[Vm-dev] [commit] r2253 - Integrate Henrik Johansen's fix for the
nanosleep call in the heartbeat.
Eliot Miranda
eliot.miranda at gmail.com
Fri Aug 13 22:05:41 UTC 2010
Hi Henrik,
On Fri, Aug 13, 2010 at 2:56 PM, Henrik Sperre Johansen <
henrik.s.johansen at veloxit.no> wrote:
>
> On 13.08.2010 23:14, commits at squeakvm.org wrote:
>
>
> Author: eliot
> Date: 2010-08-13 14:14:21 -0700 (Fri, 13 Aug 2010)
> New Revision: 2253
>
> Modified:
> branches/Cog/platforms/unix/vm/sqUnixHeartbeat.c
> Log:
> Integrate Henrik Johansen's fix for the nanosleep call in the heartbeat.
>
>
> Modified: branches/Cog/platforms/unix/vm/sqUnixHeartbeat.c
> ===================================================================
> --- branches/Cog/platforms/unix/vm/sqUnixHeartbeat.c 2010-08-11 18:03:02 UTC (rev 2252)
> +++ branches/Cog/platforms/unix/vm/sqUnixHeartbeat.c 2010-08-13 21:14:21 UTC (rev 2253)
> @@ -607,6 +607,8 @@
> struct timespec naptime = beatperiod;
>
> while (nanosleep(&naptime, &naptime) == -1
> + /* oversleeps can return tv_sec = -1 tv_nsec approx 999999999 */
> + && naptime.tv_sec >= 0 /* avoid undoc'ed oversleep behaviour */
> && (naptime.tv_sec > 0 || naptime.tv_nsec > MINSLEEPNS)) /*repeat*/
> if (errno != EINTR) {
> perror("nanosleep");
>
> To be finicky, it's not actually undocumented though, if I interpreted the
> man pages correctly :)
> http://www.opengroup.org/onlinepubs/009695399/functions/nanosleep.html
>
> http://developer.apple.com/mac/library/documentation/Darwin/Reference/ManPages/man2/nanosleep.2.html
>
> "If the rmtp argument is non-NULL, the*timespec* structure referenced by
> it is updated to contain the amount of time remaining in the interval (the
> requested time minus the time actually slept). "
>
> Since it also specifies that the valid range for tv_nsec is 0 - 999999999,
> a negative value for tv_sec is the only valid option when it has overslept
> before being interrupted.
>
You're right. When I speed-read "If rmtp is non-NULL, the timespec structure
it references is updated to contain the unslept amount (the request time
minus the time actually slept)." I ignored "the request time minus the time
actually slept" and assumed it would not return a negative amount. I'll
change the code.
thanks again,
Eliot
> Cheers,
> Henry
>
>
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