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

On Fri, Apr 01, 2011 at 10:13:23PM +0200, Erik Faye-Lund wrote:

On Fri, Apr 1, 2011 at 10:05 PM, Jeff King [off-list ref] wrote:

quoted

On Fri, Apr 01, 2011 at 09:57:14PM +0200, Erik Faye-Lund wrote:

quoted

quoted

But this does not help the case at hand in any way. How would you interrupt a
thread that is blocked in ReadFile()? The point of pthread_cancel() is that
it interrupts blocked system calls

There is no mention of such a guarantee in POSIX (section 2.9.5 Thread
Cancellation), so relying on that is undefined behavior.

Eh? My pthreads(7) says that read() is required to be a cancellation
point acrroding to POSIX. I didn't dig up the actual reference in the
standard, though.

I don't understand where the implementor would get that from after
reading through it, but if there's something I've missed we can fix it
by replacing my pthread_cancel with this, no?

Out of curiosity, which POSIX are you reading? My page references
POSIX.1-2001, but technically pthreads were originally defined in
POSIX.1c-1995.

static inline int pthread_cancel(pthread_t thread)
{
	SetEvent(thread.cancel_event);
	CancelSynchronousIo(thread.handle);
}

There are a ton of cancellation points, not just I/O (e.g., sleep).
However, interrupting a read would probably be sufficient for git's
purposes.

-Peff