Function clusterNodeSetSlotBit

src/cluster.cpp:3904–3926

Set the slot bit and return the old value. */

/* Set the slot bit and return the old value. */
int clusterNodeSetSlotBit(clusterNode *n, int slot) {
    int old = bitmapTestBit(n->slots,slot);
    bitmapSetBit(n->slots,slot);
    if (!old) {
        n->numslots++;
        /* When a master gets its first slot, even if it has no slaves,
         * it gets flagged with MIGRATE_TO, that is, the master is a valid
         * target for replicas migration, if and only if at least one of
         * the other masters has slaves right now.
         *
         * Normally masters are valid targets of replica migration if:
         * 1. The used to have slaves (but no longer have).
         * 2. They are slaves failing over a master that used to have slaves.
         *
         * However new masters with slots assigned are considered valid
         * migration targets if the rest of the cluster is not a slave-less.
         *
         * See https://github.com/redis/redis/issues/3043 for more info. */
        if (n->numslots == 1 && clusterMastersHaveSlaves())
            n->flags |= CLUSTER_NODE_MIGRATE_TO;
    }
    return old;
}

/* Clear the slot bit and return the old value. */
int clusterNodeClearSlotBit(clusterNode *n, int slot) {