Synchronously requests current epoch.

Signed-off-by: Shubham Gupta <shubham.gupta@chromium.org>

Author: shubhamg13

example-compositor/compositor/src/main.rs

@@ -498,7 +498,7 @@ fn main() {
             // as required.
             renderer.update();
             renderer.render(device_size, 0).unwrap();
-            let _ = renderer.flush_pipeline_info();
+            let _ = api.flush_pipeline_info();
 
             // Construct a simple display list that can be drawn and composited by DC.
             let mut txn = Transaction::new();

examples/common/boilerplate.rs

@@ -312,7 +312,7 @@ pub fn main_wrapper<E: Example>(
 
         renderer.update();
         renderer.render(device_size, 0).unwrap();
-        let _ = renderer.flush_pipeline_info();
+        let _ = api.flush_pipeline_info();
         example.draw_custom(&*gl);
         windowed_context.swap_buffers().ok();
 

webrender/src/internal_types.rs

@@ -9,7 +9,7 @@ use api::units::*;
 use crate::render_api::DebugCommand;
 use crate::composite::NativeSurfaceOperation;
 use crate::device::TextureFilter;
-use crate::renderer::{FullFrameStats, PipelineInfo};
+use crate::renderer::FullFrameStats;
 use crate::gpu_cache::GpuCacheUpdateList;
 use crate::gpu_types::BlurEdgeMode;
 use crate::frame_builder::Frame;
@@ -1366,7 +1366,6 @@ pub enum ResultMsg {
         resource_updates: ResourceUpdateList,
         memory_pressure: bool,
     },
-    PublishPipelineInfo(PipelineInfo),
     PublishDocument(
         FramePublishId,
         DocumentId,

webrender/src/render_api.rs

@@ -25,6 +25,7 @@ use crate::api::DEFAULT_TILE_SIZE;
 use crate::api::units::*;
 use crate::api_resources::ApiResources;
 use glyph_rasterizer::SharedFontResources;
+use crate::renderer::PipelineInfo;
 use crate::scene_builder_thread::{SceneBuilderRequest, SceneBuilderResult};
 use crate::intern::InterningMemoryReport;
 use crate::profiler::{self, TransactionProfile};
@@ -1010,6 +1011,8 @@ pub enum ApiMsg {
     DebugCommand(DebugCommand),
     /// Message from the scene builder thread.
     SceneBuilderResult(SceneBuilderResult),
+    /// Request pipeline infos.
+    RequestPipelineInfo(Sender<PipelineInfo>),
 }
 
 impl fmt::Debug for ApiMsg {
@@ -1023,6 +1026,7 @@ impl fmt::Debug for ApiMsg {
             ApiMsg::ReportMemory(..) => "ApiMsg::ReportMemory",
             ApiMsg::DebugCommand(..) => "ApiMsg::DebugCommand",
             ApiMsg::SceneBuilderResult(..) => "ApiMsg::SceneBuilderResult",
+            ApiMsg::RequestPipelineInfo(..) => "ApiMsg::RequestPipelineInfo",
         })
     }
 }
@@ -1454,6 +1458,20 @@ impl RenderApi {
             SceneBuilderRequest::SetParameter(parameter)
         );
     }
+
+    /// Flush and return the current PipelineInfo.
+    pub fn flush_pipeline_info(&self) -> PipelineInfo {
+        let (tx, rx) = single_msg_channel();
+        self.scene_sender.send(SceneBuilderRequest::FlushPipelineInfo(tx)).unwrap();
+        rx.recv().unwrap()
+    }
+
+    /// Returns the Epoch of the current frame in a pipeline.
+    pub fn current_epoch(&self, document_id: DocumentId, pipeline_id: PipelineId) -> Option<Epoch> {
+        let (tx, rx) = single_msg_channel();
+        self.scene_sender.send(SceneBuilderRequest::CurrentEpoch(document_id, pipeline_id, tx)).unwrap();
+        rx.recv().unwrap()
+    }
 }
 
