Re: [PATCH] check_client_connection: use tcp state on linux

[Eric Wong <e@80x24.org>]

Simon Eskildsen <simon.eskildsen@shopify.com> wrote:
> Here's another update Eric!

Thanks, a few teeny issues fixed up locally (but commented
inline, below).

However, there's a bigger problem which I'm Cc:-ing Aman about
for tmm1/gctools changing process_client in the internal API.

I won't burden him maintaining extra versions, nor will I force
users to use a certain version of unicorn or gctools to match.

Aman: for reference, relevant messages in the archives:

https://bogomips.org/unicorn-public/?q=d:20170222-+check_client_connection&x=t

(TL;DR: I don't expect Aman will have to do anything,
 just keeping him in the loop)

> +++ b/lib/unicorn/http_server.rb
> @@ -558,8 +558,8 @@ def e100_response_write(client, env)
> 
>    # once a client is accepted, it is processed in its entirety here
>    # in 3 easy steps: read request, call app, write app response
> -  def process_client(client)
> -    status, headers, body = @app.call(env = @request.read(client))
> +  def process_client(client, listener)
> +    status, headers, body = @app.call(env = @request.read(client, listener))

I can squash this fix in, locally:

diff --git a/lib/unicorn/oob_gc.rb b/lib/unicorn/oob_gc.rb
index 5572e59..74a1d51 100644
--- a/lib/unicorn/oob_gc.rb
+++ b/lib/unicorn/oob_gc.rb
@@ -67,8 +67,8 @@ def self.new(app, interval = 5, path = %r{\A/})
 
   #:stopdoc:
   PATH_INFO = "PATH_INFO"
-  def process_client(client)
-    super(client) # Unicorn::HttpServer#process_client
+  def process_client(client, listener)
+    super(client, listener) # Unicorn::HttpServer#process_client
     if OOBGC_PATH =~ OOBGC_ENV[PATH_INFO] && ((@@nr -= 1) <= 0)
       @@nr = OOBGC_INTERVAL
       OOBGC_ENV.clear

However, https://github.com/tmm1/gctools also depends on this
undocumented internal API of ours; and I will not consider
breaking it for release...

Pushed to the "ccc-tcp" branch @ git://bogomips.org/unicorn
(commit beaee769c6553bf4e0260be2507b8235f0aa764f)

>      begin
>        return if @request.hijacked?
> @@ -655,7 +655,7 @@ def worker_loop(worker)
>          # Unicorn::Worker#kgio_tryaccept is not like accept(2) at all,
>          # but that will return false
>          if client = sock.kgio_tryaccept
> -          process_client(client)
> +          process_client(client, sock)
>            nr += 1
>            worker.tick = time_now.to_i
>          end


> @@ -28,6 +29,7 @@ class Unicorn::HttpParser
>    # Drop these frozen strings when Ruby 2.2 becomes more prevalent,
>    # 2.2+ optimizes hash assignments when used with literal string keys
>    HTTP_RESPONSE_START = [ 'HTTP', '/1.1 ']
> +  EMPTY_ARRAY = [].freeze

(minor) this was made before commit e06b699683738f22
("http_request: freeze constant strings passed IO#write")
but I've trivially fixed it up, locally.

> +    def check_client_connection(socket, listener) # :nodoc:
> +      if Kgio::TCPServer === listener
> +        @@tcp_info ||= Raindrops::TCP_Info.new(socket)
> +        @@tcp_info.get!(socket)
> +        raise Errno::EPIPE, "client closed connection".freeze,
> EMPTY_ARRAY if closed_state?(@@tcp_info.state)

(minor) I needed to wrap that line since I use gigantic fonts
(fixed up locally)