http2: add diagnostics channel 'http2.client.stream.finish'

Signed-off-by: Darshan Sen <raisinten@gmail.com>
PR-URL: https://github.com/nodejs/node/pull/58317
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/diagnostics_channel.md

@@ -1224,6 +1224,14 @@ Emitted when a stream is started on the client.
 
 Emitted when an error occurs during the processing of a stream on the client.
 
+`http2.client.stream.finish`
+
+* `stream` {ClientHttp2Stream}
+* `headers` {HTTP/2 Headers Object}
+* `flags` {number}
+
+Emitted when a stream is received on the client.
+
 #### Modules
 
 > Stability: 1 - Experimental

lib/internal/http2/core.js

@@ -188,6 +188,7 @@ const dc = require('diagnostics_channel');
 const onClientStreamCreatedChannel = dc.channel('http2.client.stream.created');
 const onClientStreamStartChannel = dc.channel('http2.client.stream.start');
 const onClientStreamErrorChannel = dc.channel('http2.client.stream.error');
+const onClientStreamFinishChannel = dc.channel('http2.client.stream.finish');
 
 let debug = require('internal/util/debuglog').debuglog('http2', (fn) => {
   debug = fn;
@@ -427,6 +428,15 @@ function onSessionHeaders(handle, id, cat, flags, headers, sensitiveHeaders) {
       reqAsync.runInAsyncScope(process.nextTick, null, emit, stream, event, obj, flags, headers);
     else
       process.nextTick(emit, stream, event, obj, flags, headers);
+    if ((event === 'response' ||
+         event === 'push') &&
+        onClientStreamFinishChannel.hasSubscribers) {
+      onClientStreamFinishChannel.publish({
+        stream,
+        headers: obj,
+        flags: flags,
+      });
+    }
   }
   if (endOfStream) {
     stream.push(null);

test/parallel/test-diagnostics-channel-http2-client-stream-finish.js

@@ -0,0 +1,63 @@
+'use strict';
+
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+// This test ensures that the built-in HTTP/2 diagnostics channels are reporting
+// the diagnostics messages for the 'http2.client.stream.finish' channel when
+// ClientHttp2Streams are received by both:
+// - the 'response' event
+// - the 'push' event
+
+const Countdown = require('../common/countdown');
+const assert = require('assert');
+const dc = require('diagnostics_channel');
+const http2 = require('http2');
+const { Duplex } = require('stream');
+
+const clientHttp2StreamFinishCount = 2;
+
+dc.subscribe('http2.client.stream.finish', common.mustCall(({ stream, headers, flags }) => {
+  // Since ClientHttp2Stream is not exported from any module, this just checks
+  // if the stream is an instance of Duplex and the constructor name is
+  // 'ClientHttp2Stream'.
+  assert.ok(stream instanceof Duplex);
+  assert.strictEqual(stream.constructor.name, 'ClientHttp2Stream');
+
+  assert.ok(headers && !Array.isArray(headers) && typeof headers === 'object');
+
+  assert.strictEqual(typeof flags, 'number');
+}, clientHttp2StreamFinishCount));
+
+const server = http2.createServer();
+server.on('stream', common.mustCall((stream) => {
+  stream.respond();
+  stream.end();
+
+  stream.pushStream({}, common.mustSucceed((pushStream) => {
+    pushStream.respond();
+    pushStream.end();
+  }));
+}));
+
+server.listen(0, common.mustCall(() => {
+  const port = server.address().port;
+  const client = http2.connect(`http://localhost:${port}`);
+
+  const countdown = new Countdown(clientHttp2StreamFinishCount, () => {
+    client.close();
+    server.close();
+  });
+
+  const stream = client.request({});
+  stream.on('response', common.mustCall(() => {
+    countdown.dec();
+  }));
+
+  client.on('stream', common.mustCall((pushStream) => {
+    pushStream.on('push', common.mustCall(() => {
+      countdown.dec();
+    }));
+  }));
+}));