v2: perf(response,listener): Response fast-paths and responseViaCache improvements

src/listener.ts

@@ -26,6 +26,30 @@ type OutgoingHasOutgoingEnded = Http2ServerResponse & {
   [outgoingEnded]?: () => void
 }
 
+const makeCloseHandler = (
+  req: any,
+  incoming: IncomingMessage | Http2ServerRequest,
+  outgoing: ServerResponse | Http2ServerResponse,
+  needsBodyCleanup: boolean
+): (() => void) =>
+  () => {
+    if (incoming.errored) {
+      req[abortRequest](incoming.errored.toString())
+    } else if (!outgoing.writableFinished) {
+      req[abortRequest]('Client connection prematurely closed.')
+    }
+
+    if (needsBodyCleanup && !incoming.readableEnded) {
+      setTimeout(() => {
+        if (!incoming.readableEnded) {
+          setTimeout(() => {
+            incoming.destroy()
+          })
+        }
+      })
+    }
+  }
+
 const handleRequestError = (): Response =>
   new Response(null, {
     status: 400,
@@ -70,10 +94,43 @@ const responseViaCache = async (
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   let [status, body, header] = (res as any)[cacheKey] as InternalCache
 
-  let hasContentLength = false
+  // Fast path: no custom headers — create the final header object in one shot
+  // (avoids shape transitions from mutating a single-key object).
   if (!header) {
-    header = { 'content-type': 'text/plain; charset=UTF-8' }
-  } else if (header instanceof Headers) {
+    if (body == null) {
+      outgoing.writeHead(status, {})
+      outgoing.end()
+    } else if (typeof body === 'string') {
+      outgoing.writeHead(status, {
+        'content-type': 'text/plain; charset=UTF-8',
+        'Content-Length': Buffer.byteLength(body),
+      })
+      outgoing.end(body)
+    } else if (body instanceof Uint8Array) {
+      outgoing.writeHead(status, {
+        'content-type': 'text/plain; charset=UTF-8',
+        'Content-Length': body.byteLength,
+      })
+      outgoing.end(body)
+    } else if (body instanceof Blob) {
+      outgoing.writeHead(status, {
+        'content-type': 'text/plain; charset=UTF-8',
+        'Content-Length': body.size,
+      })
+      outgoing.end(new Uint8Array(await body.arrayBuffer()))
+    } else {
+      outgoing.writeHead(status, { 'content-type': 'text/plain; charset=UTF-8' })
+      flushHeaders(outgoing)
+      await writeFromReadableStream(body, outgoing)?.catch(
+        (e) => handleResponseError(e, outgoing) as undefined
+      )
+    }
+    ;(outgoing as OutgoingHasOutgoingEnded)[outgoingEnded]?.()
+    return
+  }
+
+  let hasContentLength = false
+  if (header instanceof Headers) {
     hasContentLength = header.has('content-length')
     header = buildOutgoingHttpHeaders(header)
   } else if (Array.isArray(header)) {
@@ -101,7 +158,9 @@ const responseViaCache = async (
   }
 
   outgoing.writeHead(status, header)
-  if (typeof body === 'string' || body instanceof Uint8Array) {
+  if (body == null) {
+    outgoing.end()
+  } else if (typeof body === 'string' || body instanceof Uint8Array) {
     outgoing.end(body)
   } else if (body instanceof Blob) {
     outgoing.end(new Uint8Array(await body.arrayBuffer()))
@@ -238,31 +297,30 @@ export const getRequestListener = (
   ) => {
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     let res, req: any
+    let needsBodyCleanup = false
 
     try {
       // `fetchCallback()` requests a Request object, but global.Request is expensive to generate,
       // so generate a pseudo Request object with only the minimum required information.
       req = newRequest(incoming, options.hostname)
 
