trigger.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

							  true, NULL, trigtuple);
}

void
ExecBSDeleteTriggers(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_DELETE];
	tgindx = trigdesc->tg_before_statement[TRIGGER_EVENT_DELETE];

	if (ntrigs == 0)
		return;

	LocTriggerData.type = T_TriggerData;
	LocTriggerData.tg_event = TRIGGER_EVENT_DELETE |
		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
ExecASDeleteTriggers(EState *estate, ResultRelInfo *relinfo)
{
	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

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

bool
ExecBRDeleteTriggers(EState *estate, ResultRelInfo *relinfo,
					 ItemPointer tupleid,
					 CommandId cid)
{
	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
	int			ntrigs = trigdesc->n_before_row[TRIGGER_EVENT_DELETE];
	int		   *tgindx = trigdesc->tg_before_row[TRIGGER_EVENT_DELETE];
	bool		result = true;
	TriggerData LocTriggerData;
	HeapTuple	trigtuple;
	HeapTuple	newtuple;
	TupleTableSlot *newSlot;
	int			i;

	trigtuple = GetTupleForTrigger(estate, relinfo, tupleid, cid, &newSlot);
	if (trigtuple == NULL)
		return false;

	LocTriggerData.type = T_TriggerData;
	LocTriggerData.tg_event = TRIGGER_EVENT_DELETE |
		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 = trigtuple;
		LocTriggerData.tg_trigtuplebuf = InvalidBuffer;
		LocTriggerData.tg_trigger = trigger;
		newtuple = ExecCallTriggerFunc(&LocTriggerData,
									   tgindx[i],
									   relinfo->ri_TrigFunctions,
									   relinfo->ri_TrigInstrument,
									   GetPerTupleMemoryContext(estate));
		if (newtuple == NULL)
		{
			result = false;		/* tell caller to suppress delete */
			break;
		}
		if (newtuple != trigtuple)
			heap_freetuple(newtuple);
	}
	heap_freetuple(trigtuple);

	return result;
}

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

	if (trigdesc && trigdesc->n_after_row[TRIGGER_EVENT_DELETE] > 0)
	{
		HeapTuple	trigtuple = GetTupleForTrigger(estate, relinfo,
												   tupleid,
												   (CommandId) 0,
												   NULL);

		AfterTriggerSaveEvent(relinfo, TRIGGER_EVENT_DELETE,
							  true, trigtuple, NULL);
		heap_freetuple(trigtuple);
	}
}

void
ExecBSUpdateTriggers(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_UPDATE];
	tgindx = trigdesc->tg_before_statement[TRIGGER_EVENT_UPDATE];

	if (ntrigs == 0)
		return;

	LocTriggerData.type = T_TriggerData;
	LocTriggerData.tg_event = TRIGGER_EVENT_UPDATE |
		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
ExecASUpdateTriggers(EState *estate, ResultRelInfo *relinfo)
{
	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

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

HeapTuple
ExecBRUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
					 ItemPointer tupleid, HeapTuple newtuple,
					 CommandId cid)
{
	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;
	int			ntrigs = trigdesc->n_before_row[TRIGGER_EVENT_UPDATE];
	int		   *tgindx = trigdesc->tg_before_row[TRIGGER_EVENT_UPDATE];
	TriggerData LocTriggerData;
	HeapTuple	trigtuple;
	HeapTuple	oldtuple;
	HeapTuple	intuple = newtuple;
	TupleTableSlot *newSlot;
	int			i;

	trigtuple = GetTupleForTrigger(estate, relinfo, tupleid, cid, &newSlot);
	if (trigtuple == NULL)
		return NULL;

	/*
	 * In READ COMMITTED isolation level it's possible that newtuple was
	 * changed due to concurrent update.
	 */
	if (newSlot != NULL)
		intuple = newtuple = ExecRemoveJunk(estate->es_junkFilter, newSlot);

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

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

void
ExecARUpdateTriggers(EState *estate, ResultRelInfo *relinfo,
					 ItemPointer tupleid, HeapTuple newtuple)
{
	TriggerDesc *trigdesc = relinfo->ri_TrigDesc;

	if (trigdesc && trigdesc->n_after_row[TRIGGER_EVENT_UPDATE] > 0)
	{
		HeapTuple	trigtuple = GetTupleForTrigger(estate, relinfo,
												   tupleid,
												   (CommandId) 0,
												   NULL);

		AfterTriggerSaveEvent(relinfo, TRIGGER_EVENT_UPDATE,
							  true, trigtuple, newtuple);
		heap_freetuple(trigtuple);
	}
}


static HeapTuple
GetTupleForTrigger(EState *estate, ResultRelInfo *relinfo,
				   ItemPointer tid, CommandId cid,
				   TupleTableSlot **newSlot)
{
	Relation	relation = relinfo->ri_RelationDesc;
	HeapTupleData tuple;
	HeapTuple	result;
	Buffer		buffer;

	if (newSlot != NULL)
	{
		HTSU_Result test;
		ItemPointerData update_ctid;
		TransactionId update_xmax;

		*newSlot = NULL;

