eventloop: Signal Machine removal through return values

The Machine handler should not really do anything after it has decided
it wants to be destroyed, so it seems better to enforce this by having
the handler return this action.

1 files changed, 36 insertions, 30 deletions

diff --git a/src/itf_http.rs b/src/itf_http.rs
index cda923f..012323c 100644
--- a/src/itf_http.rs
+++ b/src/itf_http.rs
@@ -2,11 +2,12 @@ use mio::{Ready,Token,Event};
 use mio::tcp::TcpStream;
 use std::net::SocketAddr;
 use std::io::ErrorKind;
-use listener::Interface;
-use eventloop::{Machine,Context,TToken};
 use std::sync::Arc;
 use netbuf::Buf;
 
+use listener::Interface;
+use eventloop::{Machine,Context,TToken,Action};
+
 
 // TODO: Set a max size on the buffers and provide backpressure
 pub struct ItfHttp {
@@ -21,6 +22,15 @@ pub struct ItfHttp {
 }
 
 
+macro_rules! try_act {
+    ( $e: expr ) => {{
+        if let Some(x) = $e {
+            return Some(x);
+        }
+    }};
+}
+
+
 impl ItfHttp {
     pub fn new(ctx: &mut Context, itf: Arc<Interface>, sock: TcpStream, addr: SocketAddr) -> ItfHttp {
         let io = ctx.register(&sock, Ready::readable());
@@ -36,22 +46,21 @@ impl ItfHttp {
         }
     }
 
-    fn handle_read(&mut self, ctx: &mut Context) {
+    fn handle_read(&mut self) -> Option<Action> {
         match self.rbuf.read_from(&mut self.sock) {
             Err(err) => {
                 match err.kind() {
                     ErrorKind::WouldBlock | ErrorKind::Interrupted => { },
                     _ => {
                         debug!("{}: Read error: {}", self.addr, err);
-                        self.remove(ctx);
+                        return Some(Action::Remove);
                     }
                 }
-                return;
+                return None;
             },
             Ok(0) => {
                 debug!("{}: Connection closed", self.addr);
-                self.remove(ctx);
-                return;
+                return Some(Action::Remove);
             },
             _ => {}
         }
@@ -59,31 +68,30 @@ impl ItfHttp {
         // through some handlers to get a response and send it back. But for now let's just act
         // like we wanted to be an echo server all along.
         self.rbuf.write_to(&mut self.wbuf).unwrap();
+        None
     }
 
-    fn handle_write(&mut self, ctx: &mut Context) {
+    fn handle_write(&mut self) -> Option<Action> {
         if let Err(err) = self.wbuf.write_to(&mut self.sock) {
             match err.kind() {
                 ErrorKind::WouldBlock | ErrorKind::Interrupted => { },
                 _ => {
                     debug!("{}: Write error: {}", self.addr, err);
-                    self.remove(ctx);
+                    return Some(Action::Remove);
                 }
             }
         }
+        None
     }
 
-    fn set_ioreg(&mut self, ctx: &mut Context) {
+    fn set_ioreg(&mut self, ctx: &mut Context) -> Option<Action> {
         // Optimization: If the write buffer was empty before but contains data now, we can already
         // try to write it out at this point. This way we can avoid going through the event loop if
         // the OS buffers have enough space.
         // TODO: Measure how effective this is in practice; if this only tends to happen on the
         // first write to a new socket then it might not be worth the effort.
         if self.wbuf.len() > 0 && !self.ioreg.contains(Ready::writable()) {
-            self.handle_write(ctx);
-            if ctx.is_removed() {
-                return;
-            }
+            try_act!(self.handle_write());
         }
 
         let mut reg = Ready::readable();
@@ -95,32 +103,30 @@ impl ItfHttp {
             ctx.reregister(&self.sock, self.io, self.ioreg);
         }
         ctx.reset_timeout(self.iotimeout, self.itf.cfg.io_timeout);
-    }
-
-    fn remove(&mut self, ctx: &mut Context) {
-        self.itf.release();
-        ctx.deregister(&self.sock, self.io);
-        ctx.cancel_timeout(self.iotimeout);
-        ctx.remove();
+        None
     }
 }
 
 
 impl Machine for ItfHttp {
-    fn handle(&mut self, ctx: &mut Context, ev: Event) {
+    fn handle(&mut self, ctx: &mut Context, ev: Event) -> Option<Action> {
         if ev.kind().is_readable() {
-            self.handle_read(ctx);
+            try_act!(self.handle_read());
         }
-        if !ctx.is_removed() && ev.kind().is_writable() {
-            self.handle_write(ctx);
-        }
-        if !ctx.is_removed() {
-            self.set_ioreg(ctx);
+        if ev.kind().is_writable() {
+            try_act!(self.handle_write());
         }
+        self.set_ioreg(ctx)
     }
 
-    fn timeout(&mut self, ctx: &mut Context, _: TToken) {
+    fn timeout(&mut self, _: &mut Context, _: TToken) -> Option<Action> {
         debug!("{}: No IO activity in {} seconds", self.addr, self.itf.cfg.io_timeout.as_secs());
-        self.remove(ctx);
+        Some(Action::Remove)
+    }
+
+    fn remove(&mut self, ctx: &mut Context) {
+        self.itf.release();
+        ctx.deregister(&self.sock, self.io);
+        ctx.cancel_timeout(self.iotimeout);
     }
 }