Refactor devtools server (#35735)

Previously, the devtools code was structured like this (in pseudocode):
```rust
fn run() {
    let member_1;
    let member_2;

    fn foo(&member_1) {
        // ...
    }

    fn bar(&member_1, &member_2) {
        // ...
    }

    loop {
        match get_message() {
            Message1 => foo(&member_1),
            Message2 => bar(&member_1, &member_2),

        }
    }
}
```

This is not very idiomatic rust. And, more importantly, it makes it hard
to edit this code with an IDE, because "find all references" and similar
actions don't properly work. (member_1 inside "foo" is a different
variable than member_1 inside "bar" or "run").

Instead, the code is now structured (roughly) like this:

```rust
struct DevtoolsInstance {
    member_1,
    member_2,
}

impl DevtoolsInstance {
    fn foo(&self) {
        // ...
    }

    fn bar(&self) {
        // ...
    }

    fn run(&self) {
        loop {
            match get_message() {
                Message1 => self.foo(),
                Message2 => self.bar(),

            }
        }
    }
}
```

In my opinion, this is an improvement and should make future additions
to the devtools server easier. No behaviour change is intended.

Signed-off-by: Simon Wülker <simon.wuelker@arcor.de>

components/devtools/lib.rs

@@ -128,7 +128,11 @@ pub fn start_server(port: u16, embedder: EmbedderProxy) -> Sender<DevtoolsContro
         let sender = sender.clone();
         thread::Builder::new()
             .name("Devtools".to_owned())
-            .spawn(move || run_server(sender, receiver, port, embedder))
+            .spawn(move || {
+                if let Some(instance) = DevtoolsInstance::create(sender, receiver, port, embedder) {
+                    instance.run()
+                }
+            })
             .expect("Thread spawning failed");
     }
     sender
@@ -137,12 +141,23 @@ pub fn start_server(port: u16, embedder: EmbedderProxy) -> Sender<DevtoolsContro
 #[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
 pub(crate) struct StreamId(u32);
 
-fn run_server(
+struct DevtoolsInstance {
+    actors: Arc<Mutex<ActorRegistry>>,
+    browsing_contexts: HashMap<BrowsingContextId, String>,
+    receiver: Receiver<DevtoolsControlMsg>,
+    pipelines: HashMap<PipelineId, BrowsingContextId>,
+    actor_workers: HashMap<WorkerId, String>,
+    actor_requests: HashMap<String, String>,
+    connections: HashMap<StreamId, TcpStream>,
+}
+
+impl DevtoolsInstance {
+    fn create(
         sender: Sender<DevtoolsControlMsg>,
         receiver: Receiver<DevtoolsControlMsg>,
         port: u16,
         embedder: EmbedderProxy,
-) {
+    ) -> Option<Self> {
         let bound = TcpListener::bind(("0.0.0.0", port)).ok().and_then(|l| {
             l.local_addr()
                 .map(|addr| addr.port())
@@ -151,26 +166,23 @@ fn run_server(
         });
 
         // A token shared with the embedder to bypass permission prompt.
+        let port = if bound.is_some() { Ok(port) } else { Err(()) };
         let token = format!("{:X}", servo_rand::ServoRng::default().next_u32());
-
-    let port = bound.as_ref().map(|(_, port)| *port).ok_or(());
         embedder.send(EmbedderMsg::OnDevtoolsStarted(port, token.clone()));
 
         let listener = match bound {
             Some((l, _)) => l,
-        None => return,
+            None => {
+                return None;
+            },
         };
 
+        // Create basic actors
         let mut registry = ActorRegistry::new();
-
         let performance = PerformanceActor::new(registry.new_name("performance"));
-
         let device = DeviceActor::new(registry.new_name("device"));
-
         let preference = PreferenceActor::new(registry.new_name("preference"));
-
         let process = ProcessActor::new(registry.new_name("process"));
-
         let root = Box::new(RootActor {
             tabs: vec![],
             workers: vec![],
@@ -189,114 +201,161 @@ fn run_server(
 
         let actors = registry.create_shareable();
 
-    let mut accepted_connections = HashMap::new();
-    let mut browsing_contexts: HashMap<_, String> = HashMap::new();
-    let mut pipelines = HashMap::new();
-    let mut actor_requests = HashMap::new();
-    let mut actor_workers = HashMap::new();
+        let instance = Self {
+            actors,
+            browsing_contexts: HashMap::new(),
+            pipelines: HashMap::new(),
+            receiver,
+            actor_requests: HashMap::new(),
+            actor_workers: HashMap::new(),
+            connections: HashMap::new(),
+        };
 
