denoland-deno/std/http/racing_server.ts

// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
import { serve, ServerRequest } from "./server.ts";
import { delay } from "../util/async.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");

async function delayedRespond(request: ServerRequest): Promise<void> {
  await delay(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 });
}

console.log("Racing server listening...\n");

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++;
}