Build Sharded PubSub command routing based on channel/slot ownership

[hpatro]

Copied from: redis/ioredis#1759

Hi! It seems there is an issue with the spublish()/ssubscribe() methods added in 6285e80:

import { Cluster } from "ioredis";

const clusterNodes = [
  {
    host: "localhost",
    port: 7000,
  },
  {
    host: "localhost",
    port: 7001,
  },
  {
    host: "localhost",
    port: 7002,
  },
  {
    host: "localhost",
    port: 7003,
  },
  {
    host: "localhost",
    port: 7004,
  },
  {
    host: "localhost",
    port: 7005,
  },
];

const pubClient = new Cluster(clusterNodes);
const subClient = pubClient.duplicate();

subClient.ssubscribe("foo", () => {
  pubClient.spublish("foo", "bar");
});

subClient.on("smessage", (_, message) => {
  console.log("got", message); // never received
});

The smessage event is not received. It works with classic publish()/subscribe() though:

subClient.subscribe("foo", () => {
  pubClient.publish("foo", "bar");
});

subClient.on("message", (_, message) => {
  console.log("got", message); // prints "got bar"
});

My docker-compose.yml, for reproducibility:

services:
  redis-cluster:
    image: grokzen/redis-cluster:7.0.10
    ports:
      - "7000-7005:7000-7005"

The test case here looks a bit weird, shouldn't it be something like:

const pub = new Cluster(options);
const ssub = new Cluster(options);

ssub.ssubscribe("test cluster", function () {
  pub.spublish("test shard channel", "hi");

  // node1.write(node1.findClientByName("ioredis-cluster(subscriber)"), [
  //   "smessage",
  //   "test shard channel",
  //   "hi",
  // ]);
});

Thanks in advance!

---

I think this hurts the adoption of iovalkey and user(s) seems to settle on other alternatives due to missing support.

[mcollina]

This is a good feature to add! Would you like to send a PR?