Function RM_CreateTimer

src/module.cpp:6509–6568

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) {
    static uint64_t pending_key;
    static mstime_t pending_period = -1; 

    RedisModuleTimer *timer = (RedisModuleTimer*)zmalloc(sizeof(*timer), MALLOC_LOCAL);
    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++;
        }
    }

    bool fNeedPost = (pending_period < 0);    // If pending_period is already set, then a PostFunction is in flight and we don't need to set a new one
    if (pending_period < 0 || period < pending_period) {
        pending_period = period;
        pending_key = key;
    }

    /* 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 (fNeedPost) {
        aePostFunction(g_pserver->rgthreadvar[IDX_EVENT_LOOP_MAIN].el, []{
            if (aeTimer != -1) {
                raxIterator ri;
                raxStart(&ri,Timers);
                raxSeek(&ri,"^",NULL,0);
                raxNext(&ri);
                if (memcmp(ri.key,&pending_key,sizeof(key)) == 0) {
                    /* This is the first key, we need to re-install the timer according
                    * to the just added event. */
                    aeDeleteTimeEvent(g_pserver->rgthreadvar[IDX_EVENT_LOOP_MAIN].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(g_pserver->rgthreadvar[IDX_EVENT_LOOP_MAIN].el,pending_period,moduleTimerHandler,NULL,NULL);
            }

            pending_period = -1;
        });
    }