pl_exec.c

来自「postgresql8.3.4源码,开源数据库」· C语言 代码 · 共 2,523 行 · 第 1/5 页

	{
		rec_new->tup = trigdata->tg_trigtuple;
		rec_new->tupdesc = trigdata->tg_relation->rd_att;
		rec_old->tup = NULL;
		rec_old->tupdesc = NULL;
	}
	else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
	{
		rec_new->tup = trigdata->tg_newtuple;
		rec_new->tupdesc = trigdata->tg_relation->rd_att;
		rec_old->tup = trigdata->tg_trigtuple;
		rec_old->tupdesc = trigdata->tg_relation->rd_att;
	}
	else if (TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
	{
		rec_new->tup = NULL;
		rec_new->tupdesc = NULL;
		rec_old->tup = trigdata->tg_trigtuple;
		rec_old->tupdesc = trigdata->tg_relation->rd_att;
	}
	else
		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_table_name_varno]);
	var->value = DirectFunctionCall1(namein,
			CStringGetDatum(RelationGetRelationName(trigdata->tg_relation)));
	var->isnull = false;
	var->freeval = true;

	var = (PLpgSQL_var *) (estate.datums[func->tg_table_schema_varno]);
	var->value = DirectFunctionCall1(namein,
									 CStringGetDatum(
													 get_namespace_name(
														RelationGetNamespace(
												   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]));
	}

	estate.err_text = gettext_noop("during function entry");

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

	/*
	 * Let the instrumentation plugin peek at this function
	 */
	if (*plugin_ptr && (*plugin_ptr)->func_beg)
		((*plugin_ptr)->func_beg) (&estate, func);

	/*
	 * 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")));
	}

	estate.err_stmt = NULL;
	estate.err_text = gettext_noop("during function exit");

	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));
	}

	/*
	 * Let the instrumentation plugin peek at this function
	 */
	if (*plugin_ptr && (*plugin_ptr)->func_end)
		((*plugin_ptr)->func_end) (&estate, func);

	/* Clean up any leftover temporary memory */
	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_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.
		 *
		 * If both err_text and err_stmt are set, use the err_text as
		 * description, but report the err_stmt's line number.  When err_stmt
		 * is not set, we're in function entry/exit, or some such place not
		 * attached to a specific line number.
		 */
		if (estate->err_stmt != NULL)
		{
			/*
			 * translator: last %s is a phrase such as "during statement block
			 * local variable initialization"
			 */
			errcontext("PL/pgSQL function \"%s\" line %d %s",
					   estate->err_func->fn_name,
					   estate->err_stmt->lineno,
					   gettext(estate->err_text));
		}
		else
		{
			/*
			 * 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 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
		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
	 */
	estate->err_text = gettext_noop("during statement block local variable initialization");

	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 any old value, in case re-entering block */
					free_var(var);

					/* Initially it contains a NULL */
					var->value = (Datum) 0;
					var->isnull = true;

					if (var->default_val == NULL)
					{
						/*
						 * If needed, give the datatype a chance to reject
						 * NULLs, by assigning a NULL to the variable. We
						 * claim the value is of type UNKNOWN, not the var's
						 * datatype, else coercion will be skipped. (Do this
						 * before the notnull check to be consistent with
						 * exec_assign_value.)
						 */
						if (!var->datatype->typinput.fn_strict)
						{
							bool		valIsNull = true;

							exec_assign_value(estate,
											  (PLpgSQL_datum *) var,
											  (Datum) 0,
											  UNKNOWNOID,
											  &valIsNull);
						}
						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;
		ExprContext *old_eval_econtext = estate->eval_econtext;
		EState	   *old_eval_estate = estate->eval_estate;
		long int	old_eval_estate_simple_id = estate->eval_estate_simple_id;

		estate->err_text = gettext_noop("during statement block entry");

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

		PG_TRY();
		{
			/*
			 * We need to run the block's statements with a new eval_econtext
			 * that belongs to the current subtransaction; if we try to use
			 * the outer econtext then ExprContext shutdown callbacks will be
			 * called at the wrong times.
			 */
			plpgsql_create_econtext(estate);

			estate->err_text = NULL;

			/* Run the block's statements */
			rc = exec_stmts(estate, block->body);

			estate->err_text = gettext_noop("during statement block exit");

			/*
			 * If the block ended with RETURN, we may need to copy the return
			 * value out of the subtransaction eval_context.  This is
			 * currently only needed for scalar result types --- rowtype
			 * values will always exist in the function's own memory context.
			 */
			if (rc == PLPGSQL_RC_RETURN &&
				!estate->retisset &&
				!estate->retisnull &&
				estate->rettupdesc == NULL)
			{
				int16		resTypLen;
				bool		resTypByVal;

				get_typlenbyval(estate->rettype, &resTypLen, &resTypByVal);
				estate->retval = datumCopy(estate->retval,
										   resTypByVal, resTypLen);
			}