pl_exec.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

		elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, or UPDATE");

	/*
	 * Assign the special tg_ variables
	 */

	var = (PLpgSQL_var *) (estate.datums[func->tg_op_varno]);
	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("INSERT"));
	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("UPDATE"));
	else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("DELETE"));
	else
		elog(ERROR, "unrecognized trigger action: not INSERT, DELETE, or UPDATE");
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_name_varno]);
	var->value = DirectFunctionCall1(namein,
							  CStringGetDatum(trigdata->tg_trigger->tgname));
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_when_varno]);
	if (TRIGGER_FIRED_BEFORE(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("BEFORE"));
	else if (TRIGGER_FIRED_AFTER(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("AFTER"));
	else
		elog(ERROR, "unrecognized trigger execution time: not BEFORE or AFTER");
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_level_varno]);
	if (TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("ROW"));
	else if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
		var->value = DirectFunctionCall1(textin, CStringGetDatum("STATEMENT"));
	else
		elog(ERROR, "unrecognized trigger event type: not ROW or STATEMENT");
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_relid_varno]);
	var->value = ObjectIdGetDatum(trigdata->tg_relation->rd_id);
	var->isnull = false;
	var->freeval = false;

	var = (PLpgSQL_var *) (estate.datums[func->tg_relname_varno]);
	var->value = DirectFunctionCall1(namein,
			CStringGetDatum(RelationGetRelationName(trigdata->tg_relation)));
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_nargs_varno]);
	var->value = Int16GetDatum(trigdata->tg_trigger->tgnargs);
	var->isnull = false;
	var->freeval = false;

	/*
	 * Store the trigger argument values into the special execution state
	 * variables
	 */
	estate.err_text = gettext_noop("while storing call arguments into local variables");
	estate.trig_nargs = trigdata->tg_trigger->tgnargs;
	if (estate.trig_nargs == 0)
		estate.trig_argv = NULL;
	else
	{
		estate.trig_argv = palloc(sizeof(Datum) * estate.trig_nargs);
		for (i = 0; i < trigdata->tg_trigger->tgnargs; i++)
			estate.trig_argv[i] = DirectFunctionCall1(textin,
						   CStringGetDatum(trigdata->tg_trigger->tgargs[i]));
	}

	/*
	 * Set the magic variable FOUND to false
	 */
	exec_set_found(&estate, false);

	/*
	 * Now call the toplevel block of statements
	 */
	estate.err_text = NULL;
	estate.err_stmt = (PLpgSQL_stmt *) (func->action);
	rc = exec_stmt_block(&estate, func->action);
	if (rc != PLPGSQL_RC_RETURN)
	{
		estate.err_stmt = NULL;
		estate.err_text = NULL;

		/*
		 * Provide a more helpful message if a CONTINUE has been used outside
		 * a loop.
		 */
		if (rc == PLPGSQL_RC_CONTINUE)
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
					 errmsg("CONTINUE cannot be used outside a loop")));
		else
			ereport(ERROR,
			   (errcode(ERRCODE_S_R_E_FUNCTION_EXECUTED_NO_RETURN_STATEMENT),
				errmsg("control reached end of trigger procedure without RETURN")));
	}

	if (estate.retisset)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("trigger procedure cannot return a set")));

	/*
	 * Check that the returned tuple structure has the same attributes, the
	 * relation that fired the trigger has. A per-statement trigger always
	 * needs to return NULL, so we ignore any return value the function itself
	 * produces (XXX: is this a good idea?)
	 *
	 * XXX This way it is possible, that the trigger returns a tuple where
	 * attributes don't have the correct atttypmod's length. It's up to the
	 * trigger's programmer to ensure that this doesn't happen. Jan
	 */
	if (estate.retisnull || TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
		rettup = NULL;
	else
	{
		if (!compatible_tupdesc(estate.rettupdesc,
								trigdata->tg_relation->rd_att))
			ereport(ERROR,
					(errcode(ERRCODE_DATATYPE_MISMATCH),
					 errmsg("returned tuple structure does not match table of trigger event")));
		/* Copy tuple to upper executor memory */
		rettup = SPI_copytuple((HeapTuple) (estate.retval));
	}

	/* Clean up any leftover temporary memory */
	if (estate.eval_econtext != NULL)
		FreeExprContext(estate.eval_econtext);
	estate.eval_econtext = NULL;
	exec_eval_cleanup(&estate);

	/*
	 * Pop the error context stack
	 */
	error_context_stack = plerrcontext.previous;

	/*
	 * Return the trigger's result
	 */
	return rettup;
}


/*
 * error context callback to let us supply a call-stack traceback
 */
static void
plpgsql_exec_error_callback(void *arg)
{
	PLpgSQL_execstate *estate = (PLpgSQL_execstate *) arg;

