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

Signed-off-by: Darshan Sen <raisinten@gmail.com>
PR-URL: #58560
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

Author: RaisinTen

doc/api/diagnostics_channel.md

@@ -1260,6 +1260,14 @@ Emitted when a stream is started on the server.
 
 Emitted when an error occurs during the processing of a stream on the server.
 
+`http2.server.stream.finish`
+
+*`stream` {ServerHttp2Stream}
+*`headers` {HTTP/2 Headers Object}
+*`flags` {number}
+
+Emitted when a stream is sent on the server.
+
 #### Modules
 
 > Stability: 1 - Experimental

lib/internal/http2/core.js

@@ -193,6 +193,7 @@ const onClientStreamCloseChannel = dc.channel('http2.client.stream.close');
 constonServerStreamCreatedChannel=dc.channel('http2.server.stream.created');
 constonServerStreamStartChannel=dc.channel('http2.server.stream.start');
 constonServerStreamErrorChannel=dc.channel('http2.server.stream.error');
+constonServerStreamFinishChannel=dc.channel('http2.server.stream.finish');
 
 letdebug=require('internal/util/debuglog').debuglog('http2',(fn)=>{
 debug=fn;
@@ -2917,8 +2918,17 @@ class ServerHttp2Stream extends Http2Stream {
 }
 
 constret=this[kHandle].respond(headersList,streamOptions);
-if(ret<0)
+if(ret<0){
 this.destroy(newNghttpError(ret));
+}elseif(onServerStreamFinishChannel.hasSubscribers){
+// No point in running this if the respond() call above fails because
+// that would mean that it is an invalid call.
+onServerStreamFinishChannel.publish({
+stream: this,
+ headers,
+flags: state.flags,
+});
+}
 }
 
 // Initiate a response using an open FD. Note that there are fewer

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

@@ -0,0 +1,61 @@
+'use strict';
+
+constcommon=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.server.stream.finish' channel when
+// ServerHttp2Streams#respond() sends a regular stream as well as a push stream.
+
+constCountdown=require('../common/countdown');
+constassert=require('assert');
+constdc=require('diagnostics_channel');
+consthttp2=require('http2');
+const{ Duplex }=require('stream');
+
+constserverHttp2StreamFinishCount=2;
+
+dc.subscribe('http2.server.stream.finish',common.mustCall(({ stream, headers, flags })=>{
+// Since ServerHttp2Stream is not exported from any module, this just checks
+// if the stream is an instance of Duplex and the constructor name is
+// 'ServerHttp2Stream'.
+assert.ok(streaminstanceofDuplex);
+assert.strictEqual(stream.constructor.name,'ServerHttp2Stream');
+
+assert.ok(headers&&!Array.isArray(headers)&&typeofheaders==='object');
+
+assert.strictEqual(typeofflags,'number');
+},serverHttp2StreamFinishCount));
+
+constserver=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(()=>{
+constport=server.address().port;
+constclient=http2.connect(`http://localhost:${port}`);
+
+constcountdown=newCountdown(serverHttp2StreamFinishCount,()=>{
+client.close();
+server.close();
+});
+
+conststream=client.request({});
+stream.on('response',common.mustCall(()=>{
+countdown.dec();
+}));
+
+client.on('stream',common.mustCall((pushStream)=>{
+pushStream.on('push',common.mustCall(()=>{
+countdown.dec();
+}));
+}));
+}));