net: Start reducing number of IPCs channels used for fetch with a FetchThread (#33863)

Instead of creating a `ROUTER` for each fetch, create a fetch thread
which handles all incoming and outcoming fetch requests. Now messages
involving fetches carry a "request id" which indicates which fetch is
being addressed by the message. This greatly reduces the number of file
descriptors used by fetch.

In addition, the interface for kicking off fetches is simplified when
using the `Listener` with `Document`s and the `GlobalScope`.

This does not fix all leaked file descriptors / mach ports, but greatly
eliminates the number used. Now tests can be run without limiting
procesess on modern macOS systems.

Followup work:

1. There are more instances where fetch is done using the old method.
   Some of these require more changes in order to be converted to the
   `FetchThread` approach.
2. Eliminate usage of IPC channels when doing redirects.
3. Also eliminate the IPC channel used for cancel handling.
4. This change opens up the possiblity of controlling the priority of
   fetch requests.

Fixes #29834.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

Cargo.lock

@@ -4718,6 +4718,7 @@ dependencies = [
  "base",
  "content-security-policy",
  "cookie 0.18.1",
+ "crossbeam-channel",
  "embedder_traits",
  "headers",
  "http",

components/constellation/network_listener.rs

@@ -13,7 +13,7 @@ use ipc_channel::ipc;
 use ipc_channel::router::ROUTER;
 use log::warn;
 use net::http_loader::{set_default_accept_language, DOCUMENT_ACCEPT_HEADER_VALUE};
-use net_traits::request::{Referrer, RequestBuilder};
+use net_traits::request::{Referrer, RequestBuilder, RequestId};
 use net_traits::response::ResponseInit;
 use net_traits::{
     CoreResourceMsg, FetchChannels, FetchMetadata, FetchResponseMsg, IpcSend, NetworkError,
@@ -91,7 +91,9 @@ impl NetworkListener {
             Box::new(move |message| {
                 let msg = message.to();
                 match msg {
-                    Ok(FetchResponseMsg::ProcessResponse(res)) => listener.check_redirect(res),
+                    Ok(FetchResponseMsg::ProcessResponse(request_id, res)) => {
+                        listener.check_redirect(request_id, res)
+                    },
                     Ok(msg_) => listener.send(msg_),
                     Err(e) => warn!("Error while receiving network listener message: {}", e),
                 };
@@ -103,7 +105,11 @@ impl NetworkListener {
         }
     }
 
-    fn check_redirect(&mut self, message: Result<FetchMetadata, NetworkError>) {
+    fn check_redirect(
+        &mut self,
+        request_id: RequestId,
+        message: Result<FetchMetadata, NetworkError>,
+    ) {
         match message {
             Ok(res_metadata) => {
                 let metadata = match res_metadata {
@@ -160,13 +166,16 @@ impl NetworkListener {
                     _ => {
                         // Response should be processed by script thread.
                         self.should_send = true;
-                        self.send(FetchResponseMsg::ProcessResponse(Ok(res_metadata)));
+                        self.send(FetchResponseMsg::ProcessResponse(
+                            request_id,
+                            Ok(res_metadata),
+                        ));
                     },
                 };
             },
             Err(e) => {
                 self.should_send = true;
-                self.send(FetchResponseMsg::ProcessResponse(Err(e)))
+                self.send(FetchResponseMsg::ProcessResponse(request_id, Err(e)))
             },
         };
     }

components/fonts/font_context.rs

@@ -658,10 +658,11 @@ impl RemoteWebFontDownloader {
 
         let core_resource_thread_clone = state.core_resource_thread.clone();
         fetch_async(
-            request,
             &core_resource_thread_clone,
-            move |response_message| match downloader.handle_web_font_fetch_message(response_message)
+            request,
-            {
+            None,
+            Box::new(move |response_message| {
+                match downloader.handle_web_font_fetch_message(response_message) {
                     DownloaderResponseResult::InProcess => {},
                     DownloaderResponseResult::Finished => {
                         if !downloader.process_downloaded_font_and_signal_completion(&state) {
@@ -673,7 +674,8 @@ impl RemoteWebFontDownloader {
                     DownloaderResponseResult::Failure => downloader
                         .font_context
                         .process_next_web_font_source(state.clone()),
-            },
+                }
+            }),
         )
     }
 
@@ -747,10 +749,10 @@ impl RemoteWebFontDownloader {
         response_message: FetchResponseMsg,
     ) -> DownloaderResponseResult {
         match response_message {
-            FetchResponseMsg::ProcessRequestBody | FetchResponseMsg::ProcessRequestEOF => {
+            FetchResponseMsg::ProcessRequestBody(..) | FetchResponseMsg::ProcessRequestEOF(..) => {
                 DownloaderResponseResult::InProcess
             },
-            FetchResponseMsg::ProcessResponse(meta_result) => {
+            FetchResponseMsg::ProcessResponse(_, meta_result) => {
                 trace!(
                     "@font-face {} metadata ok={:?}",
                     self.web_font_family_name,
@@ -759,7 +761,7 @@ impl RemoteWebFontDownloader {
                 *self.response_valid.lock() = meta_result.is_ok();
                 DownloaderResponseResult::InProcess
             },
-            FetchResponseMsg::ProcessResponseChunk(new_bytes) => {
+            FetchResponseMsg::ProcessResponseChunk(_, new_bytes) => {
                 trace!(
                     "@font-face {} chunk={:?}",
                     self.web_font_family_name,
@@ -770,7 +772,7 @@ impl RemoteWebFontDownloader {
                 }
                 DownloaderResponseResult::InProcess
             },
-            FetchResponseMsg::ProcessResponseEOF(response) => {
+            FetchResponseMsg::ProcessResponseEOF(_, response) => {
                 trace!(
                     "@font-face {} EOF={:?}",
                     self.web_font_family_name,

components/net/fetch/methods.rs

@@ -465,7 +465,7 @@ pub async fn main_fetch(
     let mut response_loaded = false;
     let mut response = if !response.is_network_error() && !request.integrity_metadata.is_empty() {
         // Step 19.1.
-        wait_for_response(&mut response, target, done_chan).await;
+        wait_for_response(request, &mut response, target, done_chan).await;
         response_loaded = true;
 
         // Step 19.2.
@@ -487,12 +487,12 @@ pub async fn main_fetch(
     if request.synchronous {
         // process_response is not supposed to be used
         // by sync fetch, but we overload it here for simplicity
-        target.process_response(&response);
+        target.process_response(request, &response);
         if !response_loaded {
-            wait_for_response(&mut response, target, done_chan).await;
+            wait_for_response(request, &mut response, target, done_chan).await;
         }
         // overloaded similarly to process_response
-        target.process_response_eof(&response);
+        target.process_response_eof(request, &response);
         return response;
     }
 
@@ -507,15 +507,15 @@ pub async fn main_fetch(
     }
 
     // Step 22.
-    target.process_response(&response);
+    target.process_response(request, &response);
 
     // Step 23.
     if !response_loaded {
-        wait_for_response(&mut response, target, done_chan).await;
+        wait_for_response(request, &mut response, target, done_chan).await;
     }
 
     // Step 24.
-    target.process_response_eof(&response);
+    target.process_response_eof(request, &response);
 
     if let Ok(http_cache) = context.state.http_cache.write() {
         http_cache.update_awaiting_consumers(request, &response);
@@ -527,6 +527,7 @@ pub async fn main_fetch(
 }
 
 async fn wait_for_response(
+    request: &Request,
     response: &mut Response,
     target: Target<'_>,
     done_chan: &mut DoneChannel,
@@ -535,7 +536,7 @@ async fn wait_for_response(
         loop {
             match ch.1.recv().await {
                 Some(Data::Payload(vec)) => {
-                    target.process_response_chunk(vec);
+                    target.process_response_chunk(request, vec);
                 },
                 Some(Data::Done) => {
                     break;
@@ -555,7 +556,7 @@ async fn wait_for_response(
             // in case there was no channel to wait for, the body was
             // obtained synchronously via scheme_fetch for data/file/about/etc
             // We should still send the body across as a chunk
-            target.process_response_chunk(vec.clone());
+            target.process_response_chunk(request, vec.clone());
         } else {
             assert_eq!(*body, ResponseBody::Empty)
         }

components/net/image_cache.rs

@@ -581,9 +581,9 @@ impl ImageCache for ImageCacheImpl {
     /// Inform the image cache about a response for a pending request.
     fn notify_pending_response(&self, id: PendingImageId, action: FetchResponseMsg) {
         match (action, id) {
-            (FetchResponseMsg::ProcessRequestBody, _) |
+            (FetchResponseMsg::ProcessRequestBody(..), _) |
-            (FetchResponseMsg::ProcessRequestEOF, _) => (),
+            (FetchResponseMsg::ProcessRequestEOF(..), _) => (),
-            (FetchResponseMsg::ProcessResponse(response), _) => {
+            (FetchResponseMsg::ProcessResponse(_, response), _) => {
                 debug!("Received {:?} for {:?}", response.as_ref().map(|_| ()), id);
                 let mut store = self.store.lock().unwrap();
                 let pending_load = store.pending_loads.get_by_key_mut(&id).unwrap();
@@ -608,7 +608,7 @@ impl ImageCache for ImageCacheImpl {
                 pending_load.final_url = final_url;
                 pending_load.cors_status = cors_status;
             },
-            (FetchResponseMsg::ProcessResponseChunk(data), _) => {
+            (FetchResponseMsg::ProcessResponseChunk(_, data), _) => {
                 debug!("Got some data for {:?}", id);
                 let mut store = self.store.lock().unwrap();
                 let pending_load = store.pending_loads.get_by_key_mut(&id).unwrap();
@@ -627,7 +627,7 @@ impl ImageCache for ImageCacheImpl {
                     pending_load.metadata = Some(img_metadata);
                 }
             },
-            (FetchResponseMsg::ProcessResponseEOF(result), key) => {
+            (FetchResponseMsg::ProcessResponseEOF(_, result), key) => {
                 debug!("Received EOF for {:?}", key);
                 match result {
                     Ok(_) => {

components/net/tests/data_loader.rs

@@ -7,8 +7,8 @@ use std::ops::Deref;
 use headers::{ContentType, HeaderMapExt};
 use hyper_serde::Serde;
 use mime::{self, Mime};
-use net_traits::request::{Origin, Referrer, Request};
+use net_traits::request::Referrer;
-use net_traits::response::{HttpsState, ResponseBody};
+use net_traits::response::ResponseBody;
 use net_traits::{FetchMetadata, FilteredMetadata, NetworkError};
 use servo_url::ServoUrl;
 
@@ -21,15 +21,13 @@ fn assert_parse(
     charset: Option<&str>,
     data: Option<&[u8]>,
 ) {
+    use net_traits::request::RequestBuilder;
+
     let url = ServoUrl::parse(url).unwrap();
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .pipeline_id(None)
-        Some(origin),
+        .build();
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
 
     let response = fetch(&mut request, None);
 

components/net/tests/fetch.rs

@@ -33,15 +33,15 @@ use net::test::HttpState;
 use net_traits::filemanager_thread::FileTokenCheck;
 use net_traits::http_status::HttpStatus;
 use net_traits::request::{
-    Destination, Origin, RedirectMode, Referrer, Request, RequestBuilder, RequestMode,
+    Destination, RedirectMode, Referrer, Request, RequestBuilder, RequestMode,
 };
-use net_traits::response::{CacheState, HttpsState, Response, ResponseBody, ResponseType};
+use net_traits::response::{CacheState, Response, ResponseBody, ResponseType};
 use net_traits::{
     FetchTaskTarget, IncludeSubdomains, NetworkError, ReferrerPolicy, ResourceFetchTiming,
     ResourceTimingType,
 };
 use servo_arc::Arc as ServoArc;
-use servo_url::{ImmutableOrigin, ServoUrl};
+use servo_url::ServoUrl;
 use tokio_test::block_on;
 use uuid::Uuid;
 
@@ -61,14 +61,9 @@ fn test_fetch_response_is_not_network_error() {
     };
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     let fetch_response = fetch(&mut request, None);
     let _ = server.close();
 
@@ -80,14 +75,9 @@ fn test_fetch_response_is_not_network_error() {
 #[test]
 fn test_fetch_on_bad_port_is_network_error() {
     let url = ServoUrl::parse("http://www.example.org:6667").unwrap();
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     let fetch_response = fetch(&mut request, None);
     assert!(fetch_response.is_network_error());
     let fetch_error = fetch_response.get_network_error().unwrap();
@@ -105,14 +95,9 @@ fn test_fetch_response_body_matches_const_message() {
     };
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     let fetch_response = fetch(&mut request, None);
     let _ = server.close();
 
@@ -130,14 +115,9 @@ fn test_fetch_response_body_matches_const_message() {
 #[test]
 fn test_fetch_aboutblank() {
     let url = ServoUrl::parse("about:blank").unwrap();
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
 
     let fetch_response = fetch(&mut request, None);
     // We should see an opaque-filtered response.
@@ -168,12 +148,12 @@ fn test_fetch_blob() {
     impl FetchTaskTarget for FetchResponseCollector {
         fn process_request_body(&mut self, _: &Request) {}
         fn process_request_eof(&mut self, _: &Request) {}
-        fn process_response(&mut self, _: &Response) {}
+        fn process_response(&mut self, _: &Request, _: &Response) {}
-        fn process_response_chunk(&mut self, chunk: Vec<u8>) {
+        fn process_response_chunk(&mut self, _: &Request, chunk: Vec<u8>) {
             self.buffer.extend_from_slice(chunk.as_slice());
         }
         /// Fired when the response is fully fetched
-        fn process_response_eof(&mut self, response: &Response) {
+        fn process_response_eof(&mut self, _: &Request, response: &Response) {
             assert_eq!(self.buffer, self.expected);
             let _ = self.sender.send(response.clone());
         }
@@ -200,13 +180,9 @@ fn test_fetch_blob() {
     );
     let url = ServoUrl::parse(&format!("blob:{}{}", origin.as_str(), id.simple())).unwrap();
 
