Enforce HTTP/1.1 pipeline response order (#331)

http/racing_server.ts

@@ -0,0 +1,53 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import { serve, ServerRequest } from "./server.ts";
+
+const addr = Deno.args[1] || "127.0.0.1:4501";
+const server = serve(addr);
+
+const body = new TextEncoder().encode("Hello 1\n");
+const body4 = new TextEncoder().encode("World 4\n");
+
+function sleep(ms: number): Promise<void> {
+  return new Promise(res => setTimeout(res, ms));
+}
+
+async function delayedRespond(request: ServerRequest): Promise<void> {
+  await sleep(3000);
+  await request.respond({ status: 200, body });
+}
+
+async function largeRespond(request: ServerRequest, c: string): Promise<void> {
+  const b = new Uint8Array(1024 * 1024);
+  b.fill(c.charCodeAt(0));
+  await request.respond({ status: 200, body: b });
+}
+
+async function main(): Promise<void> {
+  let step = 1;
+  for await (const request of server) {
+    switch (step) {
+      case 1:
+        // Try to wait long enough.
+        // For pipelining, this should cause all the following response
+        // to block.
+        delayedRespond(request);
+        break;
+      case 2:
+        // HUGE body.
+        largeRespond(request, "a");
+        break;
+      case 3:
+        // HUGE body.
+        largeRespond(request, "b");
+        break;
+      default:
+        request.respond({ status: 200, body: body4 });
+        break;
+    }
+    step++;
+  }
+}
+
+main();
+
+console.log("Racing server listening...\n");

http/racing_server_test.ts

@@ -0,0 +1,65 @@
+const { dial, run } = Deno;
+
+import { test } from "../testing/mod.ts";
+import { assert, assertEquals } from "../testing/asserts.ts";
+import { BufReader } from "../io/bufio.ts";
+import { TextProtoReader } from "../textproto/mod.ts";
+
+let server;
+async function startServer(): Promise<void> {
+  server = run({
+    args: ["deno", "-A", "http/racing_server.ts"],
+    stdout: "piped"
+  });
+  // Once fileServer is ready it will write to its stdout.
+  const r = new TextProtoReader(new BufReader(server.stdout));
+  const [s, err] = await r.readLine();
+  assert(err == null);
+  assert(s.includes("Racing server listening..."));
+}
+function killServer(): void {
+  server.close();
+  server.stdout.close();
+}
+
+let input = `GET / HTTP/1.1
+
+GET / HTTP/1.1
+
+GET / HTTP/1.1
+
+GET / HTTP/1.1
+
+`;
+const HUGE_BODY_SIZE = 1024 * 1024;
+let output = `HTTP/1.1 200 OK
+content-length: 8
+
+Hello 1
+HTTP/1.1 200 OK
+content-length: ${HUGE_BODY_SIZE}
+
+${"a".repeat(HUGE_BODY_SIZE)}HTTP/1.1 200 OK
+content-length: ${HUGE_BODY_SIZE}
+
+${"b".repeat(HUGE_BODY_SIZE)}HTTP/1.1 200 OK
+content-length: 8
+
+World 4
+`;
+
+test(async function serverPipelineRace(): Promise<void> {
+  await startServer();
+
+  const conn = await dial("tcp", "127.0.0.1:4501");
+  const r = new TextProtoReader(new BufReader(conn));
+  await conn.write(new TextEncoder().encode(input));
+  const outLines = output.split("\n");
+  // length - 1 to disregard last empty line
+  for (let i = 0; i < outLines.length - 1; i++) {
+    const [s, err] = await r.readLine();
+    assert(!err);
+    assertEquals(s, outLines[i]);
+  }
+  killServer();
+});

http/server.ts

@@ -13,6 +13,42 @@ interface Deferred {
   resolve: () => void;
   reject: () => void;
 }
+
+function deferred(isResolved = false): Deferred {
+  let resolve, reject;
+  const promise = new Promise((res, rej) => {
+    resolve = res;
+    reject = rej;
+  });
+  if (isResolved) {
+    resolve();
+  }
+  return {
+    promise,
+    resolve,
+    reject
+  };
+}
+
+interface HttpConn extends Conn {
+  // When read by a newly created request B, lastId is the id pointing to a previous
+  // request A, such that we must wait for responses to A to complete before
+  // writing B's response.
+  lastPipelineId: number;
+  pendingDeferredMap: Map<number, Deferred>;
+}
+
+function createHttpConn(c: Conn): HttpConn {
+  const httpConn = Object.assign(c, {
+    lastPipelineId: 0,
+    pendingDeferredMap: new Map()
+  });
+
+  const resolvedDeferred = deferred(true);
+  httpConn.pendingDeferredMap.set(0, resolvedDeferred);
+  return httpConn;
+}
+
 function bufWriter(w: Writer): BufWriter {
   if (w instanceof BufWriter) {
     return w;
@@ -115,11 +151,12 @@ async function readAllIterator(
 }
 
 export class ServerRequest {
+  pipelineId: number;
   url: string;
   method: string;
   proto: string;
   headers: Headers;
-  conn: Conn;
+  conn: HttpConn;
   r: BufReader;
   w: BufWriter;
 
