Re: Remove unnecessary code from psql's watch command

Michael Paquier <michael(at)paquier(dot)xyz> writes:
> On Tue, Mar 05, 2024 at 10:05:52PM +0900, Yugo NAGATA wrote:
>> In the current code of do_watch(), sigsetjmp is called if WIN32
>> is defined, but siglongjmp is not called in the signal handler
>> in this condition. On Windows, currently, cancellation is checked
>> only by cancel_pressed, and calling sigsetjmp in do_watch() is
>> unnecessary. Therefore, we can remove code around sigsetjmp in
>> do_watch(). I've attached the patch for this fix.

> Re-reading the top comment of sigint_interrupt_enabled, it looks like
> you're right here. As long as we check for cancel_pressed there
> should be no need for any special cancellation handling here.

I don't have Windows here to test on, but does the WIN32 code
path work at all? It looks to me like cancel_pressed becoming
true doesn't get us to exit the outer loop, only the inner delay
one, meaning that trying to control-C out of a \watch will just
cause it to repeat the command even faster. That path isn't
setting the "done" variable, and it isn't checking it either,
because all of that only happens in the other #ifdef arm.

regards, tom lane