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

doc/api/diagnostics_channel.md

@@ -1217,6 +1217,13 @@ Emitted when a stream is created on the client.
 
 Emitted when a stream is started on the client.
 
+`http2.client.stream.close`
+
+* `stream` {ClientHttp2Stream}
+
+Emitted when a stream is closed on the client. The HTTP/2 error code used when
+closing the stream can be retrieved using the `stream.rstCode` property.
+
 #### Modules
 
 > Stability: 1 - Experimental

lib/internal/http2/core.js

@@ -187,6 +187,7 @@ const { _connectionListener: httpConnectionListener } = http;
 const dc = require('diagnostics_channel');
 const onClientStreamCreatedChannel = dc.channel('http2.client.stream.created');
 const onClientStreamStartChannel = dc.channel('http2.client.stream.start');
+const onClientStreamCloseChannel = dc.channel('http2.client.stream.close');
 
 let debug = require('internal/util/debuglog').debuglog('http2', (fn) => {
   debug = fn;
@@ -1968,6 +1969,7 @@ const kSubmitRstStream = 1;
 const kForceRstStream = 2;
 
 function closeStream(stream, code, rstStreamStatus = kSubmitRstStream) {
+  const type = stream[kSession][kType];
   const state = stream[kState];
   state.flags |= STREAM_FLAGS_CLOSED;
   state.rstCode = code;
@@ -1998,6 +2000,11 @@ function closeStream(stream, code, rstStreamStatus = kSubmitRstStream) {
     else
       stream.once('finish', finishFn);
   }
+
+  if (type === NGHTTP2_SESSION_CLIENT &&
+      onClientStreamCloseChannel.hasSubscribers) {
+    onClientStreamCloseChannel.publish({ stream });
+  }
 }
 
 function finishCloseStream(code) {

test/parallel/test-diagnostics-channel-http2-client-stream-close-error.js

@@ -0,0 +1,44 @@
+'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.close' channel when
+// a ClientHttp2Stream is destroyed because of an error.
+
+const assert = require('assert');
+const dc = require('diagnostics_channel');
+const http2 = require('http2');
+const { Duplex } = require('stream');
+
+dc.subscribe('http2.client.stream.close', common.mustCall(({ stream }) => {
+  // 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.strictEqual(stream.closed, true);
+  assert.strictEqual(stream.destroyed, true);
+
+  assert.strictEqual(stream.rstCode, http2.constants.NGHTTP2_CANCEL);
+}));
+
+const server = http2.createServer();
+server.listen(0, common.mustCall(() => {
+  const port = server.address().port;
+  const client = http2.connect(`http://localhost:${port}`);
+
+  const ac = new AbortController();
+  const stream = client.request({}, { signal: ac.signal });
+  ac.abort();
+
+  stream.on('error', common.mustCall((err) => {
+    assert.strictEqual(err.code, 'ABORT_ERR');
+    assert.strictEqual(err.name, 'AbortError');
+
+    client.close();
+    server.close();
+  }));
+}));

test/parallel/test-diagnostics-channel-http2-client-stream-close.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.close' channel when
+// ClientHttp2Streams created by these actions are closed:
+// - the client calling ClientHttp2Session#request()
+// - in response to an incoming 'push' event from the server
+
+const Countdown = require('../common/countdown');
+const assert = require('assert');
+const dc = require('diagnostics_channel');
+const http2 = require('http2');
+const { Duplex } = require('stream');
+
+const clientHttp2StreamCloseCount = 2;
+
+dc.subscribe('http2.client.stream.close', common.mustCall(({ stream }) => {
+  // 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.strictEqual(stream.closed, true);
+  assert.strictEqual(stream.destroyed, false);
+
+  assert.strictEqual(stream.rstCode, http2.constants.NGHTTP2_NO_ERROR);
+}, clientHttp2StreamCloseCount));
+
+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(clientHttp2StreamCloseCount, () => {
+    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();
+    }));
+  }));
+}));