trigger.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

 * possible size (trigdesc->numtriggers) if it's used at all.  This does
 * not waste space permanently since we're only building a temporary
 * trigdesc at this point.
 */
static void
InsertTrigger(TriggerDesc *trigdesc, Trigger *trigger, int indx)
{
	uint16	   *n;
	int		  **t,
			  **tp;

	if (TRIGGER_FOR_ROW(trigger->tgtype))
	{
		/* ROW trigger */
		if (TRIGGER_FOR_BEFORE(trigger->tgtype))
		{
			n = trigdesc->n_before_row;
			t = trigdesc->tg_before_row;
		}
		else
		{
			n = trigdesc->n_after_row;
			t = trigdesc->tg_after_row;
		}
	}
	else
	{
		/* STATEMENT trigger */
		if (TRIGGER_FOR_BEFORE(trigger->tgtype))
		{
			n = trigdesc->n_before_statement;
			t = trigdesc->tg_before_statement;
		}
		else
		{
			n = trigdesc->n_after_statement;
			t = trigdesc->tg_after_statement;
		}
	}

	if (TRIGGER_FOR_INSERT(trigger->tgtype))
	{
		tp = &(t[TRIGGER_EVENT_INSERT]);
		if (*tp == NULL)
			*tp = (int *) palloc(trigdesc->numtriggers * sizeof(int));
		(*tp)[n[TRIGGER_EVENT_INSERT]] = indx;
		(n[TRIGGER_EVENT_INSERT])++;
	}

	if (TRIGGER_FOR_DELETE(trigger->tgtype))
	{
		tp = &(t[TRIGGER_EVENT_DELETE]);
		if (*tp == NULL)
			*tp = (int *) palloc(trigdesc->numtriggers * sizeof(int));
		(*tp)[n[TRIGGER_EVENT_DELETE]] = indx;
		(n[TRIGGER_EVENT_DELETE])++;
	}

	if (TRIGGER_FOR_UPDATE(trigger->tgtype))
	{
		tp = &(t[TRIGGER_EVENT_UPDATE]);
		if (*tp == NULL)
			*tp = (int *) palloc(trigdesc->numtriggers * sizeof(int));
		(*tp)[n[TRIGGER_EVENT_UPDATE]] = indx;
		(n[TRIGGER_EVENT_UPDATE])++;
	}
}

/*
 * Copy a TriggerDesc data structure.
 *
 * The copy is allocated in the current memory context.
 */
TriggerDesc *
CopyTriggerDesc(TriggerDesc *trigdesc)
{
	TriggerDesc *newdesc;
	uint16	   *n;
	int		  **t,
			   *tnew;
	Trigger    *trigger;
	int			i;

	if (trigdesc == NULL || trigdesc->numtriggers <= 0)
		return NULL;

	newdesc = (TriggerDesc *) palloc(sizeof(TriggerDesc));
	memcpy(newdesc, trigdesc, sizeof(TriggerDesc));

	trigger = (Trigger *) palloc(trigdesc->numtriggers * sizeof(Trigger));
	memcpy(trigger, trigdesc->triggers,
		   trigdesc->numtriggers * sizeof(Trigger));
	newdesc->triggers = trigger;

	for (i = 0; i < trigdesc->numtriggers; i++)
	{
		trigger->tgname = pstrdup(trigger->tgname);
		if (trigger->tgnattr > 0)
		{
			int2	   *newattr;

			newattr = (int2 *) palloc(trigger->tgnattr * sizeof(int2));
			memcpy(newattr, trigger->tgattr,
				   trigger->tgnattr * sizeof(int2));
			trigger->tgattr = newattr;
		}
		if (trigger->tgnargs > 0)
		{
			char	  **newargs;
			int16		j;

			newargs = (char **) palloc(trigger->tgnargs * sizeof(char *));
			for (j = 0; j < trigger->tgnargs; j++)
				newargs[j] = pstrdup(trigger->tgargs[j]);
			trigger->tgargs = newargs;
		}
		trigger++;
	}

	n = newdesc->n_before_statement;
	t = newdesc->tg_before_statement;
	for (i = 0; i < TRIGGER_NUM_EVENT_CLASSES; i++)
	{
		if (n[i] > 0)
		{
			tnew = (int *) palloc(n[i] * sizeof(int));
			memcpy(tnew, t[i], n[i] * sizeof(int));
			t[i] = tnew;
		}
		else
			t[i] = NULL;
	}
	n = newdesc->n_before_row;
	t = newdesc->tg_before_row;
	for (i = 0; i < TRIGGER_NUM_EVENT_CLASSES; i++)
	{
		if (n[i] > 0)
		{
			tnew = (int *) palloc(n[i] * sizeof(int));
			memcpy(tnew, t[i], n[i] * sizeof(int));
			t[i] = tnew;
		}
		else
			t[i] = NULL;
	}
	n = newdesc->n_after_row;
	t = newdesc->tg_after_row;
	for (i = 0; i < TRIGGER_NUM_EVENT_CLASSES; i++)
	{
		if (n[i] > 0)
		{
			tnew = (int *) palloc(n[i] * sizeof(int));
			memcpy(tnew, t[i], n[i] * sizeof(int));
			t[i] = tnew;
		}
		else
			t[i] = NULL;
	}
	n = newdesc->n_after_statement;
	t = newdesc->tg_after_statement;
	for (i = 0; i < TRIGGER_NUM_EVENT_CLASSES; i++)
	{
		if (n[i] > 0)
		{
			tnew = (int *) palloc(n[i] * sizeof(int));
			memcpy(tnew, t[i], n[i] * sizeof(int));
			t[i] = tnew;
		}
		else
			t[i] = NULL;
	}