 impl Drop for RenderApi {

webrender/src/render_backend.rs

@@ -10,7 +10,7 @@
 
 use api::{DebugFlags, Parameter, BoolParameter, PrimitiveFlags, MinimapData};
 use api::{DocumentId, ExternalScrollId, HitTestResult};
-use api::{IdNamespace, PipelineId, RenderNotifier, SampledScrollOffset};
+use api::{IdNamespace, RenderNotifier, SampledScrollOffset};
 use api::{NotificationRequest, Checkpoint, QualitySettings};
 use api::{FramePublishId, PrimitiveKeyKind, RenderReasons};
 use api::units::*;
@@ -44,7 +44,7 @@ use crate::prim_store::{PrimitiveInstanceKind, PrimTemplateCommonData};
 use crate::prim_store::interned::*;
 use crate::profiler::{self, TransactionProfile};
 use crate::render_task_graph::RenderTaskGraphBuilder;
-use crate::renderer::{FullFrameStats, PipelineInfo};
+use crate::renderer::{FullFrameStats};
 use crate::resource_cache::ResourceCache;
 #[cfg(feature = "replay")]
 use crate::resource_cache::PlainCacheOwn;
@@ -330,13 +330,10 @@ impl ScratchBuffer {
 }
 
 struct Document {
+    #[allow(dead_code)]
     /// The id of this document
     id: DocumentId,
 
-    /// Temporary list of removed pipelines received from the scene builder
-    /// thread and forwarded to the renderer.
-    removed_pipelines: Vec<(PipelineId, DocumentId)>,
-
     view: DocumentView,
 
     /// The id and time of the current frame.
@@ -405,7 +402,6 @@ impl Document {
     ) -> Self {
         Document {
             id,
-            removed_pipelines: Vec::new(),
             view: DocumentView {
                 scene: SceneView {
                     device_rect: size.into(),
@@ -650,15 +646,6 @@ impl Document {
         self.hit_tester_is_valid = true;
     }
 
-    pub fn updated_pipeline_info(&mut self) -> PipelineInfo {
-        let removed_pipelines = self.removed_pipelines.take_and_preallocate();
-        PipelineInfo {
-            epochs: self.scene.pipeline_epochs.iter()
-                .map(|(&pipeline_id, &epoch)| ((pipeline_id, self.id), epoch)).collect(),
-            removed_pipelines,
-        }
-    }
-
     /// Returns true if the node actually changed position or false otherwise.
     pub fn set_scroll_offsets(
         &mut self,
@@ -939,7 +926,6 @@ impl RenderBackend {
            let has_built_scene = txn.built_scene.is_some();
 
             if let Some(doc) = self.documents.get_mut(&txn.document_id) {
-                doc.removed_pipelines.append(&mut txn.removed_pipelines);
                 doc.view.scene = txn.view;
                 doc.profile.merge(&mut txn.profile);
 
@@ -1308,6 +1294,9 @@ impl RenderBackend {
             ApiMsg::SceneBuilderResult(msg) => {
                 return self.process_scene_builder_result(msg, frame_counter);
             }
+            ApiMsg::RequestPipelineInfo(tx) => {
+                self.send_backend_message(SceneBuilderRequest::RequestPipelineInfo(tx));
+            }
         }
 
         // Now that we are likely out of the critical path, purge a few chunks
@@ -1698,9 +1687,6 @@ impl RenderBackend {
             let update_doc_time = profiler::ns_to_ms(zeitstempel::now() - update_doc_start);
             rendered_document.profile.set(profiler::UPDATE_DOCUMENT_TIME, update_doc_time);
 
