Hi Hackers!

This would be version v1 of this feature

Basically, the subject says it all: pl/pgperl Patch for being able to tell which function you're in. This is a hashref so it will be possible to populate new and exciting other details in the future as the need arises

This also greatly improves logging capabilities for things like catching warnings,  Because as it stands right now, there's no information that can assist with locating the source of a warning like this:

# tail -f /var/log/postgresql.log
******* GOT A WARNING - Use of uninitialized value $prefix in concatenation (.) or string at (eval 531) line 48.

Now, with $_FN you can do this:


CREATE OR REPLACE FUNCTION throw_warning() RETURNS text LANGUAGE plperlu AS $function$

use warnings;
use strict;
use Data::Dumper;

$SIG{__WARN__} = sub {
  elog(NOTICE, Dumper($_FN));

  print STDERR "In Function: $_FN->{name}: $_[0]\n";
};

my $a;
print "$a"; # uninit!

return undef;

$function$
;

This patch is against 12 which is still our production branch. This could easily be also patched against newer releases as well.

I've been using this code in production now for about 3 years, it's greatly helped track down issues.  And there shouldn't be anything platform-specific here, it's all regular perl API

I'm not sure about adding testing.  This is my first postgres patch, so any guidance on adding regression testing would be appreciated.

The rationale for this has come from the need to know the source function name, and we've typically resorted to things like this in the past:

CREATE OR REPLACE FUNCTION throw_warning() RETURNS text LANGUAGE plperlu AS $function$
my $function_name = 'throw_warning';
$SIG{__WARN__} = sub { print STDERR "In Function: $function_name: $_[0]\n"; }
$function$
;

We've literally had to copy/paste this all over and it's something that postgres should just 'give you' since it knows the name already, just like when triggers pass you $_TD with all the pertinent information

A wishlist item would be for postgres plperl to automatically prepend the function name and schema when throwing perl warnings so you don't have to do your own __WARN__ handler, but this is the next best thing.


diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index f400050f38d..24b8f98cf1e 100644
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -2116,274 +2116,298 @@ plperlu_validator(PG_FUNCTION_ARGS)
  * supplied in s, and returns a reference to it
  */
 static void
 plperl_create_sub(plperl_proc_desc *prodesc, const char *s, Oid fn_oid)
 {
 	dTHX;
 	dSP;
 	char		subname[NAMEDATALEN + 40];
 	HV		   *pragma_hv = newHV();
 	SV		   *subref = NULL;
 	int			count;
 
 	sprintf(subname, "%s__%u", prodesc->proname, fn_oid);
 
 	if (plperl_use_strict)
 		hv_store_string(pragma_hv, "strict", (SV *) newAV());
 
 	ENTER;
 	SAVETMPS;
 	PUSHMARK(SP);
 	EXTEND(SP, 4);
 	PUSHs(sv_2mortal(cstr2sv(subname)));
 	PUSHs(sv_2mortal(newRV_noinc((SV *) pragma_hv)));
 
 	/*
 	 * Use 'false' for $prolog in mkfunc, which is kept for compatibility in
 	 * case a module such as PostgreSQL::PLPerl::NYTprof replaces the function
 	 * compiler.
 	 */
 	PUSHs(&PL_sv_no);
 	PUSHs(sv_2mortal(cstr2sv(s)));
 	PUTBACK;
 
 	/*
 	 * G_KEEPERR seems to be needed here, else we don't recognize compile
 	 * errors properly.  Perhaps it's because there's another level of eval
 	 * inside mksafefunc?
 	 */
 	count = call_pv("PostgreSQL::InServer::mkfunc",
 					G_SCALAR | G_EVAL | G_KEEPERR);
 	SPAGAIN;
 
 	if (count == 1)
 	{
 		SV		   *sub_rv = (SV *) POPs;
 
 		if (sub_rv && SvROK(sub_rv) && SvTYPE(SvRV(sub_rv)) == SVt_PVCV)
 		{
 			subref = newRV_inc(SvRV(sub_rv));
 		}
 	}
 
 	PUTBACK;
 	FREETMPS;
 	LEAVE;
 
 	if (SvTRUE(ERRSV))
 		ereport(ERROR,
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV)))));
 
 	if (!subref)
 		ereport(ERROR,
 				(errcode(ERRCODE_SYNTAX_ERROR),
 				 errmsg("didn't get a CODE reference from compiling function \"%s\"",
 						prodesc->proname)));
 
 	prodesc->reference = subref;
 
 	return;
 }
 
 
 /**********************************************************************
  * plperl_init_shared_libs()		-
  **********************************************************************/
 
 static void
 plperl_init_shared_libs(pTHX)
 {
 	char	   *file = __FILE__;
 
 	newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader, file);
 	newXS("PostgreSQL::InServer::Util::bootstrap",
 		  boot_PostgreSQL__InServer__Util, file);
 	/* newXS for...::SPI::bootstrap is in select_perl_context() */
 }
 
 
 static SV  *
 plperl_call_perl_func(plperl_proc_desc *desc, FunctionCallInfo fcinfo)
 {
 	dTHX;
 	dSP;
 	SV		   *retval;
 	int			i;
 	int			count;
 	Oid		   *argtypes = NULL;
 	int			nargs = 0;
 
+	HV		   *hv;			 // hash
+	SV		   *FNsv;		 // scalar reference to the hash
+	SV		   *svFN;		 // local reference to the hash
+
 	ENTER;
 	SAVETMPS;
 
