cc: Add mailbox support to ResourceProvider write locks.

cc/raster/gpu_raster_buffer_provider.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/raster/gpu_raster_buffer_provider.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/trace_event/trace_event.h"
 #include "cc/playback/raster_source.h"
-#include "cc/raster/gpu_rasterizer.h"
 #include "cc/raster/scoped_gpu_raster.h"
 #include "cc/resources/resource.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "third_party/skia/include/core/SkMultiPictureDraw.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
 #include "third_party/skia/include/core/SkSurface.h"
 #include "third_party/skia/include/gpu/GrContext.h"
 
 namespace cc {
 namespace {
 
 class RasterBufferImpl : public RasterBuffer {
  public:
-  RasterBufferImpl(GpuRasterizer* rasterizer,
-                   const Resource* resource,
-                   uint64_t resource_content_id,
-                   uint64_t previous_content_id)
-      : rasterizer_(rasterizer),
-        lock_(rasterizer->resource_provider(), resource->id()),
-        resource_has_previous_content_(
-            resource_content_id && resource_content_id == previous_content_id) {
-  }
+  RasterBufferImpl(GpuRasterBufferProvider* client,
+                   ResourceProvider* resource_provider,
+                   ResourceId resource_id,
+                   bool async_worker_context_enabled,
+                   bool resource_has_previous_content)
+      : client_(client),
+        lock_(resource_provider, resource_id, async_worker_context_enabled),
+        resource_has_previous_content_(resource_has_previous_content) {}
 
   // Overridden from RasterBuffer:
   void Playback(
       const RasterSource* raster_source,
       const gfx::Rect& raster_full_rect,
       const gfx::Rect& raster_dirty_rect,
       uint64_t new_content_id,
       float scale,
       const RasterSource::PlaybackSettings& playback_settings) override {
     TRACE_EVENT0("cc", "RasterBufferImpl::Playback");
-    // GPU raster doesn't do low res tiles, so should always include images.
-    DCHECK(!playback_settings.skip_images);
-
-    ContextProvider::ScopedContextLock scoped_context(
-        rasterizer_->worker_context_provider());
-
-    gfx::Rect playback_rect = raster_full_rect;
-    if (resource_has_previous_content_) {
-      playback_rect.Intersect(raster_dirty_rect);
-    }
-    DCHECK(!playback_rect.IsEmpty())
-        << "Why are we rastering a tile that's not dirty?";
-
-    // TODO(danakj): Implement partial raster with raster_dirty_rect.
-    // Rasterize source into resource.
-    rasterizer_->RasterizeSource(&lock_, raster_source, raster_full_rect,
-                                 playback_rect, scale, playback_settings);
-
-    gpu::gles2::GLES2Interface* gl = scoped_context.ContextGL();
-    const uint64_t fence_sync = gl->InsertFenceSyncCHROMIUM();
-
-    // Barrier to sync worker context output to cc context.
-    gl->OrderingBarrierCHROMIUM();
-
-    // Generate sync token after the barrier for cross context synchronization.
-    gpu::SyncToken sync_token;
-    gl->GenUnverifiedSyncTokenCHROMIUM(fence_sync, sync_token.GetData());
-    lock_.UpdateResourceSyncToken(sync_token);
+    client_->PlaybackOnWorkerThread(
+        &lock_, resource_has_previous_content_, raster_source, raster_full_rect,
+        raster_dirty_rect, new_content_id, scale, playback_settings);
   }
 
  private:
-  GpuRasterizer* rasterizer_;
-  ResourceProvider::ScopedWriteLockGr lock_;
+  GpuRasterBufferProvider* client_;
+  ResourceProvider::ScopedWriteLockGL lock_;
   bool resource_has_previous_content_;
 
   DISALLOW_COPY_AND_ASSIGN(RasterBufferImpl);
 };
 
