feat(binlog): refs #4409 New function for binlog queue monitoring

db/routines/util/functions/binlogQueue_getDelay.sql

@@ -0,0 +1,45 @@
+DELIMITER $$
+CREATE OR REPLACE DEFINER=`root`@`localhost` FUNCTION `util`.`binlogQueue_getDelay`(vCode VARCHAR(255))
+	RETURNS BIGINT
+	NOT DETERMINISTIC
+BEGIN
+/**
+ * Returns the difference between the current position of the binary log and
+ * the passed queue.
+ *
+ * @param vCode The queue code
+ * @return The difference in MB
+ */
+	DECLARE vCurLogName VARCHAR(255);
+	DECLARE vCurPosition BIGINT;
+	DECLARE vQueueLogName VARCHAR(255);
+	DECLARE vQueuePosition BIGINT;
+	DECLARE vDelay BIGINT;
+
+	SELECT VARIABLE_VALUE INTO vCurLogName
+		FROM information_schema.GLOBAL_STATUS
+		WHERE VARIABLE_NAME = 'BINLOG_SNAPSHOT_FILE';
+
+	SELECT VARIABLE_VALUE INTO vCurPosition
+		FROM information_schema.GLOBAL_STATUS
+		WHERE VARIABLE_NAME = 'BINLOG_SNAPSHOT_POSITION';
+
+	SELECT logName, `position`
+		INTO vQueueLogName, vQueuePosition
+		FROM binlogQueue
+		WHERE code = vCode;
+
+	IF vQueuePosition IS NULL THEN
+		RETURN NULL;
+	END IF;
+
+	SET vDelay =
+		vCurPosition - CAST(vQueuePosition AS SIGNED) +
+		@@max_binlog_size * (
+			CAST(REGEXP_SUBSTR(vCurLogName, '[0-9]+') AS SIGNED) -
+			CAST(REGEXP_SUBSTR(vQueueLogName, '[0-9]+') AS SIGNED)
+		);
+
+	RETURN ROUND(vDelay / POW(1024, 2));
+END$$
+DELIMITER ;