From 058630d0412797e1f1c1f306beaf59a4bcd44ee3 Mon Sep 17 00:00:00 2001
From: Nikolay Kim <fafhrd91@gmail.com>
Date: Sat, 3 Mar 2018 11:16:55 -0800
Subject: [PATCH] simplify channels list management

---
 src/server/channel.rs  | 49 ++++++++++++++++++------------------------
 src/server/settings.rs |  4 ++--
 2 files changed, 23 insertions(+), 30 deletions(-)

diff --git a/src/server/channel.rs b/src/server/channel.rs
index febd5fe77..2416a3f66 100644
--- a/src/server/channel.rs
+++ b/src/server/channel.rs
@@ -18,15 +18,6 @@ enum HttpProtocol<T: IoStream, H: 'static> {
     Unknown(Rc<WorkerSettings<H>>, Option<SocketAddr>, T, BytesMut),
 }
 
-impl<T: IoStream, H: 'static> HttpProtocol<T, H> {
-    fn is_unknown(&self) -> bool {
-        match *self {
-            HttpProtocol::Unknown(_, _, _, _) => true,
-            _ => false
-        }
-    }
-}
-
 enum ProtocolKind {
     Http1,
     Http2,
@@ -44,15 +35,14 @@ impl<T, H> HttpChannel<T, H> where T: IoStream, H: HttpHandler + 'static
                       io: T, peer: Option<SocketAddr>, http2: bool) -> HttpChannel<T, H>
     {
         settings.add_channel();
+
         if http2 {
             HttpChannel {
-                node: None,
-                proto: Some(HttpProtocol::H2(
+                node: None, proto: Some(HttpProtocol::H2(
                     h2::Http2::new(settings, io, peer, Bytes::new()))) }
         } else {
             HttpChannel {
-                node: None,
-                proto: Some(HttpProtocol::Unknown(
+                node: None, proto: Some(HttpProtocol::Unknown(
                     settings, peer, io, BytesMut::with_capacity(4096))) }
         }
     }
@@ -78,15 +68,18 @@ impl<T, H> Future for HttpChannel<T, H> where T: IoStream, H: HttpHandler + 'sta
     type Error = ();
 
     fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
-        if !self.proto.as_ref().map(|p| p.is_unknown()).unwrap_or(false) && self.node.is_none() {
-            self.node = Some(Node::new(self));
-            match self.proto {
+        if !self.node.is_none() {
+            let el = self as *mut _;
+            self.node = Some(Node::new(el));
+            let _ = match self.proto {
                 Some(HttpProtocol::H1(ref mut h1)) =>
-                    h1.settings().head().insert(self.node.as_ref().unwrap()),
+                    self.node.as_ref().map(|n| h1.settings().head().insert(n)),
                 Some(HttpProtocol::H2(ref mut h2)) =>
-                    h2.settings().head().insert(self.node.as_ref().unwrap()),
-                _ => (),
-            }
+                    self.node.as_ref().map(|n| h2.settings().head().insert(n)),
+                Some(HttpProtocol::Unknown(ref mut settings, _, _, _)) =>
+                    self.node.as_ref().map(|n| settings.head().insert(n)),
+                None => unreachable!(),
+            };
         }
 
         let kind = match self.proto {
@@ -95,7 +88,7 @@ impl<T, H> Future for HttpChannel<T, H> where T: IoStream, H: HttpHandler + 'sta
                 match result {
                     Ok(Async::Ready(())) | Err(_) => {
                         h1.settings().remove_channel();
-                        self.node.as_mut().unwrap().remove();
+                        self.node.as_mut().map(|n| n.remove());
                     },
                     _ => (),
                 }
@@ -106,7 +99,7 @@ impl<T, H> Future for HttpChannel<T, H> where T: IoStream, H: HttpHandler + 'sta
                 match result {
                     Ok(Async::Ready(())) | Err(_) => {
                         h2.settings().remove_channel();
-                        self.node.as_mut().unwrap().remove();
+                        self.node.as_mut().map(|n| n.remove());
                     },
                     _ => (),
                 }
@@ -117,6 +110,7 @@ impl<T, H> Future for HttpChannel<T, H> where T: IoStream, H: HttpHandler + 'sta
                     Ok(Async::Ready(0)) | Err(_) => {
                         debug!("Ignored premature client disconnection");
                         settings.remove_channel();
+                        self.node.as_mut().map(|n| n.remove());
                         return Err(())
                     },
                     _ => (),
@@ -163,11 +157,11 @@ pub(crate) struct Node<T>
 
 impl<T> Node<T>
 {
-    fn new(el: &mut T) -> Self {
+    fn new(el: *mut T) -> Self {
         Node {
             next: None,
             prev: None,
-            element: el as *mut _,
+            element: el,
         }
     }
 
@@ -187,14 +181,13 @@ impl<T> Node<T>
     }
 
     fn remove(&mut self) {
-        #[allow(mutable_transmutes)]
         unsafe {
-            let mut prev = self.prev.take();
+            self.element = ptr::null_mut();
             let next = self.next.take();
+            let mut prev = self.prev.take();
 
             if let Some(ref mut prev) = prev {
-                let p: &mut Node<()> = mem::transmute(prev.as_ref().unwrap());
-                p.next = next;
+                prev.as_mut().unwrap().next = next;
             }
         }
     }
diff --git a/src/server/settings.rs b/src/server/settings.rs
index 50be1f7e7..b0b8eb552 100644
--- a/src/server/settings.rs
+++ b/src/server/settings.rs
@@ -63,7 +63,7 @@ pub(crate) struct WorkerSettings<H> {
     bytes: Rc<SharedBytesPool>,
     messages: Rc<helpers::SharedMessagePool>,
     channels: Cell<usize>,
-    node: Node<()>,
+    node: Box<Node<()>>,
 }
 
 impl<H> WorkerSettings<H> {
@@ -75,7 +75,7 @@ impl<H> WorkerSettings<H> {
             bytes: Rc::new(SharedBytesPool::new()),
             messages: Rc::new(helpers::SharedMessagePool::new()),
             channels: Cell::new(0),
-            node: Node::head(),
+            node: Box::new(Node::head()),
         }
     }