Re: Interruptible sleeps (was Re: CommitFest 2009-07: Yay, Kevin! Thanks, reviewers!)

Fujii Masao <masao.fujii@gmail.com> writes:
>> +               * XXX: Is it safe to elog(ERROR) in a signal handler?
>> 
>> No, it isn't.

> We should use elog(FATAL) or check proc_exit_inprogress, instead?

elog(FATAL) is *certainly* not a better idea.  I think there's really
nothing that can be done, you just have to silently ignore the error.
BTW, if we retry, there had probably better be a limit on how many times
to retry ...

> +		if (errno != EAGAIN && errno != EWOULDBLOCK)
> +		{
> +			/*
> +			 * XXX: Is it safe to elog(ERROR) in a signal handler?
> +			 */
> +			elog(ERROR, "write() on self-pipe failed: %m");
> +		}
> +		if (errno == EINTR)
> +			goto retry;

> "errno == EINTR)" seems to be never checked.

Another issue with coding like that is that it supposes elog() won't
change errno.

			regards, tom lane