	/* safety check, shouldn't happen */
	if (estate->err_func == NULL)
		return;

	/* if we are doing RAISE, don't report its location */
	if (estate->err_text == raise_skip_msg)
		return;

	if (estate->err_stmt != NULL)
	{
		/* translator: last %s is a plpgsql statement type name */
		errcontext("PL/pgSQL function \"%s\" line %d at %s",
				   estate->err_func->fn_name,
				   estate->err_stmt->lineno,
				   plpgsql_stmt_typename(estate->err_stmt));
	}
	else if (estate->err_text != NULL)
	{
		/*
		 * We don't expend the cycles to run gettext() on err_text unless we
		 * actually need it.  Therefore, places that set up err_text should
		 * use gettext_noop() to ensure the strings get recorded in the
		 * message dictionary.
		 */

		/*
		 * translator: last %s is a phrase such as "while storing call
		 * arguments into local variables"
		 */
		errcontext("PL/pgSQL function \"%s\" %s",
				   estate->err_func->fn_name,
				   gettext(estate->err_text));
	}
	else
		errcontext("PL/pgSQL function \"%s\"",
				   estate->err_func->fn_name);
}


/* ----------
 * Support function for initializing local execution variables
 * ----------
 */
static PLpgSQL_datum *
copy_plpgsql_datum(PLpgSQL_datum *datum)
{
	PLpgSQL_datum *result;

	switch (datum->dtype)
	{
		case PLPGSQL_DTYPE_VAR:
			{
				PLpgSQL_var *new = palloc(sizeof(PLpgSQL_var));

				memcpy(new, datum, sizeof(PLpgSQL_var));
				/* Ensure the value is null (possibly not needed?) */
				new->value = 0;
				new->isnull = true;
				new->freeval = false;

				result = (PLpgSQL_datum *) new;
			}
			break;

		case PLPGSQL_DTYPE_REC:
			{
				PLpgSQL_rec *new = palloc(sizeof(PLpgSQL_rec));

				memcpy(new, datum, sizeof(PLpgSQL_rec));
				/* Ensure the value is null (possibly not needed?) */
				new->tup = NULL;
				new->tupdesc = NULL;
				new->freetup = false;
				new->freetupdesc = false;

				result = (PLpgSQL_datum *) new;
			}
			break;

		case PLPGSQL_DTYPE_ROW:
		case PLPGSQL_DTYPE_RECFIELD:
		case PLPGSQL_DTYPE_ARRAYELEM:
		case PLPGSQL_DTYPE_TRIGARG:

			/*
			 * These datum records are read-only at runtime, so no need to
			 * copy them
			 */
			result = datum;
			break;

		default:
			elog(ERROR, "unrecognized dtype: %d", datum->dtype);
			result = NULL;		/* keep compiler quiet */
			break;
	}

	return result;
}


static bool
exception_matches_conditions(ErrorData *edata, PLpgSQL_condition *cond)
{
	for (; cond != NULL; cond = cond->next)
	{
		int			sqlerrstate = cond->sqlerrstate;

		/*
		 * OTHERS matches everything *except* query-canceled; if you're
		 * foolish enough, you can match that explicitly.
		 */
		if (sqlerrstate == 0)
		{
			if (edata->sqlerrcode != ERRCODE_QUERY_CANCELED)
				return true;
		}
		/* Exact match? */
		else if (edata->sqlerrcode == sqlerrstate)
			return true;
		/* Category match? */
		else if (ERRCODE_IS_CATEGORY(sqlerrstate) &&
				 ERRCODE_TO_CATEGORY(edata->sqlerrcode) == sqlerrstate)
			return true;
	}
	return false;
}


/* ----------
 * exec_stmt_block			Execute a block of statements
 * ----------
 */
static int
exec_stmt_block(PLpgSQL_execstate *estate, PLpgSQL_stmt_block *block)
{
	volatile int rc = -1;
	int			i;
	int			n;

	/*
	 * First initialize all variables declared in this block
	 */
	for (i = 0; i < block->n_initvars; i++)
	{
		n = block->initvarnos[i];

		switch (estate->datums[n]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) (estate->datums[n]);

					free_var(var);
					if (!var->isconst || var->isnull)
					{
						if (var->default_val == NULL)
						{
							var->value = (Datum) 0;
							var->isnull = true;
							if (var->notnull)
								ereport(ERROR,
									(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
									 errmsg("variable \"%s\" declared NOT NULL cannot default to NULL",
											var->refname)));
						}
						else
						{
							exec_assign_expr(estate, (PLpgSQL_datum *) var,
											 var->default_val);
						}
					}
				}
				break;

			case PLPGSQL_DTYPE_REC:
				{
					PLpgSQL_rec *rec = (PLpgSQL_rec *) (estate->datums[n]);