		/*
		 * lock tuple for update
		 */
ltrmark:;
		tuple.t_self = *tid;
		test = heap_lock_tuple(relation, &tuple, &buffer,
							   &update_ctid, &update_xmax, cid,
							   LockTupleExclusive, false);
		switch (test)
		{
			case HeapTupleSelfUpdated:
				/* treat it as deleted; do not process */
				ReleaseBuffer(buffer);
				return NULL;

			case HeapTupleMayBeUpdated:
				break;

			case HeapTupleUpdated:
				ReleaseBuffer(buffer);
				if (IsXactIsoLevelSerializable)
					ereport(ERROR,
							(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
							 errmsg("could not serialize access due to concurrent update")));
				else if (!ItemPointerEquals(&update_ctid, &tuple.t_self))
				{
					/* it was updated, so look at the updated version */
					TupleTableSlot *epqslot;

					epqslot = EvalPlanQual(estate,
										   relinfo->ri_RangeTableIndex,
										   &update_ctid,
										   update_xmax,
										   cid);
					if (!TupIsNull(epqslot))
					{
						*tid = update_ctid;
						*newSlot = epqslot;
						goto ltrmark;
					}
				}

				/*
				 * if tuple was deleted or PlanQual failed for updated tuple -
				 * we have not process this tuple!
				 */
				return NULL;

			default:
				ReleaseBuffer(buffer);
				elog(ERROR, "unrecognized heap_lock_tuple status: %u", test);
				return NULL;	/* keep compiler quiet */
		}
	}
	else
	{
		PageHeader	dp;
		ItemId		lp;

		buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid));

		dp = (PageHeader) BufferGetPage(buffer);
		lp = PageGetItemId(dp, ItemPointerGetOffsetNumber(tid));

		Assert(ItemIdIsUsed(lp));

		tuple.t_datamcxt = NULL;
		tuple.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
		tuple.t_len = ItemIdGetLength(lp);
		tuple.t_self = *tid;
		tuple.t_tableOid = RelationGetRelid(relation);
	}

	result = heap_copytuple(&tuple);
	ReleaseBuffer(buffer);

	return result;
}


/* ----------
 * After-trigger stuff
 *
 * The AfterTriggersData struct holds data about pending AFTER trigger events
 * during the current transaction tree.  (BEFORE triggers are fired
 * immediately so we don't need any persistent state about them.)  The struct
 * and most of its subsidiary data are kept in TopTransactionContext; however
 * the individual event records are kept in CurTransactionContext, so that
 * they will easily go away during subtransaction abort.
 *
 * Because the list of pending events can grow large, we go to some effort
 * to minimize memory consumption.	We do not use the generic List mechanism
 * but thread the events manually.
 *
 * XXX We need to be able to save the per-event data in a file if it grows too
 * large.
 * ----------
 */

/* Per-trigger SET CONSTRAINT status */
typedef struct SetConstraintTriggerData
{
	Oid			sct_tgoid;
	bool		sct_tgisdeferred;
} SetConstraintTriggerData;

typedef struct SetConstraintTriggerData *SetConstraintTrigger;

/*
 * SET CONSTRAINT intra-transaction status.
 *
 * We make this a single palloc'd object so it can be copied and freed easily.
 *
 * all_isset and all_isdeferred are used to keep track
 * of SET CONSTRAINTS ALL {DEFERRED, IMMEDIATE}.
 *
 * trigstates[] stores per-trigger tgisdeferred settings.
 */
typedef struct SetConstraintStateData
{
	bool		all_isset;
	bool		all_isdeferred;
	int			numstates;		/* number of trigstates[] entries in use */
	int			numalloc;		/* allocated size of trigstates[] */
	SetConstraintTriggerData trigstates[1];		/* VARIABLE LENGTH ARRAY */
} SetConstraintStateData;

typedef SetConstraintStateData *SetConstraintState;


/*
 * Per-trigger-event data
 *
 * Note: ate_firing_id is meaningful when either AFTER_TRIGGER_DONE
 * or AFTER_TRIGGER_IN_PROGRESS is set.  It indicates which trigger firing
 * cycle the trigger was or will be fired in.
 */
typedef struct AfterTriggerEventData *AfterTriggerEvent;

typedef struct AfterTriggerEventData
{
	AfterTriggerEvent ate_next; /* list link */
	TriggerEvent ate_event;		/* event type and status bits */
	CommandId	ate_firing_id;	/* ID for firing cycle */
	Oid			ate_tgoid;		/* the trigger's ID */
	Oid			ate_relid;		/* the relation it's on */
	ItemPointerData ate_oldctid;	/* specific tuple(s) involved */
	ItemPointerData ate_newctid;
} AfterTriggerEventData;

/* A list of events */
typedef struct AfterTriggerEventList
{
	AfterTriggerEvent head;
	AfterTriggerEvent tail;
} AfterTriggerEventList;


/*
 * All per-transaction data for the AFTER TRIGGERS module.
 *
 * AfterTriggersData has the following fields:
 *
 * firing_counter is incremented for each call of afterTriggerInvokeEvents.
 * We mark firable events with the current firing cycle's ID so that we can
 * tell which ones to work on.	This ensures sane behavior if a trigger
 * function chooses to do SET CONSTRAINTS: the inner SET CONSTRAINTS will
 * only fire those events that weren't already scheduled for firing.
 *
 * state keeps track of the transaction-local effects of SET CONSTRAINTS.
 * This is saved and restored across failed subtransactions.
 *
 * events is the current list of deferred events.  This is global across
 * all subtransactions of the current transaction.	In a subtransaction
 * abort, we know that the events added by the subtransaction are at the
 * end of the list, so it is relatively easy to discard them.
 *
 * query_depth is the current depth of nested AfterTriggerBeginQuery calls
 * (-1 when the stack is empty).
 *
 * query_stack[query_depth] is a list of AFTER trigger events queued by the
 * current query (and the query_stack entries below it are lists of trigger
 * events queued by calling queries).  None of these are valid until the
 * matching AfterTriggerEndQuery call occurs.  At that point we fire
 * immediate-mode triggers, and append any deferred events to the main events
 * list.