race condition in http/2 around connection preface

Expected behavior

h2 clients should buffer messages until after the connection preface has been sent

Actual behavior

h2 will try to write http/2 frames before writing the connection preface.

Steps to reproduce

Construct a netty pipeline, add an http2connectionhandler, call connect, then immediately try writing an http/2 message.

Minimal yet complete reproducer code (or URL to code)

Remove this line: https://github.com/twitter/finagle/blob/develop/finagle-http2/src/main/scala/com/twitter/finagle/http2/Http2Transporter.scala#L113 and then try running our test suite.

https://github.com/twitter/finagle

Netty version

4.1.7 (goes back as far as 4.1.0, I think)

JVM version (e.g. java -version)

8

OS version (e.g. uname -a)

Darwin tw-172-25-138-25.office.twttr.net 14.5.0 Darwin Kernel Version 14.5.0: Sun Sep 25 22:07:15 PDT 2016; root:xnu-2782.50.9~1/RELEASE_X86_64 x86_64

[mosesn]

OK, this isn’t high priority for us, since we have something working, but I’ll see if I can schedule some time for a PR for this.

[mosesn]

@Scottmitch I almost forgot–the reason I filed this ticket was because I found that it wasn’t always triggered on channelActive, so right now I have to try to guess when the preface will be sent. As an example, if I’m using ALPN to decide whether to install the http/2 connection handler or not, when I add the handler, channelActive has already been triggered, so instead it sends the connection preface on handlerAdded. This means I need a different buffering handler depending upon how it’s added to the pipeline.