1 files changed, 141 insertions, 0 deletions
diff --git a/actionpack/lib/action_controller/metal/live.rb b/actionpack/lib/action_controller/metal/live.rb
new file mode 100644
index 0000000000..32e5afa335
--- /dev/null
+++ b/actionpack/lib/action_controller/metal/live.rb
@@ -0,0 +1,141 @@
+require 'action_dispatch/http/response'
+require 'delegate'
+
+module ActionController
+  # Mix this module in to your controller, and all actions in that controller
+  # will be able to stream data to the client as it's written.
+  #
+  #   class MyController < ActionController::Base
+  #     include ActionController::Live
+  #
+  #     def stream
+  #       response.headers['Content-Type'] = 'text/event-stream'
+  #       100.times {
+  #         response.stream.write "hello world\n"
+  #         sleep 1
+  #       }
+  #       response.stream.close
+  #     end
+  #   end
+  #
+  # There are a few caveats with this use. You *cannot* write headers after the
+  # response has been committed (Response#committed? will return truthy).
+  # Calling +write+ or +close+ on the response stream will cause the response
+  # object to be committed. Make sure all headers are set before calling write
+  # or close on your stream.
+  #
+  # You *must* call close on your stream when you're finished, otherwise the
+  # socket may be left open forever.
+  #
+  # The final caveat is that your actions are executed in a separate thread than
+  # the main thread. Make sure your actions are thread safe, and this shouldn't
+  # be a problem (don't share state across threads, etc).
+  module Live
+    class Buffer < ActionDispatch::Response::Buffer #:nodoc:
+      def initialize(response)
+        super(response, SizedQueue.new(10))
+      end
+
+      def write(string)
+        unless @response.committed?
+          @response.headers["Cache-Control"] = "no-cache"
+          @response.headers.delete "Content-Length"
+        end
+
+        super
+      end
+
+      def each
+        while str = @buf.pop
+          yield str
+        end
+      end
+
+      def close
+        super
+        @buf.push nil
+      end
+    end
+
+    class Response < ActionDispatch::Response #:nodoc: all
+      class Header < DelegateClass(Hash)
+        def initialize(response, header)
+          @response = response
+          super(header)
+        end
+
+        def []=(k,v)
+          if @response.committed?
+            raise ActionDispatch::IllegalStateError, 'header already sent'
+          end
+
+          super
+        end
+
+        def merge(other)
+          self.class.new @response, __getobj__.merge(other)
+        end
+
+        def to_hash
+          __getobj__.dup
+        end
+      end
+
+      def commit!
+        headers.freeze
+        super
+      end
+
+      private
+
+      def build_buffer(response, body)
+        buf = Live::Buffer.new response
+        body.each { |part| buf.write part }
+        buf
+      end
+
+      def merge_default_headers(original, default)
+        Header.new self, super
+      end
+    end
+
+    def process(name)
+      t1 = Thread.current
+      locals = t1.keys.map { |key| [key, t1[key]] }
+
+      # This processes the action in a child thread. It lets us return the
+      # response code and headers back up the rack stack, and still process
+      # the body in parallel with sending data to the client
+      Thread.new {
+        t2 = Thread.current
+        t2.abort_on_exception = true
+
+        # Since we're processing the view in a different thread, copy the
+        # thread locals from the main thread to the child thread. :'(
+        locals.each { |k,v| t2[k] = v }
+
+        begin
+          super(name)
+        ensure
+          @_response.commit!
+        end
+      }
+
+      @_response.await_commit
+    end
+
+    def response_body=(body)
+      super
+      response.stream.close if response
+    end
+
+    def set_response!(request)
+      if request.env["HTTP_VERSION"] == "HTTP/1.0"
+        super
+      else
+        @_response         = Live::Response.new
+        @_response.request = request
+      end
+    end
+  end
+end