cc: Optimize decode scheduling for checker-images.

cc/tiles/tile_manager.cc

 // Copyright 2012 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/tiles/tile_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 407 matching lines @@
 
   use_gpu_rasterization_ = use_gpu_rasterization;
   scheduled_raster_task_limit_ = scheduled_raster_task_limit;
   resource_pool_ = resource_pool;
   image_controller_.SetImageDecodeCache(image_decode_cache);
   tile_task_manager_ = TileTaskManagerImpl::Create(task_graph_runner);
   raster_buffer_provider_ = raster_buffer_provider;
 }
 
 void TileManager::Release(Tile* tile) {
+  if (tile->raster_task_scheduled_with_checker_images())
+    num_of_tiles_with_checker_images_--;
+  DCHECK_GE(num_of_tiles_with_checker_images_, 0);
+
   FreeResourcesForTile(tile);
   tiles_.erase(tile->id());
 }
 
 void TileManager::DidFinishRunningTileTasksRequiredForActivation() {
   TRACE_EVENT0("cc",
                "TileManager::DidFinishRunningTileTasksRequiredForActivation");
   TRACE_EVENT_ASYNC_STEP_INTO1("cc", "ScheduledTasks", this, "running", "state",
                                ScheduledTasksStateAsValue());
   // TODO(vmpstr): Temporary check to debug crbug.com/642927.
@@ skipping 241 matching lines @@
       }
     }
 
     // Prepaint tiles that are far away are only processed for images.
     if (!tile->required_for_activation() && !tile->required_for_draw() &&
         prioritized_tile.is_process_for_images_only()) {
       work_to_schedule.tiles_to_process_for_images.push_back(prioritized_tile);
       continue;
     }
 
+    // Tiles in the raster queue should either require raster or decode for
+    // checker-images. If this tile does not need raster, process it only to
+    // build the decode queue for checkered images.
+    // Note that performing this check after the solid color analysis is not
+    // necessary for correctness.
+    if (!tile->draw_info().NeedsRaster()) {
+      DCHECK(tile->draw_info().is_checker_imaged());
+      DCHECK(prioritized_tile.should_decode_checkered_images_for_tile());
+
+      AddCheckeredImagesToDecodeQueue(
+          prioritized_tile, raster_color_space,
+          &work_to_schedule.checker_image_decode_queue);
+      continue;
+    }
+
     // We won't be able to schedule this tile, so break out early.
     if (work_to_schedule.tiles_to_raster.size() >=
         scheduled_raster_task_limit_) {
       all_tiles_that_need_to_be_rasterized_are_scheduled_ = false;
       break;
     }
 
     tile->scheduled_priority_ = schedule_priority++;
 
     DCHECK(tile->draw_info().mode() == TileDrawInfo::OOM_MODE ||
@@ skipping 25 matching lines @@
 
     // If we couldn't fit the tile into our current memory limit, then we're
     // done.
     if (!memory_usage_is_within_limit) {
       if (tile_is_needed_now)
         had_enough_memory_to_schedule_tiles_needed_now = false;
       all_tiles_that_need_to_be_rasterized_are_scheduled_ = false;
       break;
     }
 
-    // If we were able to assign memory to this tile, create a raster task if
-    // necessary.
-    if (!tile->raster_task_) {
+    // If the tile has a scheduled task that will rasterize a resource with
+    // checker-imaged content, add those images to the decode queue. Note that
+    // we add all images as we process the raster priority queue to ensure that
+    // images are added to the decode queue in raster priority order.
+    if (tile->HasRasterTask()) {
+      if (tile->raster_task_scheduled_with_checker_images() &&
+          prioritized_tile.should_decode_checkered_images_for_tile()) {
+        AddCheckeredImagesToDecodeQueue(
+            prioritized_tile, raster_color_space,
+            &work_to_schedule.checker_image_decode_queue);
+      }
+    } else {
+      // Creating the raster task here will acquire resources, but
+      // this resource usage has already been accounted for above.
       tile->raster_task_ =
-          CreateRasterTask(prioritized_tile, raster_color_space);
+          CreateRasterTask(prioritized_tile, client_->GetRasterColorSpace(),
+                           &work_to_schedule.checker_image_decode_queue);
     }
 
     memory_usage += memory_required_by_tile_to_be_scheduled;
     work_to_schedule.tiles_to_raster.push_back(prioritized_tile);
   }
 