-    /// Process the input from a single devtools client until EOF.
-    fn handle_client(actors: Arc<Mutex<ActorRegistry>>, mut stream: TcpStream, id: StreamId) {
-        debug!("connection established to {}", stream.peer_addr().unwrap());
-        {
+        thread::Builder::new()
+            .name("DevtoolsCliAcceptor".to_owned())
+            .spawn(move || {
+                // accept connections and process them, spawning a new thread for each one
+                for stream in listener.incoming() {
+                    let mut stream = stream.expect("Can't retrieve stream");
+                    if !allow_devtools_client(&mut stream, &embedder, &token) {
+                        continue;
+                    };
+                    // connection succeeded and accepted
+                    sender
+                        .send(DevtoolsControlMsg::FromChrome(
+                            ChromeToDevtoolsControlMsg::AddClient(stream),
+                        ))
+                        .unwrap();
+                }
+            })
+            .expect("Thread spawning failed");
+
+        Some(instance)
+    }
+
+    fn run(mut self) {
+        let mut next_id = StreamId(0);
+        while let Ok(msg) = self.receiver.recv() {
+            trace!("{:?}", msg);
+            match msg {
+                DevtoolsControlMsg::FromChrome(ChromeToDevtoolsControlMsg::AddClient(stream)) => {
+                    let actors = self.actors.clone();
+                    let id = next_id;
+                    next_id = StreamId(id.0 + 1);
+                    self.connections.insert(id, stream.try_clone().unwrap());
+
+                    // Inform every browsing context of the new stream
+                    for name in self.browsing_contexts.values() {
                         let actors = actors.lock().unwrap();
-            let msg = actors.find::<RootActor>("root").encodable();
-            if let Err(e) = stream.write_json_packet(&msg) {
-                warn!("Error writing response: {:?}", e);
-                return;
-            }
+                        let browsing_context = actors.find::<BrowsingContextActor>(name);
+                        let mut streams = browsing_context.streams.borrow_mut();
+                        streams.insert(id, stream.try_clone().unwrap());
                     }
 
-        'outer: loop {
-            match stream.read_json_packet() {
-                Ok(Some(json_packet)) => {
-                    if let Err(()) = actors.lock().unwrap().handle_message(
-                        json_packet.as_object().unwrap(),
-                        &mut stream,
+                    thread::Builder::new()
+                        .name("DevtoolsClientHandler".to_owned())
+                        .spawn(move || handle_client(actors, stream.try_clone().unwrap(), id))
+                        .expect("Thread spawning failed");
+                },
+                DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::FramerateTick(
+                    actor_name,
+                    tick,
+                )) => self.handle_framerate_tick(actor_name, tick),
+                DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::TitleChanged(
+                    pipeline,
+                    title,
+                )) => self.handle_title_changed(pipeline, title),
+                DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::NewGlobal(
+                    ids,
+                    script_sender,
+                    pageinfo,
+                )) => self.handle_new_global(ids, script_sender, pageinfo),
+                DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::Navigate(
+                    browsing_context,
+                    state,
+                )) => self.handle_navigate(browsing_context, state),
+                DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::ConsoleAPI(
                     id,
-                    ) {
-                        debug!("error: devtools actor stopped responding");
-                        let _ = stream.shutdown(Shutdown::Both);
-                        break 'outer;
+                    console_message,
+                    worker_id,
+                )) => self.handle_console_message(id, worker_id, console_message),
+                DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::ReportPageError(
+                    id,
+                    page_error,
+                )) => self.handle_page_error(id, None, page_error),
+                DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::ReportCSSError(
+                    id,
+                    css_error,
+                )) => {
+                    let mut console_message = ConsoleMessageBuilder::new(
+                        LogLevel::Warn,
+                        css_error.filename,
+                        css_error.line,
+                        css_error.column,
+                    );
+                    console_message.add_argument(css_error.msg.into());
+
+                    self.handle_console_message(id, None, console_message.finish())
+                },
+                DevtoolsControlMsg::FromChrome(ChromeToDevtoolsControlMsg::NetworkEvent(
+                    request_id,
+                    network_event,
+                )) => {
+                    // copy the connections vector
+                    let mut connections = Vec::<TcpStream>::new();
+                    for stream in self.connections.values() {
+                        connections.push(stream.try_clone().unwrap());
                     }
+
+                    let pipeline_id = match network_event {
+                        NetworkEvent::HttpResponse(ref response) => response.pipeline_id,
+                        NetworkEvent::HttpRequest(ref request) => request.pipeline_id,
+                    };
+                    self.handle_network_event(connections, pipeline_id, request_id, network_event);
                 },
-                Ok(None) => {
-                    debug!("error: EOF");
-                    break 'outer;
-                },
-                Err(err_msg) => {
-                    debug!("error: {}", err_msg);
-                    break 'outer;
-                },
+                DevtoolsControlMsg::FromChrome(ChromeToDevtoolsControlMsg::ServerExitMsg) => break,
             }
         }
 
