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PL/Tcl: Add event trigger support

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From: Dimitri Fontaine <dimitri@2ndQuadrant.fr>
pull/6/head
Peter Eisentraut 12 years ago
parent 45e02e3232
commit a5036ca998
4 changed files with 188 additions and 23 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 59
      doc/src/sgml/pltcl.sgml
  2. 23
      src/pl/tcl/expected/pltcl_setup.out
  3. 111
      src/pl/tcl/pltcl.c
  4. 18
      src/pl/tcl/sql/pltcl_setup.sql

59
doc/src/sgml/pltcl.sgml
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@ -711,6 +711,65 @@ CREATE TRIGGER trig_mytab_modcount BEFORE INSERT OR UPDATE ON mytab
</para>
</sect1>
<sect1 id="pltcl-event-trigger">
<title>Event Trigger Procedures in PL/Tcl</title>
<indexterm>
<primary>event trigger</primary>
<secondary>in PL/Tcl</secondary>
</indexterm>
<para>
Event trigger procedures can be written in PL/Tcl.
<productname>PostgreSQL</productname> requires that a procedure that is
to be called as an event trigger must be declared as a function with no
arguments and a return type of <literal>event_trigger</>.
</para>
<para>
The information from the trigger manager is passed to the procedure body
in the following variables:
<variablelist>
<varlistentry>
<term><varname>$TG_event</varname></term>
<listitem>
<para>
The name of the event the trigger is fired for.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>$TG_tag</varname></term>
<listitem>
<para>
The command tag for which the trigger is fired.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
The return value of the trigger procedure is ignored.
</para>
<para>
Here's a little example event trigger procedure that simply raises
a <literal>NOTICE</literal> message each time a supported command is
executed:
<programlisting>
CREATE OR REPLACE FUNCTION tclsnitch() RETURNS event_trigger AS $$
elog NOTICE "tclsnitch: $TG_event $TG_tag"
$$ LANGUAGE pltcl;
CREATE EVENT TRIGGER tcl_a_snitch ON ddl_command_start EXECUTE PROCEDURE tclsnitch();
</programlisting>
</para>
</sect1>
<sect1 id="pltcl-unknown">
<title>Modules and the <function>unknown</> Command</title>
<para>

23
src/pl/tcl/expected/pltcl_setup.out
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@ -519,3 +519,26 @@ select tcl_date_week(2001,10,24);
42
(1 row)
-- test pltcl event triggers
create or replace function tclsnitch() returns event_trigger language pltcl as $$
elog NOTICE "tclsnitch: $TG_event $TG_tag"
$$;
create event trigger tcl_a_snitch on ddl_command_start execute procedure tclsnitch();
create event trigger tcl_b_snitch on ddl_command_end execute procedure tclsnitch();
create or replace function foobar() returns int language sql as $$select 1;$$;
NOTICE: tclsnitch: ddl_command_start CREATE FUNCTION
NOTICE: tclsnitch: ddl_command_end CREATE FUNCTION
alter function foobar() cost 77;
NOTICE: tclsnitch: ddl_command_start ALTER FUNCTION
NOTICE: tclsnitch: ddl_command_end ALTER FUNCTION
drop function foobar();
NOTICE: tclsnitch: ddl_command_start DROP FUNCTION
NOTICE: tclsnitch: ddl_command_end DROP FUNCTION
create table foo();
NOTICE: tclsnitch: ddl_command_start CREATE TABLE
NOTICE: tclsnitch: ddl_command_end CREATE TABLE
drop table foo;
NOTICE: tclsnitch: ddl_command_start DROP TABLE
NOTICE: tclsnitch: ddl_command_end DROP TABLE
drop event trigger tcl_a_snitch;
drop event trigger tcl_b_snitch;