   // Note that we should try and further reduce memory in case the above loop
   // didn't reduce memory. This ensures that we always release as many resources
   // as possible to stay within the memory limit.
   eviction_priority_queue = FreeTileResourcesUntilUsageIsWithinLimit(
       std::move(eviction_priority_queue), hard_memory_limit, &memory_usage);
 
+  // At this point, if we ran out of memory when allocating resources and we
+  // couldn't go past even the NOW bin, this means we have evicted resources
+  // from all tiles with a lower priority while we still might have resources
+  // holding checker-imaged content. The invalidations for these resources will
+  // be generated only if the skipped images are decoded. So we must schedule
+  // decodes for these tiles to update their content.
+  if (!had_enough_memory_to_schedule_tiles_needed_now &&
+      num_of_tiles_with_checker_images_ > 0) {
+    for (; !raster_priority_queue->IsEmpty(); raster_priority_queue->Pop()) {
+      const PrioritizedTile& prioritized_tile = raster_priority_queue->Top();
+
+      if (prioritized_tile.priority().priority_bin > TilePriority::NOW)
+        break;
+
+      if (!prioritized_tile.should_decode_checkered_images_for_tile())
+        continue;
+
+      Tile* tile = prioritized_tile.tile();
+      if (tile->draw_info().is_checker_imaged() ||

[vmpstr, 2017/04/20 20:59:33]

Is this going to be false for tiles that don't have a resource at all?

A common case for when we'll hit this is if the memory policy is ALLOW_NOTHING
in which case the memory budget is exactly 0 (and we'll evict everything that we
can). In that case, I don't think we want to decode stuff, do we? You should be
able to trigger this behavior by making a tab hidden. 



As a random thought, I think this performs ok with partial raster as well right?
Like what happens if we have a checkered resource in the resource pool and
something gets invalidated. we'll grab that resource. I think it's ok, since
either that tile still needs to be checker imaged or we have already invalidated
due to image decode. But can you confirm?

[Khushal, 2017/04/20 21:54:22]

Yup.
If the memory policy is ALLOW_NOTHING, then
|had_enough_memory_to_schedule_tiles_needed_now| should be false, since we will
break at line 658, not 748. So we won't decode anything in that case. The
BuildsImageDecodeQueue test in tile_manager_unittest takes care of this.
Yup, that's exactly what will be the case. Whether the resource is valid or not
depends on when the state for skipping an image on it changes. And any change in
this state has to be accompanied with tiles for it being invalidated.

+          tile->raster_task_scheduled_with_checker_images()) {
+        AddCheckeredImagesToDecodeQueue(
+            prioritized_tile, raster_color_space,
+            &work_to_schedule.checker_image_decode_queue);
+      }
+    }
+  }
+
   UMA_HISTOGRAM_BOOLEAN("TileManager.ExceededMemoryBudget",
                         !had_enough_memory_to_schedule_tiles_needed_now);
   did_oom_on_last_assign_ = !had_enough_memory_to_schedule_tiles_needed_now;
 
   memory_stats_from_last_assign_.total_budget_in_bytes =
       global_state_.hard_memory_limit_in_bytes;
   memory_stats_from_last_assign_.total_bytes_used = memory_usage.memory_bytes();
   DCHECK_GE(memory_stats_from_last_assign_.total_bytes_used, 0);
   memory_stats_from_last_assign_.had_enough_memory =
       had_enough_memory_to_schedule_tiles_needed_now;
 
   TRACE_EVENT_END2("cc", "TileManager::AssignGpuMemoryToTiles",
                    "all_tiles_that_need_to_be_rasterized_are_scheduled",
                    all_tiles_that_need_to_be_rasterized_are_scheduled_,
                    "had_enough_memory_to_schedule_tiles_needed_now",
                    had_enough_memory_to_schedule_tiles_needed_now);
   return work_to_schedule;
 }
 
 void TileManager::FreeResourcesForTile(Tile* tile) {
   TileDrawInfo& draw_info = tile->draw_info();
+
+  if (draw_info.is_checker_imaged())
+    num_of_tiles_with_checker_images_--;
+  DCHECK_GE(num_of_tiles_with_checker_images_, 0);
+
   Resource* resource = draw_info.TakeResource();
   if (resource) {
     resource_pool_->ReleaseResource(resource);
     pending_gpu_work_tiles_.erase(tile);
   }
 }
 
 void TileManager::FreeResourcesForTileAndNotifyClientIfTileWasReadyToDraw(
     Tile* tile) {
   bool was_ready_to_draw = tile->draw_info().IsReadyToDraw();
   FreeResourcesForTile(tile);
   if (was_ready_to_draw)
     client_->NotifyTileStateChanged(tile);
 }
 
