add "copy_stream" config directive

This allows using IO::Splice.copy_stream from the "io_splice"
RubyGem on recent Linux systems.  This also allows users to
disable copy_stream usage entirely and use traditional
response_body.each calls which are compatible with all Rack
servers (to workaround bugs in IO.copy_stream under 1.9.2-p180).

5 files changed, 53 insertions, 12 deletions

diff --git a/lib/rainbows/configurator.rb b/lib/rainbows/configurator.rb
index 29d905b..a1d90cb 100644
--- a/lib/rainbows/configurator.rb
+++ b/lib/rainbows/configurator.rb
@@ -27,6 +27,7 @@ module Rainbows::Configurator
     :keepalive_requests => 100,
     :client_max_body_size => 1024 * 1024,
     :client_header_buffer_size => 1024,
+    :copy_stream => IO.respond_to?(:copy_stream) ? IO : false,
   })
 
   # Configures \Rainbows! with a given concurrency model to +use+ and
@@ -161,6 +162,44 @@ module Rainbows::Configurator
     check!
     set_int(:client_header_buffer_size, bytes, 1)
   end
+
+  # Allows overriding the +klass+ where the +copy_stream+ method is
+  # used to do efficient copying of regular files, pipes, and sockets.
+  #
+  # This is only used with multi-threaded concurrency models:
+  #
+  # * ThreadSpawn
+  # * ThreadPool
+  # * WriterThreadSpawn
+  # * WriterThreadPool
+  # * XEpollThreadSpawn
+  # * XEpollThreadPool
+  #
+  # Due to existing {bugs}[http://redmine.ruby-lang.org/search?q=copy_stream]
+  # in the Ruby IO.copy_stream implementation, \Rainbows! uses the
+  # "sendfile" RubyGem that instead of copy_stream to transfer regular files
+  # to clients.  The "sendfile" RubyGem also supports more operating systems,
+  # and works with more concurrency models.
+  #
+  # Recent Linux 2.6 users may override this with "IO::Splice" from the
+  # "io_splice" RubyGem:
+  #
+  #   require "io/splice"
+  #   Rainbows! do
+  #     copy_stream IO::Splice
+  #   end
+  #
+  # Keep in mind that splice(2) itself is a relatively new system call
+  # and has been buggy in many older Linux kernels.
+  #
+  # Default: IO on Ruby 1.9+, false otherwise
+  def copy_stream(klass)
+    check!
+    if klass && ! klass.respond_to?(:copy_stream)
+      abort "#{klass} must respond to `copy_stream' or be `false'"
+    end
+    set[:copy_stream] = klass
+  end
 end
 
 # :enddoc:
diff --git a/lib/rainbows/http_server.rb b/lib/rainbows/http_server.rb
index 62a5927..0fbc38f 100644
--- a/lib/rainbows/http_server.rb
+++ b/lib/rainbows/http_server.rb
@@ -2,6 +2,7 @@
 # :enddoc:
 
 class Rainbows::HttpServer < Unicorn::HttpServer
+  attr_accessor :copy_stream
   attr_accessor :worker_connections
   attr_accessor :keepalive_timeout
   attr_accessor :client_header_buffer_size
diff --git a/lib/rainbows/response.rb b/lib/rainbows/response.rb
index 65599e9..fac2c0e 100644
--- a/lib/rainbows/response.rb
+++ b/lib/rainbows/response.rb
@@ -6,6 +6,7 @@ module Rainbows::Response
   KeepAlive = "keep-alive"
   Content_Length = "Content-Length".freeze
   Transfer_Encoding = "Transfer-Encoding".freeze
+  Rainbows.config!(self, :copy_stream)
 
   # private file class for IO objects opened by Rainbows! itself (and not
   # the app or middleware)
@@ -67,7 +68,7 @@ module Rainbows::Response
     end
 
     # generic response writer, used for most dynamically-generated responses
-    # and also when IO.copy_stream and/or IO#trysendfile is unavailable
+    # and also when copy_stream and/or IO#trysendfile is unavailable
     def write_response(status, headers, body, alive)
       write_headers(status, headers, alive)
       write_body_each(body)
@@ -89,29 +90,29 @@ module Rainbows::Response
     include Sendfile
   end
 
-  if IO.respond_to?(:copy_stream)
+  if COPY_STREAM
     unless IO.method_defined?(:trysendfile)
       module CopyStream
         def write_body_file(body, range)
-          range ? IO.copy_stream(body, self, range[1], range[0]) :
-                  IO.copy_stream(body, self, nil, 0)
+          range ? COPY_STREAM.copy_stream(body, self, range[1], range[0]) :
+                  COPY_STREAM.copy_stream(body, self, nil, 0)
         end
       end
       include CopyStream
     end
 
-    # write_body_stream is an alias for write_body_each if IO.copy_stream
+    # write_body_stream is an alias for write_body_each if copy_stream
     # isn't used or available.
     def write_body_stream(body)
-      IO.copy_stream(io = body_to_io(body), self)
+      COPY_STREAM.copy_stream(io = body_to_io(body), self)
       ensure
         close_if_private(io)
     end
-  else # ! IO.respond_to?(:copy_stream)
+  else # ! COPY_STREAM
     alias write_body_stream write_body_each
-  end  # ! IO.respond_to?(:copy_stream)
+  end  # ! COPY_STREAM
 
-  if IO.method_defined?(:trysendfile) || IO.respond_to?(:copy_stream)
+  if IO.method_defined?(:trysendfile) || COPY_STREAM
     HTTP_RANGE = 'HTTP_RANGE'
     Content_Range = 'Content-Range'.freeze
 
@@ -181,5 +182,5 @@ module Rainbows::Response
       end
     end
     include ToPath
-  end # IO.respond_to?(:copy_stream) || IO.method_defined?(:trysendfile)
+  end # COPY_STREAM || IO.method_defined?(:trysendfile)
 end
diff --git a/lib/rainbows/writer_thread_pool/client.rb b/lib/rainbows/writer_thread_pool/client.rb
index f02826e..fd537ed 100644
--- a/lib/rainbows/writer_thread_pool/client.rb
+++ b/lib/rainbows/writer_thread_pool/client.rb
@@ -18,7 +18,7 @@ class Rainbows::WriterThreadPool::Client < Struct.new(:to_io, :q)
       }
     end
 
-    if IO.respond_to?(:copy_stream) || IO.method_defined?(:trysendfile)
+    if Rainbows::Response::COPY_STREAM
       def write_response(status, headers, body, alive)
         if body.respond_to?(:close)
           write_response_close(status, headers, body, alive)
diff --git a/lib/rainbows/writer_thread_spawn/client.rb b/lib/rainbows/writer_thread_spawn/client.rb
index e5c8854..de51c17 100644
--- a/lib/rainbows/writer_thread_spawn/client.rb
+++ b/lib/rainbows/writer_thread_spawn/client.rb
@@ -21,7 +21,7 @@ class Rainbows::WriterThreadSpawn::Client < Struct.new(:to_io, :q, :thr)
       }
     end
 
-    if IO.respond_to?(:copy_stream) || IO.method_defined?(:trysendfile)
+    if Rainbows::Response::COPY_STREAM
       def write_response(status, headers, body, alive)
         self.q ||= queue_writer
         if body.respond_to?(:close)