Merge pull request #312 from reem/acceptor-pool

feat(server): Rewrite the accept loop into a custom thread pool.

examples/hello.rs

@@ -13,6 +13,7 @@ fn hello(_: Request, res: Response) {
 }
 
 fn main() {
-    hyper::Server::http(Ipv4Addr(127, 0, 0, 1), 3000).listen(hello).unwrap();
+    let _listening = hyper::Server::http(Ipv4Addr(127, 0, 0, 1), 3000)
+        .listen(hello).unwrap();
     println!("Listening on http://127.0.0.1:3000");
 }

examples/server.rs

@@ -51,7 +51,6 @@ fn echo(mut req: Request, mut res: Response) {
 
 fn main() {
     let server = Server::http(Ipv4Addr(127, 0, 0, 1), 1337);
-    let mut listening = server.listen(echo).unwrap();
+    let _guard = server.listen(echo).unwrap();
     println!("Listening on http://127.0.0.1:1337");
-    listening.await();
 }

src/lib.rs

@@ -1,5 +1,5 @@
 #![feature(core, collections, hash, io, os, path, std_misc,
-           slicing_syntax, box_syntax)]
+           slicing_syntax, box_syntax, unsafe_destructor)]
 #![deny(missing_docs)]
 #![cfg_attr(test, deny(warnings))]
 #![cfg_attr(test, feature(alloc, test))]
@@ -130,12 +130,16 @@ extern crate "rustc-serialize" as serialize;
 extern crate time;
 extern crate url;
 extern crate openssl;
-#[macro_use] extern crate log;
-#[cfg(test)] extern crate test;
 extern crate "unsafe-any" as uany;
 extern crate cookie;
 extern crate unicase;
 
+#[macro_use]
+extern crate log;
+
+#[cfg(test)]
+extern crate test;
+
 pub use std::old_io::net::ip::{SocketAddr, IpAddr, Ipv4Addr, Ipv6Addr, Port};
 pub use mimewrapper::mime;
 pub use url::Url;

src/server/acceptor.rs

@@ -0,0 +1,95 @@
+use std::thread::{Thread, JoinGuard};
+use std::sync::Arc;
+use std::sync::mpsc;
+use net::NetworkAcceptor;
+
+pub struct AcceptorPool<A: NetworkAcceptor> {
+    acceptor: A
+}
+
+impl<A: NetworkAcceptor> AcceptorPool<A> {
+    /// Create a thread pool to manage the acceptor.
+    pub fn new(acceptor: A) -> AcceptorPool<A> {
+        AcceptorPool { acceptor: acceptor }
+    }
+
+    /// Runs the acceptor pool. Blocks until the acceptors are closed.
+    ///
+    /// ## Panics
+    ///
+    /// Panics if threads == 0.
+    pub fn accept<F: Fn(A::Stream) + Send + Sync>(self,
+                                                  work: F,
+                                                  threads: usize) -> JoinGuard<'static, ()> {
+        assert!(threads != 0, "Can't accept on 0 threads.");
+
+        // Replace with &F when Send changes land.
+        let work = Arc::new(work);
+
+        let (super_tx, supervisor_rx) = mpsc::channel();
+
+        let spawn =
+            move || spawn_with(super_tx.clone(), work.clone(), self.acceptor.clone());
+
+        // Go
+        for _ in 0..threads { spawn() }
+
+        // Spawn the supervisor
+        Thread::scoped(move || for () in supervisor_rx.iter() { spawn() })
+    }
+}
+
+fn spawn_with<A, F>(supervisor: mpsc::Sender<()>, work: Arc<F>, mut acceptor: A)
+where A: NetworkAcceptor,
+      F: Fn(<A as NetworkAcceptor>::Stream) + Send + Sync {
+    use std::old_io::EndOfFile;
+
+    Thread::spawn(move || {
+        let sentinel = Sentinel::new(supervisor, ());
+
+        loop {
+            match acceptor.accept() {
+                Ok(stream) => work(stream),
+                Err(ref e) if e.kind == EndOfFile => {
+                    debug!("Server closed.");
+                    sentinel.cancel();
+                    return;
+                },
+
+                Err(e) => {
+                    error!("Connection failed: {}", e);
+                }
+            }
+        }
+    });
+}
+
+struct Sentinel<T: Send> {
+    value: Option<T>,
+    supervisor: mpsc::Sender<T>,
+    active: bool
+}
+
+impl<T: Send> Sentinel<T> {
+    fn new(channel: mpsc::Sender<T>, data: T) -> Sentinel<T> {
+        Sentinel {
+            value: Some(data),
+            supervisor: channel,
+            active: true
+        }
+    }
+
+    fn cancel(mut self) { self.active = false; }
+}
+
+#[unsafe_destructor]
+impl<T: Send> Drop for Sentinel<T> {
+    fn drop(&mut self) {
+        // If we were cancelled, get out of here.
+        if !self.active { return; }
+
+        // Respawn ourselves
+        let _ = self.supervisor.send(self.value.take().unwrap());
+    }
+}
+

