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Extend plsample example to include a trigger handler.

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Mark Wong and Konstantina Skovola, reviewed by Chapman Flack

Discussion: https://postgr.es/m/Yd8Cz22eHi80XS30@workstation-mark-wong
pull/81/head
Tom Lane 3 years ago
parent 9f8a050f68
commit 2f4d0d6799
3 changed files with 274 additions and 3 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. 81
      src/test/modules/plsample/expected/plsample.out
  2. 173
      src/test/modules/plsample/plsample.c
  3. 23
      src/test/modules/plsample/sql/plsample.sql

81
src/test/modules/plsample/expected/plsample.out
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@ -34,3 +34,84 @@ NOTICE: argument: 0; name: a1; value: {foo,bar,hoge}
(1 row)
CREATE FUNCTION my_trigger_func() RETURNS trigger AS $$
if TD_event == "INSERT"
return TD_NEW
elseif TD_event == "UPDATE"
return TD_NEW
else
return "OK"
end
$$ language plsample;
CREATE TABLE my_table (num integer, description text);
CREATE TRIGGER my_trigger_func BEFORE INSERT OR UPDATE ON my_table
FOR EACH ROW EXECUTE FUNCTION my_trigger_func();
CREATE TRIGGER my_trigger_func2 AFTER INSERT OR UPDATE ON my_table
FOR EACH ROW EXECUTE FUNCTION my_trigger_func(8);
INSERT INTO my_table (num, description)
VALUES (1, 'first');
NOTICE: source text of function "my_trigger_func":
if TD_event == "INSERT"
return TD_NEW
elseif TD_event == "UPDATE"
return TD_NEW
else
return "OK"
end
NOTICE: trigger name: my_trigger_func
NOTICE: trigger relation: my_table
NOTICE: trigger relation schema: public
NOTICE: triggered by INSERT
NOTICE: triggered BEFORE
NOTICE: triggered per row
NOTICE: source text of function "my_trigger_func":
if TD_event == "INSERT"
return TD_NEW
elseif TD_event == "UPDATE"
return TD_NEW
else
return "OK"
end
NOTICE: trigger name: my_trigger_func2
NOTICE: trigger relation: my_table
NOTICE: trigger relation schema: public
NOTICE: triggered by INSERT
NOTICE: triggered AFTER
NOTICE: triggered per row
NOTICE: trigger arg[0]: 8
UPDATE my_table
SET description = 'first, modified once'
WHERE num = 1;
NOTICE: source text of function "my_trigger_func":
if TD_event == "INSERT"
return TD_NEW
elseif TD_event == "UPDATE"
return TD_NEW
else
return "OK"
end
NOTICE: trigger name: my_trigger_func
NOTICE: trigger relation: my_table
NOTICE: trigger relation schema: public
NOTICE: triggered by UPDATE
NOTICE: triggered BEFORE
NOTICE: triggered per row
NOTICE: source text of function "my_trigger_func":
if TD_event == "INSERT"
return TD_NEW
elseif TD_event == "UPDATE"
return TD_NEW
else
return "OK"
end
NOTICE: trigger name: my_trigger_func2
NOTICE: trigger relation: my_table
NOTICE: trigger relation schema: public
NOTICE: triggered by UPDATE
NOTICE: triggered AFTER
NOTICE: triggered per row
NOTICE: trigger arg[0]: 8

