Use a protocol for the engine

src/servo/engine.rs

@@ -1,6 +1,5 @@
 import gfx::renderer::{Renderer, Sink};
-import task::spawn_listener;
-import comm::chan;
+import pipes::{spawn_service, select};
 import layout::layout_task;
 import layout_task::Layout;
 import content::{Content, ExecuteMsg, ParseMsg, ExitMsg, create_content};
@@ -12,6 +11,10 @@ import image_cache_task::{ImageCacheTask, image_cache_task, ImageCacheTaskClient
 
 import pipes::{port, chan};
 
+fn macros() {
+    include!("macros.rs");
+}
+
 struct Engine<S:Sink send copy> {
     let sink: S;
 
@@ -37,28 +40,45 @@ struct Engine<S:Sink send copy> {
         self.content = content;
     }
 
-    fn start() -> comm::Chan<Msg> {
-        do spawn_listener::<Msg> |request| {
-            while self.handle_request(request.recv()) {
-                // Go on...
+    fn start() -> EngineProto::client::Running {
+        do spawn_service(EngineProto::init) |request| {
+            // this could probably be an @vector
+            let mut request = ~[move request];
+
+            loop {
+                match move select(move request) {
+                  (_, some(ref message), ref requests) => {
+                    match move self.handle_request(move_ref!(message)) {
+                      some(ref req) =>
+                          request = vec::append_one(move_ref!(requests),
+                                                    move_ref!(req)),
+                      none => break
+                    }
+                  }
+
+                  _ => fail ~"select returned something unexpected."
+                }
             }
         }
     }
 
-    fn handle_request(request: Msg) -> bool {
-        match request {
-          LoadURLMsg(url) => {
+    fn handle_request(+request: EngineProto::Running)
+        -> option<EngineProto::server::Running>
+    {
+        import EngineProto::*;
+        match move request {
+          LoadURL(ref url, ref next) => {
             // TODO: change copy to move once we have match move
-            let url = copy url;
+            let url = move_ref!(url);
             if url.path.ends_with(".js") {
                 self.content.send(ExecuteMsg(url))
             } else {
                 self.content.send(ParseMsg(url))
             }
-            return true;
+            return some(move_ref!(next));
           }
 
-          ExitMsg(sender) => {
+          Exit(ref channel) => {
             self.content.send(content::ExitMsg);
             self.layout.send(layout_task::ExitMsg);
             
@@ -70,15 +90,20 @@ struct Engine<S:Sink send copy> {
             self.image_cache_task.exit();
             self.resource_task.send(resource_task::Exit);
 
-            sender.send(());
-            return false;
+            server::Exited(move_ref!(channel));
+            return none;
           }
         }
     }
 }
 
-enum Msg {
-    LoadURLMsg(url),
-    ExitMsg(chan<()>)
-}
+proto! EngineProto {
+    Running:send {
+        LoadURL(url) -> Running,
+        Exit -> Exiting
+    }
 
+    Exiting:recv {
+        Exited -> !
+    }
+}

src/servo/macros.rs

@@ -0,0 +1,9 @@
+{
+    macro_rules! move_ref {
+        { $x:expr } => { unsafe { let y <- *ptr::addr_of(*$x); y } }
+    }
+
+    macro_rules! move_val {
+        { $x:expr } => { unsafe { let y <- *ptr::addr_of(*$x); y } }
+    }
+}

src/servo/servo.rs

@@ -1,9 +1,11 @@
 import comm::*;
+import option::swap_unwrap;
 import gfx::renderer;
 import platform::osmain;
 import osmain::{OSMain, AddKeyHandler};
 import opts::{Opts, Screen, Png};
-import engine::{Engine, LoadURLMsg};
+import engine::Engine;
+import engine::EngineProto;
 
 import url_to_str = std::net::url::to_str;
 import util::url::make_url;
@@ -39,12 +41,14 @@ fn run_pipeline_screen(urls: ~[~str]) {
 
     // Create a serve instance
     let engine = Engine(osmain);
-    let engine_chan = engine.start();
+    let mut engine_chan = some(engine.start());
 
     for urls.each |filename| {
         let url = make_url(filename, none);
         #debug["master: Sending url `%s`", url_to_str(url)];
-        engine_chan.send(LoadURLMsg(url));
+        engine_chan =
+            some(EngineProto::client::LoadURL(swap_unwrap(&mut engine_chan),
+                                              url));
         #debug["master: Waiting for keypress"];
 
         match keypress_from_osmain.try_recv() {
@@ -55,9 +59,8 @@ fn run_pipeline_screen(urls: ~[~str]) {
 
     // Shut everything down
     #debug["master: Shut down"];
-    let (exit_chan, exit_response_from_engine) = pipes::stream();
-    engine_chan.send(engine::ExitMsg(exit_chan));
-    exit_response_from_engine.recv();
+    let engine_chan = EngineProto::client::Exit(option::unwrap(engine_chan));
+    pipes::recv(engine_chan);
 
     osmain.send(osmain::Exit);
 }
@@ -74,16 +77,16 @@ fn run_pipeline_png(-url: ~str, outfile: ~str) {
         let sink = PngSink(pngdata_from_sink);
         let engine = Engine(sink);
         let engine_chan = engine.start();
-        engine_chan.send(LoadURLMsg(make_url(url, none)));
+        let engine_chan =
+            EngineProto::client::LoadURL(engine_chan, make_url(url, none));
 
         match buffered_file_writer(outfile) {
           ok(writer) => writer.write(pngdata_from_sink.recv()),
           err(e) => fail e
         }
 
-        let (exit_chan, exit_response_from_engine) = pipes::stream();
-        engine_chan.send(engine::ExitMsg(exit_chan));
-        exit_response_from_engine.recv();
+        let engine_chan = EngineProto::client::Exit(engine_chan);
+        pipes::recv(engine_chan);
         sink.send(pngsink::Exit);
     })
 }