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

Signed-off-by: Darshan Sen <raisinten@gmail.com>
PR-URL: #58449
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>

Author: RaisinTen

doc/api/diagnostics_channel.md

@@ -1246,6 +1246,13 @@ closing the stream can be retrieved using the `stream.rstCode` property.
 
 Emitted when a stream is created on the server.
 
+`http2.server.stream.start`
+
+*`stream` {ServerHttp2Stream}
+*`headers` {HTTP/2 Headers Object}
+
+Emitted when a stream is started on the server.
+
 #### Modules
 
 > Stability: 1 - Experimental

lib/internal/http2/core.js

@@ -191,6 +191,7 @@ const onClientStreamErrorChannel = 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');
+constonServerStreamStartChannel=dc.channel('http2.server.stream.start');
 
 letdebug=require('internal/util/debuglog').debuglog('http2',(fn)=>{
 debug=fn;
@@ -373,6 +374,12 @@ function onSessionHeaders(handle, id, cat, flags, headers, sensitiveHeaders) {
 headers: obj,
 });
 }
+if(onServerStreamStartChannel.hasSubscribers){
+onServerStreamStartChannel.publish({
+ stream,
+headers: obj,
+});
+}
 if(endOfStream){
 stream.push(null);
 }
@@ -2838,7 +2845,16 @@ class ServerHttp2Stream extends Http2Stream {
 if(headRequest)
 stream[kState].flags|=STREAM_FLAGS_HEAD_REQUEST;
 
-process.nextTick(callback,null,stream,headers,0);
+process.nextTick(()=>{
+if(onServerStreamStartChannel.hasSubscribers){
+onServerStreamStartChannel.publish({
+ stream,
+ headers,
+});
+}
+
+callback(null,stream,headers,0);
+});
 
 if(onServerStreamCreatedChannel.hasSubscribers){
 onServerStreamCreatedChannel.publish({

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

@@ -0,0 +1,65 @@
+'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.start' channel only
+// after the 'http2.server.stream.created' channel.
+
+constCountdown=require('../common/countdown');
+constassert=require('assert');
+constdc=require('diagnostics_channel');
+consthttp2=require('http2');
+
+constserverHttp2StreamCreationCount=2;
+
+constmap={};
+
+dc.subscribe('http2.server.stream.created',common.mustCall(({ stream, headers })=>{
+map[stream.id]={ ...map[stream.id],'createdTime': process.hrtime.bigint()};
+},serverHttp2StreamCreationCount));
+
+dc.subscribe('http2.server.stream.start',common.mustCall(({ stream, headers })=>{
+map[stream.id]={ ...map[stream.id],'startTime': process.hrtime.bigint()};
+},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();
+
+consttimings=Object.values(map);
+assert.strictEqual(timings.length,serverHttp2StreamCreationCount);
+
+for(const{ createdTime, startTime }oftimings){
+assert.ok(createdTime<startTime);
+}
+});
+
+conststream=client.request({});
+stream.on('response',common.mustCall(()=>{
+countdown.dec();
+}));
+
+client.on('stream',common.mustCall((pushStream)=>{
+pushStream.on('push',common.mustCall(()=>{
+countdown.dec();
+}));
+}));
+}));

test/parallel/test-diagnostics-channel-http2-server-stream-start.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.start' channel when
+// ServerHttp2Streams are started 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.start',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();
+}));
+}));
+}));