Auto merge of servo#28739 - wusyong:ipc-bytes, r=jdm

Send webrender message's data through IPCBytesChannel

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---
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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #servo#28738 (GitHub issue number if applicable)

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- [x] There are tests for these changes OR
- [ ] These changes do not require tests because ___

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For display list data, I tested with https://svelte.dev/docs in release build. I seems to have 20~30% improvement on `Display List Construction` when I profiling.

For image data, I tested with http://slither.io/ (on the page for you to customize snek). It seems identical and I'm not sure where should I look at when profiling.

Author: bors-servo

components/compositing/compositor.rs

@@ -626,25 +626,28 @@ impl<Window: WindowMethods + ?Sized> IOCompositor<Window> {
                 size,
                 pipeline,
                 size2,
-                data,
+                receiver,
                 descriptor,
-            )) => {
-                self.waiting_on_pending_frame = true;
-                let mut txn = webrender_api::Transaction::new();
-                txn.set_display_list(
-                    epoch,
-                    None,
-                    size,
-                    (
-                        pipeline,
-                        size2,
-                        webrender_api::BuiltDisplayList::from_data(data, descriptor),
-                    ),
-                    true,
-                );
-                txn.generate_frame();
-                self.webrender_api
-                    .send_transaction(self.webrender_document, txn);
+            )) => match receiver.recv() {
+                Ok(data) => {
+                    self.waiting_on_pending_frame = true;
+                    let mut txn = webrender_api::Transaction::new();
+                    txn.set_display_list(
+                        epoch,
+                        None,
+                        size,
+                        (
+                            pipeline,
+                            size2,
+                            webrender_api::BuiltDisplayList::from_data(data, descriptor),
+                        ),
+                        true,
+                    );
+                    txn.generate_frame();
+                    self.webrender_api
+                        .send_transaction(self.webrender_document, txn);
+                },
+                Err(e) => warn!("error receiving display data: {:?}", e),
             },
 
             WebrenderMsg::Layout(script_traits::WebrenderMsg::HitTest(
@@ -668,12 +671,25 @@ impl<Window: WindowMethods + ?Sized> IOCompositor<Window> {
                 let mut txn = webrender_api::Transaction::new();
                 for update in updates {
                     match update {
-                        script_traits::ImageUpdate::AddImage(key, desc, data) => {
-                            txn.add_image(key, desc, data, None)
+                        script_traits::SerializedImageUpdate::AddImage(key, desc, data) => {
+                            match data.to_image_data() {
+                                Ok(data) => txn.add_image(key, desc, data, None),
+                                Err(e) => warn!("error when sending image data: {:?}", e),
+                            }
+                        },
+                        script_traits::SerializedImageUpdate::DeleteImage(key) => {
+                            txn.delete_image(key)
                         },
-                        script_traits::ImageUpdate::DeleteImage(key) => txn.delete_image(key),
-                        script_traits::ImageUpdate::UpdateImage(key, desc, data) => {
-                            txn.update_image(key, desc, data, &webrender_api::DirtyRect::All)
+                        script_traits::SerializedImageUpdate::UpdateImage(key, desc, data) => {
+                            match data.to_image_data() {
+                                Ok(data) => txn.update_image(
+                                    key,
+                                    desc,
+                                    data,
+                                    &webrender_api::DirtyRect::All,
+                                ),
+                                Err(e) => warn!("error when sending image data: {:?}", e),
+                            }
                         },
                     }
                 }

components/script_traits/lib.rs

@@ -71,8 +71,8 @@ use webrender_api::units::{
     DeviceIntSize, DevicePixel, LayoutPixel, LayoutPoint, LayoutSize, WorldPoint,
 };
 use webrender_api::{
-    BuiltDisplayList, DocumentId, ExternalScrollId, ImageData, ImageDescriptor, ImageKey,
-    ScrollClamping,
+    BuiltDisplayList, DocumentId, ExternalImageData, ExternalScrollId, ImageData, ImageDescriptor,
+    ImageKey, ScrollClamping,
 };
 use webrender_api::{BuiltDisplayListDescriptor, HitTestFlags, HitTestResult};
 
@@ -1123,7 +1123,7 @@ pub enum WebrenderMsg {
         LayoutSize,
         webrender_api::PipelineId,
         LayoutSize,
-        Vec<u8>,
+        ipc::IpcBytesReceiver,
         BuiltDisplayListDescriptor,
     ),
     /// Perform a hit test operation. The result will be returned via
@@ -1138,7 +1138,7 @@ pub enum WebrenderMsg {
     /// provided channel sender.
     GenerateImageKey(IpcSender<ImageKey>),
     /// Perform a resource update operation.
-    UpdateImages(Vec<ImageUpdate>),
+    UpdateImages(Vec<SerializedImageUpdate>),
 }
 
