salix/db/routines/cache/procedures/cache_calc_start.sql

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DELIMITER $$
CREATE OR REPLACE DEFINER=`root`@`localhost` PROCEDURE `cache`.`cache_calc_start`(OUT `v_calc` INT, INOUT `v_refresh` INT, IN `v_cache_name` VARCHAR(50), IN `v_params` VARCHAR(100))
proc: BEGIN
DECLARE v_valid BOOL;
DECLARE v_lock_id VARCHAR(100);
DECLARE v_cache_id INT;
DECLARE v_expires DATETIME;
DECLARE v_clean_time DATETIME;
DECLARE vLastRefresh DATETIME;
DECLARE EXIT HANDLER FOR SQLEXCEPTION
BEGIN
IF v_lock_id IS NOT NULL THEN
DO RELEASE_LOCK(v_lock_id);
END IF;
RESIGNAL;
END;
SET v_params = IFNULL(v_params, '');
-- Si el servidor se ha reiniciado invalida todos los calculos.
SELECT COUNT(*) > 0 INTO v_valid FROM cache_valid;
IF !v_valid
THEN
DELETE FROM cache_calc;
INSERT INTO cache_valid (valid) VALUES (TRUE);
END IF;
-- Obtiene un bloqueo exclusivo para que no haya problemas de concurrencia.
SET v_lock_id = CONCAT_WS('/', v_cache_name, v_params);
IF !GET_LOCK(v_lock_id, 30)
THEN
SET v_calc = NULL;
SET v_refresh = FALSE;
LEAVE proc;
END IF;
-- Comprueba si el calculo solicitado existe y esta actualizado.
SELECT c.id, ca.id, ca.expires, ca.last_refresh
INTO v_cache_id, v_calc, v_expires, vLastRefresh
FROM cache c
LEFT JOIN cache_calc ca
ON ca.cache_id = c.id AND ca.params = v_params COLLATE 'utf8_general_ci'
WHERE c.name = v_cache_name COLLATE 'utf8_general_ci';
-- Si existe una calculo valido libera el bloqueo y devuelve su identificador.
IF !v_refresh AND NOW() < v_expires AND vLastRefresh >= CURDATE()
THEN
DO RELEASE_LOCK(v_lock_id);
SET v_refresh = FALSE;
LEAVE proc;
END IF;
-- Si el calculo no existe le crea una entrada en la tabla de calculos.
IF v_calc IS NULL
THEN
INSERT INTO cache_calc SET
cache_id = v_cache_id,
cacheName = v_cache_name,
params = v_params,
last_refresh = NULL,
expires = NULL,
connection_id = CONNECTION_ID();
SET v_calc = LAST_INSERT_ID();
ELSE
UPDATE cache_calc
SET
last_refresh = NULL,
expires = NULL,
connection_id = CONNECTION_ID()
WHERE id = v_calc;
END IF;
-- Si se debe recalcular mantiene el bloqueo y devuelve su identificador.
SET v_refresh = TRUE;
END$$
DELIMITER ;