173
src/test/modules/plsample/plsample.c
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@ -19,6 +19,7 @@
#include "catalog/pg_type.h"
#include "commands/event_trigger.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "funcapi.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
@ -29,6 +30,7 @@ PG_MODULE_MAGIC;
PG_FUNCTION_INFO_V1(plsample_call_handler);
static Datum plsample_func_handler(PG_FUNCTION_ARGS);
static HeapTuple plsample_trigger_handler(PG_FUNCTION_ARGS);
/*
* Handle function, procedure, and trigger calls.
@ -38,6 +40,11 @@ plsample_call_handler(PG_FUNCTION_ARGS)
{
Datum retval = (Datum) 0;
/*
* Many languages will require cleanup that happens even in the event of
* an error. That can happen in the PG_FINALLY block. If none is needed,
* this PG_TRY construct can be omitted.
*/
PG_TRY();
{
/*
@ -51,6 +58,7 @@ plsample_call_handler(PG_FUNCTION_ARGS)
* (TriggerData *) fcinfo->context includes the information of the
* context.
*/
retval = PointerGetDatum(plsample_trigger_handler(fcinfo));
}
else if (CALLED_AS_EVENT_TRIGGER(fcinfo))
{
@ -58,6 +66,8 @@ plsample_call_handler(PG_FUNCTION_ARGS)
* This function is called as an event trigger function, where
* (EventTriggerData *) fcinfo->context includes the information
* of the context.
*
* TODO: provide an example handler.
*/
}
else
@ -101,9 +111,9 @@ plsample_func_handler(PG_FUNCTION_ARGS)
FmgrInfo result_in_func;
int numargs;
/* Fetch the source text of the function. */
pl_tuple = SearchSysCache(PROCOID,
ObjectIdGetDatum(fcinfo->flinfo->fn_oid), 0, 0, 0);
/* Fetch the function's pg_proc entry. */
pl_tuple = SearchSysCache1(PROCOID,
ObjectIdGetDatum(fcinfo->flinfo->fn_oid));
if (!HeapTupleIsValid(pl_tuple))
elog(ERROR, "cache lookup failed for function %u",
fcinfo->flinfo->fn_oid);
@ -185,3 +195,160 @@ plsample_func_handler(PG_FUNCTION_ARGS)
ret = InputFunctionCall(&result_in_func, source, result_typioparam, -1);
PG_RETURN_DATUM(ret);
}
/*
* plsample_trigger_handler
*
* Function called by the call handler for trigger execution.
*/
static HeapTuple
plsample_trigger_handler(PG_FUNCTION_ARGS)
{
TriggerData *trigdata = (TriggerData *) fcinfo->context;
char *string;
volatile HeapTuple rettup;
HeapTuple pl_tuple;
Datum ret;
char *source;
bool isnull;
Form_pg_proc pl_struct;
char *proname;
int rc PG_USED_FOR_ASSERTS_ONLY;
/* Make sure this is being called from a trigger. */
if (!CALLED_AS_TRIGGER(fcinfo))
elog(ERROR, "not called by trigger manager");
/* Connect to the SPI manager */
if (SPI_connect() != SPI_OK_CONNECT)
elog(ERROR, "could not connect to SPI manager");
rc = SPI_register_trigger_data(trigdata);
Assert(rc >= 0);
/* Fetch the function's pg_proc entry. */
pl_tuple = SearchSysCache1(PROCOID,
ObjectIdGetDatum(fcinfo->flinfo->fn_oid));
if (!HeapTupleIsValid(pl_tuple))
elog(ERROR, "cache lookup failed for function %u",
fcinfo->flinfo->fn_oid);
/*
* Code Retrieval
*
* Extract and print the source text of the function. This can be used as
* a base for the function validation and execution.
*/
pl_struct = (Form_pg_proc) GETSTRUCT(pl_tuple);
proname = pstrdup(NameStr(pl_struct->proname));
ret = SysCacheGetAttr(PROCOID, pl_tuple, Anum_pg_proc_prosrc, &isnull);
if (isnull)
elog(ERROR, "could not find source text of function \"%s\"",
proname);
source = DatumGetCString(DirectFunctionCall1(textout, ret));
ereport(NOTICE,
(errmsg("source text of function \"%s\": %s",
proname, source)));
/*
* We're done with the pg_proc tuple, so release it. (Note that the
* "proname" and "source" strings are now standalone copies.)
*/
ReleaseSysCache(pl_tuple);
/*
* Code Augmentation
*
* The source text may be augmented here, such as by wrapping it as the
