configurator: enable "rewindable_input" directive

This allows users to override the current Rack spec and disable
the rewindable input requirement.  This can allow applications
to use less I/O to minimize the performance impact when
processing uploads.

3 files changed, 46 insertions, 8 deletions

diff --git a/lib/unicorn/configurator.rb b/lib/unicorn/configurator.rb
index dd515a7..2a83dea 100644
--- a/lib/unicorn/configurator.rb
+++ b/lib/unicorn/configurator.rb
@@ -39,6 +39,7 @@ class Unicorn::Configurator
       },
     :pid => nil,
     :preload_app => false,
+    :rewindable_input => true, # for Rack 2.x: (Rack::VERSION[0] <= 1),
   }
   #:startdoc:
 
@@ -373,12 +374,22 @@ class Unicorn::Configurator
   # cause the master process to exit with an error.
 
   def preload_app(bool)
-    case bool
-    when TrueClass, FalseClass
-      set[:preload_app] = bool
-    else
-      raise ArgumentError, "preload_app=#{bool.inspect} not a boolean"
-    end
+    set_bool(:preload_app, bool)
+  end
+
+  # Toggles making <code>env["rack.input"]</code> rewindable.
+  # Disabling rewindability can improve performance by lowering
+  # I/O and memory usage for applications that accept uploads.
+  # Keep in mind that the Rack 1.x spec requires
+  # <code>env["rack.input"]</code> to be rewindable, so this allows
+  # intentionally violating the current Rack 1.x spec.
+  #
+  # +rewindable_input+ defaults to +true+ when used with Rack 1.x for
+  # Rack conformance.  When Rack 2.x is finalized, this will most
+  # likely default to +false+ while still conforming to the newer
+  # (less demanding) spec.
+  def rewindable_input(bool)
+    set_bool(:rewindable_input, bool)
   end
 
   # Allow redirecting $stderr to a given path.  Unlike doing this from
@@ -469,6 +480,15 @@ private
     end
   end
 
+  def set_bool(var, bool) #:nodoc:
+    case bool
+    when true, false
+      set[var] = bool
+    else
+      raise ArgumentError, "#{var}=#{bool.inspect} not a boolean"
+    end
+  end
+
   def set_hook(var, my_proc, req_arity = 2) #:nodoc:
     case my_proc
     when Proc
diff --git a/lib/unicorn/http_request.rb b/lib/unicorn/http_request.rb
index 2dcd839..1e3ac26 100644
--- a/lib/unicorn/http_request.rb
+++ b/lib/unicorn/http_request.rb
@@ -25,7 +25,15 @@ class Unicorn::HttpParser
   # A frozen format for this is about 15% faster
   REMOTE_ADDR = 'REMOTE_ADDR'.freeze
   RACK_INPUT = 'rack.input'.freeze
-  TeeInput = Unicorn::TeeInput
+  @@input_class = Unicorn::TeeInput
+
+  def self.input_class
+    @@input_class
+  end
+
+  def self.input_class=(klass)
+    @@input_class = klass
+  end
   # :startdoc:
 
   # Does the majority of the IO processing.  It has been written in
@@ -63,7 +71,8 @@ class Unicorn::HttpParser
         buf << socket.kgio_read!(16384)
       end while parse.nil?
     end
-    e[RACK_INPUT] = 0 == content_length ? NULL_IO : TeeInput.new(socket, self)
+    e[RACK_INPUT] = 0 == content_length ?
+                    NULL_IO : @@input_class.new(socket, self)
     e.merge!(DEFAULTS)
   end
 end
diff --git a/lib/unicorn/http_server.rb b/lib/unicorn/http_server.rb
index 69b7cc8..f0dca7c 100644
--- a/lib/unicorn/http_server.rb
+++ b/lib/unicorn/http_server.rb
@@ -355,6 +355,15 @@ class Unicorn::HttpServer
     kill_each_worker(:KILL)
   end
 
+  def rewindable_input
+    Unicorn::HttpRequest.input_class.method_defined?(:rewind)
+  end
+
+  def rewindable_input=(bool)
+    Unicorn::HttpRequest.input_class = bool ?
+                                Unicorn::TeeInput : Unicorn::StreamInput
+  end
+
   private
 
   # wait for a signal hander to wake us up and then consume the pipe