perf(standard-server): optimize event-iterator payload for void returns

Author: unnoq

packages/standard-server-fetch/src/event-iterator.test.ts

@@ -165,11 +165,28 @@ describe('toEventStream', () => {
       .pipeThrough(new TextDecoderStream())
       .getReader()
 
-    expect((await reader.read()).value).toEqual('event: message\nid: id-1\ndata: {"order":1}\n\n')
-    expect((await reader.read()).value).toEqual('event: message\nretry: 20000\ndata: {"order":2}\n\n')
-    expect((await reader.read()).value).toEqual('event: message\n\n')
-    expect((await reader.read()).value).toEqual('event: done\nretry: 40000\nid: id-4\ndata: {"order":4}\n\n')
-    expect((await reader.read()).done).toEqual(true)
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\nid: id-1\ndata: {"order":1}\n\n' })
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\nretry: 20000\ndata: {"order":2}\n\n' })
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\n\n' })
+    expect((await reader.read())).toEqual({ done: false, value: 'event: done\nretry: 40000\nid: id-4\ndata: {"order":4}\n\n' })
+    expect((await reader.read())).toEqual({ done: true, value: undefined })
+  })
+
+  it('without return', async () => {
+    async function* gen() {
+      yield withEventMeta({ order: 1 }, { id: 'id-1' })
+      yield withEventMeta({ order: 2 }, { retry: 20000 })
+      yield undefined
+    }
+
+    const reader = toEventStream(gen(), {})
+      .pipeThrough(new TextDecoderStream())
+      .getReader()
+
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\nid: id-1\ndata: {"order":1}\n\n' })
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\nretry: 20000\ndata: {"order":2}\n\n' })
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\n\n' })
+    expect((await reader.read())).toEqual({ done: true, value: undefined })
   })
 
   it('with normal error', async () => {

packages/standard-server-fetch/src/event-iterator.ts

@@ -115,11 +115,15 @@ export function toEventStream(
 
         clearInterval(timeout)
 
-        controller.enqueue(encodeEventMessage({
-          ...getEventMeta(value.value),
-          event: value.done ? 'done' : 'message',
-          data: stringifyJSON(value.value),
-        }))
+        const meta = getEventMeta(value.value)
+
+        if (!value.done || value.value !== undefined || meta !== undefined) {
+          controller.enqueue(encodeEventMessage({
+            ...meta,
+            event: value.done ? 'done' : 'message',
+            data: stringifyJSON(value.value),
+          }))
+        }
 
         if (value.done) {
           controller.close()

packages/standard-server-node/src/event-iterator.test.ts

@@ -165,11 +165,28 @@ describe('toEventStream', () => {
       .pipeThrough(new TextDecoderStream())
       .getReader()
 
-    expect((await reader.read()).value).toEqual('event: message\nid: id-1\ndata: {"order":1}\n\n')
-    expect((await reader.read()).value).toEqual('event: message\nretry: 20000\ndata: {"order":2}\n\n')
-    expect((await reader.read()).value).toEqual('event: message\n\n')
-    expect((await reader.read()).value).toEqual('event: done\nretry: 40000\nid: id-4\ndata: {"order":4}\n\n')
-    expect((await reader.read()).done).toEqual(true)
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\nid: id-1\ndata: {"order":1}\n\n' })
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\nretry: 20000\ndata: {"order":2}\n\n' })
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\n\n' })
+    expect((await reader.read())).toEqual({ done: false, value: 'event: done\nretry: 40000\nid: id-4\ndata: {"order":4}\n\n' })
+    expect((await reader.read())).toEqual({ done: true, value: undefined })
+  })
+
+  it('without return', async () => {
+    async function* gen() {
+      yield withEventMeta({ order: 1 }, { id: 'id-1' })
+      yield withEventMeta({ order: 2 }, { retry: 20000 })
+      yield undefined
+    }
+
+    const reader = Readable.toWeb(toEventStream(gen(), {}))
+      .pipeThrough(new TextDecoderStream())
+      .getReader()
+
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\nid: id-1\ndata: {"order":1}\n\n' })
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\nretry: 20000\ndata: {"order":2}\n\n' })
+    expect((await reader.read())).toEqual({ done: false, value: 'event: message\n\n' })
+    expect((await reader.read())).toEqual({ done: true, value: undefined })
   })
 
   it('with normal error', async () => {

packages/standard-server-node/src/event-iterator.ts

@@ -116,11 +116,15 @@ export function toEventStream(
 
         clearInterval(timeout)
 
-        controller.enqueue(encodeEventMessage({
-          ...getEventMeta(value.value),
-          event: value.done ? 'done' : 'message',
-          data: stringifyJSON(value.value),
-        }))
+        const meta = getEventMeta(value.value)
+
+        if (!value.done || value.value !== undefined || meta !== undefined) {
+          controller.enqueue(encodeEventMessage({
+            ...meta,
+            event: value.done ? 'done' : 'message',
+            data: stringifyJSON(value.value),
+          }))
+        }
 
         if (value.done) {
           controller.close()