+void TileManager::PartitionImagesForCheckering(
+    const PrioritizedTile& prioritized_tile,
+    const gfx::ColorSpace& raster_color_space,
+    std::vector<DrawImage>* sync_decoded_images,
+    std::vector<sk_sp<const SkImage>>* checkered_images) {
+  Tile* tile = prioritized_tile.tile();
+  std::vector<DrawImage> images_in_tile;
+  prioritized_tile.raster_source()->GetDiscardableImagesInRect(
+      tile->enclosing_layer_rect(), tile->raster_transform().scale(),
+      raster_color_space, &images_in_tile);
+  WhichTree tree = tile->tiling()->tree();
+
+  for (auto& draw_image : images_in_tile) {
+    if (checker_image_tracker_.ShouldCheckerImage(draw_image.image(), tree))
+      checkered_images->push_back(draw_image.image());
+    else
+      sync_decoded_images->push_back(draw_image);
+  }
+}
+
+void TileManager::AddCheckeredImagesToDecodeQueue(

[vmpstr, 2017/04/20 20:59:32]

nit: I guess I was just hoping to reuse the function above but make
sync_decoded_images be able to be nullptr (and checkered_images too). Up to you
though, I think this fine as well.

[Khushal, 2017/04/20 21:54:22]

Its a few more lines of code extra at call-sites for iterating through the
checker-imaged tile and adding to queue. Looked like it could use its own
function.

+    const PrioritizedTile& prioritized_tile,
+    const gfx::ColorSpace& raster_color_space,
+    CheckerImageTracker::ImageDecodeQueue* image_decode_queue) {
+  Tile* tile = prioritized_tile.tile();
+  std::vector<DrawImage> images_in_tile;
+  prioritized_tile.raster_source()->GetDiscardableImagesInRect(
+      tile->enclosing_layer_rect(), tile->raster_transform().scale(),
+      raster_color_space, &images_in_tile);
+  WhichTree tree = tile->tiling()->tree();
+
+  for (auto& draw_image : images_in_tile) {
+    if (checker_image_tracker_.ShouldCheckerImage(draw_image.image(), tree))
+      image_decode_queue->push_back(draw_image.image());
+  }
+}
+
 void TileManager::ScheduleTasks(
     const PrioritizedWorkToSchedule& work_to_schedule) {
   const std::vector<PrioritizedTile>& tiles_that_need_to_be_rasterized =
       work_to_schedule.tiles_to_raster;
   TRACE_EVENT1("cc", "TileManager::ScheduleTasks", "count",
                tiles_that_need_to_be_rasterized.size());
 
   DCHECK(did_check_for_completed_tasks_since_last_schedule_tasks_);
 
   if (!has_scheduled_tile_tasks_) {
@@ skipping 81 matching lines @@
   }
 
   // TODO(vmpstr): SOON is misleading here, but these images can come from
   // several diffent tiles. Rethink what we actually want to trace here. Note
   // that I'm using SOON, since it can't be NOW (these are prepaint).
   ImageDecodeCache::TracingInfo tracing_info(prepare_tiles_count_,
                                              TilePriority::SOON);
   std::vector<scoped_refptr<TileTask>> new_locked_image_tasks =
       image_controller_.SetPredecodeImages(std::move(new_locked_images),
                                            tracing_info);
-
   for (auto& task : new_locked_image_tasks) {
     auto decode_it = std::find_if(graph_.nodes.begin(), graph_.nodes.end(),
                                   [&task](const TaskGraph::Node& node) {
                                     return node.task == task.get();
                                   });
     // If this task is already in the graph, then we don't have to insert it.
     if (decode_it != graph_.nodes.end())
       continue;
 
     InsertNodeForDecodeTask(&graph_, task.get(), false, priority++);
@@ skipping 28 matching lines @@
                     kAllDoneTaskPriority, all_count);
 
