Live query pubsub adapter (#2902)

* Moves LiveQuery pub/sub to adapter folder

* Adds ability to provide custom adapter for LiveQuery pubsub

* Adds test for function based adapter

* Pass all options to createSubscriber

* nits

src/Adapters/PubSub/EventEmitterPubSub.js

@@ -0,0 +1,59 @@
+import events from 'events';
+
+let emitter = new events.EventEmitter();
+
+class Publisher {
+  emitter: any;
+
+  constructor(emitter: any) {
+    this.emitter = emitter;
+  }
+
+  publish(channel: string, message: string): void {
+    this.emitter.emit(channel, message);
+  }
+}
+
+class Subscriber extends events.EventEmitter {
+  emitter: any;
+  subscriptions: any;
+
+  constructor(emitter: any) {
+    super();
+    this.emitter = emitter;
+    this.subscriptions = new Map();
+  }
+
+  subscribe(channel: string): void {
+    let handler = (message) => {
+      this.emit('message', channel, message);
+    }
+    this.subscriptions.set(channel, handler);
+    this.emitter.on(channel, handler);
+  }
+
+  unsubscribe(channel: string): void {
+    if (!this.subscriptions.has(channel)) {
+      return;
+    }
+    this.emitter.removeListener(channel, this.subscriptions.get(channel));
+    this.subscriptions.delete(channel);
+  }
+}
+
+function createPublisher(): any {
+  return new Publisher(emitter);
+}
+
+function createSubscriber(): any {
+  return new Subscriber(emitter);
+}
+
+let EventEmitterPubSub = {
+  createPublisher,
+  createSubscriber
+}
+
+export {
+  EventEmitterPubSub
+}

src/Adapters/PubSub/RedisPubSub.js

@@ -0,0 +1,18 @@
+import redis from 'redis';
+
+function createPublisher({redisURL}): any {
+  return redis.createClient(redisURL, { no_ready_check: true });
+}
+
+function createSubscriber({redisURL}): any {
+  return redis.createClient(redisURL, { no_ready_check: true });
+}
+
+const RedisPubSub = {
+  createPublisher,
+  createSubscriber
+}
+
+export {
+  RedisPubSub
+}