+	/* Give functions some metadata about what's going on in $_FN (Similar to $_TD for triggers) */
+
+	FNsv = get_sv("main::_FN", GV_ADD);
+	if (!FNsv)
+		ereport(ERROR,
+				(errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),
+				 errmsg("couldn't fetch $_FN")));
+
+	hv = newHV(); // create new hash
+	hv_store_string(hv, "name", cstr2sv(desc->proname));
+
+	save_item(FNsv);			/* local $_FN */
+
+	sv_upgrade(FNsv, SVt_RV);
+	SvRV_set(FNsv, (SV*)hv);
+	SvROK_on(FNsv);
+
+	svFN = newRV_noinc((SV *) hv); // reference to the new hash
+	sv_setsv(FNsv, svFN);
+
 	PUSHMARK(SP);
 	EXTEND(sp, desc->nargs);
 
 	/* Get signature for true functions; inline blocks have no args. */
 	if (fcinfo->flinfo->fn_oid)
 		get_func_signature(fcinfo->flinfo->fn_oid, &argtypes, &nargs);
 	Assert(nargs == desc->nargs);
 
 	for (i = 0; i < desc->nargs; i++)
 	{
 		if (fcinfo->args[i].isnull)
 			PUSHs(&PL_sv_undef);
 		else if (desc->arg_is_rowtype[i])
 		{
 			SV		   *sv = plperl_hash_from_datum(fcinfo->args[i].value);
 
 			PUSHs(sv_2mortal(sv));
 		}
 		else
 		{
 			SV		   *sv;
 			Oid			funcid;
 
 			if (OidIsValid(desc->arg_arraytype[i]))
 				sv = plperl_ref_from_pg_array(fcinfo->args[i].value, desc->arg_arraytype[i]);
 			else if ((funcid = get_transform_fromsql(argtypes[i], current_call_data->prodesc->lang_oid, current_call_data->prodesc->trftypes)))
 				sv = (SV *) DatumGetPointer(OidFunctionCall1(funcid, fcinfo->args[i].value));
 			else
 			{
 				char	   *tmp;
 
 				tmp = OutputFunctionCall(&(desc->arg_out_func[i]),
 										 fcinfo->args[i].value);
 				sv = cstr2sv(tmp);
 				pfree(tmp);
 			}
 
 			PUSHs(sv_2mortal(sv));
 		}
 	}
 	PUTBACK;
 
 	/* Do NOT use G_KEEPERR here */
 	count = call_sv(desc->reference, G_SCALAR | G_EVAL);
 
 	SPAGAIN;
 
 	if (count != 1)
 	{
 		PUTBACK;
 		FREETMPS;
 		LEAVE;
 		ereport(ERROR,
 				(errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),
 				 errmsg("didn't get a return item from function")));
 	}
 
 	if (SvTRUE(ERRSV))
 	{
 		(void) POPs;
 		PUTBACK;
 		FREETMPS;
 		LEAVE;
 		/* XXX need to find a way to determine a better errcode here */
 		ereport(ERROR,
 				(errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),
 				 errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV)))));
 	}
 
 	retval = newSVsv(POPs);
 
 	PUTBACK;
 	FREETMPS;
 	LEAVE;
 
 	return retval;
 }
 
 
 static SV  *
 plperl_call_perl_trigger_func(plperl_proc_desc *desc, FunctionCallInfo fcinfo,
 							  SV *td)
 {
 	dTHX;
 	dSP;
 	SV		   *retval,
 			   *TDsv;
 	int			i,
 				count;
 	Trigger    *tg_trigger = ((TriggerData *) fcinfo->context)->tg_trigger;
 
 	ENTER;
 	SAVETMPS;
 
 	TDsv = get_sv("main::_TD", 0);
 	if (!TDsv)
 		ereport(ERROR,
 				(errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),
 				 errmsg("couldn't fetch $_TD")));
 
 	save_item(TDsv);			/* local $_TD */
 	sv_setsv(TDsv, td);
 
 	PUSHMARK(sp);
 	EXTEND(sp, tg_trigger->tgnargs);
 
 	for (i = 0; i < tg_trigger->tgnargs; i++)
 		PUSHs(sv_2mortal(cstr2sv(tg_trigger->tgargs[i])));
 	PUTBACK;
 
 	/* Do NOT use G_KEEPERR here */
 	count = call_sv(desc->reference, G_SCALAR | G_EVAL);
 
 	SPAGAIN;
 
 	if (count != 1)
 	{
 		PUTBACK;
 		FREETMPS;
 		LEAVE;
 		ereport(ERROR,
 				(errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),
 				 errmsg("didn't get a return item from trigger function")));
 	}
 
 	if (SvTRUE(ERRSV))
 	{
 		(void) POPs;
 		PUTBACK;
 		FREETMPS;
 		LEAVE;
 		/* XXX need to find a way to determine a better errcode here */
 		ereport(ERROR,
 				(errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),
 				 errmsg("%s", strip_trailing_ws(sv2cstr(ERRSV)))));
 	}
 
 	retval = newSVsv(POPs);
 
 	PUTBACK;
 	FREETMPS;
 	LEAVE;
 
 	return retval;
 }
 
 
 static void
 plperl_call_perl_event_trigger_func(plperl_proc_desc *desc,
 									FunctionCallInfo fcinfo,
 									SV *td)
 {
 	dTHX;
 	dSP;
 	SV		   *retval,
 			   *TDsv;
 	int			count;
 
 	ENTER;
 	SAVETMPS;
 
 	TDsv = get_sv("main::_TD", 0);
 	if (!TDsv)
 		ereport(ERROR,
 				(errcode(ERRCODE_EXTERNAL_ROUTINE_EXCEPTION),
 				 errmsg("couldn't fetch $_TD")));
 
 	save_item(TDsv);			/* local $_TD */
 	sv_setsv(TDsv, td);
 
 	PUSHMARK(sp);

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