Re: [Boost-bugs] [Boost C++ Libraries] #12744: winapi::set_timer_resolution inadvertently changes timer resolution (Windows)

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #12744: winapi::set_timer_resolution inadvertently changes timer resolution (Windows)
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2018-03-01 19:49:37

#12744: winapi::set_timer_resolution inadvertently changes timer resolution
(Windows)
-------------------------------------+------------------------------
  Reporter:  Terry Kim <yuminkim@…>  |      Owner:  Ion Gaztañaga
      Type:  Bugs                    |     Status:  closed
 Milestone:  To Be Determined        |  Component:  interprocess
   Version:  Boost 1.63.0            |   Severity:  Problem
Resolution:  fixed                   |   Keywords:  timer resolution
-------------------------------------+------------------------------

Comment (by anonymous):

 I know this bug is closed, but I wanted to add a comment explaining the
 previous behavior.  I just spent 2 days tracking down why our timer
 resolution was getting messed up.  (We were using a previous Boost
 version).

 First of all, the call to NtSetTimerResolution is a private ntdll
 function.  Not an API you should be using, or especially assuming the
 behavior of.  There is no official documentation.  The second argument
 (called 'set') that was false, is not meant to be a benign query of the
 timer resolution.  Instead, it 'unsets' the process's request for a custom
 timer resolution.  This would be used by the proper Public api in
 winmm.dll and the calls for timeBeginPeriod/timeEndPeriod.

 By calling NtSetTimerResolution with set=false.  Future calls to
 timeBeginPeriod/timeEndPeriod had no effect if there was already a
 timeBeginPeriod call outstanding.  Most likely winmm (which likely tracks
 the pairs of timeBeginPeriod/timeEndPeriod calls) was now out of sync with
 its interaction with ntdll.

-- 
Ticket URL: <https://svn.boost.org/trac10/ticket/12744#comment:3>
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