-        actors.lock().unwrap().cleanup(id);
+        // Shut down all active connections
+        for connection in self.connections.values_mut() {
+            let _ = connection.shutdown(Shutdown::Both);
+        }
     }
 
-    fn handle_framerate_tick(actors: Arc<Mutex<ActorRegistry>>, actor_name: String, tick: f64) {
-        let mut actors = actors.lock().unwrap();
+    fn handle_framerate_tick(&self, actor_name: String, tick: f64) {
+        let mut actors = self.actors.lock().unwrap();
         let framerate_actor = actors.find_mut::<FramerateActor>(&actor_name);
         framerate_actor.add_tick(tick);
     }
 
-    fn handle_navigate(
-        actors: Arc<Mutex<ActorRegistry>>,
-        browsing_contexts: &HashMap<BrowsingContextId, String>,
-        browsing_context: BrowsingContextId,
-        state: NavigationState,
-    ) {
-        let actor_name = browsing_contexts.get(&browsing_context).unwrap();
-        actors
+    fn handle_navigate(&self, browsing_context: BrowsingContextId, state: NavigationState) {
+        let actor_name = self.browsing_contexts.get(&browsing_context).unwrap();
+        self.actors
             .lock()
             .unwrap()
             .find::<BrowsingContextActor>(actor_name)
             .navigate(state);
     }
 
-    fn handle_title_changed(
-        actors: Arc<Mutex<ActorRegistry>>,
-        pipelines: &HashMap<PipelineId, BrowsingContextId>,
-        browsing_contexts: &HashMap<BrowsingContextId, String>,
-        pipeline: PipelineId,
-        title: String,
-    ) {
-        let bc = match pipelines.get(&pipeline) {
-            Some(bc) => bc,
-            None => return,
-        };
-        let name = match browsing_contexts.get(bc) {
-            Some(name) => name,
-            None => return,
-        };
-        let actors = actors.lock().unwrap();
-        let browsing_context = actors.find::<BrowsingContextActor>(name);
-        browsing_context.title_changed(pipeline, title);
-    }
-
     // We need separate actor representations for each script global that exists;
     // clients can theoretically connect to multiple globals simultaneously.
     // TODO: move this into the root or target modules?
-    #[allow(clippy::too_many_arguments)]
     fn handle_new_global(
-        actors: Arc<Mutex<ActorRegistry>>,
+        &mut self,
         ids: (BrowsingContextId, PipelineId, Option<WorkerId>),
         script_sender: IpcSender<DevtoolScriptControlMsg>,
-        browsing_contexts: &mut HashMap<BrowsingContextId, String>,
-        pipelines: &mut HashMap<PipelineId, BrowsingContextId>,
-        actor_workers: &mut HashMap<WorkerId, String>,
         page_info: DevtoolsPageInfo,
-        connections: &HashMap<StreamId, TcpStream>,
     ) {
-        let mut actors = actors.lock().unwrap();
+        let mut actors = self.actors.lock().unwrap();
 
         let (browsing_context, pipeline, worker_id) = ids;
 
         let console_name = actors.new_name("console");
 
         let parent_actor = if let Some(id) = worker_id {
-            assert!(pipelines.get(&pipeline).is_some());
-            assert!(browsing_contexts.get(&browsing_context).is_some());
+            assert!(self.pipelines.contains_key(&pipeline));
+            assert!(self.browsing_contexts.contains_key(&browsing_context));
 
             let thread = ThreadActor::new(actors.new_name("context"));
             let thread_name = thread.name();
@@ -316,13 +375,14 @@ fn run_server(
             let root = actors.find_mut::<RootActor>("root");
             root.workers.push(worker.name.clone());
 
-            actor_workers.insert(id, worker_name.clone());
+            self.actor_workers.insert(id, worker_name.clone());
             actors.register(Box::new(worker));
 