-    let mut request = Request::new(
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-        url,
+        .origin(origin.origin())
-        Some(Origin::Origin(origin.origin())),
+        .build();
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
 
     let (sender, receiver) = unbounded();
 
@@ -246,14 +222,9 @@ fn test_file() {
         .unwrap();
     let url = ServoUrl::from_file_path(path.clone()).unwrap();
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
 
     let pool = CoreResourceThreadPool::new(1);
     let pool_handle = Arc::new(pool);
@@ -294,14 +265,9 @@ fn test_file() {
 #[test]
 fn test_fetch_ftp() {
     let url = ServoUrl::parse("ftp://not-supported").unwrap();
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     let fetch_response = fetch(&mut request, None);
     assert!(fetch_response.is_network_error());
 }
@@ -309,14 +275,9 @@ fn test_fetch_ftp() {
 #[test]
 fn test_fetch_bogus_scheme() {
     let url = ServoUrl::parse("bogus://whatever").unwrap();
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     let fetch_response = fetch(&mut request, None);
     assert!(fetch_response.is_network_error());
 }
@@ -360,15 +321,7 @@ fn test_cors_preflight_fetch() {
     let (server, url) = make_server(handler);
 
     let target_url = url.clone().join("a.html").unwrap();
-
+    let mut request = RequestBuilder::new(url, Referrer::ReferrerUrl(target_url)).build();
-    let origin = Origin::Origin(ImmutableOrigin::new_opaque());
-    let mut request = Request::new(
-        url.clone(),
-        Some(origin),
-        Referrer::ReferrerUrl(target_url),
-        None,
-        HttpsState::None,
-    );
     request.referrer_policy = Some(ReferrerPolicy::Origin);
     request.use_cors_preflight = true;
     request.mode = RequestMode::CorsMode;
@@ -418,14 +371,7 @@ fn test_cors_preflight_cache_fetch() {
     };
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(ImmutableOrigin::new_opaque());
+    let mut request = RequestBuilder::new(url, Referrer::NoReferrer).build();
-    let mut request = Request::new(
-        url.clone(),
-        Some(origin.clone()),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     request.use_cors_preflight = true;
     request.mode = RequestMode::CorsMode;
     let mut wrapped_request0 = request.clone();
@@ -485,14 +431,7 @@ fn test_cors_preflight_fetch_network_error() {
     };
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(ImmutableOrigin::new_opaque());
+    let mut request = RequestBuilder::new(url, Referrer::NoReferrer).build();
-    let mut request = Request::new(
-        url,
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     request.method = Method::from_bytes(b"CHICKEN").unwrap();
     request.use_cors_preflight = true;
     request.mode = RequestMode::CorsMode;
@@ -519,14 +458,9 @@ fn test_fetch_response_is_basic_filtered() {
     };
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     let fetch_response = fetch(&mut request, None);
     let _ = server.close();
 
@@ -587,14 +521,7 @@ fn test_fetch_response_is_cors_filtered() {
     let (server, url) = make_server(handler);
 
     // an origin mis-match will stop it from defaulting to a basic filtered response
-    let origin = Origin::Origin(ImmutableOrigin::new_opaque());
+    let mut request = RequestBuilder::new(url, Referrer::NoReferrer).build();
-    let mut request = Request::new(
-        url,
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     request.mode = RequestMode::CorsMode;
     let fetch_response = fetch(&mut request, None);
     let _ = server.close();
@@ -626,14 +553,7 @@ fn test_fetch_response_is_opaque_filtered() {
     let (server, url) = make_server(handler);
 
     // an origin mis-match will fall through to an Opaque filtered response
-    let origin = Origin::Origin(ImmutableOrigin::new_opaque());
+    let mut request = RequestBuilder::new(url, Referrer::NoReferrer).build();
-    let mut request = Request::new(
-        url,
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     let fetch_response = fetch(&mut request, None);
     let _ = server.close();
 
@@ -679,14 +599,9 @@ fn test_fetch_response_is_opaque_redirect_filtered() {
 
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     request.redirect_mode = RedirectMode::Manual;
     let fetch_response = fetch(&mut request, None);
     let _ = server.close();
@@ -718,14 +633,9 @@ fn test_fetch_with_local_urls_only() {
     let (server, server_url) = make_server(handler);
 
     let do_fetch = |url: ServoUrl| {
-        let origin = Origin::Origin(url.origin());
+        let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-        let mut request = Request::new(
+            .origin(url.origin())
-            url,
+            .build();
-            Some(origin),
-            Referrer::NoReferrer,
-            None,
-            HttpsState::None,
-        );
 
         // Set the flag.
         request.local_urls_only = true;
@@ -786,14 +696,9 @@ fn test_fetch_with_hsts() {
             HstsEntry::new("localhost".to_owned(), IncludeSubdomains::NotIncluded, None).unwrap(),
         );
     }
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     // Set the flag.
     request.local_urls_only = false;
     let response = fetch_with_context(&mut request, &mut context);
@@ -935,14 +840,9 @@ fn test_fetch_with_sri_network_error() {
     };
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     // To calulate hash use :
     // echo -n "alert('Hello, Network Error');" | openssl dgst -sha384 -binary | openssl base64 -A
     request.integrity_metadata =
@@ -964,14 +864,9 @@ fn test_fetch_with_sri_sucess() {
     };
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     // To calulate hash use :
     // echo -n "alert('Hello, Network Error');" | openssl dgst -sha384 -binary | openssl base64 -A
     request.integrity_metadata =
@@ -1009,15 +904,10 @@ fn test_fetch_blocked_nosniff() {
 
         let (server, url) = make_server(handler);
 
-        let origin = Origin::Origin(url.origin());
+        let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-        let mut request = Request::new(
+            .origin(url.origin())
-            url,
+            .destination(destination)
-            Some(origin),
+            .build();
-            Referrer::NoReferrer,
-            None,
-            HttpsState::None,
-        );
-        request.destination = destination;
         let fetch_response = fetch(&mut request, None);
         let _ = server.close();
 
@@ -1059,14 +949,9 @@ fn setup_server_and_fetch(message: &'static [u8], redirect_cap: u32) -> Response
 
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
     let fetch_response = fetch(&mut request, None);
     let _ = server.close();
     fetch_response
@@ -1152,15 +1037,10 @@ fn test_fetch_redirect_updates_method_runner(
 
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .method(method)
-        Some(origin),
+        .build();
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
-    request.method = method;
 
     let _ = fetch(&mut request, None);
     let _ = server.close();
@@ -1240,15 +1120,9 @@ fn test_fetch_async_returns_complete_response() {
     };
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
-
     let fetch_response = fetch(&mut request, None);
 
     let _ = server.close();
@@ -1264,15 +1138,7 @@ fn test_opaque_filtered_fetch_async_returns_complete_response() {
     let (server, url) = make_server(handler);
 
     // an origin mis-match will fall through to an Opaque filtered response
-    let origin = Origin::Origin(ImmutableOrigin::new_opaque());
+    let mut request = RequestBuilder::new(url, Referrer::NoReferrer).build();
-    let mut request = Request::new(
-        url,
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
-
     let fetch_response = fetch(&mut request, None);
 
     let _ = server.close();
@@ -1304,16 +1170,10 @@ fn test_opaque_redirect_filtered_fetch_async_returns_complete_response() {
     };
 
     let (server, url) = make_server(handler);
-
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let origin = Origin::Origin(url.origin());
+        .origin(url.origin())
-    let mut request = Request::new(
+        .redirect_mode(RedirectMode::Manual)
-        url,
+        .build();
-        Some(origin),
-        Referrer::NoReferrer,
-        None,
-        HttpsState::None,
-    );
-    request.redirect_mode = RedirectMode::Manual;
 
     let fetch_response = fetch(&mut request, None);
 
@@ -1333,14 +1193,11 @@ fn test_fetch_with_devtools() {
 
     let (server, url) = make_server(handler);
 
-    let origin = Origin::Origin(url.origin());
+    let mut request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-    let mut request = Request::new(
+        .origin(url.origin())
-        url.clone(),
+        .redirect_mode(RedirectMode::Manual)
-        Some(origin),
+        .pipeline_id(Some(TEST_PIPELINE_ID))
-        Referrer::NoReferrer,
+        .build();
-        Some(TEST_PIPELINE_ID),
-        HttpsState::None,
-    );
 
     let (devtools_chan, devtools_port) = unbounded();
 

components/net/tests/http_cache.rs

@@ -6,8 +6,8 @@ use base::id::TEST_PIPELINE_ID;
 use http::header::{HeaderValue, EXPIRES};
 use http::StatusCode;
 use net::http_cache::HttpCache;
-use net_traits::request::{Origin, Referrer, Request};
+use net_traits::request::{Referrer, RequestBuilder};
-use net_traits::response::{HttpsState, Response, ResponseBody};
+use net_traits::response::{Response, ResponseBody};
 use net_traits::{ResourceFetchTiming, ResourceTimingType};
 use servo_url::ServoUrl;
 use tokio::sync::mpsc::unbounded_channel as unbounded;
@@ -20,13 +20,10 @@ fn test_refreshing_resource_sets_done_chan_the_appropriate_value() {
         ResponseBody::Done(vec![]),
     ];
     let url = ServoUrl::parse("https://servo.org").unwrap();
-    let request = Request::new(
+    let request = RequestBuilder::new(url.clone(), Referrer::NoReferrer)
-        url.clone(),
+        .pipeline_id(Some(TEST_PIPELINE_ID))
-        Some(Origin::Origin(url.clone().origin())),
+        .origin(url.origin())
-        Referrer::NoReferrer,
+        .build();
-        Some(TEST_PIPELINE_ID),
-        HttpsState::None,
-    );
     let timing = ResourceFetchTiming::new(ResourceTimingType::Navigation);
     let mut response = Response::new(url.clone(), timing);
     // Expires header makes the response cacheable.

components/net/tests/http_loader.rs

@@ -1426,12 +1426,12 @@ fn test_fetch_compressed_response_update_count() {
     impl FetchTaskTarget for FetchResponseCollector {
         fn process_request_body(&mut self, _: &Request) {}
         fn process_request_eof(&mut self, _: &Request) {}
-        fn process_response(&mut self, _: &Response) {}
+        fn process_response(&mut self, _: &Request, _: &Response) {}
-        fn process_response_chunk(&mut self, _: Vec<u8>) {
+        fn process_response_chunk(&mut self, _: &Request, _: Vec<u8>) {
             self.update_count += 1;
         }
         /// Fired when the response is fully fetched
-        fn process_response_eof(&mut self, _: &Response) {
+        fn process_response_eof(&mut self, _: &Request, _: &Response) {
             let _ = self.sender.send(self.update_count);
         }
     }

components/net/tests/main.rs

@@ -121,10 +121,10 @@ fn new_fetch_context(
 impl FetchTaskTarget for FetchResponseCollector {
     fn process_request_body(&mut self, _: &Request) {}
     fn process_request_eof(&mut self, _: &Request) {}
-    fn process_response(&mut self, _: &Response) {}
+    fn process_response(&mut self, _: &Request, _: &Response) {}
-    fn process_response_chunk(&mut self, _: Vec<u8>) {}
+    fn process_response_chunk(&mut self, _: &Request, _: Vec<u8>) {}
     /// Fired when the response is fully fetched
-    fn process_response_eof(&mut self, response: &Response) {
+    fn process_response_eof(&mut self, _: &Request, response: &Response) {
         let _ = self.sender.send(response.clone());
     }
 }

components/script/document_loader.rs

@@ -6,9 +6,9 @@
 //!
 //! <https://html.spec.whatwg.org/multipage/#the-end>
 
-use ipc_channel::ipc::IpcSender;
+use ipc_channel::ipc;
 use net_traits::request::RequestBuilder;
-use net_traits::{CoreResourceMsg, FetchChannels, FetchResponseMsg, IpcSend, ResourceThreads};
+use net_traits::{fetch_async, BoxedFetchCallback, ResourceThreads};
 use servo_url::ServoUrl;
 
 use crate::dom::bindings::root::Dom;
@@ -111,33 +111,37 @@ impl DocumentLoader {
         self.blocking_loads.push(load);
     }
 
-    /// Initiate a new fetch.
+    /// Initiate a new fetch given a response callback.
-    pub fn fetch_async(
+    pub fn fetch_async_with_callback(
         &mut self,
         load: LoadType,
         request: RequestBuilder,
-        fetch_target: IpcSender<FetchResponseMsg>,
+        callback: BoxedFetchCallback,
     ) {
         self.add_blocking_load(load);
-        self.fetch_async_background(request, fetch_target);
+        self.fetch_async_background(request, callback, None);
     }
 
     /// Initiate a new fetch that does not block the document load event.
     pub fn fetch_async_background(
         &mut self,
         request: RequestBuilder,
-        fetch_target: IpcSender<FetchResponseMsg>,
+        callback: BoxedFetchCallback,
+        cancel_override: Option<ipc::IpcReceiver<()>>,
     ) {
+        let canceller = cancel_override.unwrap_or_else(|| {
             let mut canceller = FetchCanceller::new();
             let cancel_receiver = canceller.initialize();
             self.cancellers.push(canceller);
-        self.resource_threads
+            cancel_receiver
-            .sender()
+        });
-            .send(CoreResourceMsg::Fetch(
+
+        fetch_async(
+            &self.resource_threads.core_thread,
             request,
-                FetchChannels::ResponseMsg(fetch_target, Some(cancel_receiver)),
+            Some(canceller),
-            ))
+            callback,
-            .unwrap();
+        );
     }
 
     /// Mark an in-progress network request complete.

