CREATE FUNCTION concurrent_lock_check(p_dest_table text, p_lock_wait int DEFAULT NULL) RETURNS boolean
    LANGUAGE plpgsql SECURITY DEFINER
    AS $$
DECLARE

v_adv_lock          boolean;
v_dest_table        text;
v_lock_iter         int;

BEGIN

SELECT dest_table INTO v_dest_table FROM @extschema@.refresh_config WHERE dest_table = p_dest_table;
IF v_dest_table IS NULL THEN
    RAISE EXCEPTION 'Destination table given in argument (%) is not managed by mimeo', p_dest_table;
END IF;

v_adv_lock := pg_try_advisory_xact_lock(hashtext('mimeo advisory lock'), hashtext(v_dest_table));

IF v_adv_lock = 'false' AND p_lock_wait IS NOT NULL THEN

    IF p_lock_wait > 0 THEN

        -- Use the "try" advisory lock since we want to check at intervals whether it's available
        v_lock_iter = 0;
        WHILE (v_adv_lock = 'false') AND (v_lock_iter >= p_lock_wait) LOOP
            v_lock_iter := v_lock_iter + 1;
            v_adv_lock := pg_try_advisory_xact_lock(hashtext('mimeo advisory lock'), hashtext(v_dest_table));
            PERFORM pg_sleep(1);
        END LOOP;

   ELSE
        -- Since we want to wait indefinitely, can just call normal transaction advisory lock since it waits forever for true
        PERFORM pg_advisory_xact_lock(hashtext('mimeo advisory lock'), hashtext(v_dest_table));
        v_adv_lock := 'true';
   END IF; -- END p_lock_wait > 0 check check

END IF; -- END v_adv_lock check

RETURN v_adv_lock;

END
$$;