Re: Restart pg_usleep when interrupted

On Thu, Jul 11, 2024 at 01:10:25PM -0500, Sami Imseih wrote:
>> I'm curious why we wouldn't just subtract "elapsed_time" from "delay" at
>> the bottom of the while loop to avoid needing this extra check.
>
> Can you elaborate further? I am not sure how this will work since delay is a timespec
> and elapsed time is an instr_time.
>
> Also, in every iteration of the loop, the delay must be set to the remaining time. The
> purpose of the elapsed_time is to make sure that we don´t surpass requested time
> delay as an additional safeguard.

I'm imagining something like this:

struct timespec delay;
TimestampTz end_time;

end_time = TimestampTzPlusMilliseconds(GetCurrentTimestamp(), msec);

do
{
long secs;
int microsecs;

TimestampDifference(GetCurrentTimestamp(), end_time,
&secs, &microsecs);

delay.tv_sec = secs;
delay.tv_nsec = microsecs * 1000;

} while (nanosleep(&delay, NULL) == -1 && errno == EINTR);

--
nathan