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

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

			/* Revert to outer eval_econtext */
			estate->eval_econtext = old_eval_econtext;
			estate->eval_estate = old_eval_estate;
			estate->eval_estate_simple_id = old_eval_estate_simple_id;

			/*
			 * 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;

			estate->err_text = gettext_noop("during exception cleanup");

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

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

			/* Revert to outer eval_econtext */
			estate->eval_econtext = old_eval_econtext;
			estate->eval_estate = old_eval_estate;
			estate->eval_estate_simple_id = old_eval_estate_simple_id;

			/*
			 * 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;

					estate->err_text = NULL;

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

					free_var(state_var);
					state_var->value = (Datum) 0;
					free_var(errm_var);
					errm_var->value = (Datum) 0;
					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
		 */
		estate->err_text = NULL;

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

	estate->err_text = NULL;

	/*
	 * 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;
	}

	foreach(s, stmts)
	{
		PLpgSQL_stmt *stmt = (PLpgSQL_stmt *) lfirst(s);
		int			rc = exec_stmt(estate, stmt);

		if (rc != PLPGSQL_RC_OK)
			return rc;
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt			Distribute one statement to the statements
 *				type specific execution function.
 * ----------
 */
static int
exec_stmt(PLpgSQL_execstate *estate, PLpgSQL_stmt *stmt)
{
	PLpgSQL_stmt *save_estmt;
	int			rc = -1;

	save_estmt = estate->err_stmt;
	estate->err_stmt = stmt;

	/* Let the plugin know that we are about to execute this statement */
	if (*plugin_ptr && (*plugin_ptr)->stmt_beg)
		((*plugin_ptr)->stmt_beg) (estate, stmt);

	CHECK_FOR_INTERRUPTS();

	switch (stmt->cmd_type)
	{
		case PLPGSQL_STMT_BLOCK:
			rc = exec_stmt_block(estate, (PLpgSQL_stmt_block *) stmt);
			break;

		case PLPGSQL_STMT_ASSIGN:
			rc = exec_stmt_assign(estate, (PLpgSQL_stmt_assign *) stmt);
			break;

		case PLPGSQL_STMT_PERFORM:
			rc = exec_stmt_perform(estate, (PLpgSQL_stmt_perform *) stmt);
			break;

		case PLPGSQL_STMT_GETDIAG:
			rc = exec_stmt_getdiag(estate, (PLpgSQL_stmt_getdiag *) stmt);
			break;

		case PLPGSQL_STMT_IF:
			rc = exec_stmt_if(estate, (PLpgSQL_stmt_if *) stmt);
			break;

		case PLPGSQL_STMT_LOOP:
			rc = exec_stmt_loop(estate, (PLpgSQL_stmt_loop *) stmt);
			break;

		case PLPGSQL_STMT_WHILE:
			rc = exec_stmt_while(estate, (PLpgSQL_stmt_while *) stmt);
			break;

		case PLPGSQL_STMT_FORI:
			rc = exec_stmt_fori(estate, (PLpgSQL_stmt_fori *) stmt);
			break;

		case PLPGSQL_STMT_FORS:
			rc = exec_stmt_fors(estate, (PLpgSQL_stmt_fors *) stmt);
			break;

		case PLPGSQL_STMT_EXIT:
			rc = exec_stmt_exit(estate, (PLpgSQL_stmt_exit *) stmt);
			break;

		case PLPGSQL_STMT_RETURN:
			rc = exec_stmt_return(estate, (PLpgSQL_stmt_return *) stmt);
			break;

		case PLPGSQL_STMT_RETURN_NEXT:
			rc = exec_stmt_return_next(estate, (PLpgSQL_stmt_return_next *) stmt);
			break;

		case PLPGSQL_STMT_RETURN_QUERY:
			rc = exec_stmt_return_query(estate, (PLpgSQL_stmt_return_query *) stmt);
			break;

		case PLPGSQL_STMT_RAISE:
			rc = exec_stmt_raise(estate, (PLpgSQL_stmt_raise *) stmt);
			break;

		case PLPGSQL_STMT_EXECSQL:
			rc = exec_stmt_execsql(estate, (PLpgSQL_stmt_execsql *) stmt);
			break;

		case PLPGSQL_STMT_DYNEXECUTE:
			rc = exec_stmt_dynexecute(estate, (PLpgSQL_stmt_dynexecute *) stmt);
			break;

		case PLPGSQL_STMT_DYNFORS:
			rc = exec_stmt_dynfors(estate, (PLpgSQL_stmt_dynfors *) stmt);
			break;

		case PLPGSQL_STMT_OPEN:
			rc = exec_stmt_open(estate, (PLpgSQL_stmt_open *) stmt);
			break;

		case PLPGSQL_STMT_FETCH:
			rc = exec_stmt_fetch(estate, (PLpgSQL_stmt_fetch *) stmt);
			break;

		case PLPGSQL_STMT_CLOSE:
			rc = exec_stmt_close(estate, (PLpgSQL_stmt_close *) stmt);
			break;

		default:
			estate->err_stmt = save_estmt;
			elog(ERROR, "unrecognized cmdtype: %d", stmt->cmd_type);
	}

