feat: allow providing a buffer for pubsub subscribe call

.changeset/angry-clocks-sniff.md

@@ -0,0 +1,20 @@
+---
+'@graphql-yoga/subscription': minor
+---
+
+Support providing a `RepeaterBuffer` to the `PubSub.subscribe` method, by using the new object based call signature.
+
+```ts
+import { createPubSub } from 'graphql-yoga'
+import { SlidingBuffer } from '@repeaterjs/repeater'
+
+const pubSub = createPubSub()
+
+pubSub.subscribe({
+  topic: "userChanged",
+  id: "1",
+  buffer: new SlidingBuffer(1_000)
+})
+```
+
+Learn more about buffers on the [Repeater.js website](https://repeater.js.org/docs/safety#3-buffering-and-dropping-values).

packages/subscription/src/create-pub-sub.ts

@@ -1,5 +1,5 @@
 import type { TypedEventTarget } from '@graphql-yoga/typed-event-target';
-import { Repeater } from '@repeaterjs/repeater';
+import { Repeater, type RepeaterBuffer } from '@repeaterjs/repeater';
 import { CustomEvent } from '@whatwg-node/events';
 
 type PubSubPublishArgsByKey = {
@@ -45,9 +45,15 @@ export type PubSub<TPubSubPublishArgsByKey extends PubSubPublishArgsByKey> = {
    * Subscribe to a topic.
    */
   subscribe<TKey extends Extract<keyof TPubSubPublishArgsByKey, string>>(
-    ...[routingKey, id]: TPubSubPublishArgsByKey[TKey][1] extends undefined
-      ? [TKey]
-      : [TKey, TPubSubPublishArgsByKey[TKey][0]]
+    args: {
+      topic: string;
+    } & (TPubSubPublishArgsByKey[TKey][1] extends undefined
+      ? {
+          id?: void;
+        }
+      : {
+          id: TPubSubPublishArgsByKey[TKey][0];
+        }),
   ): Repeater<
     TPubSubPublishArgsByKey[TKey][1] extends undefined
       ? MapToNull<TPubSubPublishArgsByKey[TKey][0]>
@@ -78,15 +84,23 @@ export const createPubSub = <TPubSubPublishArgsByKey extends PubSubPublishArgsBy
       target.dispatchEvent(event);
     },
     subscribe<TKey extends Extract<keyof TPubSubPublishArgsByKey, string>>(
-      ...[routingKey, id]: TPubSubPublishArgsByKey[TKey][1] extends undefined
-        ? [TKey]
-        : [TKey, TPubSubPublishArgsByKey[TKey][0]]
+      args: {
+        /** Topic to subscribe to */
+        topic: string;
+        buffer?: RepeaterBuffer | undefined;
+      } & (TPubSubPublishArgsByKey[TKey][1] extends undefined
+        ? {
+            id?: void;
+          }
+        : {
+            id: TPubSubPublishArgsByKey[TKey][0];
+          }),
     ): Repeater<
       TPubSubPublishArgsByKey[TKey][1] extends undefined
         ? TPubSubPublishArgsByKey[TKey][0]
         : TPubSubPublishArgsByKey[TKey][1]
     > {
-      const topic = id === undefined ? routingKey : `${routingKey}:${id as number}`;
+      const topic = args.id === undefined ? args.topic : `${args.topic}:${args.id}`;
 
       return new Repeater(function subscriptionRepeater(next, stop) {
         stop.then(function subscriptionRepeaterStopHandler() {
@@ -98,7 +112,7 @@ export const createPubSub = <TPubSubPublishArgsByKey extends PubSubPublishArgsBy
         function pubsubEventListener(event: PubSubEvent<TPubSubPublishArgsByKey, TKey>) {
           next(event.detail);
         }
-      });
+      }, args.buffer);
     },
   };
 };