Short-circuit readRequest() and OP_ACCEPT

cli/js/net.ts

@@ -1,8 +1,10 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+import { ErrorKind, DenoError } from "./errors.ts";
 import { EOF, Reader, Writer, Closer } from "./io.ts";
 import { read, write, close } from "./files.ts";
 import * as dispatch from "./dispatch.ts";
 import { sendSync, sendAsync } from "./dispatch_json.ts";
+import { createResolvable } from "./util.ts";
 
 export type Transport = "tcp";
 // TODO support other types:
@@ -85,30 +87,33 @@ export class ConnImpl implements Conn {
 }
 
 export class ListenerImpl implements Listener {
-  constructor(
-    readonly rid: number,
-    public addr: Addr,
-    private closing: boolean = false
-  ) {}
+  private closed = createResolvable<void>();
+
+  constructor(readonly rid: number, public addr: Addr, closing = false) {
+    if (closing) {
+      this.closed.resolve();
+    }
+  }
 
   async accept(): Promise<Conn> {
-    const res = await sendAsync(dispatch.OP_ACCEPT, { rid: this.rid });
+    const res = await Promise.race([
+      sendAsync(dispatch.OP_ACCEPT, { rid: this.rid }),
+      this.closed.then(() => {
+        throw new DenoError(ErrorKind.Other, "Listener has been closed");
+      })
+    ]);
     return new ConnImpl(res.rid, res.remoteAddr, res.localAddr);
   }
 
   close(): void {
-    this.closing = true;
+    this.closed.resolve();
     close(this.rid);
   }
 
   async next(): Promise<IteratorResult<Conn>> {
-    if (this.closing) {
-      return { value: undefined, done: true };
-    }
     return await this.accept()
       .then(value => ({ value, done: false }))
       .catch(e => {
-        // It wouldn't be correct to simply check this.closing here.
         // TODO: Get a proper error kind for this case, don't check the message.
         // The current error kind is Other.
         if (e.message == "Listener has been closed") {

std/http/server.ts

@@ -474,11 +474,13 @@ class EventType<T> {
 
 export class Server implements AsyncIterable<ServerRequest> {
   private closing = false;
+  private closed = deferred<void>();
 
   constructor(public listener: Listener) {}
 
   close(): void {
     this.closing = true;
+    this.closed.resolve();
     this.listener.close();
   }
 
@@ -493,7 +495,10 @@ export class Server implements AsyncIterable<ServerRequest> {
 
     while (!this.closing) {
       try {
-        req = await readRequest(conn, bufr);
+        req = await Promise.race([
+          readRequest(conn, bufr),
+          this.closed.then((): Deno.EOF => Deno.EOF)
+        ]);
       } catch (e) {
         err = e;
         break;