@@ -204,23 +241,26 @@ export class ServerRequest {
   }
 
   async respond(r: Response): Promise<void> {
-    return writeResponse(this.w, r);
+    // Check and wait if the previous request is done responding.
+    const lastPipelineId = this.pipelineId - 1;
+    const lastPipelineDeferred = this.conn.pendingDeferredMap.get(
+      lastPipelineId
+    );
+    assert(!!lastPipelineDeferred);
+    await lastPipelineDeferred.promise;
+    // If yes, delete old deferred and proceed with writing.
+    this.conn.pendingDeferredMap.delete(lastPipelineId);
+    // Write our response!
+    await writeResponse(this.w, r);
+    // Signal the next pending request that it can start writing.
+    const currPipelineDeferred = this.conn.pendingDeferredMap.get(
+      this.pipelineId
+    );
+    assert(!!currPipelineDeferred);
+    currPipelineDeferred.resolve();
   }
 }
 
-function deferred(): Deferred {
-  let resolve, reject;
-  const promise = new Promise((res, rej) => {
-    resolve = res;
-    reject = rej;
-  });
-  return {
-    promise,
-    resolve,
-    reject
-  };
-}
-
 interface ServeEnv {
   reqQueue: ServerRequest[];
   serveDeferred: Deferred;
@@ -235,7 +275,7 @@ interface ServeEnv {
  * See https://v8.dev/blog/fast-async
  */
 async function readRequest(
-  c: Conn,
+  c: HttpConn,
   bufr?: BufReader
 ): Promise<[ServerRequest, BufState]> {
   if (!bufr) {
@@ -243,6 +283,13 @@ async function readRequest(
   }
   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;
@@ -277,7 +324,7 @@ function maybeHandleReq(
   env.serveDeferred.resolve(); // signal while loop to process it
 }
 
-function serveConn(env: ServeEnv, conn: Conn, bufr?: BufReader): void {
+function serveConn(env: ServeEnv, conn: HttpConn, bufr?: BufReader): void {
   readRequest(conn, bufr).then(maybeHandleReq.bind(null, env, conn));
 }
 
@@ -298,7 +345,8 @@ export async function* serve(
       listener.accept().then(handleConn);
     };
     handleConn = (conn: Conn) => {
-      serveConn(env, conn); // don't block
+      const httpConn = createHttpConn(conn);
+      serveConn(env, httpConn); // don't block
       scheduleAccept(); // schedule next accept
     };
 

http/server_test.ts

@@ -19,6 +19,28 @@ interface ResponseTest {
 const enc = new TextEncoder();
 const dec = new TextDecoder();
 
+interface Deferred {
+  promise: Promise<{}>;
+  resolve: () => void;
+  reject: () => void;
+}
+
+function deferred(isResolved = false): Deferred {
+  let resolve, reject;
+  const promise = new Promise((res, rej) => {
+    resolve = res;
+    reject = rej;
+  });
+  if (isResolved) {
+    resolve();
+  }
+  return {
+    promise,
+    resolve,
+    reject
+  };
+}
+
 const responseTests: ResponseTest[] = [
   // Default response
   {
@@ -44,7 +66,24 @@ test(async function responseWrite() {
     const buf = new Buffer();
     const bufw = new BufWriter(buf);
     const request = new ServerRequest();
+    request.pipelineId = 1;
     request.w = bufw;
+    request.conn = {
+      localAddr: "",
+      remoteAddr: "",
+      rid: -1,
+      closeRead: () => {},
+      closeWrite: () => {},
+      read: async () => {
+        return { eof: true, nread: 0 };
+      },
+      write: async () => {
+        return -1;
+      },
+      close: () => {},
+      lastPipelineId: 0,
+      pendingDeferredMap: new Map([[0, deferred(true)], [1, deferred()]])
+    };
 
     await request.respond(testCase.response);
     assertEquals(buf.toString(), testCase.raw);

http/test.ts

@@ -1,3 +1,4 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
 import "./server_test.ts";
 import "./file_server_test.ts";
+import "./racing_server_test.ts";