   // Synchronize worker with compositor.
   raster_buffer_provider_->OrderingBarrier();
 
   // Schedule running of |raster_queue_|. This replaces any previously
   // scheduled tasks and effectively cancels all tasks not present
   // in |raster_queue_|.
   tile_task_manager_->ScheduleTasks(&graph_);
 
+  // Schedule running of the checker-image decode queue. This replaces the
+  // previously scheduled queue and effectively cancels image decodes from the
+  // previous queue, if not already started.
+  checker_image_tracker_.ScheduleImageDecodeQueue(
+      std::move(work_to_schedule.checker_image_decode_queue));
+
   did_check_for_completed_tasks_since_last_schedule_tasks_ = false;
 
   TRACE_EVENT_ASYNC_STEP_INTO1("cc", "ScheduledTasks", this, "running", "state",
                                ScheduledTasksStateAsValue());
 }
 
 scoped_refptr<TileTask> TileManager::CreateRasterTask(
     const PrioritizedTile& prioritized_tile,
-    const gfx::ColorSpace& color_space) {
+    const gfx::ColorSpace& color_space,
+    CheckerImageTracker::ImageDecodeQueue* checker_image_decode_queue) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("cc.debug"),
                "TileManager::CreateRasterTask");
-
   Tile* tile = prioritized_tile.tile();
+  TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug"),
+               "TileManager::CreateRasterTask", "Tile", tile->id());
 
   // Get the resource.
   uint64_t resource_content_id = 0;
   Resource* resource = nullptr;
   gfx::Rect invalidated_rect = tile->invalidated_content_rect();
   if (UsePartialRaster() && tile->invalidated_id()) {
     resource = resource_pool_->TryAcquireResourceForPartialRaster(
         tile->id(), tile->invalidated_content_rect(), tile->invalidated_id(),
         &invalidated_rect);
   }
 
   if (resource) {
     resource_content_id = tile->invalidated_id();
     DCHECK_EQ(DetermineResourceFormat(tile), resource->format());
   } else {
     resource = resource_pool_->AcquireResource(tile->desired_texture_size(),
                                                DetermineResourceFormat(tile),
                                                color_space);
   }
 
   // For LOW_RESOLUTION tiles, we don't draw or predecode images.
   RasterSource::PlaybackSettings playback_settings;
   playback_settings.skip_images =
       prioritized_tile.priority().resolution == LOW_RESOLUTION;
 
-  // Create and queue all image decode tasks that this tile depends on.
+  // Create and queue all image decode tasks that this tile depends on. Note
+  // that we need to store the images for decode tasks in
+  // |scheduled_draw_images_| since the tile might have been destroyed by the
+  // time the raster task finishes.
   TileTask::Vector decode_tasks;
-  std::vector<DrawImage>& images = scheduled_draw_images_[tile->id()];
-  ImageIdFlatSet images_to_skip;
-  images.clear();
+  std::vector<DrawImage>& sync_decoded_images =
+      scheduled_draw_images_[tile->id()];
+  sync_decoded_images.clear();
   if (!playback_settings.skip_images) {
-    prioritized_tile.raster_source()->GetDiscardableImagesInRect(
-        tile->enclosing_layer_rect(), tile->raster_transform().scale(),
-        color_space, &images);
-    checker_image_tracker_.FilterImagesForCheckeringForTile(
-        &images, &images_to_skip, prioritized_tile.tile()->tiling()->tree());
+    std::vector<sk_sp<const SkImage>> checkered_images;
+    PartitionImagesForCheckering(prioritized_tile, color_space,
+                                 &sync_decoded_images, &checkered_images);
+    for (const auto& image : checkered_images) {
+      ImageId image_id = image->uniqueID();
+      playback_settings.images_to_skip.insert(image_id);
+
+      // This can be the case for tiles on the active tree that will be replaced
+      // or are occluded on the pending tree. While we still need to continue
+      // skipping images for these tiles, we don't need to decode them since
+      // they will not be required on the next active tree.
+      if (prioritized_tile.should_decode_checkered_images_for_tile())
+        checker_image_decode_queue->push_back(image);
+    }
   }
 