	return newdesc;
}

/*
 * Free a TriggerDesc data structure.
 */
void
FreeTriggerDesc(TriggerDesc *trigdesc)
{
	int		  **t;
	Trigger    *trigger;
	int			i;

	if (trigdesc == NULL)
		return;

	t = trigdesc->tg_before_statement;
	for (i = 0; i < TRIGGER_NUM_EVENT_CLASSES; i++)
		if (t[i] != NULL)
			pfree(t[i]);
	t = trigdesc->tg_before_row;
	for (i = 0; i < TRIGGER_NUM_EVENT_CLASSES; i++)
		if (t[i] != NULL)
			pfree(t[i]);
	t = trigdesc->tg_after_row;
	for (i = 0; i < TRIGGER_NUM_EVENT_CLASSES; i++)
		if (t[i] != NULL)
			pfree(t[i]);
	t = trigdesc->tg_after_statement;
	for (i = 0; i < TRIGGER_NUM_EVENT_CLASSES; i++)
		if (t[i] != NULL)
			pfree(t[i]);

	trigger = trigdesc->triggers;
	for (i = 0; i < trigdesc->numtriggers; i++)
	{
		pfree(trigger->tgname);
		if (trigger->tgnattr > 0)
			pfree(trigger->tgattr);
		if (trigger->tgnargs > 0)
		{
			while (--(trigger->tgnargs) >= 0)
				pfree(trigger->tgargs[trigger->tgnargs]);
			pfree(trigger->tgargs);
		}
		trigger++;
	}
	pfree(trigdesc->triggers);
	pfree(trigdesc);
}

/*
 * Compare two TriggerDesc structures for logical equality.
 */
#ifdef NOT_USED
bool
equalTriggerDescs(TriggerDesc *trigdesc1, TriggerDesc *trigdesc2)
{
	int			i,
				j;

	/*
	 * We need not examine the "index" data, just the trigger array itself; if
	 * we have the same triggers with the same types, the derived index data
	 * should match.
	 *
	 * As of 7.3 we assume trigger set ordering is significant in the
	 * comparison; so we just compare corresponding slots of the two sets.
	 */
	if (trigdesc1 != NULL)
	{
		if (trigdesc2 == NULL)
			return false;
		if (trigdesc1->numtriggers != trigdesc2->numtriggers)
			return false;
		for (i = 0; i < trigdesc1->numtriggers; i++)
		{
			Trigger    *trig1 = trigdesc1->triggers + i;
			Trigger    *trig2 = trigdesc2->triggers + i;

			if (trig1->tgoid != trig2->tgoid)
				return false;
			if (strcmp(trig1->tgname, trig2->tgname) != 0)
				return false;
			if (trig1->tgfoid != trig2->tgfoid)
				return false;
			if (trig1->tgtype != trig2->tgtype)
				return false;
			if (trig1->tgenabled != trig2->tgenabled)
				return false;
			if (trig1->tgisconstraint != trig2->tgisconstraint)
				return false;
			if (trig1->tgconstrrelid != trig2->tgconstrrelid)
				return false;
			if (trig1->tgdeferrable != trig2->tgdeferrable)
				return false;
			if (trig1->tginitdeferred != trig2->tginitdeferred)
				return false;
			if (trig1->tgnargs != trig2->tgnargs)
				return false;
			if (trig1->tgnattr != trig2->tgnattr)
				return false;
			if (trig1->tgnattr > 0 &&
				memcmp(trig1->tgattr, trig2->tgattr,
					   trig1->tgnattr * sizeof(int2)) != 0)
				return false;
			for (j = 0; j < trig1->tgnargs; j++)
				if (strcmp(trig1->tgargs[j], trig2->tgargs[j]) != 0)
					return false;
		}
	}
	else if (trigdesc2 != NULL)
		return false;
	return true;
}
#endif   /* NOT_USED */

/*
 * 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.
 */
static HeapTuple
ExecCallTriggerFunc(TriggerData *trigdata,
					int tgindx,
					FmgrInfo *finfo,
					Instrumentation *instr,
					MemoryContext per_tuple_context)
{
	FunctionCallInfoData fcinfo;
	Datum		result;
	MemoryContext oldContext;

