Function moduleNotifyKeyspaceEvent

app/redis-6.2.6/src/module.c:5936–5966

Dispatcher for keyspace notifications to module subscriber functions. * This gets called only if at least one module requested to be notified on * keyspace notifications */

 * This gets called  only if at least one module requested to be notified on
 * keyspace notifications */
void moduleNotifyKeyspaceEvent(int type, const char *event, robj *key, int dbid) {
    /* Don't do anything if there aren't any subscribers */
    if (listLength(moduleKeyspaceSubscribers) == 0) return;

    listIter li;
    listNode *ln;
    listRewind(moduleKeyspaceSubscribers,&li);

    /* Remove irrelevant flags from the type mask */
    type &= ~(NOTIFY_KEYEVENT | NOTIFY_KEYSPACE);

    while((ln = listNext(&li))) {
        RedisModuleKeyspaceSubscriber *sub = ln->value;
        /* Only notify subscribers on events matching they registration,
         * and avoid subscribers triggering themselves */
        if ((sub->event_mask & type) && sub->active == 0) {
            RedisModuleCtx ctx = REDISMODULE_CTX_INIT;
            ctx.module = sub->module;
            ctx.client = moduleFreeContextReusedClient;
            selectDb(ctx.client, dbid);

            /* mark the handler as active to avoid reentrant loops.
             * If the subscriber performs an action triggering itself,
             * it will not be notified about it. */
            sub->active = 1;
            sub->notify_callback(&ctx, type, event, key);
            sub->active = 0;
            moduleFreeContext(&ctx);
        }
    }
}

/* Unsubscribe any notification subscribers this module has upon unloading */
void moduleUnsubscribeNotifications(RedisModule *module) {