111
src/pl/tcl/pltcl.c
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@ -27,6 +27,7 @@
#include "access/xact.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
#include "commands/event_trigger.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "fmgr.h"
@ -200,11 +201,13 @@ static Datum pltcl_handler(PG_FUNCTION_ARGS, bool pltrusted);
static Datum pltcl_func_handler(PG_FUNCTION_ARGS, bool pltrusted);
static HeapTuple pltcl_trigger_handler(PG_FUNCTION_ARGS, bool pltrusted);
static void pltcl_event_trigger_handler(PG_FUNCTION_ARGS, bool pltrusted);
static void throw_tcl_error(Tcl_Interp *interp, const char *proname);
static pltcl_proc_desc *compile_pltcl_function(Oid fn_oid, Oid tgreloid,
bool pltrusted);
bool is_event_trigger,
bool pltrusted);
static int pltcl_elog(ClientData cdata, Tcl_Interp *interp,
int argc, CONST84 char *argv[]);
@ -644,6 +647,12 @@ pltcl_handler(PG_FUNCTION_ARGS, bool pltrusted)
pltcl_current_fcinfo = NULL;
retval = PointerGetDatum(pltcl_trigger_handler(fcinfo, pltrusted));
}
else if (CALLED_AS_EVENT_TRIGGER(fcinfo))
{
pltcl_current_fcinfo = NULL;
pltcl_event_trigger_handler(fcinfo, pltrusted);
retval = (Datum) 0;
}
else
{
pltcl_current_fcinfo = fcinfo;
@ -685,7 +694,7 @@ pltcl_func_handler(PG_FUNCTION_ARGS, bool pltrusted)
/* Find or compile the function */
prodesc = compile_pltcl_function(fcinfo->flinfo->fn_oid, InvalidOid,
pltrusted);
false, pltrusted);
pltcl_current_prodesc = prodesc;
@ -844,6 +853,7 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS, bool pltrusted)
/* Find or compile the function */
prodesc = compile_pltcl_function(fcinfo->flinfo->fn_oid,
RelationGetRelid(trigdata->tg_relation),
false, /* not an event trigger */
pltrusted);
pltcl_current_prodesc = prodesc;
@ -1130,6 +1140,47 @@ pltcl_trigger_handler(PG_FUNCTION_ARGS, bool pltrusted)
return rettup;
}
/**********************************************************************
* pltcl_event_trigger_handler() - Handler for event trigger calls
**********************************************************************/
static void
pltcl_event_trigger_handler(PG_FUNCTION_ARGS, bool pltrusted)
{
pltcl_proc_desc *prodesc;
Tcl_Interp *volatile interp;
EventTriggerData *tdata = (EventTriggerData *) fcinfo->context;
Tcl_DString tcl_cmd;
int tcl_rc;
/* Connect to SPI manager */
if (SPI_connect() != SPI_OK_CONNECT)
elog(ERROR, "could not connect to SPI manager");
/* Find or compile the function */
prodesc = compile_pltcl_function(fcinfo->flinfo->fn_oid,
InvalidOid, true, pltrusted);
pltcl_current_prodesc = prodesc;
interp = prodesc->interp_desc->interp;
/* Create the tcl command and call the internal proc */
Tcl_DStringInit(&tcl_cmd);
Tcl_DStringAppendElement(&tcl_cmd, prodesc->internal_proname);
Tcl_DStringAppendElement(&tcl_cmd, tdata->event);
Tcl_DStringAppendElement(&tcl_cmd, tdata->tag);
tcl_rc = Tcl_GlobalEval(interp, Tcl_DStringValue(&tcl_cmd));
Tcl_DStringFree(&tcl_cmd);
/* Check for errors reported by Tcl. */
if (tcl_rc != TCL_OK)
throw_tcl_error(interp, prodesc->user_proname);
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish() failed");
}
/**********************************************************************
* throw_tcl_error - ereport an error returned from the Tcl interpreter
@ -1168,7 +1219,8 @@ throw_tcl_error(Tcl_Interp *interp, const char *proname)
* (InvalidOid) when compiling a plain function.
**********************************************************************/
static pltcl_proc_desc *
compile_pltcl_function(Oid fn_oid, Oid tgreloid, bool pltrusted)
compile_pltcl_function(Oid fn_oid, Oid tgreloid,
bool is_event_trigger, bool pltrusted)
{
HeapTuple procTup;
Form_pg_proc procStruct;
@ -1245,10 +1297,13 @@ compile_pltcl_function(Oid fn_oid, Oid tgreloid, bool pltrusted)
* "_trigger" when appropriate to ensure the normal and trigger
* cases are kept separate.
************************************************************/
if (!is_trigger)