	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, (Node *) trigdata, NULL);

	result = FunctionCallInvoke(&fcinfo);

	MemoryContextSwitchTo(oldContext);

	/*
	 * Trigger protocol allows function to return a null pointer, but NOT to
	 * set the isnull result flag.
	 */
	if (fcinfo.isnull)
		ereport(ERROR,
				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				 errmsg("trigger function %u returned null value",
						fcinfo.flinfo->fn_oid)));

	/*
	 * If doing EXPLAIN ANALYZE, stop charging time to this trigger, and count
	 * one "tuple returned" (really the number of firings).
	 */
	if (instr)
		InstrStopNode(instr + tgindx, true);

	return (HeapTuple) DatumGetPointer(result);
}

void
ExecBSInsertTriggers(EState *estate, ResultRelInfo *relinfo)
{
	TriggerDesc *trigdesc;
	int			ntrigs;
	int		   *tgindx;
	int			i;
	TriggerData LocTriggerData;

	trigdesc = relinfo->ri_TrigDesc;

	if (trigdesc == NULL)
		return;

	ntrigs = trigdesc->n_before_statement[TRIGGER_EVENT_INSERT];
	tgindx = trigdesc->tg_before_statement[TRIGGER_EVENT_INSERT];

	if (ntrigs == 0)
		return;

	LocTriggerData.type = T_TriggerData;
	LocTriggerData.tg_event = TRIGGER_EVENT_INSERT |
		TRIGGER_EVENT_BEFORE;
	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
	LocTriggerData.tg_trigtuple = NULL;
	LocTriggerData.tg_newtuple = NULL;
	LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
	LocTriggerData.tg_newtuplebuf = InvalidBuffer;
	for (i = 0; i < ntrigs; i++)
	{
		Trigger    *trigger = &trigdesc->triggers[tgindx[i]];
		HeapTuple	newtuple;

		if (!trigger->tgenabled)
			continue;
		LocTriggerData.tg_trigger = trigger;
		newtuple = ExecCallTriggerFunc(&LocTriggerData,
									   tgindx[i],
									   relinfo->ri_TrigFunctions,
									   relinfo->ri_TrigInstrument,
									   GetPerTupleMemoryContext(estate));

		if (newtuple)
			ereport(ERROR,
					(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
				  errmsg("BEFORE STATEMENT trigger cannot return a value")));
	}
}

void
ExecASInsertTriggers(EState *estate, ResultRelInfo *relinfo)
{
	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

	if (trigdesc && trigdesc->n_after_statement[TRIGGER_EVENT_INSERT] > 0)
		AfterTriggerSaveEvent(relinfo, TRIGGER_EVENT_INSERT,
							  false, NULL, NULL);
}

HeapTuple
ExecBRInsertTriggers(EState *estate, ResultRelInfo *relinfo,
					 HeapTuple trigtuple)
{
	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
	int			ntrigs = trigdesc->n_before_row[TRIGGER_EVENT_INSERT];
	int		   *tgindx = trigdesc->tg_before_row[TRIGGER_EVENT_INSERT];
	HeapTuple	newtuple = trigtuple;
	HeapTuple	oldtuple;
	TriggerData LocTriggerData;
	int			i;

	LocTriggerData.type = T_TriggerData;
	LocTriggerData.tg_event = TRIGGER_EVENT_INSERT |
		TRIGGER_EVENT_ROW |
		TRIGGER_EVENT_BEFORE;
	LocTriggerData.tg_relation = relinfo->ri_RelationDesc;
	LocTriggerData.tg_newtuple = NULL;
	LocTriggerData.tg_newtuplebuf = InvalidBuffer;
	for (i = 0; i < ntrigs; i++)
	{
		Trigger    *trigger = &trigdesc->triggers[tgindx[i]];

		if (!trigger->tgenabled)
			continue;
		LocTriggerData.tg_trigtuple = oldtuple = newtuple;
		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
		LocTriggerData.tg_trigger = trigger;
		newtuple = ExecCallTriggerFunc(&LocTriggerData,
									   tgindx[i],
									   relinfo->ri_TrigFunctions,
									   relinfo->ri_TrigInstrument,
									   GetPerTupleMemoryContext(estate));
		if (oldtuple != newtuple && oldtuple != trigtuple)
			heap_freetuple(oldtuple);
		if (newtuple == NULL)
			break;
	}
	return newtuple;
}

void
ExecARInsertTriggers(EState *estate, ResultRelInfo *relinfo,
					 HeapTuple trigtuple)
{
	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

	if (trigdesc && trigdesc->n_after_row[TRIGGER_EVENT_INSERT] > 0)
		AfterTriggerSaveEvent(relinfo, TRIGGER_EVENT_INSERT,