expose a ControlPing api

document transports

properly handle connection flow control tracking.

src/proto/connection.rs

@@ -1,7 +1,7 @@
 use {ConnectionError, Frame, FrameSize};
 use client::Client;
 use frame::{self, SettingSet, StreamId};
-use proto::{self, ControlSettings, Peer, ReadySink, ControlFlow, WindowSize};
+use proto::{self, ControlFlow, ControlPing, ControlSettings, Peer, PingPayload, ReadySink, WindowSize};
 use server::Server;
 
 use tokio_io::{AsyncRead, AsyncWrite};
@@ -58,8 +58,23 @@ impl<T, P, B> ControlFlow for Connection<T, P, B>
         self.inner.poll_remote_window_update(id)
     }
 
-    fn grow_local_window(&mut self, id: StreamId, incr: WindowSize) -> Result<(), ConnectionError> {
+    fn expand_local_window(&mut self, id: StreamId, incr: WindowSize) -> Result<(), ConnectionError> {
-        self.inner.grow_local_window(id, incr)
+        self.inner.expand_local_window(id, incr)
+    }
+}
+
+impl<T, P, B> ControlPing for Connection<T, P, B>
+    where T: AsyncRead + AsyncWrite,
+          T: ControlPing,
+          P: Peer,
+          B: IntoBuf,
+{
+    fn start_ping(&mut self, body: PingPayload) -> StartSend<PingPayload, ConnectionError> {
+        self.inner.start_ping(body)
+    }
+
+    fn pop_pong(&mut self) -> Option<PingPayload> {
+        self.inner.pop_pong()
     }
 }
 

src/proto/flow_control.rs

@@ -13,14 +13,15 @@ pub struct FlowControl<T>  {
 
     /// Tracks the connection-level flow control window for receiving data from the
     /// remote.
-    local_flow_controller: FlowControlState,
+    connection_local_flow_controller: FlowControlState,
 
     /// Tracks the onnection-level flow control window for receiving data from the remote.
-    remote_flow_controller: FlowControlState,
+    connection_remote_flow_controller: FlowControlState,
 
     /// Holds the list of streams on which local window updates may be sent.
     // XXX It would be cool if this didn't exist.
     pending_local_window_updates: VecDeque<StreamId>,
+    pending_local_connection_window_update: bool,
 
     /// If a window update can't be sent immediately, it may need to be saved to be sent later.
     sending_local_window_update: Option<frame::WindowUpdate>,
@@ -45,98 +46,31 @@ impl<T, U> FlowControl<T>
             inner,
             initial_local_window_size,
             initial_remote_window_size,
-            local_flow_controller: FlowControlState::with_initial_size(initial_local_window_size),
+            connection_local_flow_controller: FlowControlState::with_initial_size(initial_local_window_size),
-            remote_flow_controller: FlowControlState::with_next_update(initial_remote_window_size),
+            connection_remote_flow_controller: FlowControlState::with_next_update(initial_remote_window_size),
             blocked_remote_window_update: None,
             sending_local_window_update: None,
             pending_local_window_updates: VecDeque::new(),
+            pending_local_connection_window_update: false,
         }
     }
 }
 
