could you please add pub/sub support?

[sddongxh]

Thanks.

[andreasgerstmayr]

Reading https://redis.io/commands/pubsub you can send PUBLISH/SUBSCRIBE to any node in the cluster. You can use redisClusterAsyncCommandToNode() to send a command directly to a specific node.

Should hiredis-cluster send the command a specific node by hashing the channel (as it does for regular Redis keys)?

[zuiderkwast]

Should hiredis-cluster send the command a specific node by hashing the channel (as it does for regular Redis keys)?

No, pubsub channels are not sharded like keys. They are forwarded between the Redis nodes in a cluster, so you can subscribe to any node and publish to any node. (Pubsub doesn't scale that well in a large cluster since all messages are forwarded to all nodes, but that's different topic.)

I'm not sure what is the best way to implement this in hiredis-cluster but it can be good to know that when using pubsub, you typically need a dedicated connection to receive published messages. The documentation of SUBSCRIBE says:

Once the client enters the subscribed state it is not supposed to issue any other commands, except for additional SUBSCRIBE, PSUBSCRIBE, UNSUBSCRIBE, PUNSUBSCRIBE, PING, RESET and QUIT commands.

[Edit] For commands like PUBSUB CHANNELS and PUBSUB NUMSUB, you need to send the command to all nodes and then combine the results.