src/server/mod.rs

@@ -1,10 +1,8 @@
 //! HTTP Server
-use std::old_io::{Listener, EndOfFile, BufferedReader, BufferedWriter};
+use std::old_io::{Listener, BufferedReader, BufferedWriter};
 use std::old_io::net::ip::{IpAddr, Port, SocketAddr};
 use std::os;
-use std::sync::{Arc, TaskPool};
-use std::thread::{Builder, JoinGuard};
-
+use std::thread::JoinGuard;
 
 pub use self::request::Request;
 pub use self::response::Response;
@@ -19,9 +17,13 @@ use net::{NetworkListener, NetworkStream, NetworkAcceptor,
           HttpAcceptor, HttpListener};
 use version::HttpVersion::{Http10, Http11};
 
+use self::acceptor::AcceptorPool;
+
 pub mod request;
 pub mod response;
 
+mod acceptor;
+
 /// A server can listen on a TCP socket.
 ///
 /// Once listening, it will create a `Request`/`Response` pair for each
@@ -71,17 +73,27 @@ S: NetworkStream + Clone + Send> Server<L> {
         let acceptor = try!(self.listener.listen((self.ip, self.port)));
         let socket = try!(acceptor.socket_name());
 
-        let mut captured = acceptor.clone();
-        let guard = Builder::new().name("hyper acceptor".to_string()).scoped(move || {
-            let handler = Arc::new(handler);
         debug!("threads = {:?}", threads);
-            let pool = TaskPool::new(threads);
-            for conn in captured.incoming() {
-                match conn {
-                    Ok(mut stream) => {
+        let pool = AcceptorPool::new(acceptor.clone());
+        let work = move |stream| handle_connection(stream, &handler);
+
+        Ok(Listening {
+            _guard: pool.accept(work, threads),
+            socket: socket,
+            acceptor: acceptor
+        })
+    }
+
+    /// Binds to a socket and starts handling connections.
+    pub fn listen<H: Handler>(self, handler: H) -> HttpResult<Listening<L::Acceptor>> {
+        self.listen_threads(handler, os::num_cpus() * 5 / 4)
+    }
+
+}
+
+fn handle_connection<S, H>(mut stream: S, handler: &H)
+where S: NetworkStream + Clone, H: Handler {
     debug!("Incoming stream");
-                        let handler = handler.clone();
-                        pool.execute(move || {
     let addr = match stream.peer_name() {
         Ok(addr) => addr,
         Err(e) => {
@@ -89,6 +101,7 @@ S: NetworkStream + Clone + Send> Server<L> {
             return;
         }
     };
+
     let mut rdr = BufferedReader::new(stream.clone());
     let mut wrt = BufferedWriter::new(stream);
 
@@ -117,51 +130,17 @@ S: NetworkStream + Clone + Send> Server<L> {
         handler.handle(req, res);
         debug!("keep_alive = {:?}", keep_alive);
     }
-
-                        });
-                    },
-                    Err(ref e) if e.kind == EndOfFile => {
-                        debug!("server closed");
-                        break;
-                    },
-                    Err(e) => {
-                        error!("Connection failed: {}", e);
-                        continue;
-                    }
-                }
-            }
-        });
-
-        Ok(Listening {
-            acceptor: acceptor,
-            guard: Some(guard),
-            socket: socket,
-        })
-    }
-
-    /// Binds to a socket and starts handling connections.
-    pub fn listen<H: Handler>(self, handler: H) -> HttpResult<Listening<L::Acceptor>> {
-        self.listen_threads(handler, os::num_cpus() * 5 / 4)
-    }
-
 }
 
 /// A listening server, which can later be closed.
 pub struct Listening<A = HttpAcceptor> {
     acceptor: A,
-    guard: Option<JoinGuard<'static, ()>>,
+    _guard: JoinGuard<'static, ()>,
     /// The socket addresses that the server is bound to.
     pub socket: SocketAddr,
 }
 
 impl<A: NetworkAcceptor> Listening<A> {
-    /// Causes the current thread to wait for this listening to complete.
-    pub fn await(&mut self) {
-        if let Some(guard) = self.guard.take() {
-            let _ = guard.join();
-        }
-    }
-
     /// Stop the server from listening to its socket address.
     pub fn close(&mut self) -> HttpResult<()> {
         debug!("closing server");