-      let incomingEnded =
-        !autoCleanupIncoming || incoming.method === 'GET' || incoming.method === 'HEAD'
-      if (!incomingEnded) {
+      // For non-GET/HEAD requests, mark for body stream wrapping and H2 cleanup.
+      needsBodyCleanup =
+        autoCleanupIncoming && !(incoming.method === 'GET' || incoming.method === 'HEAD')
+      if (needsBodyCleanup) {
         ;(incoming as IncomingMessageWithWrapBodyStream)[wrapBodyStream] = true
-        incoming.on('end', () => {
-          incomingEnded = true
-        })
 
         if (incoming instanceof Http2ServerRequest) {
           // a Http2ServerResponse instance requires additional processing on exit
           // since outgoing.on('close') is not called even after outgoing.end() is called
           // when the state is incomplete
           ;(outgoing as OutgoingHasOutgoingEnded)[outgoingEnded] = () => {
             // incoming is not consumed to the end
-            if (!incomingEnded) {
+            if (!incoming.readableEnded) {
               setTimeout(() => {
                 // in the case of a simple POST request, the cleanup process may be done automatically
-                // and end is called at this point. At that point, nothing is done.
-                if (!incomingEnded) {
+                // and readableEnded is true at this point. At that point, nothing is done.
+                if (!incoming.readableEnded) {
                   setTimeout(() => {
                     incoming.destroy()
                     // a Http2ServerResponse instance will not terminate without also calling outgoing.destroy()
@@ -275,42 +333,32 @@ export const getRequestListener = (
         }
       }
 
-      // Detect if request was aborted.
-      outgoing.on('close', () => {
-        let abortReason: string | undefined
-        if (incoming.errored) {
-          abortReason = incoming.errored.toString()
-        } else if (!outgoing.writableFinished) {
-          abortReason = 'Client connection prematurely closed.'
-        }
-        if (abortReason !== undefined) {
-          req[abortRequest](abortReason)
-        }
-
-        // incoming is not consumed to the end
-        if (!incomingEnded) {
-          setTimeout(() => {
-            // in the case of a simple POST request, the cleanup process may be done automatically
-            // and end is called at this point. At that point, nothing is done.
-            if (!incomingEnded) {
-              setTimeout(() => {
-                incoming.destroy()
-              })
-            }
-          })
-        }
-      })
-
       res = fetchCallback(req, { incoming, outgoing } as HttpBindings) as
         | Response
         | Promise<Response>
       if (cacheKey in res) {
-        // synchronous, cacheable response
+        // Synchronous cacheable response — no close listener needed.
+        // No I/O events can fire between fetchCallback returning and responseViaCache
+        // completing, so abort detection is not needed here.
+        if (needsBodyCleanup && !incoming.readableEnded) {
+          // Handler returned without consuming the body; schedule destruction so
+          // the socket is freed even if the client never sends the rest of the body.
+          setTimeout(() => {
+            if (!incoming.readableEnded) {
+              setTimeout(() => incoming.destroy())
+            }
+          })
+        }
         return responseViaCache(res as Response, outgoing)
       }
+      // Async response — create and register close listener only now, avoiding
+      // closure allocation on the synchronous hot path.
+      outgoing.on('close', makeCloseHandler(req, incoming, outgoing, needsBodyCleanup))
     } catch (e: unknown) {
       if (!res) {
         if (options.errorHandler) {
+          // Async error handler — register close listener so client disconnect aborts the signal.
+          if (req) outgoing.on('close', makeCloseHandler(req, incoming, outgoing, needsBodyCleanup))
           res = await options.errorHandler(req ? e : toRequestError(e))
           if (!res) {
             return

src/response.ts

@@ -9,7 +9,7 @@ export const cacheKey = Symbol('cache')
 
 export type InternalCache = [
   number,
-  string | ReadableStream,
+  string | ReadableStream | null,
   Record<string, string> | [string, string][] | Headers | OutgoingHttpHeaders | undefined,
 ]
 interface LightResponse {
@@ -47,12 +47,14 @@ export class Response {
     }
 
     if (
+      body === null ||
+      body === undefined ||
       typeof body === 'string' ||
       typeof (body as ReadableStream)?.getReader !== 'undefined' ||
       body instanceof Blob ||
       body instanceof Uint8Array
     ) {
-      ;(this as any)[cacheKey] = [init?.status || 200, body, headers || init?.headers]
+      ;(this as any)[cacheKey] = [init?.status || 200, body ?? null, headers || init?.headers]
     }
   }
 
