diff options
-rw-r--r-- | actioncable/CHANGELOG.md | 5 | ||||
-rw-r--r-- | actioncable/lib/action_cable/connection/stream.rb | 57 | ||||
-rw-r--r-- | actioncable/lib/action_cable/connection/stream_event_loop.rb | 46 | ||||
-rw-r--r-- | actioncable/test/stubs/test_server.rb | 4 |
4 files changed, 100 insertions, 12 deletions
diff --git a/actioncable/CHANGELOG.md b/actioncable/CHANGELOG.md index dec6f7c027..2e6c2f2afc 100644 --- a/actioncable/CHANGELOG.md +++ b/actioncable/CHANGELOG.md @@ -1,3 +1,8 @@ +* Buffer writes to websocket connections, to avoid blocking threads + that could be doing more useful things. + + *Matthew Draper*, *Tinco Andringa* + * Protect against concurrent writes to a websocket connection from multiple threads; the underlying OS write is not always threadsafe. diff --git a/actioncable/lib/action_cable/connection/stream.rb b/actioncable/lib/action_cable/connection/stream.rb index 5a2aace0ba..d66e1b4e41 100644 --- a/actioncable/lib/action_cable/connection/stream.rb +++ b/actioncable/lib/action_cable/connection/stream.rb @@ -14,6 +14,9 @@ module ActionCable @rack_hijack_io = nil @write_lock = Mutex.new + + @write_head = nil + @write_buffer = Queue.new end def each(&callback) @@ -30,14 +33,62 @@ module ActionCable end def write(data) - @write_lock.synchronize do - return @rack_hijack_io.write(data) if @rack_hijack_io - return @stream_send.call(data) if @stream_send + if @stream_send + return @stream_send.call(data) end + + if @write_lock.try_lock + begin + if @write_head.nil? && @write_buffer.empty? + written = @rack_hijack_io.write_nonblock(data, exception: false) + + case written + when :wait_writable + # proceed below + when data.bytesize + return data.bytesize + else + @write_head = data.byteslice(written, data.bytesize) + @event_loop.writes_pending @rack_hijack_io + + return data.bytesize + end + end + ensure + @write_lock.unlock + end + end + + @write_buffer << data + @event_loop.writes_pending @rack_hijack_io + + data.bytesize rescue EOFError, Errno::ECONNRESET @socket_object.client_gone end + def flush_write_buffer + @write_lock.synchronize do + loop do + if @write_head.nil? + return true if @write_buffer.empty? + @write_head = @write_buffer.pop + end + + written = @rack_hijack_io.write_nonblock(@write_head, exception: false) + case written + when :wait_writable + return false + when @write_head.bytesize + @write_head = nil + else + @write_head = @write_head.byteslice(written, @write_head.bytesize) + return false + end + end + end + end + def receive(data) @socket_object.parse(data) end diff --git a/actioncable/lib/action_cable/connection/stream_event_loop.rb b/actioncable/lib/action_cable/connection/stream_event_loop.rb index 106b948c45..eec24638b6 100644 --- a/actioncable/lib/action_cable/connection/stream_event_loop.rb +++ b/actioncable/lib/action_cable/connection/stream_event_loop.rb @@ -5,7 +5,7 @@ module ActionCable module Connection class StreamEventLoop def initialize - @nio = @thread = nil + @nio = @executor = @thread = nil @map = {} @stopping = false @todo = Queue.new @@ -20,13 +20,14 @@ module ActionCable def post(task = nil, &block) task ||= block - Concurrent.global_io_executor << task + spawn + @executor << task end def attach(io, stream) @todo << lambda do - @map[io] = stream - @nio.register(io, :r) + @map[io] = @nio.register(io, :r) + @map[io].value = stream end wakeup end @@ -39,6 +40,15 @@ module ActionCable wakeup end + def writes_pending(io) + @todo << lambda do + if monitor = @map[io] + monitor.interests = :rw + end + end + wakeup + end + def stop @stopping = true wakeup if @nio @@ -52,6 +62,13 @@ module ActionCable return if @thread && @thread.status @nio ||= NIO::Selector.new + + @executor ||= Concurrent::ThreadPoolExecutor.new( + min_threads: 1, + max_threads: 10, + max_queue: 0, + ) + @thread = Thread.new { run } return true @@ -77,12 +94,25 @@ module ActionCable monitors.each do |monitor| io = monitor.io - stream = @map[io] + stream = monitor.value begin - stream.receive io.read_nonblock(4096) - rescue IO::WaitReadable - next + if monitor.writable? + if stream.flush_write_buffer + monitor.interests = :r + end + next unless monitor.readable? + end + + incoming = io.read_nonblock(4096, exception: false) + case incoming + when :wait_readable + next + when nil + stream.close + else + stream.receive incoming + end rescue # We expect one of EOFError or Errno::ECONNRESET in # normal operation (when the client goes away). But if diff --git a/actioncable/test/stubs/test_server.rb b/actioncable/test/stubs/test_server.rb index b64ff33789..02be72d0cb 100644 --- a/actioncable/test/stubs/test_server.rb +++ b/actioncable/test/stubs/test_server.rb @@ -28,7 +28,9 @@ class TestServer @event_loop ||= if @config.use_faye ActionCable::Connection::FayeEventLoop.new else - ActionCable::Connection::StreamEventLoop.new + ActionCable::Connection::StreamEventLoop.new.tap do |loop| + loop.instance_variable_set(:@executor, Concurrent.global_io_executor) + end end end |