components/script/dom/document.rs

@@ -11,7 +11,7 @@ use std::default::Default;
 use std::mem;
 use std::rc::Rc;
 use std::slice::from_ref;
-use std::sync::LazyLock;
+use std::sync::{LazyLock, Mutex};
 use std::time::{Duration, Instant};
 
 use base::cross_process_instant::CrossProcessInstant;
@@ -28,7 +28,7 @@ use encoding_rs::{Encoding, UTF_8};
 use euclid::default::{Point2D, Rect, Size2D};
 use html5ever::{local_name, namespace_url, ns, LocalName, Namespace, QualName};
 use hyper_serde::Serde;
-use ipc_channel::ipc::{self, IpcSender};
+use ipc_channel::ipc;
 use js::rust::{HandleObject, HandleValue};
 use keyboard_types::{Code, Key, KeyState};
 use metrics::{
@@ -41,7 +41,7 @@ use net_traits::request::RequestBuilder;
 use net_traits::response::HttpsState;
 use net_traits::CookieSource::NonHTTP;
 use net_traits::CoreResourceMsg::{GetCookiesForUrl, SetCookiesForUrl};
-use net_traits::{FetchResponseMsg, IpcSend, ReferrerPolicy};
+use net_traits::{FetchResponseListener, IpcSend, ReferrerPolicy};
 use num_traits::ToPrimitive;
 use percent_encoding::percent_decode;
 use profile_traits::ipc as profile_ipc;
@@ -178,6 +178,7 @@ use crate::dom::wheelevent::WheelEvent;
 use crate::dom::window::{ReflowReason, Window};
 use crate::dom::windowproxy::WindowProxy;
 use crate::fetch::FetchCanceller;
+use crate::network_listener::{NetworkListener, PreInvoke};
 use crate::realms::{AlreadyInRealm, InRealm};
 use crate::script_runtime::{CanGc, CommonScriptMsg, ScriptThreadEventCategory};
 use crate::script_thread::{MainThreadScriptMsg, ScriptThread};
@@ -2132,16 +2133,53 @@ impl Document {
         }
     }
 
-    pub fn fetch_async(
+    /// Add the CSP list and HTTPS state to a given request.
+    ///
+    /// TODO: Can this hapen for all requests that go through the document?
+    pub(crate) fn prepare_request(&self, request: RequestBuilder) -> RequestBuilder {
+        request
+            .csp_list(self.get_csp_list().map(|list| list.clone()))
+            .https_state(self.https_state.get())
+    }
+
+    pub(crate) fn fetch<Listener: FetchResponseListener + PreInvoke + Send + 'static>(
         &self,
         load: LoadType,
-        mut request: RequestBuilder,
+        request: RequestBuilder,
-        fetch_target: IpcSender<FetchResponseMsg>,
+        listener: Listener,
     ) {
-        request.csp_list = self.get_csp_list().map(|x| x.clone());
+        let (task_source, canceller) = self
-        request.https_state = self.https_state.get();
+            .window()
-        let mut loader = self.loader.borrow_mut();
+            .task_manager()
-        loader.fetch_async(load, request, fetch_target);
+            .networking_task_source_with_canceller();
+        let callback = NetworkListener {
+            context: std::sync::Arc::new(Mutex::new(listener)),
+            task_source,
+            canceller: Some(canceller),
+        }
+        .to_callback();
+        self.loader_mut()
+            .fetch_async_with_callback(load, request, callback);
+    }
+
+    pub(crate) fn fetch_background<Listener: FetchResponseListener + PreInvoke + Send + 'static>(
+        &self,
+        request: RequestBuilder,
+        listener: Listener,
+        cancel_override: Option<ipc::IpcReceiver<()>>,
+    ) {
+        let (task_source, canceller) = self
+            .window()
+            .task_manager()
+            .networking_task_source_with_canceller();
+        let callback = NetworkListener {
+            context: std::sync::Arc::new(Mutex::new(listener)),
+            task_source,
+            canceller: Some(canceller),
+        }
+        .to_callback();
+        self.loader_mut()
+            .fetch_async_background(request, callback, cancel_override);
     }
 
     // https://html.spec.whatwg.org/multipage/#the-end

components/script/dom/eventsource.rs

@@ -17,7 +17,7 @@ use js::conversions::ToJSValConvertible;
 use js::jsval::UndefinedValue;
 use js::rust::HandleObject;
 use mime::{self, Mime};
-use net_traits::request::{CacheMode, CorsSettings, Destination, RequestBuilder};
+use net_traits::request::{CacheMode, CorsSettings, Destination, RequestBuilder, RequestId};
 use net_traits::{
     CoreResourceMsg, FetchChannels, FetchMetadata, FetchResponseListener, FetchResponseMsg,
     FilteredMetadata, NetworkError, ResourceFetchTiming, ResourceTimingType,
@@ -336,15 +336,15 @@ impl EventSourceContext {
 }
 
 impl FetchResponseListener for EventSourceContext {
-    fn process_request_body(&mut self) {
+    fn process_request_body(&mut self, _: RequestId) {
         // TODO
     }
 
-    fn process_request_eof(&mut self) {
+    fn process_request_eof(&mut self, _: RequestId) {
         // TODO
     }
 
-    fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>) {
+    fn process_response(&mut self, _: RequestId, metadata: Result<FetchMetadata, NetworkError>) {
         match metadata {
             Ok(fm) => {
                 let meta = match fm {
@@ -378,7 +378,7 @@ impl FetchResponseListener for EventSourceContext {
         }
     }
 
-    fn process_response_chunk(&mut self, chunk: Vec<u8>) {
+    fn process_response_chunk(&mut self, _: RequestId, chunk: Vec<u8>) {
         let mut input = &*chunk;
         if let Some(mut incomplete) = self.incomplete_utf8.take() {
             match incomplete.try_complete(input) {
@@ -417,7 +417,11 @@ impl FetchResponseListener for EventSourceContext {
         }
     }
 
-    fn process_response_eof(&mut self, _response: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
+        &mut self,
+        _: RequestId,
+        _response: Result<ResourceFetchTiming, NetworkError>,
+    ) {
         if self.incomplete_utf8.take().is_some() {
             self.parse("\u{FFFD}".chars());
         }

components/script/dom/globalscope.rs

@@ -9,7 +9,7 @@ use std::collections::{HashMap, VecDeque};
 use std::ops::Index;
 use std::rc::Rc;
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 use std::thread::JoinHandle;
 use std::time::{Duration, Instant, SystemTime, UNIX_EPOCH};
 use std::{mem, ptr};
@@ -45,9 +45,12 @@ use net_traits::filemanager_thread::{
     FileManagerResult, FileManagerThreadMsg, ReadFileProgress, RelativePos,
 };
 use net_traits::image_cache::ImageCache;
-use net_traits::request::Referrer;
+use net_traits::request::{Referrer, RequestBuilder};
 use net_traits::response::HttpsState;
-use net_traits::{CoreResourceMsg, CoreResourceThread, IpcSend, ResourceThreads};
+use net_traits::{
+    fetch_async, CoreResourceMsg, CoreResourceThread, FetchResponseListener, IpcSend,
+    ResourceThreads,
+};
 use profile_traits::{ipc as profile_ipc, mem as profile_mem, time as profile_time};
 use script_traits::serializable::{BlobData, BlobImpl, FileBlob};
 use script_traits::transferable::MessagePortImpl;
@@ -117,6 +120,7 @@ use crate::dom::window::Window;
 use crate::dom::workerglobalscope::WorkerGlobalScope;
 use crate::dom::workletglobalscope::WorkletGlobalScope;
 use crate::microtask::{Microtask, MicrotaskQueue, UserMicrotask};
+use crate::network_listener::{NetworkListener, PreInvoke};
 use crate::realms::{enter_realm, AlreadyInRealm, InRealm};
 use crate::script_module::{DynamicModuleList, ModuleScript, ModuleTree, ScriptFetchOptions};
 use crate::script_runtime::{
@@ -3391,6 +3395,38 @@ impl GlobalScope {
 
         Ok(message_clone.get())
     }
+
+    pub(crate) fn fetch<Listener: FetchResponseListener + PreInvoke + Send + 'static>(
+        &self,
+        request_builder: RequestBuilder,
+        context: Arc<Mutex<Listener>>,
+        task_source: NetworkingTaskSource,
+        cancellation_sender: Option<ipc::IpcReceiver<()>>,
+    ) {
+        let canceller = Some(self.task_canceller(TaskSourceName::Networking));
+        let network_listener = NetworkListener {
+            context,
+            task_source,
+            canceller,
+        };
+        self.fetch_with_network_listener(request_builder, network_listener, cancellation_sender);
+    }
+
+    pub(crate) fn fetch_with_network_listener<
+        Listener: FetchResponseListener + PreInvoke + Send + 'static,
+    >(
+        &self,
+        request_builder: RequestBuilder,
+        network_listener: NetworkListener<Listener>,
+        cancellation_receiver: Option<ipc::IpcReceiver<()>>,
+    ) {
+        fetch_async(
+            &self.core_resource_thread(),
+            request_builder,
+            cancellation_receiver,
+            network_listener.to_callback(),
+        );
+    }
 }
 
 /// Returns the Rust global scope from a JS global object.

components/script/dom/htmlimageelement.rs

@@ -6,7 +6,7 @@ use std::cell::Cell;
 use std::collections::HashSet;
 use std::default::Default;
 use std::rc::Rc;
-use std::sync::{Arc, Mutex};
+use std::sync::Arc;
 use std::{char, mem};
 
 use app_units::{Au, AU_PER_PX};
@@ -26,7 +26,9 @@ use net_traits::image_cache::{
     ImageCache, ImageCacheResult, ImageOrMetadataAvailable, ImageResponse, PendingImageId,
     PendingImageResponse, UsePlaceholder,
 };
-use net_traits::request::{CorsSettings, Destination, Initiator, Referrer, RequestBuilder};
+use net_traits::request::{
+    CorsSettings, Destination, Initiator, Referrer, RequestBuilder, RequestId,
+};
 use net_traits::{
     FetchMetadata, FetchResponseListener, FetchResponseMsg, NetworkError, ReferrerPolicy,
     ResourceFetchTiming, ResourceTimingType,
@@ -92,7 +94,7 @@ use crate::dom::window::Window;
 use crate::fetch::create_a_potential_cors_request;
 use crate::image_listener::{generate_cache_listener_for_element, ImageCacheListener};
 use crate::microtask::{Microtask, MicrotaskRunnable};
-use crate::network_listener::{self, NetworkListener, PreInvoke, ResourceTimingListener};
+use crate::network_listener::{self, PreInvoke, ResourceTimingListener};
 use crate::realms::enter_realm;
 use crate::script_runtime::CanGc;
 use crate::script_thread::ScriptThread;
@@ -218,13 +220,19 @@ struct ImageContext {
 }
 
 impl FetchResponseListener for ImageContext {
-    fn process_request_body(&mut self) {}
+    fn process_request_body(&mut self, _: RequestId) {}
-    fn process_request_eof(&mut self) {}
+    fn process_request_eof(&mut self, _: RequestId) {}
 
-    fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>) {
+    fn process_response(
+        &mut self,
+        request_id: RequestId,
+        metadata: Result<FetchMetadata, NetworkError>,
+    ) {
         debug!("got {:?} for {:?}", metadata.as_ref().map(|_| ()), self.url);
-        self.image_cache
+        self.image_cache.notify_pending_response(
-            .notify_pending_response(self.id, FetchResponseMsg::ProcessResponse(metadata.clone()));
+            self.id,
+            FetchResponseMsg::ProcessResponse(request_id, metadata.clone()),
+        );
 
         let metadata = metadata.ok().map(|meta| match meta {
             FetchMetadata::Unfiltered(m) => m,
@@ -262,16 +270,24 @@ impl FetchResponseListener for ImageContext {
         };
     }
 
-    fn process_response_chunk(&mut self, payload: Vec<u8>) {
+    fn process_response_chunk(&mut self, request_id: RequestId, payload: Vec<u8>) {
         if self.status.is_ok() {
-            self.image_cache
+            self.image_cache.notify_pending_response(
-                .notify_pending_response(self.id, FetchResponseMsg::ProcessResponseChunk(payload));
+                self.id,
+                FetchResponseMsg::ProcessResponseChunk(request_id, payload),
+            );
         }
     }
 
-    fn process_response_eof(&mut self, response: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
-        self.image_cache
+        &mut self,
-            .notify_pending_response(self.id, FetchResponseMsg::ProcessResponseEOF(response));
+        request_id: RequestId,
+        response: Result<ResourceFetchTiming, NetworkError>,
+    ) {
+        self.image_cache.notify_pending_response(
+            self.id,
+            FetchResponseMsg::ProcessResponseEOF(request_id, response),
+        );
     }
 
     fn resource_timing_mut(&mut self) -> &mut ResourceFetchTiming {
@@ -377,7 +393,7 @@ impl HTMLImageElement {
         let document = document_from_node(self);
         let window = window_from_node(self);
 
-        let context = Arc::new(Mutex::new(ImageContext {
+        let context = ImageContext {
             image_cache: window.image_cache(),
             status: Ok(()),
             id,
@@ -385,24 +401,7 @@ impl HTMLImageElement {
             doc: Trusted::new(&document),
             resource_timing: ResourceFetchTiming::new(ResourceTimingType::Resource),
             url: img_url.clone(),
-        }));
-
-        let (action_sender, action_receiver) = ipc::channel().unwrap();
-        let (task_source, canceller) = document
-            .window()
-            .task_manager()
-            .networking_task_source_with_canceller();
-        let listener = NetworkListener {
-            context,
-            task_source,
-            canceller: Some(canceller),
         };
-        ROUTER.add_route(
-            action_receiver.to_opaque(),
-            Box::new(move |message| {
-                listener.notify_fetch(message.to().unwrap());
-            }),
-        );
 
         let request = image_fetch_request(
             img_url.clone(),
@@ -420,9 +419,7 @@ impl HTMLImageElement {
 
         // This is a background load because the load blocker already fulfills the
         // purpose of delaying the document's load event.
-        document
+        document.fetch_background(request, context, None);
-            .loader_mut()
-            .fetch_async_background(request, action_sender);
     }
 
     // Steps common to when an image has been loaded.

