nodejs/test/parallel/test-async-hooks-http-agent.js

'use strict';
// Flags: --expose-internals
const common = require('../common');
const assert = require('assert');
const { async_id_symbol } = require('internal/async_hooks').symbols;
const http = require('http');

// Regression test for https://github.com/nodejs/node/issues/13325
// Checks that an http.Agent properly asyncReset()s a reused socket handle, and
// re-assigns the fresh async id to the reused `net.Socket` instance.

// Make sure a single socket is transparently reused for 2 requests.
const agent = new http.Agent({
  keepAlive: true,
  keepAliveMsecs: Infinity,
  maxSockets: 1
});

const server = http.createServer(common.mustCall((req, res) => {
  req.once('data', common.mustCallAtLeast(() => {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.write('foo');
  }));
  req.on('end', common.mustCall(() => {
    res.end('bar');
  }));
}, 2)).listen(0, common.mustCall(() => {
  const port = server.address().port;
  const payload = 'hello world';

  // First request. This is useless except for adding a socket to the
  // agent’s pool for reuse.
  const r1 = http.request({
    agent, port, method: 'POST'
  }, common.mustCall((res) => {
    // Remember which socket we used.
    const socket = res.socket;
    const asyncIdAtFirstRequest = socket[async_id_symbol];
    assert.ok(asyncIdAtFirstRequest > 0, `${asyncIdAtFirstRequest} > 0`);
    // Check that request and response share their socket.
    assert.strictEqual(r1.socket, socket);

    res.on('data', common.mustCallAtLeast(() => {}));
    res.on('end', common.mustCall(() => {
      // setImmediate() to give the agent time to register the freed socket.
      setImmediate(common.mustCall(() => {
        // The socket is free for reuse now.
        assert.strictEqual(socket[async_id_symbol], -1);

        // Second request. To re-create the exact conditions from the
        // referenced issue, we use a POST request without chunked encoding
        // (hence the Content-Length header) and call .end() after the
        // response header has already been received.
        const r2 = http.request({
          agent, port, method: 'POST', headers: {
            'Content-Length': payload.length
          }
        }, common.mustCall((res) => {
          const asyncId = res.socket[async_id_symbol];
          assert.ok(asyncId > 0, `${asyncId} > 0`);
          assert.strictEqual(r2.socket, socket);
          // Empty payload, to hit the “right” code path.
          r2.end('');

          res.on('data', common.mustCallAtLeast(() => {}));
          res.on('end', common.mustCall(() => {
            // Clean up to let the event loop stop.
            server.close();
            agent.destroy();
          }));
        }));

        // Schedule a payload to be written immediately, but do not end the
        // request just yet.
        r2.write(payload);
      }));
    }));
  }));
  r1.end(payload);
}));