feat(medusa,event-bus-local,event-bus-redis): Event Bus modules (#2599)

packages/utils/src/bundles.ts

@@ -0,0 +1,3 @@
+export * as DecoratorUtils from "./decorators";
+export * as EventBusUtils from "./event-bus";
+

packages/utils/src/event-bus/index.ts

@@ -0,0 +1,89 @@
+import { EventBusTypes } from "@medusajs/types"
+import { ulid } from "ulid"
+
+export abstract class AbstractEventBusModuleService
+  implements EventBusTypes.IEventBusModuleService
+{
+  protected eventToSubscribersMap_: Map<
+    string | symbol,
+    EventBusTypes.SubscriberDescriptor[]
+  > = new Map()
+
+  public get eventToSubscribersMap(): Map<
+    string | symbol,
+    EventBusTypes.SubscriberDescriptor[]
+  > {
+    return this.eventToSubscribersMap_
+  }
+
+  abstract emit<T>(
+    eventName: string,
+    data: T,
+    options: Record<string, unknown>
+  ): Promise<void>
+  abstract emit<T>(data: EventBusTypes.EmitData<T>[]): Promise<void>
+
+  public subscribe(
+    eventName: string | symbol,
+    subscriber: EventBusTypes.Subscriber,
+    context?: EventBusTypes.SubscriberContext
+  ): this {
+    if (typeof subscriber !== `function`) {
+      throw new Error("Subscriber must be a function")
+    }
+    /**
+     * If context is provided, we use the subscriberId from it
+     * otherwise we generate a random using a ulid
+     */
+
+    const randId = ulid()
+    const event = eventName.toString()
+
+    const subscriberId = context?.subscriberId ?? `${event}-${randId}`
+
+    const newSubscriberDescriptor = { subscriber, id: subscriberId }
+
+    const existingSubscribers = this.eventToSubscribersMap_.get(event) ?? []
+
+    const subscriberAlreadyExists = existingSubscribers.find(
+      (sub) => sub.id === subscriberId
+    )
+
+    if (subscriberAlreadyExists) {
+      throw Error(`Subscriber with id ${subscriberId} already exists`)
+    }
+
+    this.eventToSubscribersMap_.set(event, [
+      ...existingSubscribers,
+      newSubscriberDescriptor,
+    ])
+
+    return this
+  }
+
+  unsubscribe(
+    eventName: string | symbol,
+    subscriber: EventBusTypes.Subscriber,
+    context: EventBusTypes.SubscriberContext
+  ): this {
+    if (typeof subscriber !== `function`) {
+      throw new Error("Subscriber must be a function")
+    }
+
+    const existingSubscribers = this.eventToSubscribersMap_.get(eventName)
+
+    if (existingSubscribers?.length) {
+      const subIndex = existingSubscribers?.findIndex(
+        (sub) => sub.id === context?.subscriberId
+      )
+
+      if (subIndex !== -1) {
+        this.eventToSubscribersMap_
+          .get(eventName)
+          ?.splice(subIndex as number, 1)
+      }
+    }
+
+    return this
+  }
+}

packages/utils/src/index.ts

@@ -1 +1,4 @@
+export * from "./bundles"
 export * from "./decorators"
+export * from "./event-bus"
+