components/script/dom/htmllinkelement.rs

@@ -5,19 +5,18 @@
 use std::borrow::{Borrow, ToOwned};
 use std::cell::Cell;
 use std::default::Default;
-use std::sync;
 
 use cssparser::{Parser as CssParser, ParserInput};
 use dom_struct::dom_struct;
 use embedder_traits::EmbedderMsg;
 use html5ever::{local_name, namespace_url, ns, LocalName, Prefix};
-use ipc_channel::ipc;
-use ipc_channel::router::ROUTER;
 use js::rust::HandleObject;
-use net_traits::request::{CorsSettings, Destination, Initiator, Referrer, RequestBuilder};
+use net_traits::request::{
+    CorsSettings, Destination, Initiator, Referrer, RequestBuilder, RequestId,
+};
 use net_traits::{
-    CoreResourceMsg, FetchChannels, FetchMetadata, FetchResponseListener, IpcSend, NetworkError,
+    FetchMetadata, FetchResponseListener, NetworkError, ReferrerPolicy, ResourceFetchTiming,
-    ReferrerPolicy, ResourceFetchTiming, ResourceTimingType,
+    ResourceTimingType,
 };
 use servo_arc::Arc;
 use servo_atoms::Atom;
@@ -56,7 +55,7 @@ use crate::dom::stylesheet::StyleSheet as DOMStyleSheet;
 use crate::dom::virtualmethods::VirtualMethods;
 use crate::fetch::create_a_potential_cors_request;
 use crate::links::LinkRelations;
-use crate::network_listener::{submit_timing, NetworkListener, PreInvoke, ResourceTimingListener};
+use crate::network_listener::{submit_timing, PreInvoke, ResourceTimingListener};
 use crate::stylesheet_loader::{StylesheetContextSource, StylesheetLoader, StylesheetOwner};
 
 #[derive(Clone, Copy, JSTraceable, MallocSizeOf, PartialEq)]
@@ -374,42 +373,14 @@ impl HTMLLinkElement {
         // (Step 7, firing load/error events is handled in the FetchResponseListener impl for PrefetchContext)
 
         // Step 8. The user agent should fetch request, with processResponseConsumeBody set to processPrefetchResponse.
-        let (action_sender, action_receiver) = ipc::channel().unwrap();
         let document = self.upcast::<Node>().owner_doc();
-        let window = document.window();
+        let fetch_context = PrefetchContext {
-
-        let (task_source, canceller) = window
-            .task_manager()
-            .networking_task_source_with_canceller();
-
-        let fetch_context = sync::Arc::new(sync::Mutex::new(PrefetchContext {
             url,
             link: Trusted::new(self),
             resource_timing: ResourceFetchTiming::new(ResourceTimingType::Resource),
-        }));
-
-        let listener = NetworkListener {
-            context: fetch_context,
-            task_source,
-            canceller: Some(canceller),
         };
 
-        ROUTER.add_route(
+        document.fetch_background(request, fetch_context, None);
-            action_receiver.to_opaque(),
-            Box::new(move |message| {
-                listener.notify_fetch(message.to().unwrap());
-            }),
-        );
-
-        window
-            .upcast::<GlobalScope>()
-            .resource_threads()
-            .sender()
-            .send(CoreResourceMsg::Fetch(
-                request,
-                FetchChannels::ResponseMsg(action_sender, None),
-            ))
-            .unwrap();
     }
 
     /// <https://html.spec.whatwg.org/multipage/#concept-link-obtain>
@@ -713,20 +684,28 @@ struct PrefetchContext {
 }
 
 impl FetchResponseListener for PrefetchContext {
-    fn process_request_body(&mut self) {}
+    fn process_request_body(&mut self, _: RequestId) {}
 
-    fn process_request_eof(&mut self) {}
+    fn process_request_eof(&mut self, _: RequestId) {}
 
-    fn process_response(&mut self, fetch_metadata: Result<FetchMetadata, NetworkError>) {
+    fn process_response(
+        &mut self,
+        _: RequestId,
+        fetch_metadata: Result<FetchMetadata, NetworkError>,
+    ) {
         _ = fetch_metadata;
     }
 
-    fn process_response_chunk(&mut self, chunk: Vec<u8>) {
+    fn process_response_chunk(&mut self, _: RequestId, chunk: Vec<u8>) {
         _ = chunk;
     }
 
     // Step 7 of `fetch and process the linked resource` in https://html.spec.whatwg.org/multipage/#link-type-prefetch
-    fn process_response_eof(&mut self, response: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
+        &mut self,
+        _: RequestId,
+        response: Result<ResourceFetchTiming, NetworkError>,
+    ) {
         if response.is_err() {
             // Step 1. If response is a network error, fire an event named error at el.
             self.link

components/script/dom/htmlmediaelement.rs

@@ -21,10 +21,10 @@ use ipc_channel::ipc::{self, IpcSharedMemory};
 use ipc_channel::router::ROUTER;
 use js::jsapi::JSAutoRealm;
 use media::{glplayer_channel, GLPlayerMsg, GLPlayerMsgForward, WindowGLContext};
-use net_traits::request::Destination;
+use net_traits::request::{Destination, RequestId};
 use net_traits::{
-    CoreResourceMsg, FetchChannels, FetchMetadata, FetchResponseListener, Metadata, NetworkError,
+    FetchMetadata, FetchResponseListener, Metadata, NetworkError, ResourceFetchTiming,
-    ResourceFetchTiming, ResourceTimingType,
+    ResourceTimingType,
 };
 use pixels::Image;
 use script_layout_interface::HTMLMediaData;
@@ -101,7 +101,7 @@ use crate::dom::videotracklist::VideoTrackList;
 use crate::dom::virtualmethods::VirtualMethods;
 use crate::fetch::{create_a_potential_cors_request, FetchCanceller};
 use crate::microtask::{Microtask, MicrotaskRunnable};
-use crate::network_listener::{self, NetworkListener, PreInvoke, ResourceTimingListener};
+use crate::network_listener::{self, PreInvoke, ResourceTimingListener};
 use crate::realms::{enter_realm, InRealm};
 use crate::script_runtime::CanGc;
 use crate::script_thread::ScriptThread;
@@ -890,36 +890,12 @@ impl HTMLMediaElement {
         }
         let (fetch_context, cancel_receiver) = HTMLMediaElementFetchContext::new();
         *current_fetch_context = Some(fetch_context);
-        let fetch_listener = Arc::new(Mutex::new(HTMLMediaElementFetchListener::new(
+        let listener =
-            self,
+            HTMLMediaElementFetchListener::new(self, url.clone(), offset.unwrap_or(0), seek_lock);
-            url.clone(),
+
-            offset.unwrap_or(0),
+        // TODO: If this is supposed to to be a "fetch" as defined in the specification
-            seek_lock,
+        // this should probably be integrated into the Document's list of cancellable fetches.
-        )));
+        document_from_node(self).fetch_background(request, listener, Some(cancel_receiver));
-        let (action_sender, action_receiver) = ipc::channel().unwrap();
-        let window = window_from_node(self);
-        let (task_source, canceller) = window
-            .task_manager()
-            .networking_task_source_with_canceller();
-        let network_listener = NetworkListener {
-            context: fetch_listener,
-            task_source,
-            canceller: Some(canceller),
-        };
-        ROUTER.add_route(
-            action_receiver.to_opaque(),
-            Box::new(move |message| {
-                network_listener.notify_fetch(message.to().unwrap());
-            }),
-        );
-        let global = self.global();
-        global
-            .core_resource_thread()
-            .send(CoreResourceMsg::Fetch(
-                request,
-                FetchChannels::ResponseMsg(action_sender, Some(cancel_receiver)),
-            ))
-            .unwrap();
     }
 
     // https://html.spec.whatwg.org/multipage/#concept-media-load-resource
@@ -2681,11 +2657,11 @@ struct HTMLMediaElementFetchListener {
 
 // https://html.spec.whatwg.org/multipage/#media-data-processing-steps-list
 impl FetchResponseListener for HTMLMediaElementFetchListener {
-    fn process_request_body(&mut self) {}
+    fn process_request_body(&mut self, _: RequestId) {}
 
-    fn process_request_eof(&mut self) {}
+    fn process_request_eof(&mut self, _: RequestId) {}
 
-    fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>) {
+    fn process_response(&mut self, _: RequestId, metadata: Result<FetchMetadata, NetworkError>) {
         let elem = self.elem.root();
 
         if elem.generation_id.get() != self.generation_id || elem.player.borrow().is_none() {
@@ -2759,7 +2735,7 @@ impl FetchResponseListener for HTMLMediaElementFetchListener {
         }
     }
 
-    fn process_response_chunk(&mut self, payload: Vec<u8>) {
+    fn process_response_chunk(&mut self, _: RequestId, payload: Vec<u8>) {
         let elem = self.elem.root();
         // If an error was received previously or if we triggered a new fetch request,
         // we skip processing the payload.
@@ -2818,7 +2794,11 @@ impl FetchResponseListener for HTMLMediaElementFetchListener {
     }
 
     // https://html.spec.whatwg.org/multipage/#media-data-processing-steps-list
-    fn process_response_eof(&mut self, status: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
+        &mut self,
+        _: RequestId,
+        status: Result<ResourceFetchTiming, NetworkError>,
+    ) {
         trace!("process response eof");
         if let Some(seek_lock) = self.seek_lock.take() {
             seek_lock.unlock(/* successful seek */ false);

components/script/dom/htmlscriptelement.rs

@@ -18,12 +18,11 @@ use dom_struct::dom_struct;
 use encoding_rs::Encoding;
 use html5ever::{local_name, namespace_url, ns, LocalName, Prefix};
 use ipc_channel::ipc;
-use ipc_channel::router::ROUTER;
 use js::jsval::UndefinedValue;
 use js::rust::{transform_str_to_source_text, CompileOptionsWrapper, HandleObject, Stencil};
 use net_traits::http_status::HttpStatus;
 use net_traits::request::{
-    CorsSettings, CredentialsMode, Destination, ParserMetadata, RequestBuilder,
+    CorsSettings, CredentialsMode, Destination, ParserMetadata, RequestBuilder, RequestId,
 };
 use net_traits::{
     FetchMetadata, FetchResponseListener, Metadata, NetworkError, ResourceFetchTiming,
@@ -351,11 +350,13 @@ struct ClassicContext {
 }
 
 impl FetchResponseListener for ClassicContext {
-    fn process_request_body(&mut self) {} // TODO(KiChjang): Perhaps add custom steps to perform fetch here?
+    // TODO(KiChjang): Perhaps add custom steps to perform fetch here?
+    fn process_request_body(&mut self, _: RequestId) {}
 
-    fn process_request_eof(&mut self) {} // TODO(KiChjang): Perhaps add custom steps to perform fetch here?
+    // TODO(KiChjang): Perhaps add custom steps to perform fetch here?
+    fn process_request_eof(&mut self, _: RequestId) {}
 
-    fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>) {
+    fn process_response(&mut self, _: RequestId, metadata: Result<FetchMetadata, NetworkError>) {
         self.metadata = metadata.ok().map(|meta| match meta {
             FetchMetadata::Unfiltered(m) => m,
             FetchMetadata::Filtered { unsafe_, .. } => unsafe_,
@@ -383,7 +384,7 @@ impl FetchResponseListener for ClassicContext {
         };
     }
 
-    fn process_response_chunk(&mut self, mut chunk: Vec<u8>) {
+    fn process_response_chunk(&mut self, _: RequestId, mut chunk: Vec<u8>) {
         if self.status.is_ok() {
             self.data.append(&mut chunk);
         }
@@ -392,7 +393,11 @@ impl FetchResponseListener for ClassicContext {
     /// <https://html.spec.whatwg.org/multipage/#fetch-a-classic-script>
     /// step 4-9
     #[allow(unsafe_code)]
-    fn process_response_eof(&mut self, response: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
+        &mut self,
+        _: RequestId,
+        response: Result<ResourceFetchTiming, NetworkError>,
+    ) {
         let (source_text, final_url) = match (response.as_ref(), self.status.as_ref()) {
             (Err(err), _) | (_, Err(err)) => {
                 // Step 6, response is an error.
@@ -538,9 +543,8 @@ fn fetch_a_classic_script(
     options: ScriptFetchOptions,
     character_encoding: &'static Encoding,
 ) {
-    let doc = document_from_node(script);
-
     // Step 1, 2.
+    let doc = document_from_node(script);
     let request = script_fetch_request(
         url.clone(),
         cors_setting,
@@ -548,10 +552,11 @@ fn fetch_a_classic_script(
         script.global().pipeline_id(),
         options.clone(),
     );
+    let request = doc.prepare_request(request);
 
     // TODO: Step 3, Add custom steps to perform fetch
 
-    let context = Arc::new(Mutex::new(ClassicContext {
+    let context = ClassicContext {
         elem: Trusted::new(script),
         kind,
         character_encoding,
@@ -561,26 +566,8 @@ fn fetch_a_classic_script(
         status: Ok(()),
         fetch_options: options,
         resource_timing: ResourceFetchTiming::new(ResourceTimingType::Resource),
-    }));
-
-    let (action_sender, action_receiver) = ipc::channel().unwrap();
-    let (task_source, canceller) = doc
-        .window()
-        .task_manager()
-        .networking_task_source_with_canceller();
-    let listener = NetworkListener {
-        context,
-        task_source,
-        canceller: Some(canceller),
     };
-
+    doc.fetch(LoadType::Script(url), request, context);
-    ROUTER.add_route(
-        action_receiver.to_opaque(),
-        Box::new(move |message| {
-            listener.notify_fetch(message.to().unwrap());
-        }),
-    );
-    doc.fetch_async(LoadType::Script(url), request, action_sender);
 }
 
 impl HTMLScriptElement {

components/script/dom/htmlvideoelement.rs

@@ -3,22 +3,21 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use std::cell::Cell;
-use std::sync::{Arc, Mutex};
+use std::sync::Arc;
 
 use dom_struct::dom_struct;
 use euclid::default::Size2D;
 use html5ever::{local_name, LocalName, Prefix};
 use ipc_channel::ipc;
-use ipc_channel::router::ROUTER;
 use js::rust::HandleObject;
 use net_traits::image_cache::{
     ImageCache, ImageCacheResult, ImageOrMetadataAvailable, ImageResponse, PendingImageId,
     UsePlaceholder,
 };
-use net_traits::request::{CredentialsMode, Destination, RequestBuilder};
+use net_traits::request::{CredentialsMode, Destination, RequestBuilder, RequestId};
 use net_traits::{
-    CoreResourceMsg, FetchChannels, FetchMetadata, FetchResponseListener, FetchResponseMsg,
+    FetchMetadata, FetchResponseListener, FetchResponseMsg, NetworkError, ResourceFetchTiming,
-    NetworkError, ResourceFetchTiming, ResourceTimingType,
+    ResourceTimingType,
 };
 use servo_media::player::video::VideoFrame;
 use servo_url::ServoUrl;
@@ -41,7 +40,7 @@ use crate::dom::performanceresourcetiming::InitiatorType;
 use crate::dom::virtualmethods::VirtualMethods;
 use crate::fetch::FetchCanceller;
 use crate::image_listener::{generate_cache_listener_for_element, ImageCacheListener};
-use crate::network_listener::{self, NetworkListener, PreInvoke, ResourceTimingListener};
+use crate::network_listener::{self, PreInvoke, ResourceTimingListener};
 use crate::script_runtime::CanGc;
 
 const DEFAULT_WIDTH: u32 = 300;
@@ -213,34 +212,11 @@ impl HTMLVideoElement {
             LoadType::Image(poster_url.clone()),
         ));
 
