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

Signed-off-by: Darshan Sen <raisinten@gmail.com>
PR-URL: #58390
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: RaisinTen

doc/api/diagnostics_channel.md

@@ -1239,6 +1239,13 @@ Emitted when a stream is received on the client.
 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.
 
+`http2.server.stream.created`
+
+*`stream` {ServerHttp2Stream}
+*`headers` {HTTP/2 Headers Object}
+
+Emitted when a stream is created on the server.
+
 #### Modules
 
 > Stability: 1 - Experimental

lib/internal/http2/core.js

@@ -190,6 +190,7 @@ const onClientStreamStartChannel = dc.channel('http2.client.stream.start');
 constonClientStreamErrorChannel=dc.channel('http2.client.stream.error');
 constonClientStreamFinishChannel=dc.channel('http2.client.stream.finish');
 constonClientStreamCloseChannel=dc.channel('http2.client.stream.close');
+constonServerStreamCreatedChannel=dc.channel('http2.server.stream.created');
 
 letdebug=require('internal/util/debuglog').debuglog('http2',(fn)=>{
 debug=fn;
@@ -367,6 +368,12 @@ function onSessionHeaders(handle, id, cat, flags, headers, sensitiveHeaders) {
 if(type===NGHTTP2_SESSION_SERVER){
 // eslint-disable-next-line no-use-before-define
 stream=newServerHttp2Stream(session,handle,id,{},obj);
+if(onServerStreamCreatedChannel.hasSubscribers){
+onServerStreamCreatedChannel.publish({
+ stream,
+headers: obj,
+});
+}
 if(endOfStream){
 stream.push(null);
 }
@@ -2835,6 +2842,13 @@ class ServerHttp2Stream extends Http2Stream {
 stream[kState].flags|=STREAM_FLAGS_HEAD_REQUEST;
 
 process.nextTick(callback,null,stream,headers,0);
+
+if(onServerStreamCreatedChannel.hasSubscribers){
+onServerStreamCreatedChannel.publish({
+ stream,
+ headers,
+});
+}
 }
 
 // Initiate a response on this Http2Stream

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

@@ -0,0 +1,60 @@
+'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.created' channel when
+// ServerHttp2Streams are created by both:
+// - in response to an incoming 'stream' event from the client
+// - the server calling ServerHttp2Stream#pushStream()
+
+constCountdown=require('../common/countdown');
+constassert=require('assert');
+constdc=require('diagnostics_channel');
+consthttp2=require('http2');
+const{ Duplex }=require('stream');
+
+constserverHttp2StreamCreationCount=2;
+
+dc.subscribe('http2.server.stream.created',common.mustCall(({ stream, headers })=>{
+// 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');
+},serverHttp2StreamCreationCount));
+
+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(serverHttp2StreamCreationCount,()=>{
+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();
+}));
+}));
+}));