* body of a function in the target language, prefixing a parameter list
* with names like TD_name, TD_relid, TD_table_name, TD_table_schema,
* TD_event, TD_when, TD_level, TD_NEW, TD_OLD, and args, using whatever
* types in the target language are convenient. The augmented text can be
* cached in a longer-lived memory context, or, if the target language
* uses a compilation step, that can be done here, caching the result of
* the compilation.
*/
/*
* Code Execution
*
* Here the function (the possibly-augmented source text, or the result of
* compilation if the target language uses such a step) should be
* executed, after binding values from the TriggerData struct to the
* appropriate parameters.
*
* In this example we just print a lot of info via ereport.
*/
PG_TRY();
{
ereport(NOTICE,
(errmsg("trigger name: %s", trigdata->tg_trigger->tgname)));
string = SPI_getrelname(trigdata->tg_relation);
ereport(NOTICE, (errmsg("trigger relation: %s", string)));
string = SPI_getnspname(trigdata->tg_relation);
ereport(NOTICE, (errmsg("trigger relation schema: %s", string)));
/* Example handling of different trigger aspects. */
if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
{
ereport(NOTICE, (errmsg("triggered by INSERT")));
rettup = trigdata->tg_trigtuple;
}
else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
{
ereport(NOTICE, (errmsg("triggered by DELETE")));
rettup = trigdata->tg_trigtuple;
}
else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
{
ereport(NOTICE, (errmsg("triggered by UPDATE")));
rettup = trigdata->tg_trigtuple;
}
else if (TRIGGER_FIRED_BY_TRUNCATE(trigdata->tg_event))
{
ereport(NOTICE, (errmsg("triggered by TRUNCATE")));
rettup = trigdata->tg_trigtuple;
}
else
elog(ERROR, "unrecognized event: %u", trigdata->tg_event);
if (TRIGGER_FIRED_BEFORE(trigdata->tg_event))
ereport(NOTICE, (errmsg("triggered BEFORE")));
else if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
ereport(NOTICE, (errmsg("triggered AFTER")));
else if (TRIGGER_FIRED_INSTEAD(trigdata->tg_event))
ereport(NOTICE, (errmsg("triggered INSTEAD OF")));
else
elog(ERROR, "unrecognized when: %u", trigdata->tg_event);
if (TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
ereport(NOTICE, (errmsg("triggered per row")));
else if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
ereport(NOTICE, (errmsg("triggered per statement")));
else
elog(ERROR, "unrecognized level: %u", trigdata->tg_event);
/*
* Iterate through all of the trigger arguments, printing each input
* value.
*/
for (int i = 0; i < trigdata->tg_trigger->tgnargs; i++)
ereport(NOTICE,
(errmsg("trigger arg[%i]: %s", i,
trigdata->tg_trigger->tgargs[i])));
}
PG_CATCH();
{
/* Error cleanup code would go here */
PG_RE_THROW();
}
PG_END_TRY();
if (SPI_finish() != SPI_OK_FINISH)
elog(ERROR, "SPI_finish() failed");
return rettup;
}

23
src/test/modules/plsample/sql/plsample.sql
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@ -13,3 +13,26 @@ AS $$
Example of source with void result.
$$ LANGUAGE plsample;
SELECT plsample_result_void('{foo, bar, hoge}');
CREATE FUNCTION my_trigger_func() RETURNS trigger AS $$
if TD_event == "INSERT"
return TD_NEW
elseif TD_event == "UPDATE"
return TD_NEW
else
return "OK"
end
$$ language plsample;
CREATE TABLE my_table (num integer, description text);
CREATE TRIGGER my_trigger_func BEFORE INSERT OR UPDATE ON my_table
FOR EACH ROW EXECUTE FUNCTION my_trigger_func();
CREATE TRIGGER my_trigger_func2 AFTER INSERT OR UPDATE ON my_table
FOR EACH ROW EXECUTE FUNCTION my_trigger_func(8);
INSERT INTO my_table (num, description)
VALUES (1, 'first');
UPDATE my_table
SET description = 'first, modified once'
WHERE num = 1;

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