-        let window = window_from_node(self);
+        let context = PosterFrameFetchContext::new(self, poster_url, id);
-        let context = Arc::new(Mutex::new(PosterFrameFetchContext::new(
-            self, poster_url, id,
-        )));
 
-        let (action_sender, action_receiver) = ipc::channel().unwrap();
+        // TODO: If this is supposed to to be a "fetch" as defined in the specification
-        let (task_source, canceller) = window
+        // this should probably be integrated into the Document's list of cancellable fetches.
-            .task_manager()
+        document_from_node(self).fetch_background(request, context, Some(cancel_receiver));
-            .networking_task_source_with_canceller();
-        let listener = NetworkListener {
-            context,
-            task_source,
-            canceller: Some(canceller),
-        };
-        ROUTER.add_route(
-            action_receiver.to_opaque(),
-            Box::new(move |message| {
-                listener.notify_fetch(message.to().unwrap());
-            }),
-        );
-        let global = self.global();
-        global
-            .core_resource_thread()
-            .send(CoreResourceMsg::Fetch(
-                request,
-                FetchChannels::ResponseMsg(action_sender, Some(cancel_receiver)),
-            ))
-            .unwrap();
     }
 }
 
@@ -326,12 +302,18 @@ struct PosterFrameFetchContext {
 }
 
 impl FetchResponseListener for PosterFrameFetchContext {
-    fn process_request_body(&mut self) {}
+    fn process_request_body(&mut self, _: RequestId) {}
-    fn process_request_eof(&mut self) {}
+    fn process_request_eof(&mut self, _: RequestId) {}
 
-    fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>) {
+    fn process_response(
-        self.image_cache
+        &mut self,
-            .notify_pending_response(self.id, FetchResponseMsg::ProcessResponse(metadata.clone()));
+        request_id: RequestId,
+        metadata: Result<FetchMetadata, NetworkError>,
+    ) {
+        self.image_cache.notify_pending_response(
+            self.id,
+            FetchResponseMsg::ProcessResponse(request_id, metadata.clone()),
+        );
 
         let metadata = metadata.ok().map(|meta| match meta {
             FetchMetadata::Unfiltered(m) => m,
@@ -352,19 +334,27 @@ impl FetchResponseListener for PosterFrameFetchContext {
         }
     }
 
-    fn process_response_chunk(&mut self, payload: Vec<u8>) {
+    fn process_response_chunk(&mut self, request_id: RequestId, payload: Vec<u8>) {
         if self.cancelled {
             // An error was received previously, skip processing the payload.
             return;
         }
 
-        self.image_cache
+        self.image_cache.notify_pending_response(
-            .notify_pending_response(self.id, FetchResponseMsg::ProcessResponseChunk(payload));
+            self.id,
+            FetchResponseMsg::ProcessResponseChunk(request_id, payload),
+        );
     }
 
-    fn process_response_eof(&mut self, response: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
-        self.image_cache
+        &mut self,
-            .notify_pending_response(self.id, FetchResponseMsg::ProcessResponseEOF(response));
+        request_id: RequestId,
+        response: Result<ResourceFetchTiming, NetworkError>,
+    ) {
+        self.image_cache.notify_pending_response(
+            self.id,
+            FetchResponseMsg::ProcessResponseEOF(request_id, response),
+        );
     }
 
     fn resource_timing_mut(&mut self) -> &mut ResourceFetchTiming {

components/script/dom/request.rs

@@ -17,7 +17,7 @@ use net_traits::fetch::headers::is_forbidden_method;
 use net_traits::request::{
     CacheMode as NetTraitsRequestCache, CredentialsMode as NetTraitsRequestCredentials,
     Destination as NetTraitsRequestDestination, Origin, RedirectMode as NetTraitsRequestRedirect,
-    Referrer as NetTraitsRequestReferrer, Request as NetTraitsRequest,
+    Referrer as NetTraitsRequestReferrer, Request as NetTraitsRequest, RequestBuilder,
     RequestMode as NetTraitsRequestMode, Window,
 };
 use net_traits::ReferrerPolicy as MsgReferrerPolicy;
@@ -107,11 +107,11 @@ impl Request {
 }
 
 fn net_request_from_global(global: &GlobalScope, url: ServoUrl) -> NetTraitsRequest {
-    let origin = Origin::Origin(global.get_url().origin());
+    RequestBuilder::new(url, global.get_referrer())
-    let https_state = global.get_https_state();
+        .origin(global.get_url().origin())
-    let pipeline_id = global.pipeline_id();
+        .pipeline_id(Some(global.pipeline_id()))
-    let referrer = global.get_referrer();
+        .https_state(global.get_https_state())
-    NetTraitsRequest::new(url, Some(origin), referrer, Some(pipeline_id), https_state)
+        .build()
 }
 
 // https://fetch.spec.whatwg.org/#concept-method-normalize

components/script/dom/servoparser/mod.rs

@@ -21,6 +21,7 @@ use html5ever::tree_builder::{ElementFlags, NextParserState, NodeOrText, QuirksM
 use html5ever::{local_name, namespace_url, ns, Attribute, ExpandedName, LocalName, QualName};
 use hyper_serde::Serde;
 use mime::{self, Mime};
+use net_traits::request::RequestId;
 use net_traits::{
     FetchMetadata, FetchResponseListener, Metadata, NetworkError, ResourceFetchTiming,
     ResourceTimingType,
@@ -759,11 +760,11 @@ impl ParserContext {
 }
 
 impl FetchResponseListener for ParserContext {
-    fn process_request_body(&mut self) {}
+    fn process_request_body(&mut self, _: RequestId) {}
 
-    fn process_request_eof(&mut self) {}
+    fn process_request_eof(&mut self, _: RequestId) {}
 
-    fn process_response(&mut self, meta_result: Result<FetchMetadata, NetworkError>) {
+    fn process_response(&mut self, _: RequestId, meta_result: Result<FetchMetadata, NetworkError>) {
         let (metadata, error) = match meta_result {
             Ok(meta) => (
                 Some(match meta {
@@ -914,7 +915,7 @@ impl FetchResponseListener for ParserContext {
         }
     }
 
-    fn process_response_chunk(&mut self, payload: Vec<u8>) {
+    fn process_response_chunk(&mut self, _: RequestId, payload: Vec<u8>) {
         if self.is_synthesized_document {
             return;
         }
@@ -932,7 +933,11 @@ impl FetchResponseListener for ParserContext {
     // This method is called via script_thread::handle_fetch_eof, so we must call
     // submit_resource_timing in this function
     // Resource listeners are called via net_traits::Action::process, which handles submission for them
-    fn process_response_eof(&mut self, status: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
+        &mut self,
+        _: RequestId,
+        status: Result<ResourceFetchTiming, NetworkError>,
+    ) {
         let parser = match self.parser.as_ref() {
             Some(parser) => parser.root(),
             None => return,

components/script/dom/xmlhttprequest.rs

@@ -19,7 +19,6 @@ use http::header::{self, HeaderMap, HeaderName, HeaderValue};
 use http::Method;
 use hyper_serde::Serde;
 use ipc_channel::ipc;
-use ipc_channel::router::ROUTER;
 use js::jsapi::{Heap, JS_ClearPendingException};
 use js::jsval::{JSVal, NullValue, UndefinedValue};
 use js::rust::wrappers::JS_ParseJSON;
@@ -27,11 +26,12 @@ use js::rust::HandleObject;
 use js::typedarray::{ArrayBuffer, ArrayBufferU8};
 use mime::{self, Mime, Name};
 use net_traits::http_status::HttpStatus;
-use net_traits::request::{CredentialsMode, Destination, Referrer, RequestBuilder, RequestMode};
+use net_traits::request::{
-use net_traits::CoreResourceMsg::Fetch;
+    CredentialsMode, Destination, Referrer, RequestBuilder, RequestId, RequestMode,
+};
 use net_traits::{
-    trim_http_whitespace, FetchChannels, FetchMetadata, FetchResponseListener, FilteredMetadata,
+    trim_http_whitespace, FetchMetadata, FetchResponseListener, FilteredMetadata, NetworkError,
-    NetworkError, ReferrerPolicy, ResourceFetchTiming, ResourceTimingType,
+    ReferrerPolicy, ResourceFetchTiming, ResourceTimingType,
 };
 use script_traits::serializable::BlobImpl;
 use script_traits::DocumentActivity;
@@ -71,10 +71,9 @@ use crate::dom::workerglobalscope::WorkerGlobalScope;
 use crate::dom::xmlhttprequesteventtarget::XMLHttpRequestEventTarget;
 use crate::dom::xmlhttprequestupload::XMLHttpRequestUpload;
 use crate::fetch::FetchCanceller;
-use crate::network_listener::{self, NetworkListener, PreInvoke, ResourceTimingListener};
+use crate::network_listener::{self, PreInvoke, ResourceTimingListener};
 use crate::script_runtime::{CanGc, JSContext};
 use crate::task_source::networking::NetworkingTaskSource;
-use crate::task_source::TaskSourceName;
 use crate::timers::{OneshotTimerCallback, OneshotTimerHandle};
 
 #[derive(Clone, Copy, Debug, JSTraceable, MallocSizeOf, PartialEq)]
@@ -244,15 +243,19 @@ impl XMLHttpRequest {
         cancellation_chan: ipc::IpcReceiver<()>,
     ) {
         impl FetchResponseListener for XHRContext {
-            fn process_request_body(&mut self) {
+            fn process_request_body(&mut self, _: RequestId) {
                 // todo
             }
 
-            fn process_request_eof(&mut self) {
+            fn process_request_eof(&mut self, _: RequestId) {
                 // todo
             }
 
-            fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>) {
+            fn process_response(
+                &mut self,
+                _: RequestId,
+                metadata: Result<FetchMetadata, NetworkError>,
+            ) {
                 let xhr = self.xhr.root();
                 let rv = xhr.process_headers_available(self.gen_id, metadata, CanGc::note());
                 if rv.is_err() {
@@ -260,7 +263,7 @@ impl XMLHttpRequest {
                 }
             }
 
-            fn process_response_chunk(&mut self, chunk: Vec<u8>) {
+            fn process_response_chunk(&mut self, _: RequestId, chunk: Vec<u8>) {
                 self.xhr
                     .root()
                     .process_data_available(self.gen_id, chunk, CanGc::note());
@@ -268,6 +271,7 @@ impl XMLHttpRequest {
 
             fn process_response_eof(
                 &mut self,
+                _: RequestId,
                 response: Result<ResourceFetchTiming, NetworkError>,
             ) {
                 let rv = self.xhr.root().process_response_complete(
@@ -307,26 +311,7 @@ impl XMLHttpRequest {
             }
         }
 
-        let (action_sender, action_receiver) = ipc::channel().unwrap();
+        global.fetch(init, context, task_source, Some(cancellation_chan));
-
-        let listener = NetworkListener {
-            context,
-            task_source,
-            canceller: Some(global.task_canceller(TaskSourceName::Networking)),
-        };
-        ROUTER.add_route(
-            action_receiver.to_opaque(),
-            Box::new(move |message| {
-                listener.notify_fetch(message.to().unwrap());
-            }),
-        );
-        global
-            .core_resource_thread()
-            .send(Fetch(
-                init,
-                FetchChannels::ResponseMsg(action_sender, Some(cancellation_chan)),
-            ))
-            .unwrap();
     }
 }
 

components/script/fetch.rs

@@ -6,12 +6,10 @@ use std::rc::Rc;
 use std::sync::{Arc, Mutex};
 
 use ipc_channel::ipc;
-use ipc_channel::router::ROUTER;
 use net_traits::request::{
     CorsSettings, CredentialsMode, Destination, Referrer, Request as NetTraitsRequest,
-    RequestBuilder, RequestMode, ServiceWorkersMode,
+    RequestBuilder, RequestId, RequestMode, ServiceWorkersMode,
 };
-use net_traits::CoreResourceMsg::Fetch as NetTraitsFetch;
 use net_traits::{
     CoreResourceMsg, CoreResourceThread, FetchChannels, FetchMetadata, FetchResponseListener,
     FetchResponseMsg, FilteredMetadata, Metadata, NetworkError, ResourceFetchTiming,
@@ -37,12 +35,9 @@ use crate::dom::promise::Promise;
 use crate::dom::request::Request;
 use crate::dom::response::Response;
 use crate::dom::serviceworkerglobalscope::ServiceWorkerGlobalScope;
-use crate::network_listener::{
+use crate::network_listener::{self, submit_timing_data, PreInvoke, ResourceTimingListener};
-    self, submit_timing_data, NetworkListener, PreInvoke, ResourceTimingListener,
-};
 use crate::realms::{enter_realm, InRealm};
 use crate::script_runtime::CanGc;
-use crate::task_source::TaskSourceName;
 
 struct FetchContext {
     fetch_promise: Option<TrustedPromise>,
@@ -105,6 +100,7 @@ impl Drop for FetchCanceller {
 
 fn request_init_from_request(request: NetTraitsRequest) -> RequestBuilder {
     RequestBuilder {
+        id: request.id,
         method: request.method.clone(),
         url: request.url(),
         headers: request.headers.clone(),
@@ -147,8 +143,6 @@ pub fn Fetch(
     comp: InRealm,
     can_gc: CanGc,
 ) -> Rc<Promise> {
-    let core_resource_thread = global.core_resource_thread();
-
     // Step 1. Let p be a new promise.
     let promise = Promise::new_in_current_realm(comp);
 
