Don't buffer things that shouldn't be buffered.

Author: ioquatix

actionpack/lib/action_dispatch/http/response.rb

@@ -116,7 +116,11 @@ def respond_to?(method, include_private = false)
       end
 
       def to_ary
-        @buf.to_ary
+        if @str_body
+          [body]
+        else
+          @buf = @buf.to_ary
+        end
       end
 
       def body
@@ -336,7 +340,13 @@ def message
     # Returns the content of the response as a string. This contains the contents of
     # any calls to `render`.
     def body
-      @stream.body
+      if @stream.respond_to?(:to_ary)
+        @stream.to_ary.join
+      elsif @stream.respond_to?(:body)
+        @stream.body
+      else
+        @stream
+      end
     end
 
     def write(string)
@@ -345,12 +355,16 @@ def write(string)
 
     # Allows you to manually set or override the response body.
     def body=(body)
-      if body.respond_to?(:to_path)
+      if body.is_a?(String)
+        @stream = build_buffer(self, [body])
+      elsif body.respond_to?(:to_path)
         @stream = body
-      else
+      elsif body.respond_to?(:to_ary)
         synchronize do
-          @stream = build_buffer self, munge_body_object(body)
+          @stream = build_buffer(self, body)
         end
+      else
+        @stream = body
       end
     end
 
@@ -490,10 +504,6 @@ 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 media_type
 

actionpack/test/dispatch/response_test.rb

@@ -42,7 +42,12 @@ def test_write_after_close
   def test_each_isnt_called_if_str_body_is_written
     # Controller writes and reads response body
     each_counter = 0
-    @response.body = Object.new.tap { |o| o.singleton_class.define_method(:each) { |&block| each_counter += 1; block.call "foo" } }
+
+    @response.body = Object.new.tap do |object|
+      object.singleton_class.define_method(:each) { |&block| each_counter += 1; block.call "foo" }
+      object.singleton_class.define_method(:to_ary) { enum_for(:each).to_a }
+    end
+
     @response["X-Foo"] = @response.body
 
     assert_equal 1, each_counter, "#each was not called once"
@@ -647,4 +652,17 @@ class ResponseIntegrationTest < ActionDispatch::IntegrationTest
     assert_equal("utf-8", @response.charset)
     assert_equal("012345678910", @response.body)
   end
+
+  test "response does not buffer enumerator body" do
+    # This is an enumerable body, and it should not be buffered:
+    body = Enumerator.new do |enumerator|
+      enumerator << "Hello World"
+    end
+
+    # The response created here should not attempt to buffer the body:
+    response = ActionDispatch::Response.new(200, { "content-type" => "text/plain" }, body)
+
+    # The body should be the same enumerator object, i.e. it should be passed through unchanged:
+    assert_equal body, response.body
+  end
 end

actionview/lib/action_view/renderer/streaming_template_renderer.rb

@@ -25,6 +25,13 @@ def each(&block)
         self
       end
 
+      # Returns the complete body as a string.
+      def body
+        buffer = String.new
+        each { |part| buffer << part }
+        buffer
+      end
+
       private
         # This is the same logging logic as in ShowExceptions middleware.
         def log_error(exception)