Prefer to use Fiber#transfer for reading/writing streaming chunks. (#…

…16)

lib/protocol/rack/body/streaming.rb

@@ -22,22 +22,38 @@ def initialize(block, input = nil)
 				class Output
 					def initialize(input, block)
 						stream = ::Protocol::HTTP::Body::Stream.new(input, self)
-						@fiber = Fiber.new do
+
+						@from = nil
+
+						@fiber = Fiber.new do |from|
+							@from = from
 							block.call(stream)
 							@fiber = nil
 						end
 					end
 
 					def write(chunk)
-						Fiber.yield(chunk)
+						if from = @from
+							@from = nil
+							@from = from.transfer(chunk)
+						else
+							raise RuntimeError, "Stream is not being read!"
+						end
 					end
 
 					def close
 						@fiber = nil
+
+						if from = @from
+							@from = nil
+							from.transfer(nil)
+						end
 					end
 
 					def read
-						@fiber&.resume
+						raise RuntimeError, "Stream is already being read!" if @from
+
+						@fiber&.transfer(Fiber.current)
 					end
 				end
 

test/protocol/rack/body/streaming.rb

@@ -38,4 +38,18 @@
 			expect(stream.string).to be == "HelloWorld"
 		end
 	end
+
+	with "nested fiber" do
+		let(:block) do
+			proc do |stream|
+				Fiber.new do
+					stream.write("Hello")
+				end.resume
+			end
+		end
+
+		it "can read a chunk" do
+			expect(body.read).to be == "Hello"
+		end
+	end
 end