 // Flow control utitlities.
 impl<T: ControlStreams> FlowControl<T> {
-    fn claim_local_window(&mut self, id: &StreamId, len: WindowSize) -> Result<(), ConnectionError> {
+    fn local_flow_controller(&mut self, id: StreamId) -> Option<&mut FlowControlState> {
-        let res = if id.is_zero() {
-            self.local_flow_controller.claim_window(len)
-        } else if let Some(mut stream) = self.inner.streams_mut().get_mut(&id) {
-            stream.claim_local_window(len)
-        } else {
-            // Ignore updates for non-existent streams.
-            Ok(())
-        };
-
-        res.map_err(|_| error::Reason::FlowControlError.into())
-    }
-
-    fn claim_remote_window(&mut self, id: &StreamId, len: WindowSize) -> Result<(), ConnectionError> {
-        let res = if id.is_zero() {
-            self.local_flow_controller.claim_window(len)
-        } else if let Some(mut stream) = self.inner.streams_mut().get_mut(&id) {
-            stream.claim_remote_window(len)
-        } else {
-            // Ignore updates for non-existent streams.
-            Ok(())
-        };
-
-        res.map_err(|_| error::Reason::FlowControlError.into())
-    }
-
-    /// Handles a window update received from the remote, indicating that the local may
-    /// send `incr` additional bytes.
-    ///
-    /// Connection window updates (id=0) and stream window updates are advertised
-    /// distinctly.
-    fn grow_remote_window(&mut self, id: StreamId, incr: WindowSize) {
-        if incr == 0 {
-            return;
-        }
-
         if id.is_zero() {
-            self.remote_flow_controller.grow_window(incr);
+            Some(&mut self.connection_local_flow_controller)
-        } else if let Some(mut s) = self.inner.streams_mut().get_mut(&id) {
-            s.grow_remote_window(incr);
         } else {
-            // Ignore updates for non-existent streams.
+            self.inner.streams_mut().get_mut(&id).and_then(|s| s.local_flow_controller())
-            return;
-        };
-
-        if let Some(task) = self.blocked_remote_window_update.take() {
-            task.notify();
         }
     }
-}
 
-/// Exposes a public upward API for flow control.
+   fn remote_flow_controller(&mut self, id: StreamId) -> Option<&mut FlowControlState> {
-impl<T: ControlStreams> ControlFlow for FlowControl<T> {
-    fn poll_remote_window_update(&mut self, id: StreamId) -> Poll<WindowSize, ConnectionError> {
         if id.is_zero() {
-            if let Some(sz) = self.remote_flow_controller.take_window_update() {
+            Some(&mut self.connection_remote_flow_controller)
-                return Ok(Async::Ready(sz));
-            }
-        } else if let Some(mut stream) = self.inner.streams_mut().get_mut(&id) {
-            if let Some(sz) = stream.take_remote_window_update() {
-                return Ok(Async::Ready(sz));
-            }
         } else {
-            return Err(error::User::InvalidStreamId.into());
+            self.inner.streams_mut().get_mut(&id).and_then(|s| s.remote_flow_controller())
-        }
-
-        self.blocked_remote_window_update = Some(task::current());
-        return Ok(Async::NotReady);
-    }
-
-    fn grow_local_window(&mut self, id: StreamId, incr: WindowSize) -> Result<(), ConnectionError> {
-        if id.is_zero() {
-            self.local_flow_controller.grow_window(incr);
-            self.pending_local_window_updates.push_back(id);
-            Ok(())
-        } else if let Some(mut stream) = self.inner.streams_mut().get_mut(&id) {
-            stream.grow_local_window(incr);
-            self.pending_local_window_updates.push_back(id);
-            Ok(())
-        } else {
-            Err(error::User::InvalidStreamId.into())
         }
     }
 }
@@ -154,6 +88,47 @@ impl<T: ControlStreams> ControlStreams for FlowControl<T> {
     }
 }
 
