net: Use a thread for each `AsyncResponseTarget` to avoid having to send

trait objects across process boundaries.

components/net/image_cache_task.rs

@@ -14,6 +14,7 @@ use std::collections::hash_map::Entry::{Occupied, Vacant};
 use std::mem;
 use std::sync::Arc;
 use std::sync::mpsc::{channel, Sender, Receiver, Select};
+use std::thread;
 use util::resource_files::resources_dir_path;
 use util::task::spawn_named;
 use util::taskpool::TaskPool;
@@ -100,14 +101,17 @@ struct ResourceLoadInfo {
 struct ResourceListener {
     url: Url,
     sender: Sender<ResourceLoadInfo>,
+    receiver: Receiver<ResponseAction>,
 }
 
-impl AsyncResponseTarget for ResourceListener {
-    fn invoke_with_listener(&self, action: ResponseAction) {
-        self.sender.send(ResourceLoadInfo {
-            action: action,
-            url: self.url.clone(),
-        }).unwrap();
+impl ResourceListener {
+    fn run(&self) {
+        while let Ok(action) = self.receiver.recv() {
+            self.sender.send(ResourceLoadInfo {
+                action: action,
+                url: self.url.clone(),
+            }).unwrap();
+        }
     }
 }
 
@@ -330,11 +334,17 @@ impl ImageCache {
                         e.insert(pending_load);
 
                         let load_data = LoadData::new(url.clone(), None);
+                        let (action_sender, action_receiver) = channel();
                         let listener = box ResourceListener {
                             url: url,
                             sender: self.progress_sender.clone(),
+                            receiver: action_receiver,
                         };
-                        let msg = ControlMsg::Load(load_data, LoadConsumer::Listener(listener));
+                        let msg = ControlMsg::Load(load_data,
+                                                   LoadConsumer::Listener(AsyncResponseTarget {
+                            sender: action_sender,
+                        }));
+                        thread::spawn(move || listener.run());
                         self.resource_task.send(msg).unwrap();
                     }
                 }

components/net/resource_task.rs

@@ -69,7 +69,7 @@ pub fn global_init() {
 
 pub enum ProgressSender {
     Channel(Sender<ProgressMsg>),
-    Listener(Box<AsyncResponseTarget>),
+    Listener(AsyncResponseTarget),
 }
 
 impl ProgressSender {

components/net_traits/lib.rs

@@ -114,14 +114,20 @@ impl ResponseAction {
 
 /// A target for async networking events. Commonly used to dispatch a runnable event to another
 /// thread storing the wrapped closure for later execution.
-pub trait AsyncResponseTarget {
-    fn invoke_with_listener(&self, action: ResponseAction);
+pub struct AsyncResponseTarget {
+    pub sender: Sender<ResponseAction>,
+}
+
+impl AsyncResponseTarget {
+    pub fn invoke_with_listener(&self, action: ResponseAction) {
+        self.sender.send(action).unwrap()
+    }
 }
 
 /// A wrapper for a network load that can either be channel or event-based.
 pub enum LoadConsumer {
     Channel(Sender<LoadResponse>),
-    Listener(Box<AsyncResponseTarget + Send>),
+    Listener(AsyncResponseTarget),
 }
 
 /// Handle to a resource task
@@ -195,7 +201,7 @@ impl PendingAsyncLoad {
     }
 
     /// Initiate the network request associated with this pending load, using the provided target.
-    pub fn load_async(mut self, listener: Box<AsyncResponseTarget + Send>) {
+    pub fn load_async(mut self, listener: AsyncResponseTarget) {
         self.guard.neuter();
         let load_data = LoadData::new(self.url, self.pipeline);
         let consumer = LoadConsumer::Listener(listener);

components/script/cors.rs

@@ -17,6 +17,7 @@ use net_traits::{SerializableStringResult};
 use std::ascii::AsciiExt;
 use std::borrow::ToOwned;
 use std::cell::RefCell;
+use std::sync::mpsc;
 use std::sync::{Arc, Mutex};
 use time;
 use time::{now, Timespec};
@@ -132,9 +133,14 @@ impl CORSRequest {
             listener: listener,
             response: RefCell::new(None),
         };
+        let (action_sender, action_receiver) = mpsc::channel();
         let listener = NetworkListener {
             context: Arc::new(Mutex::new(context)),
             script_chan: script_chan,
+            receiver: action_receiver,
+        };
+        let response_target = AsyncResponseTarget {
+            sender: action_sender,
         };
 