+static sk_sp<SkPicture> PlaybackToPicture(
+    const RasterSource* raster_source,
+    bool resource_has_previous_content,
+    const gfx::Size& resource_size,
+    const gfx::Rect& raster_full_rect,
+    const gfx::Rect& raster_dirty_rect,
+    float scale,
+    const RasterSource::PlaybackSettings& playback_settings) {
+  // GPU raster doesn't do low res tiles, so should always include images.
+  DCHECK(!playback_settings.skip_images);
+
+  gfx::Rect playback_rect = raster_full_rect;
+  if (resource_has_previous_content) {
+    playback_rect.Intersect(raster_dirty_rect);
+  }
+  DCHECK(!playback_rect.IsEmpty())
+      << "Why are we rastering a tile that's not dirty?";
+
+  // Play back raster_source into temp SkPicture.
+  SkPictureRecorder recorder;
+  const int flags = SkPictureRecorder::kComputeSaveLayerInfo_RecordFlag;
+  sk_sp<SkCanvas> canvas = sk_ref_sp(recorder.beginRecording(
+      resource_size.width(), resource_size.height(), NULL, flags));
+  canvas->save();
+  raster_source->PlaybackToCanvas(canvas.get(), raster_full_rect, playback_rect,
+                                  scale, playback_settings);
+  canvas->restore();
+  return recorder.finishRecordingAsPicture();
+}
+
+static void RasterizePicture(SkPicture* picture,
+                             ContextProvider* context_provider,
+                             ResourceProvider::ScopedWriteLockGL* resource_lock,
+                             bool async_worker_context_enabled,
+                             bool use_distance_field_text,
+                             bool can_use_lcd_text,
+                             int msaa_sample_count) {
+  ScopedGpuRaster gpu_raster(context_provider);
+
+  ResourceProvider::ScopedSkSurfaceProvider scoped_surface(
+      context_provider, resource_lock, async_worker_context_enabled,
+      use_distance_field_text, can_use_lcd_text, msaa_sample_count);
+  SkSurface* sk_surface = scoped_surface.sk_surface();
+  // Allocating an SkSurface will fail after a lost context.  Pretend we
+  // rasterized, as the contents of the resource don't matter anymore.
+  if (!sk_surface)
+    return;
+
+  SkMultiPictureDraw multi_picture_draw;
+  multi_picture_draw.add(sk_surface->getCanvas(), picture);
+  multi_picture_draw.draw(false);
+}
+
 }  // namespace
 
 GpuRasterBufferProvider::GpuRasterBufferProvider(
     ContextProvider* compositor_context_provider,
     ContextProvider* worker_context_provider,
     ResourceProvider* resource_provider,
     bool use_distance_field_text,
-    int gpu_rasterization_msaa_sample_count)
+    int gpu_rasterization_msaa_sample_count,
+    bool async_worker_context_enabled)
     : compositor_context_provider_(compositor_context_provider),
-      rasterizer_(new GpuRasterizer(worker_context_provider,
-                                    resource_provider,
-                                    use_distance_field_text,
-                                    gpu_rasterization_msaa_sample_count)) {
-  DCHECK(compositor_context_provider_);
+      worker_context_provider_(worker_context_provider),
+      resource_provider_(resource_provider),
+      use_distance_field_text_(use_distance_field_text),
+      msaa_sample_count_(gpu_rasterization_msaa_sample_count),
+      async_worker_context_enabled_(async_worker_context_enabled) {
+  DCHECK(compositor_context_provider);
+  DCHECK(worker_context_provider);
 }
 
 GpuRasterBufferProvider::~GpuRasterBufferProvider() {}
 
 std::unique_ptr<RasterBuffer> GpuRasterBufferProvider::AcquireBufferForRaster(
     const Resource* resource,
     uint64_t resource_content_id,
     uint64_t previous_content_id) {
+  bool resource_has_previous_content =
+      resource_content_id && resource_content_id == previous_content_id;
   return std::unique_ptr<RasterBuffer>(new RasterBufferImpl(
-      rasterizer_.get(), resource, resource_content_id, previous_content_id));
+      this, resource_provider_, resource->id(), async_worker_context_enabled_,
+      resource_has_previous_content));
 }
 