@@ -190,30 +184,18 @@ pub fn Fetch(
 
     // Step 12. Set controller to the result of calling fetch given request and
     //           processResponse given response being these steps: [..]
-    let (action_sender, action_receiver) = ipc::channel().unwrap();
     let fetch_context = Arc::new(Mutex::new(FetchContext {
         fetch_promise: Some(TrustedPromise::new(promise.clone())),
         response_object: Trusted::new(&*response),
         resource_timing: ResourceFetchTiming::new(timing_type),
     }));
-    let listener = NetworkListener {
-        context: fetch_context,
-        task_source: global.networking_task_source(),
-        canceller: Some(global.task_canceller(TaskSourceName::Networking)),
-    };
 
-    ROUTER.add_route(
+    global.fetch(
-        action_receiver.to_opaque(),
-        Box::new(move |message| {
-            listener.notify_fetch(message.to().unwrap());
-        }),
-    );
-    core_resource_thread
-        .send(NetTraitsFetch(
         request_init,
-            FetchChannels::ResponseMsg(action_sender, None),
+        fetch_context,
-        ))
+        global.networking_task_source(),
-        .unwrap();
+        None,
+    );
 
     // Step 13. Return p.
     promise
@@ -222,16 +204,20 @@ pub fn Fetch(
 impl PreInvoke for FetchContext {}
 
 impl FetchResponseListener for FetchContext {
-    fn process_request_body(&mut self) {
+    fn process_request_body(&mut self, _: RequestId) {
         // TODO
     }
 
-    fn process_request_eof(&mut self) {
+    fn process_request_eof(&mut self, _: RequestId) {
         // TODO
     }
 
     #[allow(crown::unrooted_must_root)]
-    fn process_response(&mut self, fetch_metadata: Result<FetchMetadata, NetworkError>) {
+    fn process_response(
+        &mut self,
+        _: RequestId,
+        fetch_metadata: Result<FetchMetadata, NetworkError>,
+    ) {
         let promise = self
             .fetch_promise
             .take()
@@ -285,12 +271,16 @@ impl FetchResponseListener for FetchContext {
         self.fetch_promise = Some(TrustedPromise::new(promise));
     }
 
-    fn process_response_chunk(&mut self, chunk: Vec<u8>) {
+    fn process_response_chunk(&mut self, _: RequestId, chunk: Vec<u8>) {
         let response = self.response_object.root();
         response.stream_chunk(chunk);
     }
 
-    fn process_response_eof(&mut self, _response: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
+        &mut self,
+        _: RequestId,
+        _response: Result<ResourceFetchTiming, NetworkError>,
+    ) {
         let response = self.response_object.root();
         let _ac = enter_realm(&*response);
         response.finish();
@@ -354,23 +344,25 @@ pub fn load_whole_resource(
     let mut metadata = None;
     loop {
         match action_receiver.recv().unwrap() {
-            FetchResponseMsg::ProcessRequestBody | FetchResponseMsg::ProcessRequestEOF => (),
+            FetchResponseMsg::ProcessRequestBody(..) | FetchResponseMsg::ProcessRequestEOF(..) => {
-            FetchResponseMsg::ProcessResponse(Ok(m)) => {
+                ()
+            },
+            FetchResponseMsg::ProcessResponse(_, Ok(m)) => {
                 metadata = Some(match m {
                     FetchMetadata::Unfiltered(m) => m,
                     FetchMetadata::Filtered { unsafe_, .. } => unsafe_,
                 })
             },
-            FetchResponseMsg::ProcessResponseChunk(data) => buf.extend_from_slice(&data),
+            FetchResponseMsg::ProcessResponseChunk(_, data) => buf.extend_from_slice(&data),
-            FetchResponseMsg::ProcessResponseEOF(Ok(_)) => {
+            FetchResponseMsg::ProcessResponseEOF(_, Ok(_)) => {
                 let metadata = metadata.unwrap();
                 if let Some(timing) = &metadata.timing {
                     submit_timing_data(global, url, InitiatorType::Other, timing);
                 }
                 return Ok((metadata, buf));
             },
-            FetchResponseMsg::ProcessResponse(Err(e)) |
+            FetchResponseMsg::ProcessResponse(_, Err(e)) |
-            FetchResponseMsg::ProcessResponseEOF(Err(e)) => return Err(e),
+            FetchResponseMsg::ProcessResponseEOF(_, Err(e)) => return Err(e),
         }
     }
 }

components/script/layout_image.rs

@@ -6,12 +6,10 @@
 //! to be responsible for them because there's no guarantee that the responsible nodes will still
 //! exist in the future if layout holds on to them during asynchronous operations.
 
-use std::sync::{Arc, Mutex};
+use std::sync::Arc;
 
-use ipc_channel::ipc;
-use ipc_channel::router::ROUTER;
 use net_traits::image_cache::{ImageCache, PendingImageId};
-use net_traits::request::{Destination, RequestBuilder as FetchRequestInit};
+use net_traits::request::{Destination, RequestBuilder as FetchRequestInit, RequestId};
 use net_traits::{
     FetchMetadata, FetchResponseListener, FetchResponseMsg, NetworkError, ResourceFetchTiming,
     ResourceTimingType,
@@ -25,7 +23,7 @@ use crate::dom::document::Document;
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::node::{document_from_node, Node};
 use crate::dom::performanceresourcetiming::InitiatorType;
-use crate::network_listener::{self, NetworkListener, PreInvoke, ResourceTimingListener};
+use crate::network_listener::{self, PreInvoke, ResourceTimingListener};
 
 struct LayoutImageContext {
     id: PendingImageId,
@@ -36,21 +34,35 @@ struct LayoutImageContext {
 }
 
 impl FetchResponseListener for LayoutImageContext {
-    fn process_request_body(&mut self) {}
+    fn process_request_body(&mut self, _: RequestId) {}
-    fn process_request_eof(&mut self) {}
+    fn process_request_eof(&mut self, _: RequestId) {}
-    fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>) {
+    fn process_response(
-        self.cache
+        &mut self,
-            .notify_pending_response(self.id, FetchResponseMsg::ProcessResponse(metadata));
+        request_id: RequestId,
+        metadata: Result<FetchMetadata, NetworkError>,
+    ) {
+        self.cache.notify_pending_response(
+            self.id,
+            FetchResponseMsg::ProcessResponse(request_id, metadata),
+        );
     }
 
-    fn process_response_chunk(&mut self, payload: Vec<u8>) {
+    fn process_response_chunk(&mut self, request_id: RequestId, payload: Vec<u8>) {
-        self.cache
+        self.cache.notify_pending_response(
-            .notify_pending_response(self.id, FetchResponseMsg::ProcessResponseChunk(payload));
+            self.id,
+            FetchResponseMsg::ProcessResponseChunk(request_id, payload),
+        );
     }
 
-    fn process_response_eof(&mut self, response: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
-        self.cache
+        &mut self,
-            .notify_pending_response(self.id, FetchResponseMsg::ProcessResponseEOF(response));
+        request_id: RequestId,
+        response: Result<ResourceFetchTiming, NetworkError>,
+    ) {
+        self.cache.notify_pending_response(
+            self.id,
+            FetchResponseMsg::ProcessResponseEOF(request_id, response),
+        );
     }
 
     fn resource_timing_mut(&mut self) -> &mut ResourceFetchTiming {
@@ -85,33 +97,13 @@ pub fn fetch_image_for_layout(
     cache: Arc<dyn ImageCache>,
 ) {
     let document = document_from_node(node);
-
+    let context = LayoutImageContext {
-    let context = Arc::new(Mutex::new(LayoutImageContext {
         id,
         cache,
         resource_timing: ResourceFetchTiming::new(ResourceTimingType::Resource),
         doc: Trusted::new(&document),
         url: url.clone(),
-    }));
-
-    let document = document_from_node(node);
-
-    let (action_sender, action_receiver) = ipc::channel().unwrap();
-    let (task_source, canceller) = document
-        .window()
-        .task_manager()
-        .networking_task_source_with_canceller();
-    let listener = NetworkListener {
-        context,
-        task_source,
-        canceller: Some(canceller),
     };
-    ROUTER.add_route(
-        action_receiver.to_opaque(),
-        Box::new(move |message| {
-            listener.notify_fetch(message.to().unwrap());
-        }),
-    );
 
     let request = FetchRequestInit::new(url, document.global().get_referrer())
         .origin(document.origin().immutable().clone())
@@ -119,7 +111,5 @@ pub fn fetch_image_for_layout(
         .pipeline_id(Some(document.global().pipeline_id()));
 
     // Layout image loads do not delay the document load event.
-    document
+    document.fetch_background(request, context, None);
-        .loader_mut()
-        .fetch_async_background(request, action_sender);
 }

components/script/network_listener.rs

@@ -5,7 +5,8 @@
 use std::sync::{Arc, Mutex};
 
 use net_traits::{
-    Action, FetchResponseListener, FetchResponseMsg, ResourceFetchTiming, ResourceTimingType,
+    Action, BoxedFetchCallback, FetchResponseListener, FetchResponseMsg, ResourceFetchTiming,
+    ResourceTimingType,
 };
 use servo_url::ServoUrl;
 
@@ -89,6 +90,10 @@ impl<Listener: FetchResponseListener + PreInvoke + Send + 'static> NetworkListen
     pub fn notify_fetch(&self, action: FetchResponseMsg) {
         self.notify(action);
     }
+
+    pub fn to_callback(self) -> BoxedFetchCallback {
+        Box::new(move |response_msg| self.notify_fetch(response_msg))
+    }
 }
 
 /// A gating mechanism that runs before invoking the task on the target thread.

components/script/script_module.rs

@@ -15,8 +15,6 @@ use encoding_rs::UTF_8;
 use html5ever::local_name;
 use hyper_serde::Serde;
 use indexmap::IndexSet;
-use ipc_channel::ipc;
-use ipc_channel::router::ROUTER;
 use js::jsapi::{
     CompileModule1, ExceptionStackBehavior, FinishDynamicModuleImport, GetModuleRequestSpecifier,
     GetModuleResolveHook, GetRequestedModuleSpecifier, GetRequestedModulesCount,
@@ -36,11 +34,11 @@ use js::rust::{
 use mime::Mime;
 use net_traits::http_status::HttpStatus;
 use net_traits::request::{
-    CredentialsMode, Destination, ParserMetadata, Referrer, RequestBuilder, RequestMode,
+    CredentialsMode, Destination, ParserMetadata, Referrer, RequestBuilder, RequestId, RequestMode,
 };
 use net_traits::{
-    CoreResourceMsg, FetchChannels, FetchMetadata, FetchResponseListener, IpcSend, Metadata,
+    FetchMetadata, FetchResponseListener, Metadata, NetworkError, ReferrerPolicy,
-    NetworkError, ReferrerPolicy, ResourceFetchTiming, ResourceTimingType,
+    ResourceFetchTiming, ResourceTimingType,
 };
 use servo_url::ServoUrl;
 use url::ParseError as UrlParseError;
@@ -1046,11 +1044,13 @@ struct ModuleContext {
 }
 
 impl FetchResponseListener for ModuleContext {
-    fn process_request_body(&mut self) {} // TODO(cybai): Perhaps add custom steps to perform fetch here?
+    // TODO(cybai): Perhaps add custom steps to perform fetch here?
+    fn process_request_body(&mut self, _: RequestId) {}
 
-    fn process_request_eof(&mut self) {} // TODO(cybai): Perhaps add custom steps to perform fetch here?
+    // TODO(cybai): Perhaps add custom steps to perform fetch here?
+    fn process_request_eof(&mut self, _: RequestId) {}
 
-    fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>) {
+    fn process_response(&mut self, _: RequestId, metadata: Result<FetchMetadata, NetworkError>) {
         self.metadata = metadata.ok().map(|meta| match meta {
             FetchMetadata::Unfiltered(m) => m,
             FetchMetadata::Filtered { unsafe_, .. } => unsafe_,
@@ -1078,7 +1078,7 @@ impl FetchResponseListener for ModuleContext {
         };
     }
 
-    fn process_response_chunk(&mut self, mut chunk: Vec<u8>) {
+    fn process_response_chunk(&mut self, _: RequestId, mut chunk: Vec<u8>) {
         if self.status.is_ok() {
             self.data.append(&mut chunk);
         }
@@ -1087,7 +1087,11 @@ impl FetchResponseListener for ModuleContext {
     /// <https://html.spec.whatwg.org/multipage/#fetch-a-single-module-script>
     /// Step 9-12
     #[allow(unsafe_code)]
-    fn process_response_eof(&mut self, response: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
+        &mut self,
+        _: RequestId,
+        response: Result<ResourceFetchTiming, NetworkError>,
+    ) {
         let global = self.owner.global();
 
         if let Some(window) = global.downcast::<Window>() {
@@ -1669,35 +1673,24 @@ fn fetch_single_module_script(
         resource_timing: ResourceFetchTiming::new(ResourceTimingType::Resource),
     }));
 
-    let (action_sender, action_receiver) = ipc::channel().unwrap();
     let task_source = global.networking_task_source();
     let canceller = global.task_canceller(TaskSourceName::Networking);
 
