Function pubsubSubscribePattern

app/redis-6.2.6/src/pubsub.c:194–217

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

/* Subscribe a client to a pattern. Returns 1 if the operation succeeded, or 0 if the client was already subscribed to that pattern. */
int pubsubSubscribePattern(client *c, robj *pattern) {
    dictEntry *de;
    list *clients;
    int retval = 0;

    if (listSearchKey(c->pubsub_patterns,pattern) == NULL) {
        retval = 1;
        listAddNodeTail(c->pubsub_patterns,pattern);
        incrRefCount(pattern);
        /* Add the client to the pattern -> list of clients hash table */
        de = dictFind(server.pubsub_patterns,pattern);
        if (de == NULL) {
            clients = listCreate();
            dictAdd(server.pubsub_patterns,pattern,clients);
            incrRefCount(pattern);
        } else {
            clients = dictGetVal(de);
        }
        listAddNodeTail(clients,c);
    }
    /* Notify the client */
    addReplyPubsubPatSubscribed(c,pattern);
    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. */