   // We can skip the image hijack canvas if we have no images, or no images to
   // skip during raster.
   playback_settings.use_image_hijack_canvas =
-      !images.empty() || !images_to_skip.empty();
-  playback_settings.images_to_skip = std::move(images_to_skip);
+      !sync_decoded_images.empty() || !playback_settings.images_to_skip.empty();
+
+  bool has_checker_images = !playback_settings.images_to_skip.empty();
+  tile->set_raster_task_scheduled_with_checker_images(has_checker_images);
+  if (has_checker_images)
+    num_of_tiles_with_checker_images_++;
 
   // Get the tasks for the required images.
   ImageDecodeCache::TracingInfo tracing_info(
       prepare_tiles_count_, prioritized_tile.priority().priority_bin);
-  image_controller_.GetTasksForImagesAndRef(&images, &decode_tasks,
+  image_controller_.GetTasksForImagesAndRef(&sync_decoded_images, &decode_tasks,
                                             tracing_info);
 
   std::unique_ptr<RasterBuffer> raster_buffer =
       raster_buffer_provider_->AcquireBufferForRaster(
           resource, resource_content_id, tile->invalidated_id());
   return make_scoped_refptr(new RasterTaskImpl(
       this, tile, resource, prioritized_tile.raster_source(), playback_settings,
       prioritized_tile.priority().resolution, invalidated_rect,
       prepare_tiles_count_, std::move(raster_buffer), &decode_tasks,
       use_gpu_rasterization_));
 }
 
 void TileManager::ResetSignalsForTesting() {
   signals_.reset();
 }
 
 void TileManager::OnRasterTaskCompleted(
     std::unique_ptr<RasterBuffer> raster_buffer,
     Tile::Id tile_id,
     Resource* resource,
     bool was_canceled) {
   raster_buffer_provider_->ReleaseBufferForRaster(std::move(raster_buffer));
 
   auto found = tiles_.find(tile_id);
   Tile* tile = nullptr;
+  bool raster_task_was_scheduled_with_checker_images = false;
   if (found != tiles_.end()) {
     tile = found->second;
     DCHECK(tile->raster_task_.get());
     tile->raster_task_ = nullptr;
+    raster_task_was_scheduled_with_checker_images =
+        tile->set_raster_task_scheduled_with_checker_images(false);
+    if (raster_task_was_scheduled_with_checker_images)
+      num_of_tiles_with_checker_images_--;
   }
 
   // Unref all the images.
   auto images_it = scheduled_draw_images_.find(tile_id);
   image_controller_.UnrefImages(images_it->second);
   scheduled_draw_images_.erase(images_it);
 
   if (was_canceled) {
     ++flush_stats_.canceled_count;
     resource_pool_->ReleaseResource(resource);
     return;
   }
 
   resource_pool_->OnContentReplaced(resource->id(), tile_id);
   ++flush_stats_.completed_count;
 
   if (!tile) {
     resource_pool_->ReleaseResource(resource);
     return;
   }
 
   TileDrawInfo& draw_info = tile->draw_info();
-  draw_info.set_resource(resource);
+  draw_info.set_resource(resource,
+                         raster_task_was_scheduled_with_checker_images);
   draw_info.contents_swizzled_ = DetermineResourceRequiresSwizzle(tile);
+  if (raster_task_was_scheduled_with_checker_images)
+    num_of_tiles_with_checker_images_++;
 
   // In SMOOTHNESS_TAKES_PRIORITY mode, we wait for GPU work to complete for a
   // tile before setting it as ready to draw.
   if (global_state_.tree_priority == SMOOTHNESS_TAKES_PRIORITY &&
       !raster_buffer_provider_->IsResourceReadyToDraw(resource->id())) {
     pending_gpu_work_tiles_.insert(tile);
     return;
   }
 
   draw_info.set_resource_ready_for_draw();
@@ skipping 445 matching lines @@
   all_tile_tasks_completed = false;
   did_notify_all_tile_tasks_completed = false;
 }
 
 TileManager::PrioritizedWorkToSchedule::PrioritizedWorkToSchedule() = default;
 TileManager::PrioritizedWorkToSchedule::PrioritizedWorkToSchedule(
     PrioritizedWorkToSchedule&& other) = default;
 TileManager::PrioritizedWorkToSchedule::~PrioritizedWorkToSchedule() = default;
 
 }  // namespace cc