-    let listener = NetworkListener {
+    let network_listener = NetworkListener {
         context,
         task_source,
         canceller: Some(canceller),
     };
-
-    ROUTER.add_route(
-        action_receiver.to_opaque(),
-        Box::new(move |message| {
-            listener.notify_fetch(message.to().unwrap());
-        }),
-    );
-
     match document {
-        Some(doc) => doc.fetch_async(LoadType::Script(url), request, action_sender),
+        Some(document) => {
-        None => {
+            let request = document.prepare_request(request);
-            global
+            document.loader_mut().fetch_async_with_callback(
-                .resource_threads()
+                LoadType::Script(url),
-                .sender()
-                .send(CoreResourceMsg::Fetch(
                 request,
-                    FetchChannels::ResponseMsg(action_sender, None),
+                network_listener.to_callback(),
-                ))
+            );
-                .unwrap();
         },
+        None => global.fetch_with_network_listener(request, network_listener, None),
     }
 }
 

components/script/script_thread.rs

@@ -65,7 +65,7 @@ use metrics::{PaintTimeMetrics, MAX_TASK_NS};
 use mime::{self, Mime};
 use net_traits::image_cache::{ImageCache, PendingImageResponse};
 use net_traits::request::{
-    CredentialsMode, Destination, RedirectMode, RequestBuilder, RequestMode,
+    CredentialsMode, Destination, RedirectMode, RequestBuilder, RequestId, RequestMode,
 };
 use net_traits::storage_thread::StorageType;
 use net_traits::{
@@ -2295,15 +2295,17 @@ impl ScriptThread {
             ConstellationControlMsg::StopDelayingLoadEventsMode(pipeline_id) => {
                 self.handle_stop_delaying_load_events_mode(pipeline_id)
             },
-            ConstellationControlMsg::NavigationResponse(id, fetch_data) => {
+            ConstellationControlMsg::NavigationResponse(pipeline_id, fetch_data) => {
                 match fetch_data {
-                    FetchResponseMsg::ProcessResponse(metadata) => {
+                    FetchResponseMsg::ProcessResponse(request_id, metadata) => {
-                        self.handle_fetch_metadata(id, metadata)
+                        self.handle_fetch_metadata(pipeline_id, request_id, metadata)
                     },
-                    FetchResponseMsg::ProcessResponseChunk(chunk) => {
+                    FetchResponseMsg::ProcessResponseChunk(request_id, chunk) => {
-                        self.handle_fetch_chunk(id, chunk)
+                        self.handle_fetch_chunk(pipeline_id, request_id, chunk)
+                    },
+                    FetchResponseMsg::ProcessResponseEOF(request_id, eof) => {
+                        self.handle_fetch_eof(pipeline_id, request_id, eof)
                     },
-                    FetchResponseMsg::ProcessResponseEOF(eof) => self.handle_fetch_eof(id, eof),
                     _ => unreachable!(),
                 };
             },
@@ -4106,6 +4108,7 @@ impl ScriptThread {
     fn handle_fetch_metadata(
         &self,
         id: PipelineId,
+        request_id: RequestId,
         fetch_metadata: Result<FetchMetadata, NetworkError>,
     ) {
         match fetch_metadata {
@@ -4121,21 +4124,26 @@ impl ScriptThread {
             .iter_mut()
             .find(|&&mut (pipeline_id, _)| pipeline_id == id);
         if let Some(&mut (_, ref mut ctxt)) = parser {
-            ctxt.process_response(fetch_metadata);
+            ctxt.process_response(request_id, fetch_metadata);
         }
     }
 
-    fn handle_fetch_chunk(&self, id: PipelineId, chunk: Vec<u8>) {
+    fn handle_fetch_chunk(&self, pipeline_id: PipelineId, request_id: RequestId, chunk: Vec<u8>) {
         let mut incomplete_parser_contexts = self.incomplete_parser_contexts.0.borrow_mut();
         let parser = incomplete_parser_contexts
             .iter_mut()
-            .find(|&&mut (pipeline_id, _)| pipeline_id == id);
+            .find(|&&mut (parser_pipeline_id, _)| parser_pipeline_id == pipeline_id);
         if let Some(&mut (_, ref mut ctxt)) = parser {
-            ctxt.process_response_chunk(chunk);
+            ctxt.process_response_chunk(request_id, chunk);
         }
     }
 
-    fn handle_fetch_eof(&self, id: PipelineId, eof: Result<ResourceFetchTiming, NetworkError>) {
+    fn handle_fetch_eof(
+        &self,
+        id: PipelineId,
+        request_id: RequestId,
+        eof: Result<ResourceFetchTiming, NetworkError>,
+    ) {
         let idx = self
             .incomplete_parser_contexts
             .0
@@ -4145,7 +4153,7 @@ impl ScriptThread {
 
         if let Some(idx) = idx {
             let (_, mut ctxt) = self.incomplete_parser_contexts.0.borrow_mut().remove(idx);
-            ctxt.process_response_eof(eof);
+            ctxt.process_response_eof(request_id, eof);
         }
     }
 
@@ -4177,9 +4185,13 @@ impl ScriptThread {
             None => vec![],
         };
 
-        context.process_response(Ok(FetchMetadata::Unfiltered(meta)));
+        let dummy_request_id = RequestId::new();
-        context.process_response_chunk(chunk);
+        context.process_response(dummy_request_id, Ok(FetchMetadata::Unfiltered(meta)));
-        context.process_response_eof(Ok(ResourceFetchTiming::new(ResourceTimingType::None)));
+        context.process_response_chunk(dummy_request_id, chunk);
+        context.process_response_eof(
+            dummy_request_id,
+            Ok(ResourceFetchTiming::new(ResourceTimingType::None)),
+        );
     }
 
     /// Synchronously parse a srcdoc document from a giving HTML string.
@@ -4197,9 +4209,13 @@ impl ScriptThread {
 
         let chunk = load_data.srcdoc.into_bytes();
 
-        context.process_response(Ok(FetchMetadata::Unfiltered(meta)));
+        let dummy_request_id = RequestId::new();
-        context.process_response_chunk(chunk);
+        context.process_response(dummy_request_id, Ok(FetchMetadata::Unfiltered(meta)));
-        context.process_response_eof(Ok(ResourceFetchTiming::new(ResourceTimingType::None)));
+        context.process_response_chunk(dummy_request_id, chunk);
+        context.process_response_eof(
+            dummy_request_id,
+            Ok(ResourceFetchTiming::new(ResourceTimingType::None)),
+        );
     }
 
     fn handle_css_error_reporting(

components/script/stylesheet_loader.rs

@@ -3,15 +3,12 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use std::sync::atomic::AtomicBool;
-use std::sync::Mutex;
 
 use base::id::PipelineId;
 use cssparser::SourceLocation;
 use encoding_rs::UTF_8;
-use ipc_channel::ipc;
-use ipc_channel::router::ROUTER;
 use mime::{self, Mime};
-use net_traits::request::{CorsSettings, Destination, Referrer, RequestBuilder};
+use net_traits::request::{CorsSettings, Destination, Referrer, RequestBuilder, RequestId};
 use net_traits::{
     FetchMetadata, FetchResponseListener, FilteredMetadata, Metadata, NetworkError, ReferrerPolicy,
     ResourceFetchTiming, ResourceTimingType,
@@ -43,7 +40,7 @@ use crate::dom::node::{containing_shadow_root, document_from_node, window_from_n
 use crate::dom::performanceresourcetiming::InitiatorType;
 use crate::dom::shadowroot::ShadowRoot;
 use crate::fetch::create_a_potential_cors_request;
-use crate::network_listener::{self, NetworkListener, PreInvoke, ResourceTimingListener};
+use crate::network_listener::{self, PreInvoke, ResourceTimingListener};
 use crate::script_runtime::CanGc;
 
 pub trait StylesheetOwner {
@@ -94,11 +91,11 @@ pub struct StylesheetContext {
 impl PreInvoke for StylesheetContext {}
 
 impl FetchResponseListener for StylesheetContext {
-    fn process_request_body(&mut self) {}
+    fn process_request_body(&mut self, _: RequestId) {}
 
-    fn process_request_eof(&mut self) {}
+    fn process_request_eof(&mut self, _: RequestId) {}
 
-    fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>) {
+    fn process_response(&mut self, _: RequestId, metadata: Result<FetchMetadata, NetworkError>) {
         if let Ok(FetchMetadata::Filtered {
             filtered: FilteredMetadata::Opaque | FilteredMetadata::OpaqueRedirect(_),
             ..
@@ -113,11 +110,15 @@ impl FetchResponseListener for StylesheetContext {
         });
     }
 
-    fn process_response_chunk(&mut self, mut payload: Vec<u8>) {
+    fn process_response_chunk(&mut self, _: RequestId, mut payload: Vec<u8>) {
         self.data.append(&mut payload);
     }
 
-    fn process_response_eof(&mut self, status: Result<ResourceFetchTiming, NetworkError>) {
+    fn process_response_eof(
+        &mut self,
+        _: RequestId,
+        status: Result<ResourceFetchTiming, NetworkError>,
+    ) {
         let elem = self.elem.root();
         let document = self.document.root();
         let mut successful = false;
@@ -279,7 +280,7 @@ impl<'a> StylesheetLoader<'a> {
             .elem
             .downcast::<HTMLLinkElement>()
             .map(HTMLLinkElement::get_request_generation_id);
-        let context = ::std::sync::Arc::new(Mutex::new(StylesheetContext {
+        let context = StylesheetContext {
             elem: Trusted::new(self.elem),
             source,
             url: url.clone(),
@@ -290,24 +291,7 @@ impl<'a> StylesheetLoader<'a> {
             origin_clean: true,
             request_generation_id: gen,
             resource_timing: ResourceFetchTiming::new(ResourceTimingType::Resource),
-        }));
-
-        let (action_sender, action_receiver) = ipc::channel().unwrap();
-        let (task_source, canceller) = document
-            .window()
-            .task_manager()
-            .networking_task_source_with_canceller();
-        let listener = NetworkListener {
-            context,
-            task_source,
-            canceller: Some(canceller),
         };
-        ROUTER.add_route(
-            action_receiver.to_opaque(),
-            Box::new(move |message| {
-                listener.notify_fetch(message.to().unwrap());
-            }),
-        );
 
         let owner = self
             .elem
@@ -331,8 +315,9 @@ impl<'a> StylesheetLoader<'a> {
             referrer_policy,
             integrity_metadata,
         );
+        let request = document.prepare_request(request);
 
-        document.fetch_async(LoadType::Stylesheet(url), request, action_sender);
+        document.fetch(LoadType::Stylesheet(url), request, context);
     }
 }
 

components/shared/net/Cargo.toml

@@ -17,6 +17,7 @@ doctest = false
 base = { workspace = true }
 content-security-policy = { workspace = true }
 cookie = { workspace = true }
+crossbeam-channel = { workspace = true }
 embedder_traits = { workspace = true }
 headers = { workspace = true }
 http = { workspace = true }

components/shared/net/lib.rs

@@ -4,12 +4,15 @@
 
 #![deny(unsafe_code)]
 
+use std::collections::HashMap;
 use std::fmt::Display;
-use std::sync::LazyLock;
+use std::sync::{LazyLock, OnceLock};
+use std::thread;
 
 use base::cross_process_instant::CrossProcessInstant;
 use base::id::HistoryStateId;
 use cookie::Cookie;
+use crossbeam_channel::{unbounded, Receiver, Sender};
 use headers::{ContentType, HeaderMapExt, ReferrerPolicy as ReferrerPolicyHeader};
 use http::{Error as HttpError, HeaderMap, StatusCode};
 use hyper::Error as HyperError;
@@ -20,6 +23,7 @@ use ipc_channel::Error as IpcError;
 use malloc_size_of::malloc_size_of_is_0;
 use malloc_size_of_derive::MallocSizeOf;
 use mime::Mime;
+use request::RequestId;
 use rustls::Certificate;
 use serde::{Deserialize, Serialize};
 use servo_rand::RngCore;
@@ -177,12 +181,24 @@ impl From<ReferrerPolicy> for ReferrerPolicyHeader {
 #[derive(Debug, Deserialize, Serialize)]
 pub enum FetchResponseMsg {
     // todo: should have fields for transmitted/total bytes
-    ProcessRequestBody,
+    ProcessRequestBody(RequestId),
-    ProcessRequestEOF,
+    ProcessRequestEOF(RequestId),
     // todo: send more info about the response (or perhaps the entire Response)
-    ProcessResponse(Result<FetchMetadata, NetworkError>),
+    ProcessResponse(RequestId, Result<FetchMetadata, NetworkError>),
-    ProcessResponseChunk(Vec<u8>),
+    ProcessResponseChunk(RequestId, Vec<u8>),
-    ProcessResponseEOF(Result<ResourceFetchTiming, NetworkError>),
+    ProcessResponseEOF(RequestId, Result<ResourceFetchTiming, NetworkError>),
+}
+
+impl FetchResponseMsg {
+    fn request_id(&self) -> RequestId {
+        match self {
+            FetchResponseMsg::ProcessRequestBody(id) |
+            FetchResponseMsg::ProcessRequestEOF(id) |
+            FetchResponseMsg::ProcessResponse(id, ..) |
+            FetchResponseMsg::ProcessResponseChunk(id, ..) |
+            FetchResponseMsg::ProcessResponseEOF(id, ..) => *id,
+        }
+    }
 }
 
 pub trait FetchTaskTarget {
@@ -199,15 +215,15 @@ pub trait FetchTaskTarget {
     /// <https://fetch.spec.whatwg.org/#process-response>
     ///
     /// Fired when headers are received
-    fn process_response(&mut self, response: &Response);
+    fn process_response(&mut self, request: &Request, response: &Response);
 
     /// Fired when a chunk of response content is received
-    fn process_response_chunk(&mut self, chunk: Vec<u8>);
+    fn process_response_chunk(&mut self, request: &Request, chunk: Vec<u8>);
 
     /// <https://fetch.spec.whatwg.org/#process-response-end-of-file>
     ///
     /// Fired when the response is fully fetched
-    fn process_response_eof(&mut self, response: &Response);
+    fn process_response_eof(&mut self, request: &Request, response: &Response);
 }
 