             Root::DedicatedWorker(worker_name)
         } else {
-            pipelines.insert(pipeline, browsing_context);
-            let name = browsing_contexts
+            self.pipelines.insert(pipeline, browsing_context);
+            let name = self
+                .browsing_contexts
                 .entry(browsing_context)
                 .or_insert_with(|| {
                     let browsing_context_actor = BrowsingContextActor::new(
@@ -341,7 +401,7 @@ fn run_server(
             // Add existing streams to the new browsing context
             let browsing_context = actors.find::<BrowsingContextActor>(name);
             let mut streams = browsing_context.streams.borrow_mut();
-            for (id, stream) in connections {
+            for (id, stream) in &self.connections {
                 streams.insert(*id, stream.try_clone().unwrap());
             }
 
@@ -357,73 +417,64 @@ fn run_server(
         actors.register(Box::new(console));
     }
 
-    fn handle_page_error(
-        actors: Arc<Mutex<ActorRegistry>>,
-        id: PipelineId,
-        worker_id: Option<WorkerId>,
-        page_error: PageError,
-        browsing_contexts: &HashMap<BrowsingContextId, String>,
-        actor_workers: &HashMap<WorkerId, String>,
-        pipelines: &HashMap<PipelineId, BrowsingContextId>,
-    ) {
-        let console_actor_name = match find_console_actor(
-            actors.clone(),
-            id,
-            worker_id,
-            actor_workers,
-            browsing_contexts,
-            pipelines,
-        ) {
+    fn handle_title_changed(&self, pipeline: PipelineId, title: String) {
+        let bc = match self.pipelines.get(&pipeline) {
+            Some(bc) => bc,
+            None => return,
+        };
+        let name = match self.browsing_contexts.get(bc) {
             Some(name) => name,
             None => return,
         };
-        let actors = actors.lock().unwrap();
+        let actors = self.actors.lock().unwrap();
+        let browsing_context = actors.find::<BrowsingContextActor>(name);
+        browsing_context.title_changed(pipeline, title);
+    }
+
+    fn handle_page_error(
+        &self,
+        id: PipelineId,
+        worker_id: Option<WorkerId>,
+        page_error: PageError,
+    ) {
+        let console_actor_name = match self.find_console_actor(id, worker_id) {
+            Some(name) => name,
+            None => return,
+        };
+        let actors = self.actors.lock().unwrap();
         let console_actor = actors.find::<ConsoleActor>(&console_actor_name);
         let id = worker_id.map_or(UniqueId::Pipeline(id), UniqueId::Worker);
         console_actor.handle_page_error(page_error, id, &actors);
     }
 
     fn handle_console_message(
-        actors: Arc<Mutex<ActorRegistry>>,
+        &self,
         id: PipelineId,
         worker_id: Option<WorkerId>,
         console_message: ConsoleMessage,
-        browsing_contexts: &HashMap<BrowsingContextId, String>,
-        actor_workers: &HashMap<WorkerId, String>,
-        pipelines: &HashMap<PipelineId, BrowsingContextId>,
-    ) {
-        let console_actor_name = match find_console_actor(
-            actors.clone(),
-            id,
-            worker_id,
-            actor_workers,
-            browsing_contexts,
-            pipelines,
     ) {
+        let console_actor_name = match self.find_console_actor(id, worker_id) {
             Some(name) => name,
             None => return,
         };
-        let actors = actors.lock().unwrap();
+        let actors = self.actors.lock().unwrap();
         let console_actor = actors.find::<ConsoleActor>(&console_actor_name);
         let id = worker_id.map_or(UniqueId::Pipeline(id), UniqueId::Worker);
         console_actor.handle_console_api(console_message, id, &actors);
     }
 
     fn find_console_actor(
-        actors: Arc<Mutex<ActorRegistry>>,
+        &self,
         pipeline: PipelineId,
         worker_id: Option<WorkerId>,
-        actor_workers: &HashMap<WorkerId, String>,
-        browsing_contexts: &HashMap<BrowsingContextId, String>,
-        pipelines: &HashMap<PipelineId, BrowsingContextId>,
     ) -> Option<String> {
-        let actors = actors.lock().unwrap();
+        let actors = self.actors.lock().unwrap();
         if let Some(worker_id) = worker_id {
-            let actor_name = actor_workers.get(&worker_id)?;
+            let actor_name = self.actor_workers.get(&worker_id)?;
             Some(actors.find::<WorkerActor>(actor_name).console.clone())
         } else {
-            let id = pipelines.get(&pipeline)?;
-            let actor_name = browsing_contexts.get(id)?;
+            let id = self.pipelines.get(&pipeline)?;
+            let actor_name = self.browsing_contexts.get(id)?;
             Some(
                 actors
                     .find::<BrowsingContextActor>(actor_name)
@@ -433,32 +484,19 @@ fn run_server(
         }
     }
 