 void GpuRasterBufferProvider::ReleaseBufferForRaster(
     std::unique_ptr<RasterBuffer> buffer) {
   // Nothing to do here. RasterBufferImpl destructor cleans up after itself.
 }
 
 void GpuRasterBufferProvider::OrderingBarrier() {
   TRACE_EVENT0("cc", "GpuRasterBufferProvider::OrderingBarrier");
-  compositor_context_provider_->ContextGL()->OrderingBarrierCHROMIUM();
+  gpu::gles2::GLES2Interface* gl = compositor_context_provider_->ContextGL();
+  // Synchronize with compositor.
+  GLuint64 fence = gl->InsertFenceSyncCHROMIUM();
+  gl->OrderingBarrierCHROMIUM();
+  gl->GenUnverifiedSyncTokenCHROMIUM(fence, sync_token_.GetData());
 }
 
 ResourceFormat GpuRasterBufferProvider::GetResourceFormat(
     bool must_support_alpha) const {
-  return rasterizer_->resource_provider()->best_render_buffer_format();
+  return resource_provider_->best_render_buffer_format();
 }
 
 bool GpuRasterBufferProvider::GetResourceRequiresSwizzle(
     bool must_support_alpha) const {
   // This doesn't require a swizzle because we rasterize to the correct format.
   return false;
 }
 
 void GpuRasterBufferProvider::Shutdown() {}
 
+void GpuRasterBufferProvider::PlaybackOnWorkerThread(
+    ResourceProvider::ScopedWriteLockGL* resource_lock,
+    bool resource_has_previous_content,
+    const RasterSource* raster_source,
+    const gfx::Rect& raster_full_rect,
+    const gfx::Rect& raster_dirty_rect,
+    uint64_t new_content_id,
+    float scale,
+    const RasterSource::PlaybackSettings& playback_settings) {
+  ContextProvider::ScopedContextLock scoped_context(worker_context_provider_);
+  gpu::gles2::GLES2Interface* gl = scoped_context.ContextGL();
+
+  // Synchronize with compositor if worker context is async.
+  DCHECK(sync_token_.HasData());

[piman, 2016/05/26 00:01:10]

If I understand correctly, OrderingBarrier() is called on the compositor thread,
and this is read on a worker thread. What ensures there is no data race on
sync_token_? Is OrderingBarrier() only ever called when there is no raster task
active (that's not obvious to me).

[sunnyps, 2016/05/26 01:39:27]

You're right. I overlooked the data race here. We never block the compositor
thread on the worker thread (except shutdown I think).

As per the offline discussion I've implemented indirection for accessing the
sync token - see SyncTokenProvider. I'm not very fond of this so I'll look at
GenSyncToken and see if we can remove the OrderingBarrier requirement there and
move the check to WaitSyncToken.

+  gl->WaitSyncTokenCHROMIUM(sync_token_.GetData());
+
+  sk_sp<SkPicture> picture = PlaybackToPicture(
+      raster_source, resource_has_previous_content, resource_lock->size(),
+      raster_full_rect, raster_dirty_rect, scale, playback_settings);
+
+  // Turn on distance fields for layers that have ever animated.
+  bool use_distance_field_text =
+      use_distance_field_text_ ||
+      raster_source->ShouldAttemptToUseDistanceFieldText();
+
+  RasterizePicture(picture.get(), worker_context_provider_, resource_lock,
+                   async_worker_context_enabled_, use_distance_field_text,
+                   raster_source->CanUseLCDText(), msaa_sample_count_);
+
+  const uint64_t fence_sync = gl->InsertFenceSyncCHROMIUM();
+
+  // Barrier to sync worker context output to cc context.
+  gl->OrderingBarrierCHROMIUM();
+
+  // Generate sync token after the barrier for cross context synchronization.
+  gpu::SyncToken sync_token;
+  gl->GenUnverifiedSyncTokenCHROMIUM(fence_sync, sync_token.GetData());
+  resource_lock->set_sync_token(sync_token);
+}
+
 }  // namespace cc