Re-land: cc: Cancel and re-prioritize worker pool tasks.

cc/resources/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/resources/tile_manager.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 102 matching lines @@
     TileManagerClient* client,
     ResourceProvider* resource_provider,
     size_t num_raster_threads,
     bool use_color_estimator,
     bool prediction_benchmarking,
     RenderingStatsInstrumentation* rendering_stats_instrumentation)
     : client_(client),
       resource_pool_(ResourcePool::Create(resource_provider)),
       raster_worker_pool_(RasterWorkerPool::Create(this, num_raster_threads)),
       manage_tiles_pending_(false),
-      manage_tiles_call_count_(0),
       bytes_pending_upload_(0),
       has_performed_uploads_since_last_flush_(false),
       ever_exceeded_memory_budget_(false),
       rendering_stats_instrumentation_(rendering_stats_instrumentation),
       use_color_estimator_(use_color_estimator),
       prediction_benchmarking_(prediction_benchmarking),
       did_initialize_visible_tile_(false),
-      pending_tasks_(0),
       max_pending_tasks_(kMaxNumPendingTasksPerThread * num_raster_threads) {
 }
 
 TileManager::~TileManager() {
   // Reset global state and manage. This should cause
   // our memory usage to drop to zero.
   global_state_ = GlobalStateThatImpactsTilePriority();
   AssignGpuMemoryToTiles();
   // This should finish all pending tasks and release any uninitialized
   // resources.
@@ skipping 141 matching lines @@
 
   // Sort by bin, resolution and time until needed.
   std::sort(tiles_.begin(), tiles_.end(), BinComparator());
 }
 
 void TileManager::ManageTiles() {
   TRACE_EVENT0("cc", "TileManager::ManageTiles");
   TRACE_COUNTER_ID1("cc", "TileCount", this, tiles_.size());
 
   manage_tiles_pending_ = false;
-  ++manage_tiles_call_count_;
 
   AssignBinsToTiles();
   SortTiles();
   AssignGpuMemoryToTiles();
 
   TRACE_EVENT_INSTANT1("cc", "DidManage", TRACE_EVENT_SCOPE_THREAD,
                        "state", ValueToString(BasicStateAsValue()));
 
-  // Finally, kick the rasterizer.
-  DispatchMoreTasks();
+  // Finally, schedule rasterizer tasks.
+  ScheduleTasks();
 }
 
 void TileManager::CheckForCompletedTileUploads() {
   while (!tiles_with_pending_upload_.empty()) {
     Tile* tile = tiles_with_pending_upload_.front();
     DCHECK(tile->drawing_info().resource_);
 
     // Set pixel tasks complete in the order they are posted.
     if (!resource_pool_->resource_provider()->DidSetPixelsComplete(
           tile->drawing_info().resource_->id())) {
       break;
     }
 
     // It's now safe to release the pixel buffer.
     resource_pool_->resource_provider()->ReleasePixelBuffer(
         tile->drawing_info().resource_->id());
 
     bytes_pending_upload_ -= tile->bytes_consumed_if_allocated();
     // Reset forced_upload_ since we now got the upload completed notification.
     tile->drawing_info().forced_upload_ = false;
     tile->drawing_info().memory_state_ = USING_RELEASABLE_MEMORY;
     DidFinishTileInitialization(tile);
 
     tiles_with_pending_upload_.pop();
   }
 
-  DispatchMoreTasks();
+  ScheduleTasks();
 }
 
 void TileManager::AbortPendingTileUploads() {
   while (!tiles_with_pending_upload_.empty()) {
     Tile* tile = tiles_with_pending_upload_.front();
     DCHECK(tile->drawing_info().resource_);
 
     resource_pool_->resource_provider()->AbortSetPixels(
         tile->drawing_info().resource_->id());
     resource_pool_->resource_provider()->ReleasePixelBuffer(
@@ skipping 90 matching lines @@
   return requirements.PassAs<base::Value>();
 }
 
 void TileManager::DidFinishDispatchingWorkerPoolCompletionCallbacks() {
   // If a flush is needed, do it now before starting to dispatch more tasks.
   if (has_performed_uploads_since_last_flush_) {
     resource_pool_->resource_provider()->ShallowFlushIfSupported();
     has_performed_uploads_since_last_flush_ = false;
   }
 
-  DispatchMoreTasks();
+  ScheduleTasks();
 }
 
 void TileManager::AssignGpuMemoryToTiles() {
   TRACE_EVENT0("cc", "TileManager::AssignGpuMemoryToTiles");
   size_t unreleasable_bytes = 0;
 
   // Now give memory out to the tiles until we're out, and build
   // the needs-to-be-rasterized queue.
   tiles_that_need_to_be_rasterized_.clear();
 
   // By clearing the tiles_that_need_to_be_rasterized_ vector list
   // above we move all tiles currently waiting for raster to idle state.
   // Some memory cannot be released. We figure out how much in this
-  // loop as well.
+  // loop.
   for (TileVector::const_iterator it = tiles_.begin();
        it != tiles_.end();
        ++it) {
     const Tile* tile = *it;
     if (tile->drawing_info().memory_state_ == USING_UNRELEASABLE_MEMORY)
       unreleasable_bytes += tile->bytes_consumed_if_allocated();
   }
 
