Horton

Re: why does plperl cache functions using just a bool for is_trigger

Alex Hunsaker <badalex@gmail.com>

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From: Alex Hunsaker <badalex@gmail.com>
To: Andrew Dunstan <andrew@dunslane.net>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Jan Urbański <wulczer@wulczer.org>, Postgres - Hackers <pgsql-hackers@postgresql.org>
Date: 2010-10-31T20:40:49Z
Lists: pgsql-hackers

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  1. Remove unnecessary use of trigger flag to hash plperl functions

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On Sun, Oct 31, 2010 at 12:00, Andrew Dunstan <andrew@dunslane.net> wrote:
> On 10/31/2010 11:44 AM, Tom Lane wrote:
>> Good catch, patch reverted (and regression test added).
>
> Well, I guess that answers the question of why we needed it, which nobody
> could answer before. I'm not sure I exactly understand what's going on here,
> though - I guess I need to look at it closer. At least I think we need a
> code comment on why the trigger flag is needed as part of the hash key.

The stack trace is:
#0  0x0000000000000000 in ?? ()
#1  0x00000000006c18e9 in InputFunctionCall (flinfo=0x2a039a0,
str=0x0, typioparam=0, typmod=-1)
#2  0x00007ff6d2bdf950 in plperl_func_handler (fcinfo=0x7fff4743bec0)
at plperl.c:1729

which happens because prodesc->result_in_func.fn_addr (flinfo) is
NULL.  That happens because when we are a trigger we don't setup
input/output conversion.  And with the change we get the same
proc_desc for triggers and non triggers, so if the trigger function
gets called first, any call to the direct function will use the same
proc_desc with the wrong input/out conversion.

There is a check so that trigger functions can not be called as plain
functions, but it only gets called when we do not have an entry in
plperl_proc_hash.  I think just moving that up, something the like the
attached should be enough.  Thoughts?