 #[derive(Clone, Debug, Deserialize, Serialize)]
@@ -228,43 +244,52 @@ pub enum FetchMetadata {
 }
 
 pub trait FetchResponseListener {
-    fn process_request_body(&mut self);
+    fn process_request_body(&mut self, request_id: RequestId);
-    fn process_request_eof(&mut self);
+    fn process_request_eof(&mut self, request_id: RequestId);
-    fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>);
+    fn process_response(
-    fn process_response_chunk(&mut self, chunk: Vec<u8>);
+        &mut self,
-    fn process_response_eof(&mut self, response: Result<ResourceFetchTiming, NetworkError>);
+        request_id: RequestId,
+        metadata: Result<FetchMetadata, NetworkError>,
+    );
+    fn process_response_chunk(&mut self, request_id: RequestId, chunk: Vec<u8>);
+    fn process_response_eof(
+        &mut self,
+        request_id: RequestId,
+        response: Result<ResourceFetchTiming, NetworkError>,
+    );
     fn resource_timing(&self) -> &ResourceFetchTiming;
     fn resource_timing_mut(&mut self) -> &mut ResourceFetchTiming;
     fn submit_resource_timing(&mut self);
 }
 
 impl FetchTaskTarget for IpcSender<FetchResponseMsg> {
-    fn process_request_body(&mut self, _: &Request) {
+    fn process_request_body(&mut self, request: &Request) {
-        let _ = self.send(FetchResponseMsg::ProcessRequestBody);
+        let _ = self.send(FetchResponseMsg::ProcessRequestBody(request.id));
     }
 
-    fn process_request_eof(&mut self, _: &Request) {
+    fn process_request_eof(&mut self, request: &Request) {
-        let _ = self.send(FetchResponseMsg::ProcessRequestEOF);
+        let _ = self.send(FetchResponseMsg::ProcessRequestEOF(request.id));
     }
 
-    fn process_response(&mut self, response: &Response) {
+    fn process_response(&mut self, request: &Request, response: &Response) {
-        let _ = self.send(FetchResponseMsg::ProcessResponse(response.metadata()));
+        let _ = self.send(FetchResponseMsg::ProcessResponse(
+            request.id,
+            response.metadata(),
+        ));
     }
 
-    fn process_response_chunk(&mut self, chunk: Vec<u8>) {
+    fn process_response_chunk(&mut self, request: &Request, chunk: Vec<u8>) {
-        let _ = self.send(FetchResponseMsg::ProcessResponseChunk(chunk));
+        let _ = self.send(FetchResponseMsg::ProcessResponseChunk(request.id, chunk));
     }
 
-    fn process_response_eof(&mut self, response: &Response) {
+    fn process_response_eof(&mut self, request: &Request, response: &Response) {
-        if let Some(e) = response.get_network_error() {
+        let payload = if let Some(network_error) = response.get_network_error() {
-            let _ = self.send(FetchResponseMsg::ProcessResponseEOF(Err(e.clone())));
+            Err(network_error.clone())
         } else {
-            let _ = self.send(FetchResponseMsg::ProcessResponseEOF(Ok(response
+            Ok(response.get_resource_timing().lock().unwrap().clone())
-                .get_resource_timing()
+        };
-                .lock()
+
-                .unwrap()
+        let _ = self.send(FetchResponseMsg::ProcessResponseEOF(request.id, payload));
-                .clone())));
-        }
     }
 }
 
@@ -275,14 +300,10 @@ pub struct DiscardFetch;
 
 impl FetchTaskTarget for DiscardFetch {
     fn process_request_body(&mut self, _: &Request) {}
-
     fn process_request_eof(&mut self, _: &Request) {}
-
+    fn process_response(&mut self, _: &Request, _: &Response) {}
-    fn process_response(&mut self, _: &Response) {}
+    fn process_response_chunk(&mut self, _: &Request, _: Vec<u8>) {}
-
+    fn process_response_eof(&mut self, _: &Request, _: &Response) {}
-    fn process_response_chunk(&mut self, _: Vec<u8>) {}
-
-    fn process_response_eof(&mut self, _: &Response) {}
 }
 
 pub trait Action<Listener> {
@@ -293,16 +314,25 @@ impl<T: FetchResponseListener> Action<T> for FetchResponseMsg {
     /// Execute the default action on a provided listener.
     fn process(self, listener: &mut T) {
         match self {
-            FetchResponseMsg::ProcessRequestBody => listener.process_request_body(),
+            FetchResponseMsg::ProcessRequestBody(request_id) => {
-            FetchResponseMsg::ProcessRequestEOF => listener.process_request_eof(),
+                listener.process_request_body(request_id)
-            FetchResponseMsg::ProcessResponse(meta) => listener.process_response(meta),
+            },
-            FetchResponseMsg::ProcessResponseChunk(data) => listener.process_response_chunk(data),
+            FetchResponseMsg::ProcessRequestEOF(request_id) => {
-            FetchResponseMsg::ProcessResponseEOF(data) => {
+                listener.process_request_eof(request_id)
+            },
+            FetchResponseMsg::ProcessResponse(request_id, meta) => {
+                listener.process_response(request_id, meta)
+            },
+            FetchResponseMsg::ProcessResponseChunk(request_id, data) => {
+                listener.process_response_chunk(request_id, data)
+            },
+            FetchResponseMsg::ProcessResponseEOF(request_id, data) => {
                 match data {
                     Ok(ref response_resource_timing) => {
                         // update listener with values from response
                         *listener.resource_timing_mut() = response_resource_timing.clone();
-                        listener.process_response_eof(Ok(response_resource_timing.clone()));
+                        listener
+                            .process_response_eof(request_id, Ok(response_resource_timing.clone()));
                         // TODO timing check https://w3c.github.io/resource-timing/#dfn-timing-allow-check
 
                         listener.submit_resource_timing();
@@ -311,7 +341,7 @@ impl<T: FetchResponseListener> Action<T> for FetchResponseMsg {
                     // (e.g. due to a network error) MAY be included as PerformanceResourceTiming
                     // objects in the Performance Timeline and MUST contain initialized attribute
                     // values for processed substeps of the processing model.
-                    Err(e) => listener.process_response_eof(Err(e)),
+                    Err(e) => listener.process_response_eof(request_id, Err(e)),
                 }
             },
         }
@@ -467,22 +497,110 @@ pub enum CoreResourceMsg {
     Exit(IpcSender<()>),
 }
 
-/// Instruct the resource thread to make a new request.
+enum ToFetchThreadMessage {
-pub fn fetch_async<F>(request: RequestBuilder, core_resource_thread: &CoreResourceThread, f: F)
+    StartFetch(
-where
+        /* request_builder */ RequestBuilder,
-    F: Fn(FetchResponseMsg) + Send + 'static,
+        /* cancel_chan */ Option<IpcReceiver<()>>,
-{
+        /* callback  */ BoxedFetchCallback,
-    let (action_sender, action_receiver) = ipc::channel().unwrap();
+    ),
+    FetchResponse(FetchResponseMsg),
+}
+
+pub type BoxedFetchCallback = Box<dyn Fn(FetchResponseMsg) + Send + 'static>;
+
+/// A thread to handle fetches in a Servo process. This thread is responsible for
+/// listening for new fetch requests as well as updates on those operations and forwarding
+/// them to crossbeam channels.
+struct FetchThread {
+    /// A list of active fetches. A fetch is no longer active once the
+    /// [`FetchResponseMsg::ProcessResponseEOF`] is received.
+    active_fetches: HashMap<RequestId, BoxedFetchCallback>,
+    /// A reference to the [`CoreResourceThread`] used to kick off fetch requests.
+    core_resource_thread: CoreResourceThread,
+    /// A crossbeam receiver attached to the router proxy which converts incoming fetch
+    /// updates from IPC messages to crossbeam messages as well as another sender which
+    /// handles requests from clients wanting to do fetches.
+    receiver: Receiver<ToFetchThreadMessage>,
+    /// An [`IpcSender`] that's sent with every fetch request and leads back to our
+    /// router proxy.
+    to_fetch_sender: IpcSender<FetchResponseMsg>,
+}
+
+impl FetchThread {
+    fn spawn(core_resource_thread: &CoreResourceThread) -> Sender<ToFetchThreadMessage> {
+        let (sender, receiver) = unbounded();
+        let (to_fetch_sender, from_fetch_sender) = ipc::channel().unwrap();
+
+        let sender_clone = sender.clone();
         ROUTER.add_route(
-        action_receiver.to_opaque(),
+            from_fetch_sender.to_opaque(),
-        Box::new(move |message| f(message.to().unwrap())),
+            Box::new(move |message| {
+                let message: FetchResponseMsg = message.to().unwrap();
+                let _ = sender_clone.send(ToFetchThreadMessage::FetchResponse(message));
+            }),
         );
-    core_resource_thread
+
+        let core_resource_thread = core_resource_thread.clone();
+        thread::Builder::new()
+            .name("FetchThread".to_owned())
+            .spawn(move || {
+                let mut fetch_thread = FetchThread {
+                    active_fetches: HashMap::new(),
+                    core_resource_thread,
+                    receiver,
+                    to_fetch_sender,
+                };
+                fetch_thread.run();
+            })
+            .expect("Thread spawning failed");
+        sender
+    }
+
+    fn run(&mut self) {
+        loop {
+            match self.receiver.recv().unwrap() {
+                ToFetchThreadMessage::StartFetch(request_builder, canceller, callback) => {
+                    self.active_fetches.insert(request_builder.id, callback);
+                    self.core_resource_thread
                         .send(CoreResourceMsg::Fetch(
-            request,
+                            request_builder,
-            FetchChannels::ResponseMsg(action_sender, None),
+                            FetchChannels::ResponseMsg(self.to_fetch_sender.clone(), canceller),
                         ))
                         .unwrap();
+                },
+                ToFetchThreadMessage::FetchResponse(fetch_response_msg) => {
+                    let request_id = fetch_response_msg.request_id();
+                    let fetch_finished =
+                        matches!(fetch_response_msg, FetchResponseMsg::ProcessResponseEOF(..));
+
+                    self.active_fetches
+                        .get(&request_id)
+                        .expect("Got fetch response for unknown fetch")(
+                        fetch_response_msg
+                    );
+
+                    if fetch_finished {
+                        self.active_fetches.remove(&request_id);
+                    }
+                },
+            }
+        }
+    }
+}
+
+/// Instruct the resource thread to make a new request.
+pub fn fetch_async(
+    core_resource_thread: &CoreResourceThread,
+    request: RequestBuilder,
+    canceller: Option<IpcReceiver<()>>,
+    callback: BoxedFetchCallback,
+) {
+    static FETCH_THREAD: OnceLock<Sender<ToFetchThreadMessage>> = OnceLock::new();
+    let _ = FETCH_THREAD
+        .get_or_init(|| FetchThread::spawn(core_resource_thread))
+        .send(ToFetchThreadMessage::StartFetch(
+            request, canceller, callback,
+        ));
 }
 
 #[derive(Clone, Debug, Deserialize, MallocSizeOf, Serialize)]

components/shared/net/request.rs

@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
+use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::{Arc, Mutex};
 
 use base::id::PipelineId;
@@ -17,6 +18,17 @@ use servo_url::{ImmutableOrigin, ServoUrl};
 use crate::response::HttpsState;
 use crate::{ReferrerPolicy, ResourceTimingType};
 
+#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, MallocSizeOf, PartialEq, Serialize)]
+/// An id to differeniate one network request from another.
+pub struct RequestId(usize);
+
+impl RequestId {
+    pub fn new() -> Self {
+        static NEXT_REQUEST_ID: AtomicUsize = AtomicUsize::new(0);
+        Self(NEXT_REQUEST_ID.fetch_add(1, Ordering::Relaxed))
+    }
+}
+
 /// An [initiator](https://fetch.spec.whatwg.org/#concept-request-initiator)
 #[derive(Clone, Copy, Debug, Deserialize, MallocSizeOf, PartialEq, Serialize)]
 pub enum Initiator {
@@ -223,6 +235,7 @@ impl RequestBody {
 
 #[derive(Clone, Debug, Deserialize, MallocSizeOf, Serialize)]
 pub struct RequestBuilder {
+    pub id: RequestId,
     #[serde(
         deserialize_with = "::hyper_serde::deserialize",
         serialize_with = "::hyper_serde::serialize"
@@ -272,6 +285,7 @@ pub struct RequestBuilder {
 impl RequestBuilder {
     pub fn new(url: ServoUrl, referrer: Referrer) -> RequestBuilder {
         RequestBuilder {
+            id: RequestId::new(),
             method: Method::GET,
             url,
             headers: HeaderMap::new(),
@@ -396,6 +410,11 @@ impl RequestBuilder {
         self
     }
 
+    pub fn csp_list(mut self, csp_list: Option<CspList>) -> RequestBuilder {
+        self.csp_list = csp_list;
+        self
+    }
+
     pub fn crash(mut self, crash: Option<String>) -> Self {
         self.crash = crash;
         self
@@ -403,6 +422,7 @@ impl RequestBuilder {
 
     pub fn build(self) -> Request {
         let mut request = Request::new(
+            self.id,
             self.url.clone(),
             Some(Origin::Origin(self.origin)),
             self.referrer,
@@ -443,6 +463,9 @@ impl RequestBuilder {
 /// the Fetch spec.
 #[derive(Clone, MallocSizeOf)]
 pub struct Request {
+    /// The id of this request so that the task that triggered it can route
+    /// messages to the correct listeners.
+    pub id: RequestId,
     /// <https://fetch.spec.whatwg.org/#concept-request-method>
     #[ignore_malloc_size_of = "Defined in hyper"]
     pub method: Method,
@@ -514,6 +537,7 @@ pub struct Request {
 
 impl Request {
     pub fn new(
+        id: RequestId,
         url: ServoUrl,
         origin: Option<Origin>,
         referrer: Referrer,
@@ -521,6 +545,7 @@ impl Request {
         https_state: HttpsState,
     ) -> Request {
         Request {
+            id,
             method: Method::GET,
             local_urls_only: false,
             sandboxed_storage_area_urls: false,