 #[derive(Clone, Deserialize, Serialize)]
@@ -1181,16 +1181,21 @@ impl WebrenderIpcSender {
         (pipeline, size2, list): (webrender_api::PipelineId, LayoutSize, BuiltDisplayList),
     ) {
         let (data, descriptor) = list.into_data();
+        let (sender, receiver) = ipc::bytes_channel().unwrap();
         if let Err(e) = self.0.send(WebrenderMsg::SendDisplayList(
             webrender_api::Epoch(epoch.0),
             size,
             pipeline,
             size2,
-            data,
+            receiver,
             descriptor,
         )) {
             warn!("Error sending display list: {}", e);
         }
+
+        if let Err(e) = sender.send(&data) {
+            warn!("Error sending display data: {}", e);
+        }
     }
 
     /// Perform a hit test operation. Blocks until the operation is complete and
@@ -1219,9 +1224,48 @@ impl WebrenderIpcSender {
 
     /// Perform a resource update operation.
     pub fn update_images(&self, updates: Vec<ImageUpdate>) {
+        let mut senders = Vec::new();
+        // Convert `ImageUpdate` to `SerializedImageUpdate` because `ImageData` may contain large
+        // byes. With this conversion, we send `IpcBytesReceiver` instead and use it to send the
+        // actual bytes.
+        let updates = updates
+            .into_iter()
+            .map(|update| match update {
+                ImageUpdate::AddImage(k, d, data) => {
+                    let data = match data {
+                        ImageData::Raw(r) => {
+                            let (sender, receiver) = ipc::bytes_channel().unwrap();
+                            senders.push((sender, r));
+                            SerializedImageData::Raw(receiver)
+                        },
+                        ImageData::External(e) => SerializedImageData::External(e),
+                    };
+                    SerializedImageUpdate::AddImage(k, d, data)
+                },
+                ImageUpdate::DeleteImage(k) => SerializedImageUpdate::DeleteImage(k),
+                ImageUpdate::UpdateImage(k, d, data) => {
+                    let data = match data {
+                        ImageData::Raw(r) => {
+                            let (sender, receiver) = ipc::bytes_channel().unwrap();
+                            senders.push((sender, r));
+                            SerializedImageData::Raw(receiver)
+                        },
+                        ImageData::External(e) => SerializedImageData::External(e),
+                    };
+                    SerializedImageUpdate::UpdateImage(k, d, data)
+                },
+            })
+            .collect();
+
         if let Err(e) = self.0.send(WebrenderMsg::UpdateImages(updates)) {
             warn!("error sending image updates: {}", e);
         }
+
+        senders.into_iter().for_each(|(tx, data)| {
+            if let Err(e) = tx.send(&*data) {
+                warn!("error sending image data: {}", e);
+            }
+        });
     }
 }
 
@@ -1235,3 +1279,36 @@ pub enum ImageUpdate {
     /// Update an existing image registration.
     UpdateImage(ImageKey, ImageDescriptor, ImageData),
 }
+
+#[derive(Deserialize, Serialize)]
+/// Serialized `ImageUpdate`.
+pub enum SerializedImageUpdate {
+    /// Register a new image.
+    AddImage(ImageKey, ImageDescriptor, SerializedImageData),
+    /// Delete a previously registered image registration.
+    DeleteImage(ImageKey),
+    /// Update an existing image registration.
+    UpdateImage(ImageKey, ImageDescriptor, SerializedImageData),
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+/// Serialized `ImageData`. It contains IPC byte channel receiver to prevent from loading bytes too
+/// slow.
+pub enum SerializedImageData {
+    /// A simple series of bytes, provided by the embedding and owned by WebRender.
+    /// The format is stored out-of-band, currently in ImageDescriptor.
+    Raw(ipc::IpcBytesReceiver),
+    /// An image owned by the embedding, and referenced by WebRender. This may
+    /// take the form of a texture or a heap-allocated buffer.
+    External(ExternalImageData),
+}
+
+impl SerializedImageData {
+    /// Convert to ``ImageData`.
+    pub fn to_image_data(&self) -> Result<ImageData, ipc::IpcError> {
+        match self {
+            SerializedImageData::Raw(rx) => rx.recv().map(|data| ImageData::new(data)),
+            SerializedImageData::External(image) => Ok(ImageData::External(image.clone())),
+        }
+    }
+}