Re: droped out precise time calculations in src/interfaces/libpq/fe-connect.c

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> Denis A Ustimenko wrote:
>> Beware of almost 1 second posiible error. For example: connect_timeout == 1,
>> we start at 0.999999 then finish_time == 1. If CPU is quite busy we will
>> do only one iteration. I don't know is it enough to make connection?
>> True timeout in this case == 0.000001

> Good question. What is going to happen is that select() is going to be
> passed tv_sec = 1, and it is going to sleep for one second. Now, if
> select is interrupted, another time() call is going to be made.

There is a very simple answer to this, which I think I suggested to Joe
originally, but it's not in the code now: the initial calculation of
finish_time = now() + timeout must add one. This ensures that any
roundoff error is in the conservative direction of timing out later,
rather than sooner.

regards, tom lane