+/// Exposes a public upward API for flow control.
+impl<T: ControlStreams> ControlFlow for FlowControl<T> {
+    fn poll_remote_window_update(&mut self, id: StreamId) -> Poll<WindowSize, ConnectionError> {
+        if let Some(mut flow) = self.remote_flow_controller(id) {
+            if let Some(sz) = flow.apply_window_update() {
+                return Ok(Async::Ready(sz));
+            }
+        } else {
+            return Err(error::User::InvalidStreamId.into());
+        }
+
+        self.blocked_remote_window_update = Some(task::current());
+        return Ok(Async::NotReady);
+    }
+
+    fn expand_local_window(&mut self, id: StreamId, incr: WindowSize) -> Result<(), ConnectionError> {
+        if let Some(mut fc) = self.local_flow_controller(id) {
+            fc.expand_window(incr);
+        } else {
+            return Err(error::User::InvalidStreamId.into());
+        }
+
+        if id.is_zero() {
+            self.pending_local_connection_window_update = true;
+        } else {
+            self.pending_local_window_updates.push_back(id);
+        }
+        Ok(())
+    }
+}
+
+impl<T: ControlPing> ControlPing for FlowControl<T> {
+    fn start_ping(&mut self, body: PingPayload) -> StartSend<PingPayload, ConnectionError> {
+        self.inner.start_ping(body)
+    }
+
+    fn pop_pong(&mut self) -> Option<PingPayload> {
+        self.inner.pop_pong()
+    }
+}
+
 impl<T, U> FlowControl<T>
     where T: Sink<SinkItem = Frame<U>, SinkError = ConnectionError>,
           T: ControlStreams,
@@ -161,27 +136,33 @@ impl<T, U> FlowControl<T>
     /// Returns ready when there are no pending window updates to send.
     fn poll_send_local_window_updates(&mut self) -> Poll<(), ConnectionError> {
         if let Some(f) = self.sending_local_window_update.take() {
-            if self.inner.start_send(f.into())?.is_not_ready() {
+            try_ready!(self.try_send(f));
-                self.sending_local_window_update = Some(f);
+        }
-                return Ok(Async::NotReady);
+
+        if self.pending_local_connection_window_update {
+            if let Some(incr) = self.connection_local_flow_controller.apply_window_update() {
+                try_ready!(self.try_send(frame::WindowUpdate::new(StreamId::zero(), incr)));
             }
         }
 
         while let Some(id) = self.pending_local_window_updates.pop_front() {
-            let update = self.inner.streams_mut().get_mut(&id)
+            let update = self.local_flow_controller(id).and_then(|s| s.apply_window_update());
-                .and_then(|mut s| s.take_local_window_update())
+            if let Some(incr) = update {
-                .map(|incr| frame::WindowUpdate::new(id, incr));
+                try_ready!(self.try_send(frame::WindowUpdate::new(id, incr)));
-
-            if let Some(f) = update {
-                if self.inner.start_send(f.into())?.is_not_ready() {
-                    self.sending_local_window_update = Some(f);
-                    return Ok(Async::NotReady);
-                }
             }
         }
 
         Ok(Async::Ready(()))
     }
+
+    fn try_send(&mut self, f: frame::WindowUpdate) -> Poll<(), ConnectionError> {
+        if self.inner.start_send(f.into())?.is_not_ready() {
+            self.sending_local_window_update = Some(f);
+            Ok(Async::NotReady)
+        } else {
+            Ok(Async::Ready(()))
+        }
+    }
 }
 
 /// Applies an update to an endpoint's initial window size.
@@ -219,7 +200,7 @@ impl<T> ApplySettings for FlowControl<T>
             streams.shrink_all_local_windows(decr);
         } else { 
             let incr = new_window_size - old_window_size;
-            streams.grow_all_local_windows(incr);
+            streams.expand_all_local_windows(incr);
         }
         
         self.initial_local_window_size = new_window_size;
@@ -241,7 +222,7 @@ impl<T> ApplySettings for FlowControl<T>
             streams.shrink_all_remote_windows(decr);
         } else { 
             let incr = new_window_size - old_window_size;
-            streams.grow_all_remote_windows(incr);
+            streams.expand_all_remote_windows(incr);
         }
         
         self.initial_remote_window_size = new_window_size;
@@ -263,11 +244,20 @@ impl<T> Stream for FlowControl<T>
         loop {
             match try_ready!(self.inner.poll()) {
                 Some(WindowUpdate(v)) => {
-                    self.grow_remote_window(v.stream_id(), v.size_increment());
+                    if let Some(fc) = self.remote_flow_controller(v.stream_id()) {
+                        fc.expand_window(v.size_increment());
+                    }
                 }
 
