narrow the surface area of the ControlSettings api to expose only a few remote settings

src/frame/settings.rs

@@ -20,10 +20,14 @@ pub struct SettingSet {
 }
 
 impl SettingSet {
-    pub fn initial_window_size(&self) -> u32 {
+    pub fn enable_push(&self) -> Option<bool> {
-        self.initial_window_size.unwrap_or(65_535)
+        self.enable_push.map(|n| n != 0)
     }
-    
+
+    pub fn initial_window_size(&self) -> Option<u32> {
+        self.initial_window_size
+    }
+
     pub fn max_concurrent_streams(&self) -> Option<u32> {
         self.max_concurrent_streams
     }

src/proto/connection.rs

@@ -53,6 +53,18 @@ impl<T, P, B> Connection<T, P, B>
         self.inner.update_local_settings(local)
     }
 
+    pub fn remote_initial_window_size(&self) -> u32 {
+        self.inner.remote_initial_window_size()
+    }
+
+    pub fn remote_max_concurrent_streams(&self) -> Option<u32> {
+        self.inner.remote_max_concurrent_streams()
+    }
+
+    pub fn remote_push_enabled(&self) -> Option<bool> {
+        self.inner.remote_push_enabled()
+    }
+
     pub fn start_ping(&mut self, body: PingPayload) -> StartSend<PingPayload, ConnectionError> {
         self.inner.start_ping(body)
     }

src/proto/flow_control.rs

@@ -317,28 +317,30 @@ impl<T> ApplySettings for FlowControl<T>
     fn apply_local_settings(&mut self, set: &frame::SettingSet) -> Result<(), ConnectionError> {
         self.inner.apply_local_settings(set)?;
 
-        let old_window_size = self.local_initial;
+        if let Some(new_window_size) = set.initial_window_size() {
-        let new_window_size = set.initial_window_size();
+            let old_window_size = self.local_initial;
-        if new_window_size == old_window_size {
+            if new_window_size == old_window_size {
-            return Ok(());
+                return Ok(());
-        }
+            }
 
-        self.inner.update_inital_recv_window_size(old_window_size, new_window_size);
+            self.inner.update_inital_recv_window_size(old_window_size, new_window_size);
-        self.local_initial = new_window_size;
+            self.local_initial = new_window_size;
+        }
         Ok(())
     }
 
     fn apply_remote_settings(&mut self, set: &frame::SettingSet) -> Result<(), ConnectionError> {
         self.inner.apply_remote_settings(set)?;
 
-        let old_window_size = self.remote_initial;
+        if let Some(new_window_size) = set.initial_window_size() {
-        let new_window_size = set.initial_window_size();
+            let old_window_size = self.remote_initial;
-        if new_window_size == old_window_size {
+            if new_window_size == old_window_size {
-            return Ok(());
+                return Ok(());
-        }
+            }
 
-        self.inner.update_inital_send_window_size(old_window_size, new_window_size);
+            self.inner.update_inital_send_window_size(old_window_size, new_window_size);
-        self.remote_initial = new_window_size;
+            self.remote_initial = new_window_size;
+        }
         Ok(())
     }
 }

src/proto/mod.rs

@@ -30,7 +30,7 @@ use self::framed_read::FramedRead;
 use self::framed_write::FramedWrite;
 use self::ping_pong::{ControlPing, PingPayload, PingPong};
 use self::ready::ReadySink;
-use self::settings::{ApplySettings, /*ControlSettings,*/ Settings};
+use self::settings::{ApplySettings, ControlSettings, Settings};
 use self::stream_recv_close::StreamRecvClose;
 use self::stream_recv_open::StreamRecvOpen;
 use self::stream_send_close::StreamSendClose;
@@ -165,7 +165,7 @@ impl WindowUpdate {
 /// Create a full H2 transport from an I/O handle.
 ///
 /// This is called as the final step of the client handshake future.
-pub fn from_io<T, P, B>(io: T, settings: frame::SettingSet)
+pub fn from_io<T, P, B>(io: T, local_settings: frame::SettingSet)
     -> Connection<T, P, B>
     where T: AsyncRead + AsyncWrite,
           P: Peer,
@@ -177,10 +177,9 @@ pub fn from_io<T, P, B>(io: T, settings: frame::SettingSet)
     // weird, but oh well...
     //
     // We first create a Settings directly around a framed writer
-    let transport = Settings::new(
+    let transport = Settings::new(framed_write, local_settings.clone());
-        framed_write, settings);
 
-    from_server_handshaker(transport)
+    from_server_handshaker(transport, local_settings)
 }
 
 /// Create a transport prepared to handle the server handshake.
@@ -198,16 +197,18 @@ pub fn server_handshaker<T, B>(io: T, settings: frame::SettingSet)
 }
 
