Clean up HTTP async iterator code

http/server.ts

@@ -249,102 +249,82 @@ export class ServerRequest {
 }
 
 /** Continuously read more requests from conn until EOF
- * Calls maybeHandleReq.
  * bufr is empty on a fresh TCP connection.
  * Would be passed around and reused for later request on same conn
  * TODO: make them async function after this change is done
  * https://github.com/tc39/ecma262/pull/1250
  * See https://v8.dev/blog/fast-async
  */
-async function readRequest(
-  c: HttpConn,
-  bufr: BufReader
-): Promise<[ServerRequest, BufState]> {
+async function* iterateHttpRequests(
+  c: HttpConn
+): AsyncIterableIterator<[ServerRequest | null, BufState]> {
+  const bufr = new BufReader(c);
   const bufw = new BufWriter(c);
-  const req = new ServerRequest();
-
-  // Set and incr pipeline id;
-  req.pipelineId = ++c.lastPipelineId;
-  // Set a new pipeline deferred associated with this request
-  // for future requests to wait for.
-  c.pendingDeferredMap.set(req.pipelineId, deferred());
-
-  req.conn = c;
-  req.r = bufr!;
-  req.w = bufw;
-  const tp = new TextProtoReader(bufr!);
-
-  let s: string;
-  let err: BufState;
-
-  // First line: GET /index.html HTTP/1.0
-  [s, err] = await tp.readLine();
-  if (err) {
-    return [null, err];
-  }
-  [req.method, req.url, req.proto] = s.split(" ", 3);
 
-  [req.headers, err] = await tp.readMIMEHeader();
+  for (;;) {
+    const req = new ServerRequest();
+
+    // Set and incr pipeline id;
+    req.pipelineId = ++c.lastPipelineId;
+    // Set a new pipeline deferred associated with this request
+    // for future requests to wait for.
+    c.pendingDeferredMap.set(req.pipelineId, deferred());
+
+    req.conn = c;
+    req.r = bufr!;
+    req.w = bufw;
+
+    // First line: GET /index.html HTTP/1.0
+    const tp = new TextProtoReader(bufr!);
+    let [s, err]: [string, BufState] = await tp.readLine();
+    if (err) {
+      yield [null, err];
+      return;
+    }
 
-  return [req, err];
+    [req.method, req.url, req.proto] = s.split(" ", 3);
+    [req.headers, err] = await tp.readMIMEHeader();
+    yield [req, err];
+  }
 }
 
-export class Server implements AsyncIterableIterator<ServerRequest> {
+export class Server implements AsyncIterable<ServerRequest> {
   private closing = false;
   private looping = false;
   private channel = new Channel<ServerRequest>();
 
   constructor(public listener: Listener) {}
 
-  async acceptLoop(): Promise<void> {
-    assert(!this.looping);
-    this.looping = true;
-    try {
-      while (!this.closing) {
-        const conn = await this.listener.accept();
-        this.serveConn(conn); // async!
-      }
-    } finally {
-      this.looping = false;
-    }
-  }
-
   close(): void {
     this.closing = true;
     this.listener.close();
   }
 
-  async serveConn(conn: Conn): Promise<void> {
-    const httpConn = createHttpConn(conn);
-    const bufr = new BufReader(httpConn);
-    while (true) {
-      const [req, err] = await readRequest(httpConn, bufr);
-      if (err) {
-        // TODO(ry) This should be more granular. Perhaps return back a 400 or
-        // 500 error?
-        httpConn.close();
-        break;
+  private async *iterateRequests(): AsyncIterableIterator<ServerRequest> {
+    while (!this.closing) {
+      const conn = await this.listener.accept();
+      const httpConn = createHttpConn(conn);
+
+      for await (const [req, err] of iterateHttpRequests(httpConn)) {
+        if (err) {
+          // TODO(ry) This should be more granular. Perhaps return back a 400 or
+          // 500 error?
+          httpConn.close();
+          break;
+        }
+        yield req;
       }
-
-      await this.channel.send(req);
     }
   }
 
-  async next(): Promise<IteratorResult<ServerRequest>> {
-    const req = await this.channel.recv();
-    return { done: false, value: req };
-  }
-
   [Symbol.asyncIterator](): AsyncIterableIterator<ServerRequest> {
-    return this;
+    return this.iterateRequests();
   }
 }
 
 export function serve(addr: string): Server {
   const listener = listen("tcp", addr);
-  const server = new Server(listener);
-  server.acceptLoop();
-  return server;
+  return new Server(listener);
 }
 
 export async function listenAndServe(