                 Some(Data(v)) => {
-                    self.claim_local_window(&v.stream_id(), v.len())?;
+                    if self.connection_local_flow_controller.claim_window(v.len()).is_err() {
+                        return Err(error::Reason::FlowControlError.into())
+                    }
+                    if let Some(fc) = self.local_flow_controller(v.stream_id()) {
+                        if fc.claim_window(v.len()).is_err() {
+                            return Err(error::Reason::FlowControlError.into())
+                        }
+                    }
                     return Ok(Async::Ready(Some(Data(v))));
                 }
 
@@ -277,7 +267,6 @@ impl<T> Stream for FlowControl<T>
     }
 }
 
-
 impl<T, U> Sink for FlowControl<T>
     where T: Sink<SinkItem = Frame<U>, SinkError = ConnectionError>,
           T: ReadySink,
@@ -300,7 +289,14 @@ impl<T, U> Sink for FlowControl<T>
                     return Ok(AsyncSink::NotReady(Data(v)));
                 }
 
-                self.claim_remote_window(&v.stream_id(), v.len())?;
+                if self.connection_remote_flow_controller.claim_window(v.len()).is_err() {
+                    return Err(error::User::FlowControlViolation.into());
+                }
+                if let Some(fc) = self.remote_flow_controller(v.stream_id()) {
+                    if fc.claim_window(v.len()).is_err() {
+                        return Err(error::User::FlowControlViolation.into())
+                    }
+                }
 
                 let res = self.inner.start_send(Data(v))?;
                 assert!(res.is_ready());

src/proto/flow_control_state.rs

@@ -53,7 +53,7 @@ impl FlowControlState {
 
     /// Claims the provided amount from the window, if there is enough space.
     ///
-    /// Fails when `take_window_update()` hasn't returned at least `sz` more bytes than
+    /// Fails when `apply_window_update()` hasn't returned at least `sz` more bytes than
     /// have been previously claimed.
     pub fn claim_window(&mut self, sz: WindowSize) -> Result<(), WindowUnderflow> {
         if self.window_size < sz {
@@ -65,7 +65,7 @@ impl FlowControlState {
     }
 
     /// Increase the _unadvertised_ window capacity.
-    pub fn grow_window(&mut self, sz: WindowSize) {
+    pub fn expand_window(&mut self, sz: WindowSize) {
         if sz <= self.underflow {
             self.underflow -= sz;
             return;
@@ -77,7 +77,7 @@ impl FlowControlState {
     }
 
     /// Obtains and applies an unadvertised window update.
-    pub fn take_window_update(&mut self) -> Option<WindowSize> {
+    pub fn apply_window_update(&mut self) -> Option<WindowSize> {
         if self.next_window_update == 0 {
             return None;
         }
@@ -93,29 +93,29 @@ impl FlowControlState {
 fn test_with_initial_size() {
     let mut fc = FlowControlState::with_initial_size(10);
 
-    fc.grow_window(8);
+    fc.expand_window(8);
     assert_eq!(fc.window_size, 10);
     assert_eq!(fc.next_window_update, 8);
 
-    assert_eq!(fc.take_window_update(), Some(8));
+    assert_eq!(fc.apply_window_update(), Some(8));
     assert_eq!(fc.window_size, 18);
     assert_eq!(fc.next_window_update, 0);
 
     assert!(fc.claim_window(13).is_ok());
     assert_eq!(fc.window_size, 5);
     assert_eq!(fc.next_window_update, 0);
-    assert!(fc.take_window_update().is_none());
+    assert!(fc.apply_window_update().is_none());
 }
 
 #[test]
 fn test_with_next_update() {
     let mut fc = FlowControlState::with_next_update(10);
 
-    fc.grow_window(8);
+    fc.expand_window(8);
     assert_eq!(fc.window_size, 0);
     assert_eq!(fc.next_window_update, 18);
 
-    assert_eq!(fc.take_window_update(), Some(18));
+    assert_eq!(fc.apply_window_update(), Some(18));
     assert_eq!(fc.window_size, 18);
     assert_eq!(fc.next_window_update, 0);
 }
@@ -125,13 +125,13 @@ fn test_grow_accumulates() {
     let mut fc = FlowControlState::with_initial_size(5);
 
     // Updates accumulate, though the window is not made immediately available.  Trying to
-    // claim data not returned by take_window_update results in an underflow.
+    // claim data not returned by apply_window_update results in an underflow.
 
