Capture HTTP/2 server active stream metrics

[samueldlightfoot]

Capture H2 active streams metrics for HttpServer.

Issue: #2356

[violetagg]

@samueldlightfoot We need to exclude these two new default methods from the compatibility check. Please add to build.gradle

diff --git a/reactor-netty-http/build.gradle b/reactor-netty-http/build.gradle
index 670c2dd5f..3c9f45049 100644
--- a/reactor-netty-http/build.gradle
+++ b/reactor-netty-http/build.gradle
@@ -197,6 +197,10 @@ task japicmp(type: JapicmpTask) {
 	ignoreMissingClasses = true
 	includeSynthetic = true
 	onlyIf { "$compatibleVersion" != "SKIP" }
+	methodExcludes = [
+			"reactor.netty.http.server.HttpServerMetricsRecorder#recordStreamClosed(java.net.SocketAddress)",
+			"reactor.netty.http.server.HttpServerMetricsRecorder#recordStreamOpened(java.net.SocketAddress)"
+	]
 }
 
 tasks.japicmp.dependsOn(downloadBaseline)

[samueldlightfoot]

Build failure on (windows-2019, nio). Not sure if this is a transient error or a real issue. @violetagg

[violetagg]

Build failure on (windows-2019, nio). Not sure if this is a transient error or a real issue. @violetagg

This is a flaky test and not relevant to this change.
Give me some time I'll come back to this PR in 1h.

[violetagg]

@reactor/netty-team PTAL
This PR is targeting main branch, I will take care to back port it to 1.0.x branch.

[pderop]

for the existing http server metrics, we currently have for example:

• reactor.netty.http.server.connections.active
• reactor.netty.http.server.connections.total
  etc ...

We use the same prefix, followed by the meaning of the meter (active, total, etc ...)

so, for consistency reasons, wouldn't it be better to use :

reactor.netty.http.server.steams.active instead of reactor.netty.http.server.active.streams ?

thanks.

[samueldlightfoot]

I agree - I'd aligned with the client-side counterpart 'reactor.netty.connection.provider.active.streams', but think it makes sense to be consistent within the server metrics.

[violetagg]

@pderop PTAL

[pderop]

LGTM
thanks @samueldlightfoot !

[violetagg]

@samueldlightfoot Thanks for the PR

I back ported the feature in 1.0.x branch with 23a9f4e