configurator: per-listener backlog, {rcv,snd}buf config

Instead of having global options for all listeners,
make all socket options per-listener.  This allows
reverse-proxies to pick different listeners to get
different options on different sockets.

  Given a cluster of machines (10.0.0.1, 10.0.0.2, 10.0.0.3)
  running Unicorn with the following config:

  ------------------ 8< ----------------
  listen "/tmp/local.sock", :backlog => 1
  listen "*:8080" # use the backlog=1024 default
  ------------------ 8< ----------------

  It is possible to configure a reverse proxy to try to use
  "/tmp/local.sock" first and then fall back to using the
  TCP listener on port 8080 in a failover configuration.

  Thus the nginx upstream configuration on 10.0.0.1 to
  compliment this would be:
  ------------------ 8< ----------------
  upstream unicorn_cluster {
    # reject connections ASAP if we are overloaded
    server unix:/tmp/local.sock;

    # fall back to other machines in the cluster via "backup"
    # listeners which have a large backlog queue.
    server 10.0.0.2:8080 backup;
    server 10.0.0.3:8080 backup;
  }
  ------------------ 8< ----------------

This removes the global "backlog" config option which
was inflexible with multiple machines in a cluster
and exposes the ability to change SO_SNDBUF/SO_RCVBUF
via setsockopt(2) for the first time.

1 files changed, 2 insertions, 1 deletions

diff --git a/lib/unicorn.rb b/lib/unicorn.rb
index 34189ef..d56f251 100644
--- a/lib/unicorn.rb
+++ b/lib/unicorn.rb
@@ -59,6 +59,7 @@ module Unicorn
       @request = @rd_sig = @wr_sig = nil
       @reexec_pid = 0
       @config = Configurator.new(options.merge(:use_defaults => true))
+      @listener_opts = {}
       @config.commit!(self, :skip => [:listeners, :pid])
       @listeners = []
     end
@@ -135,7 +136,7 @@ module Unicorn
     def listen(address)
       return if String === address && listener_names.include?(address)
 
-      if io = bind_listen(address, { :backlog => @backlog })
+      if io = bind_listen(address, @listener_opts[address] || {})
         if Socket == io.class
           @io_purgatory << io
           io = server_cast(io)