Add shutdown functionality to NodeStream. (#560)

Add shutdown functionality to `NodeStream`.

Add `NodeStream::shutdown` to allow triggering the shutdown process,
and `NodeStream::poll_shutdown` as the internal way to drive any
potential shutdown to completion.

core/src/nodes/handled_node.rs

@@ -20,7 +20,7 @@
 
 use muxing::StreamMuxer;
 use nodes::node::{NodeEvent, NodeStream, Substream};
-use futures::prelude::*;
+use futures::{prelude::*, stream::Fuse};
 use std::io::Error as IoError;
 use Multiaddr;
 
@@ -124,10 +124,12 @@ where
     TMuxer: StreamMuxer,
     THandler: NodeHandler<Substream<TMuxer>>,
 {
-    /// Node that handles the muxing. Can be `None` if the handled node is shutting down.
-    node: Option<NodeStream<TMuxer, TAddrFut, THandler::OutboundOpenInfo>>,
+    /// Node that handles the muxing.
+    node: Fuse<NodeStream<TMuxer, TAddrFut, THandler::OutboundOpenInfo>>,
     /// Handler that processes substreams.
     handler: THandler,
+    // True, if the node is shutting down.
+    is_shutting_down: bool
 }
 
 impl<TMuxer, TAddrFut, THandler> HandledNode<TMuxer, TAddrFut, THandler>
@@ -140,8 +142,9 @@ where
     #[inline]
     pub fn new(muxer: TMuxer, multiaddr_future: TAddrFut, handler: THandler) -> Self {
         HandledNode {
-            node: Some(NodeStream::new(muxer, multiaddr_future)),
+            node: NodeStream::new(muxer, multiaddr_future).fuse(),
             handler,
+            is_shutting_down: false
         }
     }
 
@@ -151,26 +154,26 @@ where
         self.handler.inject_event(event);
     }
 
-    /// Returns true if the inbound channel of the muxer is closed.
+    /// Returns true if the inbound channel of the muxer is open.
     ///
-    /// If `true` is returned, then no more inbound substream will be received.
+    /// If `true` is returned, more inbound substream will be received.
     #[inline]
-    pub fn is_inbound_closed(&self) -> bool {
-        self.node.as_ref().map(|n| n.is_inbound_closed()).unwrap_or(true)
+    pub fn is_inbound_open(&self) -> bool {
+        self.node.get_ref().is_inbound_open()
     }
 
-    /// Returns true if the outbound channel of the muxer is closed.
+    /// Returns true if the outbound channel of the muxer is open.
     ///
-    /// If `true` is returned, then no more outbound substream will be opened.
+    /// If `true` is returned, more outbound substream will be opened.
     #[inline]
-    pub fn is_outbound_closed(&self) -> bool {
-        self.node.as_ref().map(|n| n.is_outbound_closed()).unwrap_or(true)
+    pub fn is_outbound_open(&self) -> bool {
+        self.node.get_ref().is_outbound_open()
     }
 
     /// Returns true if the handled node is in the process of shutting down.
     #[inline]
     pub fn is_shutting_down(&self) -> bool {
-        self.node.is_none()
+        self.is_shutting_down
     }
 
     /// Indicates to the handled node that it should shut down. After calling this method, the
@@ -178,13 +181,14 @@ where
     ///
     /// After this method returns, `is_shutting_down()` should return true.
     pub fn shutdown(&mut self) {
-        if let Some(node) = self.node.take() {
-            for user_data in node.close() {
-                self.handler.inject_outbound_closed(user_data);
-            }
+        self.node.get_mut().shutdown_all();
+        self.is_shutting_down = true;
+
+        for user_data in self.node.get_mut().cancel_outgoing() {
+            self.handler.inject_outbound_closed(user_data);
         }
 
-        self.handler.shutdown();
+        self.handler.shutdown()
     }
 }
 
@@ -201,60 +205,54 @@ where
         loop {
             let mut node_not_ready = false;
 
-            match self.node.as_mut().map(|n| n.poll()) {
-                Some(Ok(Async::NotReady)) | None => {},
-                Some(Ok(Async::Ready(Some(NodeEvent::InboundSubstream { substream })))) => {
-                    self.handler.inject_substream(substream, NodeHandlerEndpoint::Listener);
-                },
-                Some(Ok(Async::Ready(Some(NodeEvent::OutboundSubstream { user_data, substream })))) => {
+            match self.node.poll()? {
+                Async::NotReady => (),
+                Async::Ready(Some(NodeEvent::InboundSubstream { substream })) => {
+                    self.handler.inject_substream(substream, NodeHandlerEndpoint::Listener)
+                }
+                Async::Ready(Some(NodeEvent::OutboundSubstream { user_data, substream })) => {
                     let endpoint = NodeHandlerEndpoint::Dialer(user_data);
-                    self.handler.inject_substream(substream, endpoint);
-                },
-                Some(Ok(Async::Ready(None))) => {
+                    self.handler.inject_substream(substream, endpoint)
+                }
+                Async::Ready(None) => {
                     node_not_ready = true;
-                    self.node = None;
-                    self.handler.shutdown();
-                },
-                Some(Ok(Async::Ready(Some(NodeEvent::Multiaddr(result))))) => {
-                    self.handler.inject_multiaddr(result);
-                },
-                Some(Ok(Async::Ready(Some(NodeEvent::OutboundClosed { user_data })))) => {
-                    self.handler.inject_outbound_closed(user_data);
-                },
-                Some(Ok(Async::Ready(Some(NodeEvent::InboundClosed)))) => {
-                    self.handler.inject_inbound_closed();
-                },
-                Some(Err(err)) => {
-                    self.node = None;
-                    return Err(err);
-                },
+                    if !self.is_shutting_down {
+                        self.handler.shutdown()
+                    }
+                }
+                Async::Ready(Some(NodeEvent::Multiaddr(result))) => {
+                    self.handler.inject_multiaddr(result)
+                }
+                Async::Ready(Some(NodeEvent::OutboundClosed { user_data })) => {
+                    self.handler.inject_outbound_closed(user_data)
+                }
+                Async::Ready(Some(NodeEvent::InboundClosed)) => {
+                    self.handler.inject_inbound_closed()
+                }
             }
 
-            match self.handler.poll() {
-                Ok(Async::NotReady) => {
+            match self.handler.poll()? {
+                Async::NotReady => {
                     if node_not_ready {
-                        break;
+                        break
                     }
-                },
-                Ok(Async::Ready(Some(NodeHandlerEvent::OutboundSubstreamRequest(user_data)))) => {
-                    if let Some(node) = self.node.as_mut() {
-                        match node.open_substream(user_data) {
+                }
+                Async::Ready(Some(NodeHandlerEvent::OutboundSubstreamRequest(user_data))) => {
+                    if self.node.get_ref().is_outbound_open() {
+                        match self.node.get_mut().open_substream(user_data) {
                             Ok(()) => (),
                             Err(user_data) => self.handler.inject_outbound_closed(user_data),
                         }
                     } else {
                         self.handler.inject_outbound_closed(user_data);
                     }
-                },
-                Ok(Async::Ready(Some(NodeHandlerEvent::Custom(event)))) => {
+                }
+                Async::Ready(Some(NodeHandlerEvent::Custom(event))) => {
                     return Ok(Async::Ready(Some(event)));
-                },
-                Ok(Async::Ready(None)) => {
-                    return Ok(Async::Ready(None));
-                },
-                Err(err) => {
-                    return Err(err);
-                },
+                }
+                Async::Ready(None) => {
+                    return Ok(Async::Ready(None))
+                }
             }
         }