RFR(S): 8037340: Linux semaphores to use CLOCK_REALTIME

[David Holmes]

On 18/03/2014 4:59 PM, Markus Gr?nlund wrote:
> Hi again,
>
> I have updated and simplified the change:
>
> http://cr.openjdk.java.net/~mgronlun/8037340/webrev02/

Thanks Markus - this looks good to me.

David

> Thanks in advance
> Markus
>
>
> -----Original Message-----
> From: Markus Gr?nlund
> Sent: den 14 mars 2014 12:12
> To: David Holmes
> Cc: serviceability-dev at openjdk.net; hotspot-runtime-dev
> Subject: RE: RFR(S): 8037340: Linux semaphores to use CLOCK_REALTIME
>
> Updated:
>
> http://cr.openjdk.java.net/~mgronlun/8037340/webrev02/
>
> /Markus
>
> -----Original Message-----
> From: David Holmes
> Sent: den 14 mars 2014 10:43
> To: Markus Gr?nlund; serviceability-dev at openjdk.net; hotspot-runtime-dev
> Subject: Re: RFR(S): 8037340: Linux semaphores are associated with CLOCK_REALTIME and need relative to absolute time conversion utility
>
> Hi Markus,
>
> This seems excessively complicated. There is no need to completely duplicate unpackTime the way you have (now we have three methods doing almost the same thing!). clock_gettime availability just shouldn't be an issue these days on our supported platforms, and in any case tying it to supports_monotonic_clock is just misleading as you may have clock_gettime but not a monotonic clock (unlikely but possible). If you are really paranoid about clock_gettime then just use gettimeofday and be done with it.
>
> Further if you insisted on taking this approach change the signature to take secs and nsecs as it is pointless converting them to a single nsecs in the caller only to break them back into separate secs and nsecs inside the method!
>
> Or if you really feel strongly about this form then change the signature to take the clock as an argument - with a default parameter providing CLOCK_MONOTONIC.
>
> But I stick by what I suggested in the bug report. Just use clock_gettime on CLOCK_REALTIME.
>
> David
>
> On 14/03/2014 7:22 PM, Markus Gr?nlund wrote:
>> Greetings,
>>
>> Kindly asking for reviews for the following changeset:
>>
>> 8037340: Linux semaphores are associated with CLOCK_REALTIME and need
>> relative to absolute time conversion utility
>>
>> Webrev: http://cr.openjdk.java.net/~mgronlun/8037340/webrev01/
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8037340
>>
>> Previously, unpackTime() was used to calculate the absolute time value
>> for passing to sem_timedwait() for waiting on a Semaphore.
>>
>> UnpackTime() has been updated to be based on CLOCK_MONOTONIC which
>> does not work for Semaphores, which are always associated with CLOCK_REALTIME.
>>
>> http://linux.die.net/man/3/sem_timedwait
>>
>> Thanks
>>
>> Markus
>>