) {
+        if (auto opt = timerInfoList.timerWait()) {
             // A: when we have timers to fire, of course
-            interval = qMax(tv.tv_sec + tv.tv_nsec / 1000000000., 0.0000001);
+            DoubleSeconds secs{*opt};
+            interval = qMax(secs.count(), 0.0000001);
         } else {
             // this shouldn't really happen, but in case it does, set the timer to fire a some point in the distant future
             interval = oneyear;
@@ -145,10 +146,10 @@ void QCocoaEventDispatcherPrivate::maybeStartCFRunLoopTimer()
         CFTimeInterval interval;
 
         // Q: when should the timer first next?
-        struct timespec tv;
-        if (timerInfoList.timerWait(tv)) {
+        if (auto opt = timerInfoList.timerWait()) {
             // A: when we have timers to fire, of course
-            interval = qMax(tv.tv_sec + tv.tv_nsec / 1000000000., 0.0000001);
+            DoubleSeconds secs{*opt};
+            interval = qMax(secs.count(), 0.0000001);
         } else {
             // no timers can fire, but we cannot stop the CFRunLoopTimer, set the timer to fire at some
             // point in the distant future (the timer interval is one year)