rev: async response bodies with DevFdResponse middleware

This new middleware should be a no-op for non-Rev concurrency
models (or by explicitly setting env['rainbows.autochunk'] to
false).

Setting env['rainbows.autochunk'] to true (the default when Rev
is used) allows (e)poll-able IO objects (sockets, pipes) to be
sent asynchronously after app.call(env) returns.

This also has a fortunate side effect of introducing a code path
which allows large, static files to be sent without slurping
them into a Rev IO::Buffer, too.  This new change works even
without the DevFdResponse middleware, so you won't have to
reconfigure your app.

This lets us epoll on response bodies that come in from a pipe
or even a socket and send them either straight through or with
chunked encoding.

1 files changed, 13 insertions, 0 deletions

diff --git a/t/async-response.ru b/t/async-response.ru
new file mode 100644
index 0000000..ef76504
--- /dev/null
+++ b/t/async-response.ru
@@ -0,0 +1,13 @@
+use Rack::Chunked
+use Rainbows::DevFdResponse
+run lambda { |env|
+  io = IO.popen('for i in 0 1 2 3 4 5 6 7 8 9; do date; sleep 1; done', 'rb')
+  io.sync = true
+  [
+    200,
+    {
+      'Content-Type' => 'text/plain',
+    },
+    io
+  ].freeze
+}