perf_hooks: add HttpRequest statistics monitoring #28445

```js
const { PerformanceObserver, performance } = require('perf_hooks');
const http = require('http');

const obs = new PerformanceObserver((items) => {
  const entry = items.getEntries()[0];
  console.log(entry.name, entry.duration);
});
obs.observe({ entryTypes: ['http'] });

const server = http.Server(function(req, res) {
  server.close();
  res.writeHead(200);
  res.end('hello world\n');
});

server.listen(0, function() {
  const req = http.request({
    port: this.address().port,
    path: '/',
    method: 'POST'
  }).end();
});
```

PR-URL: https://github.com/nodejs/node/pull/28486
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

1 files changed, 19 insertions, 1 deletions

diff --git a/lib/_http_server.js b/lib/_http_server.js
index 941d571a67..6a262eedc2 100644
--- a/lib/_http_server.js
+++ b/lib/_http_server.js
@@ -39,7 +39,12 @@ const {
   prepareError,
 } = require('_http_common');
 const { OutgoingMessage } = require('_http_outgoing');
-const { outHeadersKey, ondrain, nowDate } = require('internal/http');
+const {
+  outHeadersKey,
+  ondrain,
+  nowDate,
+  emitStatistics
+} = require('internal/http');
 const {
   defaultTriggerAsyncIdScope,
   getOrSetAsyncId
@@ -56,8 +61,11 @@ const {
   DTRACE_HTTP_SERVER_REQUEST,
   DTRACE_HTTP_SERVER_RESPONSE
 } = require('internal/dtrace');
+const { observerCounts, constants } = internalBinding('performance');
+const { NODE_PERFORMANCE_ENTRY_TYPE_HTTP } = constants;
 
 const kServerResponse = Symbol('ServerResponse');
+const kServerResponseStatistics = Symbol('ServerResponseStatistics');
 
 const STATUS_CODES = {
   100: 'Continue',
@@ -147,12 +155,22 @@ function ServerResponse(req) {
     this.useChunkedEncodingByDefault = chunkExpression.test(req.headers.te);
     this.shouldKeepAlive = false;
   }
+
+  const httpObserverCount = observerCounts[NODE_PERFORMANCE_ENTRY_TYPE_HTTP];
+  if (httpObserverCount > 0) {
+    this[kServerResponseStatistics] = {
+      startTime: process.hrtime()
+    };
+  }
 }
 Object.setPrototypeOf(ServerResponse.prototype, OutgoingMessage.prototype);
 Object.setPrototypeOf(ServerResponse, OutgoingMessage);
 
 ServerResponse.prototype._finish = function _finish() {
   DTRACE_HTTP_SERVER_RESPONSE(this.connection);
+  if (this[kServerResponseStatistics] !== undefined) {
+    emitStatistics(this[kServerResponseStatistics]);
+  }
   OutgoingMessage.prototype._finish.call(this);
 };