@@ -97,3 +99,38 @@ export class Response {
 })
 Object.setPrototypeOf(Response, GlobalResponse)
 Object.setPrototypeOf(Response.prototype, GlobalResponse.prototype)
+
+// Override Response.json() to return a LightweightResponse so the listener
+// fast-path (cacheKey check) is hit instead of falling through to ReadableStream reading.
+Object.defineProperty(Response, 'redirect', {
+  value: function redirect(url: string | URL, status = 302): Response {
+    if (![301, 302, 303, 307, 308].includes(status)) {
+      throw new RangeError('Invalid status code')
+    }
+    return new Response(null, {
+      status,
+      headers: { location: typeof url === 'string' ? url : url.href },
+    })
+  },
+  writable: true,
+  configurable: true,
+})
+
+Object.defineProperty(Response, 'json', {
+  value: function json(data?: unknown, init?: ResponseInit): Response {
+    const body = JSON.stringify(data)
+    const initHeaders = init?.headers
+    let headers: Record<string, string> | Headers
+    if (initHeaders) {
+      headers = new Headers(initHeaders)
+      if (!(headers as Headers).has('content-type')) {
+        ;(headers as Headers).set('content-type', 'application/json')
+      }
+    } else {
+      headers = { 'content-type': 'application/json' }
+    }
+    return new Response(body, { status: init?.status ?? 200, statusText: init?.statusText, headers })
+  },
+  writable: true,
+  configurable: true,
+})

test/listener.test.ts

@@ -302,6 +302,82 @@ describe('Abort request', () => {
   })
 })
 
+describe('Abort request - error path', () => {
+  it('should abort request signal when client disconnects while async error handler is running after sync throw', async () => {
+    let capturedReq: Request | undefined
+    let resolveAborted: () => void
+    const abortedPromise = new Promise<void>((r) => {
+      resolveAborted = r
+    })
+
+    const fetchCallback = (req: Request) => {
+      capturedReq = req
+      req.signal.addEventListener('abort', () => resolveAborted())
+      throw new Error('sync error')
+    }
+
+    let resolveErrorHandlerStarted: () => void
+    const errorHandlerStarted = new Promise<void>((r) => {
+      resolveErrorHandlerStarted = r
+    })
+
+    const errorHandler = async () => {
+      resolveErrorHandlerStarted()
+      await new Promise<void>(() => {}) // never resolves — client will disconnect first
+    }
+
+    const requestListener = getRequestListener(fetchCallback, { errorHandler })
+    const server = createServer(requestListener)
+
+    try {
+      const req = request(server).get('/').end(() => {})
+      await errorHandlerStarted
+      req.abort()
+      await abortedPromise
+      expect(capturedReq?.signal.aborted).toBe(true)
+    } finally {
+      server.close()
+    }
+  })
+
+  it('should abort request signal when client disconnects while async error handler is running after async throw', async () => {
+    let capturedReq: Request | undefined
+    let resolveAborted: () => void
+    const abortedPromise = new Promise<void>((r) => {
+      resolveAborted = r
+    })
+
+    const fetchCallback = async (req: Request) => {
+      capturedReq = req
+      req.signal.addEventListener('abort', () => resolveAborted())
+      throw new Error('async error')
+    }
+
+    let resolveErrorHandlerStarted: () => void
+    const errorHandlerStarted = new Promise<void>((r) => {
+      resolveErrorHandlerStarted = r
+    })
+
+    const errorHandler = async () => {
+      resolveErrorHandlerStarted()
+      await new Promise<void>(() => {}) // never resolves — client will disconnect first
+    }
+
+    const requestListener = getRequestListener(fetchCallback, { errorHandler })
+    const server = createServer(requestListener)
+
+    try {
+      const req = request(server).get('/').end(() => {})
+      await errorHandlerStarted
+      req.abort()
+      await abortedPromise
+      expect(capturedReq?.signal.aborted).toBe(true)
+    } finally {
+      server.close()
+    }
+  })
+})
+
 describe('overrideGlobalObjects', () => {
   const fetchCallback = vi.fn()