-    fc.grow_window(2);
+    fc.expand_window(2);
     assert_eq!(fc.window_size, 5);
     assert_eq!(fc.next_window_update, 2);
 
-    fc.grow_window(6);
+    fc.expand_window(6);
     assert_eq!(fc.window_size, 5);
     assert_eq!(fc.next_window_update, 8);
 
@@ -139,7 +139,7 @@ fn test_grow_accumulates() {
     assert_eq!(fc.window_size, 5);
     assert_eq!(fc.next_window_update, 8);
 
-    assert_eq!(fc.take_window_update(), Some(8));
+    assert_eq!(fc.apply_window_update(), Some(8));
     assert_eq!(fc.window_size, 13);
     assert_eq!(fc.next_window_update, 0);
 
@@ -154,7 +154,7 @@ fn test_shrink() {
     assert_eq!(fc.window_size, 5);
     assert_eq!(fc.next_window_update, 0);
 
-    fc.grow_window(3);
+    fc.expand_window(3);
     assert_eq!(fc.window_size, 5);
     assert_eq!(fc.next_window_update, 3);
     assert_eq!(fc.underflow, 0);
@@ -169,7 +169,7 @@ fn test_shrink() {
     assert_eq!(fc.next_window_update, 0);
     assert_eq!(fc.underflow, 5);
 
-    fc.grow_window(8);
+    fc.expand_window(8);
     assert_eq!(fc.window_size, 0);
     assert_eq!(fc.next_window_update, 3);
     assert_eq!(fc.underflow, 0);

src/proto/mod.rs

@@ -30,20 +30,56 @@ pub use self::settings::Settings;
 pub use self::stream_tracker::StreamTracker;
 use self::state::StreamState;
 
-/// Represents the internals of an HTTP2 connection.
+/// Represents the internals of an HTTP/2 connection.
 ///
 /// A transport consists of several layers (_transporters_) and is arranged from _top_
 /// (near the application) to _bottom_ (near the network).  Each transporter implements a
 /// Stream of frames received from the remote, and a ReadySink of frames sent to the
 /// remote.
 ///
-/// At the top of the transport, the Settings module is responsible for:
+/// ## Transport Layers
-/// - Transmitting local settings to the remote.
+///
-/// - Sending settings acknowledgements for all settings frames received from the remote.
+/// ### `Settings`
-/// - Exposing settings upward to the Connection.
+///
+/// - Receives remote settings frames and applies the settings downward through the
+///   transport (via the ApplySettings trait) before responding with acknowledgements.
+/// - Exposes ControlSettings up towards the application and transmits local settings to
+///   the remote.
+///
+/// ### `FlowControl`
+///
+/// - Tracks received data frames against the local stream and connection flow control
+///   windows.
+/// - Tracks sent data frames against the remote stream and connection flow control
+///   windows.
+/// - Tracks remote settings updates to SETTINGS_INITIAL_WINDOW_SIZE.
+/// - Exposes `ControlFlow` upwards.
+///   - Tracks received window updates against the remote stream and connection flow
+///     control windows so that upper layers may poll for updates.
+///   - Sends window updates for the local stream and connection flow control windows as
+///     instructed by upper layers.
+///
+/// ### `StreamTracker`
+///
+/// - Tracks the states of each stream.
+/// - **TODO** Enforces maximum concurrency.
+/// - Exposes `ControlStreams` so that upper layers may share stream state.
+///
+/// ### `PingPong`
+///
+/// - Acknowleges PINGs from the remote.
+/// - Exposes ControlPing that allows the application side to send ping requests to the
+///   remote. Acknowledgements from the remoe are queued to be consumed by the
+///   application.
+///
+/// ### FramedRead
+///
+/// - Decodes frames from bytes.
+///
+/// ### FramedWrite
+///
+/// - Encodes frames to bytes.
 ///
-/// All transporters below Settings must apply relevant settings before passing a frame on
-/// to another level.  For example, if the frame writer n
 type Transport<T, P, B>=
     Settings<
         FlowControl<
@@ -75,25 +111,33 @@ impl StreamMap {
 
     fn shrink_all_local_windows(&mut self, decr: u32) {
         for (_, mut s) in &mut self.inner {
-            s.shrink_local_window(decr)
+            if let Some(fc) = s.local_flow_controller() {
+                fc.shrink_window(decr);
+            }
         }
     }
 
