http: report request start and end with diagnostics_channel

PR-URL: https://github.com/nodejs/node/pull/34895
Reviewed-By: Bryan English <bryan@bryanenglish.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Gabriel Schulhof <gabriel.schulhof@intel.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

benchmark/diagnostics_channel/http.js

@@ -0,0 +1,96 @@
+'use strict';
+const common = require('../common.js');
+const dc = require('diagnostics_channel');
+const { AsyncLocalStorage } = require('async_hooks');
+const http = require('http');
+
+const bench = common.createBenchmark(main, {
+  apm: ['none', 'diagnostics_channel', 'patch'],
+  type: 'buffer',
+  len: 1024,
+  chunks: 4,
+  connections: [50, 500],
+  chunkedEnc: 1,
+  duration: 5
+});
+
+function main({ apm, connections, duration, type, len, chunks, chunkedEnc }) {
+  const done = { none, patch, diagnostics_channel }[apm]();
+
+  const server = require('../fixtures/simple-http-server.js')
+    .listen(common.PORT)
+    .on('listening', () => {
+      const path = `/${type}/${len}/${chunks}/normal/${chunkedEnc}`;
+      bench.http({
+        path,
+        connections,
+        duration
+      }, () => {
+        server.close();
+        if (done) done();
+      });
+    });
+}
+
+function none() {}
+
+function patch() {
+  const als = new AsyncLocalStorage();
+  const times = [];
+
+  const { emit } = http.Server.prototype;
+  function wrappedEmit(...args) {
+    const [name, req, res] = args;
+    if (name === 'request') {
+      als.enterWith({
+        url: req.url,
+        start: process.hrtime.bigint()
+      });
+
+      res.on('finish', () => {
+        times.push({
+          ...als.getStore(),
+          statusCode: res.statusCode,
+          end: process.hrtime.bigint()
+        });
+      });
+    }
+    return emit.apply(this, args);
+  }
+  http.Server.prototype.emit = wrappedEmit;
+
+  return () => {
+    http.Server.prototype.emit = emit;
+  };
+}
+
+function diagnostics_channel() {
+  const als = new AsyncLocalStorage();
+  const times = [];
+
+  const start = dc.channel('http.server.request.start');
+  const finish = dc.channel('http.server.response.finish');
+
+  function onStart(req) {
+    als.enterWith({
+      url: req.url,
+      start: process.hrtime.bigint()
+    });
+  }
+
+  function onFinish(res) {
+    times.push({
+      ...als.getStore(),
+      statusCode: res.statusCode,
+      end: process.hrtime.bigint()
+    });
+  }
+
+  start.subscribe(onStart);
+  finish.subscribe(onFinish);
+
+  return () => {
+    start.unsubscribe(onStart);
+    finish.unsubscribe(onFinish);
+  };
+}

lib/_http_server.js

@@ -84,6 +84,10 @@ const { observerCounts, constants } = internalBinding('performance');
 const { setTimeout, clearTimeout } = require('timers');
 const { NODE_PERFORMANCE_ENTRY_TYPE_HTTP } = constants;
 
+const dc = require('diagnostics_channel');
+const onRequestStartChannel = dc.channel('http.server.request.start');
+const onResponseFinishChannel = dc.channel('http.server.response.finish');
+
 const kServerResponse = Symbol('ServerResponse');
 const kServerResponseStatistics = Symbol('ServerResponseStatistics');
 
@@ -775,6 +779,15 @@ function clearRequestTimeout(req) {
 }
 
 function resOnFinish(req, res, socket, state, server) {
+  if (onResponseFinishChannel.hasSubscribers) {
+    onResponseFinishChannel.publish({
+      request: req,
+      response: res,
+      socket,
+      server
+    });
+  }
+
   // Usually the first incoming element should be our request.  it may
   // be that in the case abortIncoming() was called that the incoming
   // array will be empty.
@@ -862,6 +875,15 @@ function parserOnIncoming(server, socket, state, req, keepAlive) {
   res.shouldKeepAlive = keepAlive;
   DTRACE_HTTP_SERVER_REQUEST(req, socket);
 
+  if (onRequestStartChannel.hasSubscribers) {
+    onRequestStartChannel.publish({
+      request: req,
+      response: res,
+      socket,
+      server
+    });
+  }
+
   if (socket._httpMessage) {
     // There are already pending outgoing res, append.
     state.outgoing.push(res);

test/parallel/test-diagnostics-channel-http-server-start.js

@@ -0,0 +1,65 @@
+'use strict';
+
+const common = require('../common');
+const { AsyncLocalStorage } = require('async_hooks');
+const dc = require('diagnostics_channel');
+const assert = require('assert');
+const http = require('http');
+
+const incomingStartChannel = dc.channel('http.server.request.start');
+const outgoingFinishChannel = dc.channel('http.server.response.finish');
+
+const als = new AsyncLocalStorage();
+let context;
+
+// Bind requests to an AsyncLocalStorage context
+incomingStartChannel.subscribe(common.mustCall((message) => {
+  als.enterWith(message);
+  context = message;
+}));
+
+// When the request ends, verify the context has been maintained
+// and that the messages contain the expected data
+outgoingFinishChannel.subscribe(common.mustCall((message) => {
+  const data = {
+    request,
+    response,
+    server,
+    socket: request.socket
+  };
+
+  // Context is maintained
+  compare(als.getStore(), context);
+
+  compare(context, data);
+  compare(message, data);
+}));
+
+let request;
+let response;
+
+const server = http.createServer(common.mustCall((req, res) => {
+  request = req;
+  response = res;
+
+  setTimeout(() => {
+    res.end('done');
+  }, 1);
+}));
+
+server.listen(() => {
+  const { port } = server.address();
+  http.get(`http://localhost:${port}`, (res) => {
+    res.resume();
+    res.on('end', () => {
+      server.close();
+    });
+  });
+});
+
+function compare(a, b) {
+  assert.strictEqual(a.request, b.request);
+  assert.strictEqual(a.response, b.response);
+  assert.strictEqual(a.socket, b.socket);
+  assert.strictEqual(a.server, b.server);
+}