@graphql-hive/pubsub/dist/redis.js

import { Repeater } from '@repeaterjs/repeater';
import { DisposableSymbols } from '@whatwg-node/disposablestack';
import { createDeferredPromise } from '@whatwg-node/promise-helpers';

class RedisPubSub {
  #disposed = false;
  #quitOnDispose;
  #subscribers = /* @__PURE__ */ new Map();
  #subscribersSetKey;
  #redis;
  #channelPrefix;
  #boundHandleMessage;
  constructor(redis, options) {
    this.#redis = redis;
    this.#channelPrefix = options.channelPrefix;
    if (String(this.#channelPrefix || "").trim() === "") {
      throw new Error("RedisPubSub requires a non-empty channelPrefix");
    }
    this.#subscribersSetKey = `subscribers:${this.#channelPrefix}`;
    this.#quitOnDispose = !options.noQuitOnDispose;
    this.#boundHandleMessage = this.#handleMessage.bind(this);
    this.#redis.sub.on("message", this.#boundHandleMessage);
  }
  #topicToChannel(topic) {
    return `${this.#channelPrefix}:${String(topic)}`;
  }
  #topicFromChannel(channel) {
    return channel.replace(`${this.#channelPrefix}:`, "");
  }
  async subscribedTopics() {
    if (this.#disposed) {
      throw new Error("PubSub is disposed, cannot get subscribed topics");
    }
    const distinctTopics = Array.from(this.#subscribers.keys());
    for (const otherTopic of await this.#redis.pub.smembers(
      this.#subscribersSetKey
    )) {
      if (!distinctTopics.includes(otherTopic)) {
        distinctTopics.push(otherTopic);
      }
    }
    return distinctTopics;
  }
  publish(topic, data) {
    if (this.#disposed) {
      throw new Error("PubSub is disposed, cannot publish data");
    }
    return new Promise((resolve, reject) => {
      this.#redis.pub.publish(
        this.#topicToChannel(topic),
        JSON.stringify(data),
        (e) => {
          if (e) reject(e);
          else resolve();
        }
      );
    });
  }
  #handleMessage(channel, message) {
    const topic = this.#topicFromChannel(channel);
    const data = JSON.parse(message);
    const listeners = this.#subscribers.get(topic);
    if (listeners) {
      for (const l of listeners.keys()) {
        l(data);
      }
    }
  }
  subscribe(topic, listener) {
    if (this.#disposed) {
      throw new Error("PubSub is disposed, cannot subscribe to topics");
    }
    let listeners = this.#subscribers.get(topic);
    if (!listeners) {
      listeners = /* @__PURE__ */ new Map();
      this.#subscribers.set(topic, listeners);
    }
    const setArgs = [
      this.#subscribersSetKey,
      String(topic)
    ];
    if (!listener) {
      return new Repeater(async (push, stop) => {
        await this.#redis.sub.subscribe(this.#topicToChannel(topic));
        await this.#redis.pub.sadd(...setArgs);
        const { promise: settled, resolve: done } = createDeferredPromise();
        listeners.set(push, () => (stop(), settled));
        await stop;
        listeners.delete(push);
        if (listeners.size === 0) {
          this.#subscribers.delete(topic);
        }
        try {
          await this.#redis.pub.srem(...setArgs);
          await this.#redis.sub.unsubscribe(this.#topicToChannel(topic));
        } finally {
          done();
        }
      });
    }
    const listenerRef = new WeakRef(listener);
    const unsubscribe = async () => {
      const l = listenerRef.deref();
      if (l) listeners.delete(l);
      if (listeners.size === 0) {
        this.#subscribers.delete(topic);
      }
      await this.#redis.pub.srem(...setArgs);
      await this.#redis.sub.unsubscribe(this.#topicToChannel(topic));
    };
    listeners.set(listener, unsubscribe);
    return (async () => {
      await this.#redis.sub.subscribe(this.#topicToChannel(topic));
      await this.#redis.pub.sadd(...setArgs);
      return unsubscribe;
    })();
  }
  async dispose() {
    this.#disposed = true;
    this.#redis.sub.off("message", this.#boundHandleMessage);
    for (const sub of this.#subscribers.values()) {
      await Promise.all(Array.from(sub.values()).map((stop) => stop()));
      sub.clear();
    }
    this.#subscribers.clear();
    if (this.#quitOnDispose) {
      await Promise.allSettled([
        this.#redis.pub.quit(),
        this.#redis.sub.quit()
      ]);
    }
  }
  [DisposableSymbols.asyncDispose]() {
    return this.dispose();
  }
}

export { RedisPubSub };