					if (rec->freetup)
					{
						heap_freetuple(rec->tup);
						FreeTupleDesc(rec->tupdesc);
						rec->freetup = false;
					}

					rec->tup = NULL;
					rec->tupdesc = NULL;
				}
				break;

			case PLPGSQL_DTYPE_RECFIELD:
			case PLPGSQL_DTYPE_ARRAYELEM:
				break;

			default:
				elog(ERROR, "unrecognized dtype: %d",
					 estate->datums[n]->dtype);
		}
	}

	if (block->exceptions)
	{
		/*
		 * Execute the statements in the block's body inside a sub-transaction
		 */
		MemoryContext oldcontext = CurrentMemoryContext;
		ResourceOwner oldowner = CurrentResourceOwner;

		BeginInternalSubTransaction(NULL);
		/* Want to run statements inside function's memory context */
		MemoryContextSwitchTo(oldcontext);

		PG_TRY();
		{
			rc = exec_stmts(estate, block->body);

			/* Commit the inner transaction, return to outer xact context */
			ReleaseCurrentSubTransaction();
			MemoryContextSwitchTo(oldcontext);
			CurrentResourceOwner = oldowner;

			/*
			 * AtEOSubXact_SPI() should not have popped any SPI context, but
			 * just in case it did, make sure we remain connected.
			 */
			SPI_restore_connection();
		}
		PG_CATCH();
		{
			ErrorData  *edata;
			ListCell   *e;

			/* Save error info */
			MemoryContextSwitchTo(oldcontext);
			edata = CopyErrorData();
			FlushErrorState();

			/* Abort the inner transaction */
			RollbackAndReleaseCurrentSubTransaction();
			MemoryContextSwitchTo(oldcontext);
			CurrentResourceOwner = oldowner;

			/*
			 * If AtEOSubXact_SPI() popped any SPI context of the subxact, it
			 * will have left us in a disconnected state.  We need this hack
			 * to return to connected state.
			 */
			SPI_restore_connection();

			/* Look for a matching exception handler */
			foreach(e, block->exceptions->exc_list)
			{
				PLpgSQL_exception *exception = (PLpgSQL_exception *) lfirst(e);

				if (exception_matches_conditions(edata, exception->conditions))
				{
					/*
					 * Initialize the magic SQLSTATE and SQLERRM variables for
					 * the exception block. We needn't do this until we have
					 * found a matching exception.
					 */
					PLpgSQL_var *state_var;
					PLpgSQL_var *errm_var;

					state_var = (PLpgSQL_var *)
						estate->datums[block->exceptions->sqlstate_varno];
					state_var->value = DirectFunctionCall1(textin,
					   CStringGetDatum(unpack_sql_state(edata->sqlerrcode)));
					state_var->freeval = true;
					state_var->isnull = false;

					errm_var = (PLpgSQL_var *)
						estate->datums[block->exceptions->sqlerrm_varno];
					errm_var->value = DirectFunctionCall1(textin,
											CStringGetDatum(edata->message));
					errm_var->freeval = true;
					errm_var->isnull = false;

					rc = exec_stmts(estate, exception->action);

					free_var(state_var);
					free_var(errm_var);
					break;
				}
			}

			/* If no match found, re-throw the error */
			if (e == NULL)
				ReThrowError(edata);
			else
				FreeErrorData(edata);
		}
		PG_END_TRY();
	}
	else
	{
		/*
		 * Just execute the statements in the block's body
		 */
		rc = exec_stmts(estate, block->body);
	}

	/*
	 * Handle the return code.
	 */
	switch (rc)
	{
		case PLPGSQL_RC_OK:
		case PLPGSQL_RC_CONTINUE:
		case PLPGSQL_RC_RETURN:
			return rc;

		case PLPGSQL_RC_EXIT:
			if (estate->exitlabel == NULL)
				return PLPGSQL_RC_OK;
			if (block->label == NULL)
				return PLPGSQL_RC_EXIT;
			if (strcmp(block->label, estate->exitlabel))
				return PLPGSQL_RC_EXIT;
			estate->exitlabel = NULL;
			return PLPGSQL_RC_OK;

		default:
			elog(ERROR, "unrecognized rc: %d", rc);
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmts			Iterate over a list of statements
 *				as long as their return code is OK
 * ----------
 */
static int
exec_stmts(PLpgSQL_execstate *estate, List *stmts)
{
	ListCell   *s;

	if (stmts == NIL)
	{
		/*
		 * Ensure we do a CHECK_FOR_INTERRUPTS() even though there is no
		 * statement.  This prevents hangup in a tight loop if, for instance,
		 * there is a LOOP construct with an empty body.
		 */
		CHECK_FOR_INTERRUPTS();
		return PLPGSQL_RC_OK;
	}