One more thing. As I said, I only ping the DB when I startup to make sure
the config is right. It fixes the potential issue of a config error
pointing the app at a non-existent dev database in production.
In the code, I do this:
$data = $db->query($query, $retval_ref->{'most_recent_rcd'})->array or
$log->logdie;
On Sun, Oct 11, 2020 at 5:03 AM Nacho B <[email protected]> wrote:
> Thank you, MIkel,
>
> So, this ping test must be executed for each database access?
>
> I know pings are almost nothing, but adding a new non blocking loop...
> isn't it an overhead all over the application?
>
> I wonder why this so common scenario can't be managed inside the wait
> loop. Maybe there is something I still do not understand in the
> non-blocking way of life.
>
>
> Regards,
> Nacho B.
>
>
> El jueves, 8 de octubre de 2020 a las 16:49:02 UTC+2, [email protected]
> escribió:
>
>> I do something like this in the MojoMySQL.pm plugin
>> -------
>>
>> $MOJOMYSQL = Mojo::mysql->new($URL);
>>
>> # See if the damned thing is up.
>> # since we're in ::startup, we don't have the config plugin
>> available
>> # ( we pass the config filename in as "app_config" )
>> my $config = eval qx{cat $conf->{'app_config'}}
>> or $log->logdie("Couldn't read config file: " .
>> $conf->{'app_config'});
>>
>> eval {
>> local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n
>> required
>> alarm $config->{'db_ping_timeout'};
>> my $ok = $MOJOMYSQL->db->ping();
>> alarm 0;
>> };
>>
>> if ($@) {
>> $log->logdie($@) unless $@ eq "alarm\n"; # propagate
>> unexpected errors
>> # timed out
>> my $msg = qq{DB PING FAILED! (continued below)\n}
>> . qq{**** It seems that
>> $conf->{'db'} on $conf->{'host'} is down! ****\n}
>> . qq{**** app runtime env is:
>> $config->{'environment'} ****\n}
>> . qq{**** Verify correct
>> setting in $conf->{'app_config'} ****\n};
>>
>> $log->logdie($msg);
>> }
>> else {
>> # didn't
>> $log->debug("DB PING: $conf->{'db'} is up");
>> return $MOJOMYSQL;
>> };
>>
>> } # sub mojomysql
>>
>> On Thu, Oct 8, 2020 at 2:44 AM Nacho B <[email protected]> wrote:
>>
>>> Hi, I am using Mojo::Pg promises with db queries, and everything is
>>> great.
>>>
>>> But I do not how to manage the case in which database server is down and
>>> no response is arriving.
>>>
>>> I presume that I should insert a timeout somewhere, in the promise, but
>>> I do not know how.
>>>
>>>
>>> Nacho B.
>>>
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>>>
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