Function RM_CreateTimer

app/redis-6.2.6/src/module.c:6333–6376

Create a new timer that will fire after `period` milliseconds, and will call * the specified function using `data` as argument. The returned timer ID can be * used to get information from the timer or to stop it before it fires. * Note that for the common use case of a repeating timer (Re-registration * of the timer inside the RedisModuleTimerProc callback) it matters when * this API is calle

 * (If the time it takes to execute 'callback' is negligible the two
 * statements above mean the same) */
RedisModuleTimerID RM_CreateTimer(RedisModuleCtx *ctx, mstime_t period, RedisModuleTimerProc callback, void *data) {
    RedisModuleTimer *timer = zmalloc(sizeof(*timer));
    timer->module = ctx->module;
    timer->callback = callback;
    timer->data = data;
    timer->dbid = ctx->client ? ctx->client->db->id : 0;
    uint64_t expiretime = ustime()+period*1000;
    uint64_t key;

    while(1) {
        key = htonu64(expiretime);
        if (raxFind(Timers, (unsigned char*)&key,sizeof(key)) == raxNotFound) {
            raxInsert(Timers,(unsigned char*)&key,sizeof(key),timer,NULL);
            break;
        } else {
            expiretime++;
        }
    }

    /* We need to install the main event loop timer if it's not already
     * installed, or we may need to refresh its period if we just installed
     * a timer that will expire sooner than any other else (i.e. the timer
     * we just installed is the first timer in the Timers rax). */
    if (aeTimer != -1) {
        raxIterator ri;
        raxStart(&ri,Timers);
        raxSeek(&ri,"^",NULL,0);
        raxNext(&ri);
        if (memcmp(ri.key,&key,sizeof(key)) == 0) {
            /* This is the first key, we need to re-install the timer according
             * to the just added event. */
            aeDeleteTimeEvent(server.el,aeTimer);
            aeTimer = -1;
        }
        raxStop(&ri);
    }

    /* If we have no main timer (the old one was invalidated, or this is the
     * first module timer we have), install one. */
    if (aeTimer == -1)
        aeTimer = aeCreateTimeEvent(server.el,period,moduleTimerHandler,NULL,NULL);

    return key;
}

/* Stop a timer, returns REDISMODULE_OK if the timer was found, belonged to the
 * calling module, and was stopped, otherwise REDISMODULE_ERR is returned.