Re: timeout value overflow in wait for lsn

> Changing the check to FLOAT8_FITS_IN_INT32 would reject larger values.
> If we choose that limit, the timeout variable and the WaitForLSN()
> argument should also use int so that the interface matches the
> accepted range.
>
> Alternatively, we can preserve the int64 interface and check the
> deadline calculation in WaitForLSN():
>
>     if (pg_mul_s64_overflow(timeout, USECS_PER_MSEC, &timeout_us) ||
>         pg_add_s64_overflow(now, timeout_us, &endtime) ||
>         !IS_VALID_TIMESTAMP(endtime))
>
> -----------------
>
> Another option is to reject values greater than or equal with
> INT64_MAX/1000, which seems a bit hacky to me.

The max timeout value supported by WaitLatch() is INT_MAX, so I think
it's reasonable to limit the range to int32. And I think it's ok to use int64
as the argument in WaitForLSN() because convert int32 to int64 is always
safe.

--
Regards,
ChangAo Chen