Function ExecCallTriggerFunc

src/backend/commands/trigger.c:2180–2270

* Call a trigger function. * * trigdata: trigger descriptor. * tgindx: trigger's index in finfo and instr arrays. * finfo: array of cached trigger function call information. * instr: optional array of EXPLAIN ANALYZE instrumentation state. * per_tuple_context: memory context to execute the function in. * * Returns the tuple (or NULL) as returned by the function. */

 * Returns the tuple (or NULL) as returned by the function.
 */
static HeapTuple
ExecCallTriggerFunc(TriggerData *trigdata,
					int tgindx,
					FmgrInfo *finfo,
					Instrumentation *instr,
					MemoryContext per_tuple_context)
{
	LOCAL_FCINFO(fcinfo, 0);
	PgStat_FunctionCallUsage fcusage;
	Datum		result;
	MemoryContext oldContext;

	/*
	 * Protect against code paths that may fail to initialize transition table
	 * info.
	 */
	Assert(((TRIGGER_FIRED_BY_INSERT(trigdata->tg_event) ||
			 TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event) ||
			 TRIGGER_FIRED_BY_DELETE(trigdata->tg_event)) &&
			TRIGGER_FIRED_AFTER(trigdata->tg_event) &&
			!(trigdata->tg_event & AFTER_TRIGGER_DEFERRABLE) &&
			!(trigdata->tg_event & AFTER_TRIGGER_INITDEFERRED)) ||
		   (trigdata->tg_oldtable == NULL && trigdata->tg_newtable == NULL));

	finfo += tgindx;

	/*
	 * We cache fmgr lookup info, to avoid making the lookup again on each
	 * call.
	 */
	if (finfo->fn_oid == InvalidOid)
		fmgr_info(trigdata->tg_trigger->tgfoid, finfo);

	Assert(finfo->fn_oid == trigdata->tg_trigger->tgfoid);

	/*
	 * If doing EXPLAIN ANALYZE, start charging time to this trigger.
	 */
	if (instr)
		InstrStartNode(instr + tgindx);

	/*
	 * Do the function evaluation in the per-tuple memory context, so that
	 * leaked memory will be reclaimed once per tuple. Note in particular that
	 * any new tuple created by the trigger function will live till the end of
	 * the tuple cycle.
	 */
	oldContext = MemoryContextSwitchTo(per_tuple_context);

	/*
	 * Call the function, passing no arguments but setting a context.
	 */
	InitFunctionCallInfoData(*fcinfo, finfo, 0,
							 InvalidOid, (Node *) trigdata, NULL);

	pgstat_init_function_usage(fcinfo, &fcusage);

	MyTriggerDepth++;