         // TODO: this exists only to make preflight check non-blocking
@@ -145,7 +151,7 @@ impl CORSRequest {
             let mut context = listener.context.lock();
             let context = context.as_mut().unwrap();
             *context.response.borrow_mut() = Some(response);
-            listener.invoke_with_listener(ResponseAction::ResponseComplete(
+            response_target.invoke_with_listener(ResponseAction::ResponseComplete(
                     SerializableStringResult(Ok(()))));
         });
     }

components/script/document_loader.rs

@@ -73,7 +73,7 @@ impl DocumentLoader {
     }
 
     /// Create and initiate a new network request.
-    pub fn load_async(&mut self, load: LoadType, listener: Box<AsyncResponseTarget + Send>) {
+    pub fn load_async(&mut self, load: LoadType, listener: AsyncResponseTarget) {
         let pending = self.prepare_async_load(load);
         pending.load_async(listener)
     }

components/script/dom/document.rs

@@ -283,7 +283,7 @@ pub trait DocumentHelpers<'a> {
     /// https://w3c.github.io/animation-timing/#dfn-invoke-callbacks-algorithm
     fn invoke_animation_callbacks(self);
     fn prepare_async_load(self, load: LoadType) -> PendingAsyncLoad;
-    fn load_async(self, load: LoadType, listener: Box<AsyncResponseTarget + Send>);
+    fn load_async(self, load: LoadType, listener: AsyncResponseTarget);
     fn load_sync(self, load: LoadType) -> Result<(Metadata, Vec<u8>), String>;
     fn finish_load(self, load: LoadType);
     fn set_current_parser(self, script: Option<&ServoHTMLParser>);
@@ -968,7 +968,7 @@ impl<'a> DocumentHelpers<'a> for &'a Document {
         loader.prepare_async_load(load)
     }
 
-    fn load_async(self, load: LoadType, listener: Box<AsyncResponseTarget + Send>) {
+    fn load_async(self, load: LoadType, listener: AsyncResponseTarget) {
         let mut loader = self.loader.borrow_mut();
         loader.load_async(load, listener)
     }

components/script/dom/htmlscriptelement.rs

@@ -40,12 +40,14 @@ use js::jsval::UndefinedValue;
 use encoding::all::UTF_8;
 use encoding::label::encoding_from_whatwg_label;
 use encoding::types::{Encoding, EncodingRef, DecoderTrap};
-use net_traits::{Metadata, AsyncResponseListener};
+use net_traits::{Metadata, AsyncResponseListener, AsyncResponseTarget};
 use util::str::{DOMString, HTML_SPACE_CHARACTERS, StaticStringVec};
 use html5ever::tree_builder::NextParserState;
 use std::cell::{RefCell, Cell};
 use std::mem;
+use std::sync::mpsc;
 use std::sync::{Arc, Mutex};
+use std::thread;
 use string_cache::Atom;
 use url::{Url, UrlParser};
 
@@ -330,12 +332,18 @@ impl<'a> HTMLScriptElementHelpers for &'a HTMLScriptElement {
                             url: url.clone(),
                         }));
 
+                        let (action_sender, action_receiver) = mpsc::channel();
                         let listener = box NetworkListener {
                             context: context,
                             script_chan: script_chan,
+                            receiver: action_receiver,
                         };
+                        let response_target = AsyncResponseTarget {
+                            sender: action_sender,
+                        };
+                        thread::spawn(move || listener.run());
 
-                        doc.r().load_async(LoadType::Script(url), listener);
+                        doc.r().load_async(LoadType::Script(url), response_target);
 
                         if self.parser_inserted.get() {
                             doc.r().get_current_parser().unwrap().r().suspend();

components/script/dom/xmlhttprequest.rs

@@ -46,8 +46,8 @@ use js::jsval::{JSVal, NullValue, UndefinedValue};
 
 use net_traits::ControlMsg::Load;
 use net_traits::{ResourceTask, ResourceCORSData, LoadData, LoadConsumer};
-use net_traits::{AsyncResponseListener, Metadata, SerializableHeaders, SerializableMethod};
-use net_traits::{SerializableUrl};
+use net_traits::{AsyncResponseListener, AsyncResponseTarget, Metadata, SerializableHeaders};
+use net_traits::{SerializableMethod, SerializableUrl};
 use cors::{allow_cross_origin_request, CORSRequest, RequestMode, AsyncCORSResponseListener};
 use cors::CORSResponse;
 use util::str::DOMString;
@@ -59,7 +59,7 @@ use std::cell::{RefCell, Cell};
 use std::default::Default;
 use std::sync::{Mutex, Arc};
 use std::sync::mpsc::{channel, Sender, TryRecvError};
-use std::thread::sleep_ms;
+use std::thread::{self, sleep_ms};
 use time;
 use url::{Url, UrlParser};
 
