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[commit] r2253 - Integrate Henrik Johansen's fix for the nanosleep call in the heartbeat.

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[commit] r2253 - Integrate Henrik Johansen's fix for the nanosleep call in the heartbeat.

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");

Henrik Sperre Johansen

Re: [commit] r2253 - Integrate Henrik Johansen's fix for the nanosleep call in the heartbeat.

On 13.08.2010 23:14, [hidden email] 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, thetimespec 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.

Cheers,
Henry

Eliot Miranda-2

Re: [commit] r2253 - Integrate Henrik Johansen's fix for the nanosleep call in the heartbeat.

Hi Henrik,

On Fri, Aug 13, 2010 at 2:56 PM, Henrik Sperre Johansen <[hidden email]> wrote:

On 13.08.2010 23:14, [hidden email] 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, thetimespec 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