Re: [PATCH 5/4] run-command: implement abort_async for pthreads

From: Erik Faye-Lund <kusmabite@gmail.com>
Date: Apr 1, 2011, 10:15 UTC
Message-ID: <AANLkTin3+PzYcQEaaxgr9_5mgDGO5oiYDyBD_2tJqCTk@mail.gmail.com>
In-Reply-To: <AANLkTikF_xLTdY0BgaXmUXvBJTG3HD3by9zN59KwPii5@mail.gmail.com>

On Fri, Apr 1, 2011 at 11:41 AM, Erik Faye-Lund <kusmabite@gmail.com> wrote:

Show 30 quoted lines

> On Thu, Mar 31, 2011 at 8:45 PM, Jeff King <peff@peff.net> wrote:
>> We just need to cancel the thread, instead of sending it a
>> signal as we do for fork()'d async sections.
>>
>> Signed-off-by: Jeff King <peff@peff.net>
>> ---
>> This could also just be part of the merge resolution, but I thought it
>> would be easier to see what is going on if I put it here.
>>
>>  run-command.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/run-command.c b/run-command.c
>> index e31c073..46ea07d 100644
>> --- a/run-command.c
>> +++ b/run-command.c
>> @@ -607,7 +607,7 @@ void abort_async(struct async *async)
>>  #ifdef NO_PTHREADS
>
> This context-line doesn't match 3/4... Did you send out the wrong
> version of that patch?
>
>>        kill(async->pid, 15);
>>  #else
>> -       /* no clue */
>> +       pthread_cancel(async->tid);
>
> My worry about terminating a thread that's currently holding a mutex
> (implicitly through the CRT?) still applies though...
>

OK, I've read up on thread-cancellation, and this code seems correct. pthread_cancel doesn't kill the thread right away, it just signals a cancellation-event, which is checked for at certain cancellation-points. A lot of the CRT functions are defined as cancellation points, so it'll be a matter for us Win32-guys to implement pthread_testcancel() and inject that into the function-wrappers of the CRT functions that are marked as cancellation-points.