-    fn grow_all_local_windows(&mut self, incr: u32) {
+    fn expand_all_local_windows(&mut self, incr: u32) {
         for (_, mut s) in &mut self.inner {
-            s.grow_local_window(incr)
+            if let Some(fc) = s.local_flow_controller() {
+                fc.expand_window(incr);
+            }
         }
     }
 
     fn shrink_all_remote_windows(&mut self, decr: u32) {
         for (_, mut s) in &mut self.inner {
-            s.shrink_remote_window(decr)
+            if let Some(fc) = s.remote_flow_controller() {
+                fc.shrink_window(decr);
+            }
         }
     }
 
-    fn grow_all_remote_windows(&mut self, incr: u32) {
+    fn expand_all_remote_windows(&mut self, incr: u32) {
         for (_, mut s) in &mut self.inner {
-            s.grow_remote_window(incr)
+            if let Some(fc) = s.remote_flow_controller() {
+                fc.expand_window(incr);
+            }
         }
     }
 }
@@ -120,6 +164,13 @@ pub trait ControlStreams {
     fn streams_mut(&mut self) -> &mut StreamMap;
 }
 
+pub type PingPayload = [u8; 8];
+
+pub trait ControlPing {
+    fn start_ping(&mut self, body: PingPayload) -> StartSend<PingPayload, ConnectionError>;
+    fn pop_pong(&mut self) -> Option<PingPayload>;
+}
+
 /// Exposes flow control states to "upper" layers of the transport (i.e. above
 /// FlowControl).
 pub trait ControlFlow {
@@ -131,7 +182,7 @@ pub trait ControlFlow {
     /// Attempts to increase the receive capacity of a stream.
     ///
     /// Errors if the given stream is not active.
-    fn grow_local_window(&mut self, id: StreamId, incr: WindowSize) -> Result<(), ConnectionError>;
+    fn expand_local_window(&mut self, id: StreamId, incr: WindowSize) -> Result<(), ConnectionError>;
 }
 
 /// Create a full H2 transport from an I/O handle.

src/proto/ping_pong.rs

@@ -1,13 +1,16 @@
 use ConnectionError;
 use frame::{Frame, Ping, SettingSet};
+use proto::{ApplySettings, ControlPing, PingPayload, ReadySink};
+
 use futures::*;
-use proto::{ApplySettings, ReadySink};
+use std::collections::VecDeque;
 
 /// Acknowledges ping requests from the remote.
 #[derive(Debug)]
 pub struct PingPong<T, U> {
     inner: T,
-    pong: Option<Frame<U>>,
+    sending_pong: Option<Frame<U>>,
+    received_pongs: VecDeque<PingPayload>,
 }
 
 impl<T, U> PingPong<T, U>
@@ -17,7 +20,8 @@ impl<T, U> PingPong<T, U>
     pub fn new(inner: T) -> Self {
         PingPong {
             inner,
-            pong: None,
+            sending_pong: None,
+            received_pongs: VecDeque::new(),
         }
     }
 }
@@ -32,18 +36,37 @@ impl<T: ApplySettings, U> ApplySettings for PingPong<T, U> {
     }
 }
 