 /// Create a full H2 transport from the server handshaker
-pub fn from_server_handshaker<T, P, B>(settings: Settings<FramedWrite<T, B::Buf>>)
+pub fn from_server_handshaker<T, P, B>(settings: Settings<FramedWrite<T, B::Buf>>,
+                                       local_settings: frame::SettingSet)
     -> Connection<T, P, B>
     where T: AsyncRead + AsyncWrite,
           P: Peer,
           B: IntoBuf,
 {
-    let initial_recv_window_size = settings.local_settings().initial_window_size();
+    let initial_recv_window_size = local_settings.initial_window_size().unwrap_or(65_535);
-    let initial_send_window_size = settings.remote_settings().initial_window_size();
+    let local_max_concurrency = local_settings.max_concurrent_streams();
-    let local_max_concurrency = settings.local_settings().max_concurrent_streams();
+
-    let remote_max_concurrency = settings.remote_settings().max_concurrent_streams();
+    let initial_send_window_size = settings.remote_initial_window_size();
+    let remote_max_concurrency = settings.remote_max_concurrent_streams();
 
     // Replace Settings' writer with a full transport.
     let transport = settings.swap_inner(|io| {

src/proto/settings.rs

@@ -11,8 +11,10 @@ use std::io;
 /// above---Connection).
 pub trait ControlSettings {
     fn update_local_settings(&mut self, set: frame::SettingSet) -> Result<(), ConnectionError>;
-    fn local_settings(&self) -> &SettingSet;
+
-    fn remote_settings(&self) -> &SettingSet;
+    fn remote_push_enabled(&self) -> Option<bool>;
+    fn remote_max_concurrent_streams(&self) -> Option<u32>;
+    fn remote_initial_window_size(&self) -> WindowSize;
 }
 
 /// Allows settings updates to be pushed "down" the transport (i.e. from Settings down to
@@ -27,17 +29,15 @@ pub struct Settings<T> {
     // Upstream transport
     inner: T,
 
-    // Our settings
+    remote_push_enabled: Option<bool>,
-    local: SettingSet,
+    remote_max_concurrent_streams: Option<u32>,
-
+    remote_initial_window_size: WindowSize,
-    // Peer settings
-    remote: SettingSet,
 
     // Number of acks remaining to send to the peer
     remaining_acks: usize,
 
-    // True when the local settings must be flushed to the remote
+    // Holds a new set of local values to be applied.
-    local_valid_id_dirty: bool,
+    pending_local: Option<SettingSet>,
 
     // True when we have received a settings frame from the remote.
     received_remote: bool,
@@ -49,46 +49,34 @@ impl<T, U> Settings<T>
     pub fn new(inner: T, local: SettingSet) -> Settings<T> {
         Settings {
             inner: inner,
-            local: local,
+            pending_local: Some(local),
-            remote: SettingSet::default(),
+            remote_push_enabled: None,
+            remote_max_concurrent_streams: None,
+            remote_initial_window_size: 65_535,
             remaining_acks: 0,
-            local_valid_id_dirty: true,
             received_remote: false,
         }
     }
 
-    // TODO remove this
-    pub fn local_settings(&self) -> &SettingSet {
-        &self.local
-    }
-
-    // TODO replace this with settings a client needs to know about (concurrency, initial
-    // window size, etc).
-    pub fn remote_settings(&self) -> &SettingSet {
-        &self.local
-    }
-
     /// Swap the inner transport while maintaining the current state.
     pub fn swap_inner<T2, F: FnOnce(T) -> T2>(self, f: F) -> Settings<T2> {
         let inner = f(self.inner);
 
         Settings {
             inner: inner,
-            local: self.local,
+            remote_push_enabled: self.remote_push_enabled,
-            remote: self.remote,
+            remote_max_concurrent_streams: self.remote_max_concurrent_streams,
+            remote_initial_window_size: self.remote_initial_window_size,
             remaining_acks: self.remaining_acks,
-            local_valid_id_dirty: self.local_valid_id_dirty,
+            pending_local: self.pending_local,
             received_remote: self.received_remote,
         }
     }
 
     fn try_send_pending(&mut self) -> Poll<(), ConnectionError> {
-        trace!("try_send_pending; dirty={} acks={}", self.local_valid_id_dirty, self.remaining_acks);
+        trace!("try_send_pending; dirty={} acks={}", self.pending_local.is_some(), self.remaining_acks);
-        if self.local_valid_id_dirty {
+        if let Some(local) = self.pending_local.take() {
-            let frame = frame::Settings::new(self.local.clone());
+            try_ready!(self.try_send_local(local));
-            try_ready!(self.try_send(frame));
-
-            self.local_valid_id_dirty = false;
         }
 
         while self.remaining_acks > 0 {
@@ -101,9 +89,19 @@ impl<T, U> Settings<T>
         Ok(Async::Ready(()))
     }
 