-    #[allow(clippy::too_many_arguments)]
     fn handle_network_event(
-        actors: Arc<Mutex<ActorRegistry>>,
+        &mut self,
         mut connections: Vec<TcpStream>,
-        browsing_contexts: &HashMap<BrowsingContextId, String>,
-        actor_requests: &mut HashMap<String, String>,
-        actor_workers: &HashMap<WorkerId, String>,
-        pipelines: &HashMap<PipelineId, BrowsingContextId>,
         pipeline_id: PipelineId,
         request_id: String,
         network_event: NetworkEvent,
     ) {
-        let console_actor_name = match find_console_actor(
-            actors.clone(),
-            pipeline_id,
-            None,
-            actor_workers,
-            browsing_contexts,
-            pipelines,
-        ) {
+        let console_actor_name = match self.find_console_actor(pipeline_id, None) {
             Some(name) => name,
             None => return,
         };
-        let netevent_actor_name =
-            find_network_event_actor(actors.clone(), actor_requests, request_id);
-        let mut actors = actors.lock().unwrap();
+        let netevent_actor_name = self.find_network_event_actor(request_id);
+        let mut actors = self.actors.lock().unwrap();
         let actor = actors.find_mut::<NetworkEventActor>(&netevent_actor_name);
 
         match network_event {
@@ -565,13 +603,9 @@ fn run_server(
 
     // Find the name of NetworkEventActor corresponding to request_id
     // Create a new one if it does not exist, add it to the actor_requests hashmap
-    fn find_network_event_actor(
-        actors: Arc<Mutex<ActorRegistry>>,
-        actor_requests: &mut HashMap<String, String>,
-        request_id: String,
-    ) -> String {
-        let mut actors = actors.lock().unwrap();
-        match (*actor_requests).entry(request_id) {
+    fn find_network_event_actor(&mut self, request_id: String) -> String {
+        let mut actors = self.actors.lock().unwrap();
+        match self.actor_requests.entry(request_id) {
             Occupied(name) => {
                 //TODO: Delete from map like Firefox does?
                 name.into_mut().clone()
@@ -585,159 +619,6 @@ fn run_server(
             },
         }
     }
-
-    thread::Builder::new()
-        .name("DevtCliAcceptor".to_owned())
-        .spawn(move || {
-            // accept connections and process them, spawning a new thread for each one
-            for stream in listener.incoming() {
-                let mut stream = stream.expect("Can't retrieve stream");
-                if !allow_devtools_client(&mut stream, &embedder, &token) {
-                    continue;
-                };
-                // connection succeeded and accepted
-                sender
-                    .send(DevtoolsControlMsg::FromChrome(
-                        ChromeToDevtoolsControlMsg::AddClient(stream),
-                    ))
-                    .unwrap();
-            }
-        })
-        .expect("Thread spawning failed");
-
-    let mut next_id = StreamId(0);
-    while let Ok(msg) = receiver.recv() {
-        trace!("{:?}", msg);
-        match msg {
-            DevtoolsControlMsg::FromChrome(ChromeToDevtoolsControlMsg::AddClient(stream)) => {
-                let actors = actors.clone();
-                let id = next_id;
-                next_id = StreamId(id.0 + 1);
-                accepted_connections.insert(id, stream.try_clone().unwrap());
-
-                // Inform every browsing context of the new stream
-                for name in browsing_contexts.values() {
-                    let actors = actors.lock().unwrap();
-                    let browsing_context = actors.find::<BrowsingContextActor>(name);
-                    let mut streams = browsing_context.streams.borrow_mut();
-                    streams.insert(id, stream.try_clone().unwrap());
-                }
-                thread::Builder::new()
-                    .name("DevtoolsClientHandler".to_owned())
-                    .spawn(move || handle_client(actors, stream.try_clone().unwrap(), id))
-                    .expect("Thread spawning failed");
-            },
-            DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::FramerateTick(
-                actor_name,
-                tick,
-            )) => handle_framerate_tick(actors.clone(), actor_name, tick),
-            DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::TitleChanged(
-                pipeline,
-                title,
-            )) => handle_title_changed(
-                actors.clone(),
-                &pipelines,
-                &browsing_contexts,
-                pipeline,
-                title,
-            ),
-            DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::NewGlobal(
-                ids,
-                script_sender,
-                pageinfo,
-            )) => handle_new_global(
-                actors.clone(),
-                ids,
-                script_sender,