+impl<T, U> ControlPing for PingPong<T, U>
+    where T: Sink<SinkItem = Frame<U>, SinkError = ConnectionError>,
+          T: ReadySink,
+{
+    fn start_ping(&mut self, body: PingPayload) -> StartSend<PingPayload, ConnectionError> {
+        if self.inner.poll_ready()?.is_not_ready() {
+            return Ok(AsyncSink::NotReady(body));
+        }
+
+        match self.inner.start_send(Ping::ping(body).into())? {
+            AsyncSink::NotReady(_) => unreachable!(),
+            AsyncSink::Ready => Ok(AsyncSink::Ready),
+        }
+    }
+
+    fn pop_pong(&mut self) -> Option<PingPayload> {
+        self.received_pongs.pop_front()
+    }
+}
+
 impl<T, U> PingPong<T, U>
     where T: Sink<SinkItem = Frame<U>, SinkError = ConnectionError>,
 {
     fn try_send_pong(&mut self) -> Poll<(), ConnectionError> {
-        if let Some(pong) = self.pong.take() {
+        if let Some(pong) = self.sending_pong.take() {
             if let AsyncSink::NotReady(pong) = self.inner.start_send(pong)? {
                 // If the pong can't be sent, save it.
-                self.pong = Some(pong);
+                self.sending_pong = Some(pong);
                 return Ok(Async::NotReady);
             }
         }
-
         Ok(Async::Ready(()))
     }
 }
@@ -78,7 +101,7 @@ impl<T, U> Stream for PingPong<T, U>
                     // Save a pong to be sent when there is nothing more to be returned
                     // from the stream or when frames are sent to the sink.
                     let pong = Ping::pong(ping.into_payload());
-                    self.pong = Some(pong.into());
+                    self.sending_pong = Some(pong.into());
                 }
 
                 // Everything other than ping gets passed through.

src/proto/settings.rs

@@ -110,8 +110,18 @@ impl<T: ControlFlow> ControlFlow for Settings<T> {
         self.inner.poll_remote_window_update(id)
     }
 
-    fn grow_local_window(&mut self, id: StreamId, incr: WindowSize) -> Result<(), ConnectionError> {
+    fn expand_local_window(&mut self, id: StreamId, incr: WindowSize) -> Result<(), ConnectionError> {
-        self.inner.grow_local_window(id, incr)
+        self.inner.expand_local_window(id, incr)
+    }
+}
+
+impl<T: ControlPing> ControlPing for Settings<T> {
+    fn start_ping(&mut self, body: PingPayload) -> StartSend<PingPayload, ConnectionError> {
+        self.inner.start_ping(body)
+    }
+
+    fn pop_pong(&mut self) -> Option<PingPayload> {
+        self.inner.pop_pong()
     }
 }
 

src/proto/state.rs

@@ -2,7 +2,7 @@ use Peer;
 use error::ConnectionError;
 use error::Reason::*;
 use error::User::*;
-use proto::{FlowControlState, WindowSize, WindowUnderflow};
+use proto::{FlowControlState, WindowSize};
 
 /// Represents the state of an H2 stream
 ///
@@ -222,129 +222,24 @@ impl StreamState {
         }
     }
  
-    /// Updates the local flow controller so that the remote may send `incr` more bytes.
+    pub fn local_flow_controller(&mut self) -> Option<&mut FlowControlState> {
-    ///
-    /// Returns the amount of capacity created, accounting for window size changes. The
-    /// caller should send the the returned window size increment to the remote.
-    ///
-    /// If the remote is closed, None is returned.
-    pub fn grow_remote_window(&mut self, incr: WindowSize) {
         use self::StreamState::*;
         use self::PeerState::*;
 
