Re: making the backend's json parser work in frontend code

On 1/16/20 12:26 PM, Andres Freund wrote:
> Hi,
>
> On 2020-01-16 14:20:28 -0500, Tom Lane wrote:
>> David Steele <david(at)pgmasters(dot)net> writes:
>>> The way we handle this in pgBackRest is to put a TRY ... CATCH block in
>>> main() to log and exit on any uncaught THROW. That seems like a
>>> reasonable way to start here. Without memory contexts that almost
>>> certainly will mean memory leaks but I'm not sure how much that matters
>>> if the action is to exit immediately.
>>
>> If that's the expectation, we might as well replace backend ereport(ERROR)
>> with something that just prints a message and does exit(1).
>
> Well, the process might still want to do some cleanup of half-finished
> work. You'd not need to be resistant against memory leaks to do so, if
> followed by an exit. Obviously you can also do all the necessarily
> cleanup from within the ereport(ERROR) itself, but that doesn't seem
> appealing to me (not composable, harder to reuse for other programs,
> etc).

In pgBackRest we have a default handler that just logs the message to
stderr and exits (though we consider it a coding error if it gets
called). Seems like we could do the same here. Default message and
exit if no handler, but optionally allow a handler (which could RETHROW
to get to the default handler afterwards).

It seems like we've been wanting a front end version of ereport() for a
while so I'll take a look at that and see what it involves.

Regards,
--
-David
david(at)pgmasters(dot)net