Re: Why does wait_for_log() return current file size

On 2025-03-29 Sa 11:15 AM, Andres Freund wrote:
> Hi,
>
> In a test I'd like to use wait_for_log() to find a bunch of log messages
> emitted in sequence. A reasonable looking pattern for that would be:
>
> $log_location = -s $node->logfile;
>
> $log_location = $node->wait_for_log(qr/first-message/, $log_location);
> $log_location = $node->wait_for_log(qr/second-message/, $log_location);
>
> Except that that doesn't work, because what wait_for_log returns is:
>
> my $log =
> PostgreSQL::Test::Utils::slurp_file($self->logfile, $offset);
>
> return $offset + length($log) if ($log =~ m/$regexp/);
>
> Which, afaict, boils down to the current end of the logfile.
>
> Could we instead determine where in the string our regex matched, and return
> $offset + $that_magic_number
>
> Assuming that could be made work, does anybody see a reason not to do that?

In principle it seems quite reasonable, but I haven't looked at all the
current uses to see if they will be upset.

cheers

andrew

--
Andrew Dunstan
EDB:https://www.enterprisedb.com