-        if incr == 0 {
-            return;
-        }
-
-        match self {
-            &mut Open { remote: Data(ref mut fc), .. } |
-            &mut HalfClosedLocal(Data(ref mut fc)) => fc.grow_window(incr),
-            _ => {},
-        }
-    }
- 
-    pub fn claim_remote_window(&mut self, decr: WindowSize) -> Result<(), WindowUnderflow> {
-        use self::StreamState::*;
-        use self::PeerState::*;
-
-        if decr == 0 {
-            return Ok(());
-        }
-
-        match self {
-            &mut Open { remote: Data(ref mut fc), .. } |
-            &mut HalfClosedLocal(Data(ref mut fc)) => fc.claim_window(decr),
-            _ => Ok(()),
-        }
-    }
-
-    pub fn shrink_remote_window(&mut self, decr: WindowSize) {
-        use self::StreamState::*;
-        use self::PeerState::*;
-
-        if decr == 0 {
-            return;
-        }
-
         match self {
             &mut Open { local: Data(ref mut fc), .. } |
-            &mut HalfClosedLocal(Data(ref mut fc)) => fc.shrink_window(decr),
+            &mut HalfClosedRemote(Data(ref mut fc)) => Some(fc),
-            _ => {},
-        }
-    }
-
-    /// Consumes newly-advertised capacity to inform the local endpoint it may send more
-    /// data.
-    pub fn take_remote_window_update(&mut self) -> Option<WindowSize> {
-        use self::StreamState::*;
-        use self::PeerState::*;
-
-        match self {
-            &mut Open { remote: Data(ref mut fc), .. } |
-            &mut HalfClosedLocal(Data(ref mut fc)) => fc.take_window_update(),
             _ => None,
         }
     }
 
-    /// Updates the remote flow controller so that the remote may receive `incr`
+    pub fn remote_flow_controller(&mut self) -> Option<&mut FlowControlState> {
-    /// additional bytes.
-    ///
-    /// Returns the amount of capacity created, accounting for window size changes. The
-    /// caller should send the the returned window size increment to the remote.
-    pub fn grow_local_window(&mut self, incr: WindowSize) {
-        use self::StreamState::*;
-        use self::PeerState::*;
-
-        if incr == 0 {
-            return;
-        }
-
-        match self {
-            &mut Open { local: Data(ref mut fc), .. } |
-            &mut HalfClosedRemote(Data(ref mut fc)) => fc.grow_window(incr),
-            _ => {},
-        }
-    }
-
-    pub fn claim_local_window(&mut self, decr: WindowSize) -> Result<(), WindowUnderflow> {
-        use self::StreamState::*;
-        use self::PeerState::*;
-
-        if decr == 0 {
-            return Ok(());
-        }
-
-        match self {
-            &mut Open { local: Data(ref mut fc), .. } |
-            &mut HalfClosedRemote(Data(ref mut fc)) => fc.claim_window(decr),
-            _ => Ok(()),
-        }
-    }
-
-    pub fn shrink_local_window(&mut self, decr: WindowSize) {
-        use self::StreamState::*;
-        use self::PeerState::*;
-
-        if decr == 0 {
-            return;
-        }
-
-        match self {
-            &mut Open { local: Data(ref mut fc), .. } |
-            &mut HalfClosedRemote(Data(ref mut fc)) => fc.shrink_window(decr),
-            _ => {},
-        }
-    }
-
-    /// Consumes newly-advertised capacity to inform the local endpoint it may send more
-    /// data.
-    pub fn take_local_window_update(&mut self) -> Option<WindowSize> {
         use self::StreamState::*;
         use self::PeerState::*;
 
         match self {
-            &mut Open { local: Data(ref mut fc), .. } |
+            &mut Open { remote: Data(ref mut fc), .. } |
-            &mut HalfClosedRemote(Data(ref mut fc)) => fc.take_window_update(),
+            &mut HalfClosedLocal(Data(ref mut fc)) => Some(fc),
             _ => None,
         }
     }

src/proto/stream_tracker.rs

@@ -87,6 +87,18 @@ impl<T, P> ApplySettings for StreamTracker<T, P>
     }
 }
 
+impl<T, P> ControlPing for StreamTracker<T, P>
+    where T: ControlPing
+{
+    fn start_ping(&mut self, body: PingPayload) -> StartSend<PingPayload, ConnectionError> {
+        self.inner.start_ping(body)
+    }
+
+    fn pop_pong(&mut self) -> Option<PingPayload> {
+        self.inner.pop_pong()
+    }
+}
+
 impl<T, P> Stream for StreamTracker<T, P>
     where T: Stream<Item = Frame, Error = ConnectionError>,
           P: Peer,