PioneerRedisPubSub

This package implements the PubSub protocol from the Pioneer package. It allows you to use a Redis-backed PubSub woth similar interface with the AsyncPubSub and use it for your subscription resolvers.

Setup

.package(url: "https://github.com/d-exclaimation/pioneer-redis-pubsub", from: "0.1.0-beta")

Usage

Create a RedisPubSub instance (Here is an example using Vapor’s Redis integration):

import Vapor
import struct PioneerRedisPubSub.RedisPubSub
import Redis

let app = try Application(.detect())

app.redis.configuration = try RedisConfiguration(hostname: "localhost")

struct Resolver {
    let pubsub: PubSub = RedisPubSub(app.redis)
}

Now, implement your subscription resolver function, using the pubsub.asyncStream and call .toEventStream() to convert into an EventStream using AsyncEventStream

Internally calling the method .asyncStream of the RedisPubSub will send redis a SUBSCRIBE message to the topic provided if there hasn’t been a subscription for that topic.

let SOMETHING_CHANGED_TOPIC = "something_changed"

extension Resolver {
    func somethingChanged(_: Context, _: NoArguments) -> EventStream<Message> {
        pubsub.asyncStream(Message.self, for: SOMETHING_CHANGED_TOPIC).toEventStream()
    }
}

RedisPubSub manages internally a collection of subscribers (using Actors) which can be individually unsubscribe without having to close all other subcriber of the same topic. Every time the publish method is called, RedisPubSub will PUBLISH the event over redis which will be picked up by the RedisPubSub if there exist subscriber(s) for that topic.

Now, call publish method whenever you want to push an event to the subscriber(s).

await pubsub.publish(for: SOMETHING_CHANGED_TOPIC, payload: Message(id: "123"))

More information

GitHub

View Github