@@ -271,11 +271,17 @@ impl XMLHttpRequest {
             }
         }
 
+        let (action_sender, action_receiver) = channel();
         let listener = box NetworkListener {
             context: context,
             script_chan: script_chan,
+            receiver: action_receiver,
         };
-        resource_task.send(Load(load_data, LoadConsumer::Listener(listener))).unwrap();
+        let response_target = AsyncResponseTarget {
+            sender: action_sender,
+        };
+        thread::spawn(move || listener.run());
+        resource_task.send(Load(load_data, LoadConsumer::Listener(response_target))).unwrap();
     }
 }
 

components/script/network_listener.rs

@@ -3,22 +3,26 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use script_task::{ScriptChan, ScriptMsg, Runnable};
-use net_traits::{AsyncResponseTarget, AsyncResponseListener, ResponseAction};
+use net_traits::{AsyncResponseListener, ResponseAction};
+use std::sync::mpsc::Receiver;
 use std::sync::{Arc, Mutex};
 
 /// An off-thread sink for async network event runnables. All such events are forwarded to
 /// a target thread, where they are invoked on the provided context object.
 pub struct NetworkListener<T: AsyncResponseListener + PreInvoke + Send + 'static> {
     pub context: Arc<Mutex<T>>,
     pub script_chan: Box<ScriptChan+Send>,
+    pub receiver: Receiver<ResponseAction>,
 }
 
-impl<T: AsyncResponseListener + PreInvoke + Send + 'static> AsyncResponseTarget for NetworkListener<T> {
-    fn invoke_with_listener(&self, action: ResponseAction) {
-        self.script_chan.send(ScriptMsg::RunnableMsg(box ListenerRunnable {
-            context: self.context.clone(),
-            action: action,
-        })).unwrap();
+impl<T: AsyncResponseListener + PreInvoke + Send + 'static> NetworkListener<T> {
+    pub fn run(&self) {
+        while let Ok(action) = self.receiver.recv() {
+            self.script_chan.send(ScriptMsg::RunnableMsg(box ListenerRunnable {
+                context: self.context.clone(),
+                action: action,
+            })).unwrap();
+        }
     }
 }
 

components/script/script_task.rs

@@ -68,7 +68,7 @@ use msg::constellation_msg::{Failure, WindowSizeData, PipelineExitType};
 use msg::constellation_msg::Msg as ConstellationMsg;
 use msg::webdriver_msg::WebDriverScriptCommand;
 use net_traits::LoadData as NetLoadData;
-use net_traits::{ResourceTask, LoadConsumer, ControlMsg, Metadata};
+use net_traits::{AsyncResponseTarget, ResourceTask, LoadConsumer, ControlMsg, Metadata};
 use net_traits::{SerializableContentType, SerializableHeaders, SerializableMethod};
 use net_traits::{SerializableUrl};
 use net_traits::image_cache_task::{ImageCacheChan, ImageCacheTask, ImageCacheResult};
@@ -105,6 +105,7 @@ use std::rc::Rc;
 use std::result::Result;
 use std::sync::{Arc, Mutex};
 use std::sync::mpsc::{channel, Sender, Receiver, Select};
+use std::thread;
 use time::Tm;
 
 use hyper::header::{ContentType, HttpDate};
@@ -1686,9 +1687,15 @@ impl ScriptTask {
 
         let context = Arc::new(Mutex::new(ParserContext::new(id, subpage, script_chan.clone(),
                                                              load_data.url.clone())));
+        let (action_sender, action_receiver) = channel();
         let listener = box NetworkListener {
             context: context,
             script_chan: script_chan.clone(),
+            receiver: action_receiver,
+        };
+        thread::spawn(move || listener.run());
+        let response_target = AsyncResponseTarget {
+            sender: action_sender,
         };
 
         if load_data.url.scheme == "javascript" {
@@ -1703,7 +1710,7 @@ impl ScriptTask {
             data: load_data.data,
             cors: None,
             pipeline_id: Some(id),
-        }, LoadConsumer::Listener(listener))).unwrap();
+        }, LoadConsumer::Listener(response_target))).unwrap();
 
         self.incomplete_loads.borrow_mut().push(incomplete);
     }