DELIMITER $$
CREATE PROCEDURE mk_on_es_pair(IN oaddr VARCHAR(24), IN stealth_min INT, IN stealth_max INT, IN pri INT)
BEGIN
    CREATE TEMPORARY TABLE IF NOT EXISTS en_tmp ENGINE = MEMORY SELECT * FROM en_tbl WHERE 0;
    SET @oid = (SELECT os_id FROM os_tbl WHERE os_addr = oaddr);
    IF (@oid is NULL) THEN
        INSERT INTO os_tbl(os_addr) VALUES (oaddr);
        SET @oid = LAST_INSERT_ID();
    END IF;

    -- Select an EN that doesn't already have our OS paired with it..
    -- If this is a high-priority route (e.g. something that we use for an API, and must absolutely use)
    -- Then ignore restrictions, but still use the same selection algorithm

    INSERT INTO en_tmp
        SELECT * from en_tbl
            WHERE
                NOT EXISTS (
                    SELECT os_id, en_id FROM pairing_tbl
                    WHERE pairing_tbl.os_id = @oid
                        AND pairing_tbl.en_id = en_tbl.en_id
                        AND pri=0
                )
                AND (en_tbl.rs_free > 0 OR pri > 0)
                AND (en_tbl.rs_count < __RS_MAX_COUNT__ OR pri > 0)
                AND en_tbl.stealth BETWEEN stealth_min AND stealth_max
                AND en_tbl.route_expires > UNIX_TIMESTAMP(NOW())
            ORDER BY en_bw DESC, rs_count ASC, route_create_time ASC, route_expires ASC
            LIMIT 1;
    IF (ROW_COUNT()) THEN
        SET @uuid = MyUUID();
        UPDATE en_tbl SET
            rs_count = (rs_count +1),
            rs_busy = (rs_busy + 1),
            rs_free = (rs_free - 1)
            WHERE en_id = (SELECT en_id FROM en_tmp);
        INSERT INTO pairing_tbl(os_id, en_id, cr_time, pair_assigned, pair_uuid)
            VALUES(@oid, (SELECT en_id FROM en_tmp LIMIT 1),
                    UNIX_TIMESTAMP(NOW()), 1, @uuid);
    END IF;
    SELECT *, @uuid AS pair_uuid FROM en_tmp;
    DROP TABLE IF EXISTS en_tmp;
    COMMIT;
END $$
DELIMITER ;