adding a buffered stream to the response object

actionpack/lib/action_controller/metal.rb

@@ -187,7 +187,7 @@ module ActionController
     end
 
     def performed?
-      !!response_body
+      response_body || (response && response.committed?)
     end
 
     def dispatch(name, request) #:nodoc:

actionpack/lib/action_dispatch/http/response.rb

@@ -65,6 +65,36 @@ module ActionDispatch # :nodoc:
     include ActionDispatch::Http::Cache::Response
     include MonitorMixin
 
+    class Buffer # :nodoc:
+      def initialize(response, buf)
+        @response = response
+        @buf      = buf
+        @closed   = false
+      end
+
+      def write(string)
+        raise IOError, "closed stream" if closed?
+
+        @response.commit!
+        @buf.push string
+      end
+
+      def each(&block)
+        @buf.each(&block)
+      end
+
+      def close
+        @response.commit!
+        @closed = true
+      end
+
+      def closed?
+        @closed
+      end
+    end
+
+    attr_reader :stream
+
     def initialize(status = 200, header = {}, body = [])
       super()
 
@@ -76,6 +106,8 @@ module ActionDispatch # :nodoc:
       @committed    = false
       @content_type = nil
       @charset      = nil
+      @stream       = build_buffer self, @body
+
 
       if content_type = self[CONTENT_TYPE]
         type, charset = content_type.split(/;\s*charset=/)
@@ -102,7 +134,7 @@ module ActionDispatch # :nodoc:
     end
 
     def committed?
-      synchronize { @committed }
+      @committed
     end
 
     def status=(status)
@@ -151,7 +183,7 @@ module ActionDispatch # :nodoc:
     def body=(body)
       @blank = true if body == EMPTY
 
-      @body = body.respond_to?(:each) ? body : [body]
+      @body = munge_body_object(body)
     end
 
     def body_parts
@@ -214,6 +246,14 @@ module ActionDispatch # :nodoc:
 
   private
 
+    def build_buffer(response, body)
+      Buffer.new response, body
+    end
+
+    def munge_body_object(body)
+      body.respond_to?(:each) ? body : [body]
+    end
+
     def assign_default_content_type_and_charset!
       return if headers[CONTENT_TYPE].present?
 

actionpack/test/controller/streaming_test.rb

@@ -0,0 +1,30 @@
+require 'abstract_unit'
+
+module ActionController
+  class StreamingResponseTest < ActionController::TestCase
+    class TestController < ActionController::Base
+      def self.controller_path
+        'test'
+      end
+
+      def basic_stream
+        %w{ hello world }.each do |word|
+          response.stream.write word
+          response.stream.write "\n"
+        end
+        response.stream.close
+      end
+    end
+
+    tests TestController
+
+    def test_write_to_stream
+      get :basic_stream
+      assert_equal "hello\nworld\n", @response.body
+    end
+
+    def test_write_after_close
+      @response.stream
+    end
+  end
+end

actionpack/test/dispatch/response_test.rb

@@ -14,6 +14,26 @@ class ResponseTest < ActiveSupport::TestCase
     assert t.join(0.5)
   end
 
+  def test_stream_close
+    @response.stream.close
+    assert @response.stream.closed?
+  end
+
+  def test_stream_write
+    @response.stream.write "foo"
+    @response.stream.close
+    assert_equal "foo", @response.body
+  end
+
+  def test_write_after_close
+    @response.stream.close
+
+    e = assert_raises(IOError) do
+      @response.stream.write "omg"
+    end
+    assert_equal "closed stream", e.message
+  end
+
   def test_response_body_encoding
     body = ["hello".encode('utf-8')]
     response = ActionDispatch::Response.new 200, {}, body