-    fn try_send(&mut self, item: frame::Settings) -> Poll<(), ConnectionError> {
+    fn try_send_local(&mut self, local: SettingSet) -> Poll<(), ConnectionError> {
+        let frame = frame::Settings::new(local.clone()).into();
+        if self.try_send(frame)?.is_not_ready() {
+            self.pending_local = Some(local);
+            Ok(Async::NotReady)
+        } else {
+            Ok(Async::Ready(()))
+        }
+    }
+
+    fn try_send(&mut self, frame: frame::Settings) -> Poll<(), ConnectionError> {
         trace!("try_send");
-        if self.inner.start_send(item.into())?.is_ready() {
+        if self.inner.start_send(frame.into())?.is_ready() {
             Ok(Async::Ready(()))
         } else {
             Ok(Async::NotReady)
@@ -111,19 +109,24 @@ impl<T, U> Settings<T>
     }
 }
 
-impl<T> ControlSettings for Settings<T>{
+impl<T, U> ControlSettings for Settings<T>
-    fn update_local_settings(&mut self, local: frame::SettingSet) -> Result<(), ConnectionError> {
+    where T: Sink<SinkItem = Frame<U>, SinkError = ConnectionError>,
-        self.local = local;
+{
-        self.local_valid_id_dirty = true;
+    fn update_local_settings(&mut self, local: SettingSet) -> Result<(), ConnectionError> {
+        self.try_send_local(local)?;
         Ok(())
     }
 
-    fn local_settings(&self) -> &SettingSet {
+    fn remote_initial_window_size(&self) -> u32 {
-        &self.local
+        self.remote_initial_window_size
     }
 
-    fn remote_settings(&self) -> &SettingSet {
+    fn remote_max_concurrent_streams(&self) -> Option<u32> {
-        &self.remote
+        self.remote_max_concurrent_streams
+    }
+
+    fn remote_push_enabled(&self) -> Option<bool> {
+        self.remote_push_enabled
     }
 }
 
@@ -147,7 +150,16 @@ impl<T, U> Stream for Settings<T>
                         // acknowledgements.
                         let settings = v.into_set();
                         self.inner.apply_remote_settings(&settings)?;
-                        self.remote = settings;
+
+                        if let Some(sz) = settings.initial_window_size() {
+                            self.remote_initial_window_size = sz;
+                        }
+                        if let Some(max) = settings.max_concurrent_streams() {
+                            self.remote_max_concurrent_streams = Some(max);
+                        }
+                        if let Some(ok) = settings.enable_push() {
+                            self.remote_push_enabled = Some(ok);
+                        }
 
                         self.remaining_acks += 1;
                         let _ = try!(self.try_send_pending());

src/proto/stream_recv_open.rs

@@ -66,7 +66,9 @@ impl<T> ApplySettings for StreamRecvOpen<T>
 {
     fn apply_local_settings(&mut self, set: &frame::SettingSet) -> Result<(), ConnectionError> {
         self.max_concurrency = set.max_concurrent_streams();
-        self.initial_window_size = set.initial_window_size();
+        if let Some(sz) = set.initial_window_size() {
+            self.initial_window_size = sz;
+        }
         self.inner.apply_local_settings(set)
     }
 

src/proto/stream_send_open.rs

@@ -38,7 +38,9 @@ impl<T: ApplySettings> ApplySettings for StreamSendOpen<T> {
 
     fn apply_remote_settings(&mut self, set: &SettingSet) -> Result<(), ConnectionError> {
         self.max_concurrency = set.max_concurrent_streams();
-        self.initial_window_size = set.initial_window_size();
+        if let Some(sz) = set.initial_window_size() {
+            self.initial_window_size = sz;
+        }
         self.inner.apply_remote_settings(set)
     }
 }

src/server.rs

@@ -46,12 +46,13 @@ pub fn handshake2<T, B: IntoBuf>(io: T) -> Handshake<T, B>
     where T: AsyncRead + AsyncWrite + 'static,
           B: 'static, // TODO: Why is this required but not in client?
 {
-    let transport = proto::server_handshaker(io, Default::default());
+    let local_settings = frame::SettingSet::default();
+    let transport = proto::server_handshaker(io, local_settings.clone());
 
     // Flush pending settings frame and then wait for the client preface
     let handshake = Flush::new(transport)
         .and_then(ReadPreface::new)
-        .map(proto::from_server_handshaker)
+        .map(move |t| proto::from_server_handshaker(t, local_settings))
         ;
 
     Handshake { inner: Box::new(handshake) }