-            let msg = ResultMsg::PublishPipelineInfo(doc.updated_pipeline_info());
-            self.result_tx.send(msg).unwrap();
-
             // Publish the frame
             self.frame_publish_id.advance();
             let msg = ResultMsg::PublishDocument(
@@ -1710,13 +1696,6 @@ impl RenderBackend {
                 pending_update,
             );
             self.result_tx.send(msg).unwrap();
-        } else if requested_frame {
-            // WR-internal optimization to avoid doing a bunch of render work if
-            // there's no pixels. We still want to pretend to render and request
-            // a render to make sure that the callbacks (particularly the
-            // new_frame_ready callback below) has the right flags.
-            let msg = ResultMsg::PublishPipelineInfo(doc.updated_pipeline_info());
-            self.result_tx.send(msg).unwrap();
         }
 
         drain_filter(

webrender/src/renderer/init.rs

@@ -802,7 +802,6 @@ pub fn create_webrender_instance(
         vaos,
         vertex_data_textures,
         current_vertex_data_textures: 0,
-        pipeline_info: PipelineInfo::default(),
         dither_matrix_texture,
         external_image_handler: None,
         size_of_ops: make_size_of_ops(),

webrender/src/renderer/mod.rs

@@ -44,7 +44,7 @@ use api::{PipelineId, ImageRendering, Checkpoint, NotificationRequest, ImageBuff
 use api::ExternalImage;
 use api::FramePublishId;
 use api::units::*;
-use api::channel::{Sender, Receiver};
+use api::channel::{Sender, single_msg_channel, Receiver};
 pub use api::DebugFlags;
 use core::time::Duration;
 
@@ -867,8 +867,6 @@ pub struct Renderer {
     gpu_cache_frame_id: FrameId,
     gpu_cache_overflow: bool,
 
-    pipeline_info: PipelineInfo,
-
     // Manages and resolves source textures IDs to real texture IDs.
     texture_resolver: TextureResolver,
 
@@ -1017,15 +1015,6 @@ impl Renderer {
         self.clear_color = color;
     }
 
-    pub fn flush_pipeline_info(&mut self) -> PipelineInfo {
-        mem::replace(&mut self.pipeline_info, PipelineInfo::default())
-    }
-
-    /// Returns the Epoch of the current frame in a pipeline.
-    pub fn current_epoch(&self, document_id: DocumentId, pipeline_id: PipelineId) -> Option<Epoch> {
-        self.pipeline_info.epochs.get(&(pipeline_id, document_id)).cloned()
-    }
-
     fn get_next_result_msg(&mut self) -> Option<ResultMsg> {
         if self.pending_result_msg.is_none() {
             if let Ok(msg) = self.result_rx.try_recv() {
@@ -1054,12 +1043,6 @@ impl Renderer {
         // Pull any pending results and return the most recent.
         while let Some(msg) = self.get_next_result_msg() {
             match msg {
-                ResultMsg::PublishPipelineInfo(mut pipeline_info) => {
-                    for ((pipeline_id, document_id), epoch) in pipeline_info.epochs {
-                        self.pipeline_info.epochs.insert((pipeline_id, document_id), epoch);
-                    }
-                    self.pipeline_info.removed_pipelines.extend(pipeline_info.removed_pipelines.drain(..));
-                }
                 ResultMsg::PublishDocument(
                     _,
                     document_id,
@@ -5894,7 +5877,12 @@ impl Renderer {
         let y0: f32 = 30.0;
         let mut y = y0;
         let mut text_width = 0.0;
-        for ((pipeline, document_id), epoch) in  &self.pipeline_info.epochs {
+
+        let (tx, rx) = single_msg_channel();
+        self.api_tx.send(ApiMsg::RequestPipelineInfo(tx)).unwrap();
+        let pipeline_info = rx.recv().unwrap();
+
+        for ((pipeline, document_id), epoch) in  pipeline_info.epochs {
             y += dy;
             let w = debug_renderer.add_text(
                 x0, y,
@@ -6270,10 +6258,10 @@ impl ExternalImageHandler for DummyExternalImageHandler {
     fn unlock(&mut self, _key: ExternalImageId, _channel_index: u8) {}
 }
 
-#[derive(Default)]
+#[derive(Clone, Default)]
 pub struct PipelineInfo {
     pub epochs: FastHashMap<(PipelineId, DocumentId), Epoch>,
-    pub removed_pipelines: Vec<(PipelineId, DocumentId)>,
+    pub removed_pipelines: FastHashSet<(PipelineId, DocumentId)>,
 }
 
 impl Renderer {