-                &mut browsing_contexts,
-                &mut pipelines,
-                &mut actor_workers,
-                pageinfo,
-                &accepted_connections,
-            ),
-            DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::Navigate(
-                browsing_context,
-                state,
-            )) => handle_navigate(actors.clone(), &browsing_contexts, browsing_context, state),
-            DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::ConsoleAPI(
-                id,
-                console_message,
-                worker_id,
-            )) => handle_console_message(
-                actors.clone(),
-                id,
-                worker_id,
-                console_message,
-                &browsing_contexts,
-                &actor_workers,
-                &pipelines,
-            ),
-            DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::ReportPageError(
-                id,
-                page_error,
-            )) => handle_page_error(
-                actors.clone(),
-                id,
-                None,
-                page_error,
-                &browsing_contexts,
-                &actor_workers,
-                &pipelines,
-            ),
-            DevtoolsControlMsg::FromScript(ScriptToDevtoolsControlMsg::ReportCSSError(
-                id,
-                css_error,
-            )) => {
-                let mut console_message = ConsoleMessageBuilder::new(
-                    LogLevel::Warn,
-                    css_error.filename,
-                    css_error.line,
-                    css_error.column,
-                );
-                console_message.add_argument(css_error.msg.into());
-
-                handle_console_message(
-                    actors.clone(),
-                    id,
-                    None,
-                    console_message.finish(),
-                    &browsing_contexts,
-                    &actor_workers,
-                    &pipelines,
-                )
-            },
-            DevtoolsControlMsg::FromChrome(ChromeToDevtoolsControlMsg::NetworkEvent(
-                request_id,
-                network_event,
-            )) => {
-                // copy the accepted_connections vector
-                let mut connections = Vec::<TcpStream>::new();
-                for stream in accepted_connections.values() {
-                    connections.push(stream.try_clone().unwrap());
-                }
-
-                let pipeline_id = match network_event {
-                    NetworkEvent::HttpResponse(ref response) => response.pipeline_id,
-                    NetworkEvent::HttpRequest(ref request) => request.pipeline_id,
-                };
-                handle_network_event(
-                    actors.clone(),
-                    connections,
-                    &browsing_contexts,
-                    &mut actor_requests,
-                    &actor_workers,
-                    &pipelines,
-                    pipeline_id,
-                    request_id,
-                    network_event,
-                );
-            },
-            DevtoolsControlMsg::FromChrome(ChromeToDevtoolsControlMsg::ServerExitMsg) => break,
-        }
-    }
-    for connection in accepted_connections.values_mut() {
-        let _ = connection.shutdown(Shutdown::Both);
-    }
 }
 
 fn allow_devtools_client(stream: &mut TcpStream, embedder: &EmbedderProxy, token: &str) -> bool {
@@ -766,3 +647,39 @@ fn allow_devtools_client(stream: &mut TcpStream, embedder: &EmbedderProxy, token
     embedder.send(EmbedderMsg::RequestDevtoolsConnection(request_sender));
     request_receiver.recv().unwrap() == AllowOrDeny::Allow
 }
+
+/// Process the input from a single devtools client until EOF.
+fn handle_client(actors: Arc<Mutex<ActorRegistry>>, mut stream: TcpStream, id: StreamId) {
+    debug!("connection established to {}", stream.peer_addr().unwrap());
+    let msg = actors.lock().unwrap().find::<RootActor>("root").encodable();
+    if let Err(e) = stream.write_json_packet(&msg) {
+        warn!("Error writing response: {:?}", e);
+        return;
+    }
+
+    loop {
+        match stream.read_json_packet() {
+            Ok(Some(json_packet)) => {
+                if let Err(()) = actors.lock().unwrap().handle_message(
+                    json_packet.as_object().unwrap(),
+                    &mut stream,
+                    id,
+                ) {
+                    debug!("error: devtools actor stopped responding");
+                    let _ = stream.shutdown(Shutdown::Both);
+                    break;
+                }
+            },
+            Ok(None) => {
+                debug!("error: EOF");
+                break;
+            },
+            Err(err_msg) => {
+                debug!("error: {}", err_msg);
+                break;
+            },
+        }
+    }
+
+    actors.lock().unwrap().cleanup(id);
+}