Function pubsubSubscribeChannel

src/pubsub.cpp:136–161

Subscribe a client to a channel. Returns 1 if the operation succeeded, or * 0 if the client was already subscribed to that channel. */

/* Subscribe a client to a channel. Returns 1 if the operation succeeded, or
 * 0 if the client was already subscribed to that channel. */
int pubsubSubscribeChannel(client *c, robj *channel) {
    serverAssert(GlobalLocksAcquired());
    serverAssert(c->lock.fOwnLock());
    dictEntry *de;
    list *clients = NULL;
    int retval = 0;

    /* Add the channel to the client -> channels hash table */
    if (dictAdd(c->pubsub_channels,channel,NULL) == DICT_OK) {
        retval = 1;
        incrRefCount(channel);
        /* Add the client to the channel -> list of clients hash table */
        de = dictFind(g_pserver->pubsub_channels,channel);
        if (de == NULL) {
            clients = listCreate();
            dictAdd(g_pserver->pubsub_channels,channel,clients);
            incrRefCount(channel);
        } else {
            clients = (list*)dictGetVal(de);
        }
        listAddNodeTail(clients,c);
    }
    /* Notify the client */
    addReplyPubsubSubscribed(c,channel);
    return retval;
}

/* Unsubscribe a client from a channel. Returns 1 if the operation succeeded, or
 * 0 if the client was not subscribed to the specified channel. */