Function usUntilEarliestTimer

app/redis-6.2.6/src/ae.c:256–269

How many microseconds until the first timer should fire. * If there are no timers, -1 is returned. * * Note that's O(N) since time events are unsorted. * Possible optimizations (not needed by Redis so far, but...): * 1) Insert the event in order, so that the nearest is just the head. * Much better but still insertion or deletion of timers is O(N). * 2) Use a skiplist to have this operati

 * 2) Use a skiplist to have this operation as O(1) and insertion as O(log(N)).
 */
static int64_t usUntilEarliestTimer(aeEventLoop *eventLoop) {
    aeTimeEvent *te = eventLoop->timeEventHead;
    if (te == NULL) return -1;

    aeTimeEvent *earliest = NULL;
    while (te) {
        if (!earliest || te->when < earliest->when)
            earliest = te;
        te = te->next;
    }

    monotime now = getMonotonicUs();
    return (now >= earliest->when) ? 0 : earliest->when - now;
}

/* Process time events */
static int processTimeEvents(aeEventLoop *eventLoop) {