unicorn Ruby/Rack server user+dev discussion/patches/pulls/bugs/help
 help / color / Atom feed
From: Eric Wong <e@80x24.org>
To: Simon Eskildsen <simon.eskildsen@shopify.com>
Cc: unicorn-public@bogomips.org
Subject: Re: [PATCH] check_client_connection: use tcp state on linux
Date: Tue, 28 Feb 2017 21:12:54 +0000
Message-ID: <20170228211254.GA3868@whir> (raw)
In-Reply-To: <CAO3HKM6H33D5=3=TwPJYKST26dkVyh4dkfebxFpf5c7h+jv7XQ@mail.gmail.com>

Simon Eskildsen <simon.eskildsen@shopify.com> wrote:

<snip>
> I would assume you would see TIME_WAIT and CLOSE. LAST_ACK_CLOSING it
> seems pretty unlikely to hit, but not impossible. As with CLOSING,
> I've included LAST_ACK_CLOSING for completeness.

Did you mean "LAST_ACK, and CLOSING"? (not joined by underscore)

Anyways, thanks for testing and adding

> <e@80x24.org> wrote:
> > Yep, we need to account for the UNIX socket case.  I forget if
> > kgio even makes them different...
> 
> I read the implementation and verified by dumping the class when
> testing on some test boxes. You are right—it's a simple Kgio::Socket
> object, not differentiating between Kgio::TCPSocket and
> Kgio::UnixSocket at the class level. Kgio only does this if they're
> explicitly passed to override the class returned from #try_accept.
> Unicorn doesn't do this.
> 
> I've tried to find a way to determine the socket domain (INET vs.
> UNIX) on the socket object, but neither Ruby's Socket class nor Kgio
> seems to expose this. I'm not entirely sure what the simplest way to
> do this check would be. We could have the accept loop pass the correct
> class to #try_accept based on the listening socket that came back from
> #accept. If we passed the listening socket to #read after accept, we'd
> know.. but I don't like that the request knows about the listener
> either. Alternatively, we could expose the socket domain in Kgio, but
> that'll be problematic in the near-ish future as you've mentioned
> wanting to move away from Kgio as Ruby's IO library is at parity as
> per Ruby 2.4.
> 
> What do you suggest pursuing here to check whether the client socket
> is a TCP socket?

I think passing the listening socket is the best way to go about
detecting whether a socket is INET or UNIX, for now.

You're right about kgio, I'd rather not make more changes to
kgio but we will still need it to for Ruby <2.2.x users.

And #read is an overloaded name, feel free to change it :)

> Below is a patch addressing the other concerns. I had to include
> require raindrops so the `defined?` check would do the right thing, as
> the only other file that requires Raindrops is the worker one which is
> loaded after http_request. I can change the load-order or require
> raindrops in lib/unicorn.rb if you prefer.

The require is fine.  However we do not need a class variable,
below...

>  # TODO: remove redundant names
>  Unicorn.const_set(:HttpRequest, Unicorn::HttpParser)
> @@ -29,6 +30,7 @@ class Unicorn::HttpParser
>    # 2.2+ optimizes hash assignments when used with literal string keys
>    HTTP_RESPONSE_START = [ 'HTTP', '/1.1 ']
>    @@input_class = Unicorn::TeeInput
> +  @@raindrops_tcp_info_defined = defined?(Raindrops::TCP_Info)

I prefer we avoid adding this cvar, instead...

>    @@check_client_connection = false
> 
>    def self.input_class
> @@ -83,11 +85,7 @@ def read(socket)
>        false until add_parse(socket.kgio_read!(16384))
>      end
> 
> -    # detect if the socket is valid by writing a partial response:
> -    if @@check_client_connection && headers?
> -      self.response_start_sent = true
> -      HTTP_RESPONSE_START.each { |c| socket.write(c) }
> -    end
> +    check_client_connection(socket) if @@check_client_connection
> 
>      e['rack.input'] = 0 == content_length ?
>                        NULL_IO : @@input_class.new(socket, self)
> @@ -108,4 +106,27 @@ def call
>    def hijacked?
>      env.include?('rack.hijack_io'.freeze)
>    end

... we can have different methods defined:

   if defined?(Raindrops::TCP_Info) # Linux, maybe FreeBSD
     def check_client_connection(client, listener) # :nodoc:
     ...
     end
   else # portable version
     def check_client_connection(client, listener) # :nodoc:
     ...
     end
   end

And eliminate the class variable entirely.

> +
> +  private

I prefer to avoid marking methods as 'private' to ease any
ad-hoc unit testing which may come up.  Instead, rely on :nodoc:
directives to discourage people from depending on it.

Thanks.

> +  def check_client_connection(socket)
> +    if @@raindrops_tcp_info_defined
> +      tcp_info = Raindrops::TCP_Info.new(socket)
> +      raise Errno::EPIPE, "client closed connection".freeze, [] if
> closed_state?(tcp_info.state)
> +    elsif headers?
> +      self.response_start_sent = true
> +      HTTP_RESPONSE_START.each { |c| socket.write(c) }
> +    end
> +  end
> +
> +  def closed_state?(state)
> +    case state
> +    when 1 # ESTABLISHED
> +      false
> +    when 6, 7, 8, 9, 11 # TIME_WAIT, CLOSE, CLOSE_WAIT, LAST_ACK, CLOSING
> +      true
> +    else
> +      false
> +    end
> +  end
>  end

closed_state? looks good to me, good call on short-circuiting
the common case of ESTABLISHED!

  reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-25 14:03 Simon Eskildsen
2017-02-25 16:19 ` Simon Eskildsen
2017-02-25 23:12   ` Eric Wong
2017-02-27 11:44     ` Simon Eskildsen
2017-02-28 21:12       ` Eric Wong [this message]
2017-03-01  3:18         ` Eric Wong
2017-03-06 21:32           ` Simon Eskildsen
2017-03-07 22:50             ` Eric Wong
2017-03-08  0:26               ` Eric Wong
2017-03-08 12:06                 ` Simon Eskildsen
2017-03-13 20:16                   ` Simon Eskildsen
2017-03-13 20:37                     ` Eric Wong
2017-03-14 16:14                       ` Simon Eskildsen
2017-03-14 16:41                         ` Eric Wong

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://bogomips.org/unicorn/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170228211254.GA3868@whir \
    --to=e@80x24.org \
    --cc=simon.eskildsen@shopify.com \
    --cc=unicorn-public@bogomips.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

unicorn Ruby/Rack server user+dev discussion/patches/pulls/bugs/help

Archives are clonable:
	git clone --mirror https://bogomips.org/unicorn-public
	git clone --mirror http://ou63pmih66umazou.onion/unicorn-public

Newsgroups are available over NNTP:
	nntp://news.public-inbox.org/inbox.comp.lang.ruby.unicorn
	nntp://ou63pmih66umazou.onion/inbox.comp.lang.ruby.unicorn

 note: .onion URLs require Tor: https://www.torproject.org/

AGPL code for this site: git clone https://public-inbox.org/ public-inbox