if (!is_trigger && !is_event_trigger)
snprintf(internal_proname, sizeof(internal_proname),
"__PLTcl_proc_%u", fn_oid);
else
else if (is_event_trigger)
snprintf(internal_proname, sizeof(internal_proname),
"__PLTcl_proc_%u_evttrigger", fn_oid);
else if (is_trigger)
snprintf(internal_proname, sizeof(internal_proname),
"__PLTcl_proc_%u_trigger", fn_oid);
@ -1286,7 +1341,7 @@ compile_pltcl_function(Oid fn_oid, Oid tgreloid, bool pltrusted)
* Get the required information for input conversion of the
* return value.
************************************************************/
if (!is_trigger)
if (!is_trigger && !is_event_trigger)
{
typeTup =
SearchSysCache1(TYPEOID,
@ -1306,7 +1361,8 @@ compile_pltcl_function(Oid fn_oid, Oid tgreloid, bool pltrusted)
{
if (procStruct->prorettype == VOIDOID)
/* okay */ ;
else if (procStruct->prorettype == TRIGGEROID)
else if (procStruct->prorettype == TRIGGEROID ||
procStruct->prorettype == EVTTRIGGEROID)
{
free(prodesc->user_proname);
free(prodesc->internal_proname);
@ -1347,7 +1403,7 @@ compile_pltcl_function(Oid fn_oid, Oid tgreloid, bool pltrusted)
* Get the required information for output conversion
* of all procedure arguments
************************************************************/
if (!is_trigger)
if (!is_trigger && !is_event_trigger)
{
prodesc->nargs = procStruct->pronargs;
proc_internal_args[0] = '\0';
@ -1397,12 +1453,17 @@ compile_pltcl_function(Oid fn_oid, Oid tgreloid, bool pltrusted)
ReleaseSysCache(typeTup);
}
}
else
else if (is_trigger)
{
/* trigger procedure has fixed args */
strcpy(proc_internal_args,
"TG_name TG_relid TG_table_name TG_table_schema TG_relatts TG_when TG_level TG_op __PLTcl_Tup_NEW __PLTcl_Tup_OLD args");
}
else if (is_event_trigger)
{
/* event trigger procedure has fixed args */
strcpy(proc_internal_args, "TG_event TG_tag");
}
/************************************************************
* Create the tcl command to define the internal
@ -1422,20 +1483,7 @@ compile_pltcl_function(Oid fn_oid, Oid tgreloid, bool pltrusted)
Tcl_DStringAppend(&proc_internal_body, "upvar #0 ", -1);
Tcl_DStringAppend(&proc_internal_body, internal_proname, -1);
Tcl_DStringAppend(&proc_internal_body, " GD\n", -1);
if (!is_trigger)
{
for (i = 0; i < prodesc->nargs; i++)
{
if (prodesc->arg_is_rowtype[i])
{
snprintf(buf, sizeof(buf),
"array set %d $__PLTcl_Tup_%d\n",
i + 1, i + 1);
Tcl_DStringAppend(&proc_internal_body, buf, -1);
}
}
}
else
if (is_trigger)
{
Tcl_DStringAppend(&proc_internal_body,
"array set NEW $__PLTcl_Tup_NEW\n", -1);
@ -1451,6 +1499,23 @@ compile_pltcl_function(Oid fn_oid, Oid tgreloid, bool pltrusted)
"}\n"
"unset i v\n\n", -1);
}
else if (is_event_trigger)
{
/* no argument support for event triggers */
}
else
{
for (i = 0; i < prodesc->nargs; i++)
{
if (prodesc->arg_is_rowtype[i])
{
snprintf(buf, sizeof(buf),
"array set %d $__PLTcl_Tup_%d\n",
i + 1, i + 1);
Tcl_DStringAppend(&proc_internal_body, buf, -1);
}
}
}
/************************************************************
* Add user's function definition to proc body

18
src/pl/tcl/sql/pltcl_setup.sql
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@ -559,3 +559,21 @@ $$ language pltcl immutable;
select tcl_date_week(2010,1,24);
select tcl_date_week(2001,10,24);
-- test pltcl event triggers
create or replace function tclsnitch() returns event_trigger language pltcl as $$
elog NOTICE "tclsnitch: $TG_event $TG_tag"
$$;
create event trigger tcl_a_snitch on ddl_command_start execute procedure tclsnitch();
create event trigger tcl_b_snitch on ddl_command_end execute procedure tclsnitch();
create or replace function foobar() returns int language sql as $$select 1;$$;
alter function foobar() cost 77;
drop function foobar();
create table foo();
drop table foo;
drop event trigger tcl_a_snitch;
drop event trigger tcl_b_snitch;

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