	/* Let the plugin know that we have finished executing this statement */
	if (*plugin_ptr && (*plugin_ptr)->stmt_end)
		((*plugin_ptr)->stmt_end) (estate, stmt);

	estate->err_stmt = save_estmt;

	return rc;
}


/* ----------
 * exec_stmt_assign			Evaluate an expression and
 *					put the result into a variable.
 * ----------
 */
static int
exec_stmt_assign(PLpgSQL_execstate *estate, PLpgSQL_stmt_assign *stmt)
{
	Assert(stmt->varno >= 0);

	exec_assign_expr(estate, estate->datums[stmt->varno], stmt->expr);

	return PLPGSQL_RC_OK;
}

/* ----------
 * exec_stmt_perform		Evaluate query and discard result (but set
 *							FOUND depending on whether at least one row
 *							was returned).
 * ----------
 */
static int
exec_stmt_perform(PLpgSQL_execstate *estate, PLpgSQL_stmt_perform *stmt)
{
	PLpgSQL_expr *expr = stmt->expr;

	(void) exec_run_select(estate, expr, 0, NULL);
	exec_set_found(estate, (estate->eval_processed != 0));
	exec_eval_cleanup(estate);

	return PLPGSQL_RC_OK;
}

/* ----------
 * exec_stmt_getdiag					Put internal PG information into
 *										specified variables.
 * ----------
 */
static int
exec_stmt_getdiag(PLpgSQL_execstate *estate, PLpgSQL_stmt_getdiag *stmt)
{
	ListCell   *lc;

	foreach(lc, stmt->diag_items)
	{
		PLpgSQL_diag_item *diag_item = (PLpgSQL_diag_item *) lfirst(lc);
		PLpgSQL_datum *var;
		bool		isnull = false;

		if (diag_item->target <= 0)
			continue;

		var = estate->datums[diag_item->target];

		if (var == NULL)
			continue;

		switch (diag_item->kind)
		{
			case PLPGSQL_GETDIAG_ROW_COUNT:

				exec_assign_value(estate, var,
								  UInt32GetDatum(estate->eval_processed),
								  INT4OID, &isnull);
				break;

			case PLPGSQL_GETDIAG_RESULT_OID:

				exec_assign_value(estate, var,
								  ObjectIdGetDatum(estate->eval_lastoid),
								  OIDOID, &isnull);
				break;

			default:
				elog(ERROR, "unrecognized attribute request: %d",
					 diag_item->kind);
		}
	}

	return PLPGSQL_RC_OK;
}

/* ----------
 * exec_stmt_if				Evaluate a bool expression and
 *					execute the true or false body
 *					conditionally.
 * ----------
 */
static int
exec_stmt_if(PLpgSQL_execstate *estate, PLpgSQL_stmt_if *stmt)
{
	bool		value;
	bool		isnull;

	value = exec_eval_boolean(estate, stmt->cond, &isnull);
	exec_eval_cleanup(estate);

	if (!isnull && value)
	{
		if (stmt->true_body != NIL)
			return exec_stmts(estate, stmt->true_body);
	}
	else
	{
		if (stmt->false_body != NIL)
			return exec_stmts(estate, stmt->false_body);
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_loop			Loop over statements until
 *					an exit occurs.
 * ----------
 */
static int
exec_stmt_loop(PLpgSQL_execstate *estate, PLpgSQL_stmt_loop *stmt)
{
	for (;;)
	{
		int			rc = exec_stmts(estate, stmt->body);

		switch (rc)
		{
			case PLPGSQL_RC_OK:
				break;

			case PLPGSQL_RC_EXIT:
				if (estate->exitlabel == NULL)
					return PLPGSQL_RC_OK;
				if (stmt->label == NULL)
					return PLPGSQL_RC_EXIT;
				if (strcmp(stmt->label, estate->exitlabel) != 0)
					return PLPGSQL_RC_EXIT;
				estate->exitlabel = NULL;
				return PLPGSQL_RC_OK;

			case PLPGSQL_RC_CONTINUE:
				if (estate->exitlabel == NULL)
					/* anonymous continue, so re-run the loop */
					break;
				else if (stmt->label != NULL &&
						 strcmp(stmt->label, estate->exitlabel) == 0)
					/* label matches named continue, so re-run loop */
					estate->exitlabel = NULL;
				else
					/* label doesn't match named continue, so propagate upward */
					return PLPGSQL_RC_CONTINUE;
				break;

			case PLPGSQL_RC_RETURN:
				return PLPGSQL_RC_RETURN;

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

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_while			Loop over statements as long
 *					as an expression evaluates to
 *					true or an exit occurs.
 * ----------
 */
static int
exec_stmt_while(PLpgSQL_execstate *estate, PLpgSQL_stmt_while *stmt)
{
	for (;;)
	{
		int			rc;
		bool		value;
		bool		isnull;

		value = exec_eval_boolean(estate, stmt->cond, &isnull);
		exec_eval_cleanup(estate);

		if (isnull || !value)
			break;

		rc = exec_stmts(estate, stmt->body);

		switch (rc)
		{
			case PLPGSQL_RC_OK:
				break;

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

			case PLPGSQL_RC_CONTINUE:
				if (estate->exitlabel == NULL)
					/* anonymous continue, so re-run loop */
					break;
				else if (stmt->label != NULL &&
						 strcmp(stmt->label, estate->exitlabel) == 0)
					/* label matches named continue, so re-run loop */
					estate->exitlabel = NULL;
				else
					/* label doesn't match named continue, propagate upward */
					return PLPGSQL_RC_CONTINUE;
				break;

			case PLPGSQL_RC_RETURN:
				return PLPGSQL_RC_RETURN;

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