Bug 147992

Summary: WorkQueue::dispatchAfter() on Windows fires early
Product: WebKit Reporter: Mark Lam <mark.lam>
Component: Web Template FrameworkAssignee: Mark Lam <mark.lam>
Status: RESOLVED FIXED    
Severity: Normal CC: andersca, benjamin, bfulgham, cmarcelo, commit-queue, ggaren
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
the fix.
none
the fix. none

Mark Lam
Reported 2015-08-13 14:08:27 PDT
The Windows implementation of WorkQueue::dispatchAfter() uses CreateTimerQueueTimer(). Unfortunately, CreateTimerQueueTimer() is sloppy and can fire early. We need to compensate for this slop to ensure that the specified duration does expire before the callback function is called (or the JSC watchdog which depends on this can fail randomly).
Attachments
the fix. (2.81 KB, patch)
2015-08-13 14:16 PDT, Mark Lam 		no flags
DetailsFormatted DiffDiff
the fix. (2.79 KB, patch)
2015-08-13 14:18 PDT, Mark Lam 		no flags
DetailsFormatted DiffDiff
Show Obsolete (1) View All Add attachment proposed patch, testcase, etc.
Brent Fulgham
Comment 1 2015-08-13 14:15:24 PDT
It looks like the standard Windows timer ticks at ~64 ticks/second -> 15ms interval. http://download.microsoft.com/download/3/0/2/3027D574-C433-412A-A8B65E0A75D5B237/Timer-Resolution.docx See also https://msdn.microsoft.com/enus/library/system.timers.timer.interval(v=vs.110).aspx Another one: <https://msdn.microsoft.com/enus/library/windows/hardware/dn265247(v=vs.85).aspx>, check the "Controlling timer accuracy" section's first paragraph.
Mark Lam
Comment 2 2015-08-13 14:16:37 PDT
Created attachment 258932 [details] the fix.
Mark Lam
Comment 3 2015-08-13 14:18:29 PDT
Created attachment 258933 [details] the fix.
Brent Fulgham
Comment 4 2015-08-13 14:24:43 PDT
Comment on attachment 258933 [details] the fix. r=me.
WebKit Commit Bot
Comment 5 2015-08-13 16:39:20 PDT
Comment on attachment 258933 [details] the fix. Clearing flags on attachment: 258933 Committed r188415: <http://trac.webkit.org/changeset/188415>
WebKit Commit Bot
Comment 6 2015-08-13 16:39:26 PDT
All reviewed patches have been landed. Closing bug.
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