   // Global state's memory limit can decrease, causing
   // it to be less than unreleasable_bytes
   size_t bytes_allocatable =
       global_state_.memory_limit_in_bytes > unreleasable_bytes ?
       global_state_.memory_limit_in_bytes - unreleasable_bytes :
       0;
   size_t bytes_that_exceeded_memory_budget_in_now_bin = 0;
   size_t bytes_left = bytes_allocatable;
   size_t bytes_oom_in_now_bin_on_pending_tree = 0;
   TileVector tiles_requiring_memory_but_oomed;
+  bool higher_priority_tile_oomed = false;
   for (TileVector::iterator it = tiles_.begin();
        it != tiles_.end();
        ++it) {
     Tile* tile = *it;
     ManagedTileState& mts = tile->managed_state();
     ManagedTileState::DrawingInfo& drawing_info = tile->drawing_info();
 
-    // If this tile doesn't need a resource, or if the memory
-    // is unreleasable, then we do not need to do anything.
-    if (!drawing_info.requires_resource() ||
-        drawing_info.memory_state_ == USING_UNRELEASABLE_MEMORY) {
+    // If this tile doesn't need a resource, then we do not need
+    // to do anything.
+    if (!drawing_info.requires_resource())
       continue;
-    }
 
     size_t tile_bytes = tile->bytes_consumed_if_allocated();
+    // Memory is already reserved for tile with unreleasable memory
+    // so adding it to |tiles_that_need_to_be_rasterized_| doesn't
+    // affect bytes_allocatable.
+    if (drawing_info.memory_state_ == USING_UNRELEASABLE_MEMORY)
+      tile_bytes = 0;
+
     // If the tile is not needed, free it up.
     if (mts.is_in_never_bin_on_both_trees()) {
-      FreeResourcesForTile(tile);
-      drawing_info.memory_state_ = NOT_ALLOWED_TO_USE_MEMORY;
+      if (drawing_info.memory_state_ != USING_UNRELEASABLE_MEMORY) {
+        FreeResourcesForTile(tile);
+        drawing_info.memory_state_ = NOT_ALLOWED_TO_USE_MEMORY;
+      }
       continue;
     }
     // Tile is OOM.
     if (tile_bytes > bytes_left) {
-      FreeResourcesForTile(tile);
       tile->drawing_info().set_rasterize_on_demand();
       if (mts.tree_bin[PENDING_TREE] == NOW_BIN) {
         tiles_requiring_memory_but_oomed.push_back(tile);
         bytes_oom_in_now_bin_on_pending_tree += tile_bytes;
       }
+      FreeResourcesForTile(tile);
+      higher_priority_tile_oomed = true;
       continue;
     }
     drawing_info.set_use_resource();
     bytes_left -= tile_bytes;
-    if (!drawing_info.resource_ &&
-        drawing_info.memory_state_ == CAN_USE_MEMORY) {
+    // Tile shouldn't be rasterized if we've failed to assign

[vmpstr, 2013/05/06 18:05:51]

If a large tile is OOM, followed by a smaller tile that has enough memory, this
would assign memory to it (via set_use_resource) and subtract the memory from
the budget, but then not enqueue it for raster. Is this intentional? I'm not
sure I understand the intent

[reveman, 2013/05/06 21:36:27]

Yes, being assigned memory is not the same as being scheduled for raster after
this change. We need this to be different to be able to cancel tasks.

tiles_that_need_to_be_rasterized_ is essentially all tiles that have memory
assigned to them AND are high enough priority at the moment that we want them
initialized. Not adding a tile to tiles_that_need_to_be_rasterized_ will cause
any pending raster task for that tile to be cancelled asap.

made some minor changes to this code in latest patch to make it cleaner.

+    // gpu memory to a higher priority tile. This is important for
+    // two reasons:
+    // 1. Tile size should not impact raster priority.
+    // 2. Tile with unreleasable memory could otherwise incorrectly
+    //    be added as it's not affected by |bytes_allocatable|.
+    if (!drawing_info.resource_ && !higher_priority_tile_oomed)
       tiles_that_need_to_be_rasterized_.push_back(tile);
-    }
   }
 
   // In OOM situation, we iterate tiles_, remove the memory for active tree
   // and not the now bin. And give them to bytes_oom_in_now_bin_on_pending_tree
   if (!tiles_requiring_memory_but_oomed.empty()) {
     size_t bytes_freed = 0;
     for (TileVector::iterator it = tiles_.begin(); it != tiles_.end(); ++it) {
       Tile* tile = *it;
       ManagedTileState& mts = tile->managed_state();
       ManagedTileState::DrawingInfo& drawing_info = tile->drawing_info();
@@ skipping 35 matching lines @@
                         "budget", global_state_.memory_limit_in_bytes,
                         "over", bytes_that_exceeded_memory_budget_in_now_bin);
   }
   memory_stats_from_last_assign_.total_budget_in_bytes =
       global_state_.memory_limit_in_bytes;
   memory_stats_from_last_assign_.bytes_allocated =
       bytes_allocatable - bytes_left;
   memory_stats_from_last_assign_.bytes_unreleasable = unreleasable_bytes;
   memory_stats_from_last_assign_.bytes_over =
       bytes_that_exceeded_memory_budget_in_now_bin;
-
-  // Reverse two tiles_that_need_* vectors such that pop_back gets
-  // the highest priority tile.
-  std::reverse(
-      tiles_that_need_to_be_rasterized_.begin(),
-      tiles_that_need_to_be_rasterized_.end());
 }
 
 void TileManager::FreeResourcesForTile(Tile* tile) {
-  DCHECK(tile->drawing_info().memory_state_ != USING_UNRELEASABLE_MEMORY);
+  DCHECK_NE(USING_UNRELEASABLE_MEMORY, tile->drawing_info().memory_state_);

[vmpstr, 2013/05/06 18:05:51]

nit: I kinda prefer the constant to be the second parameter, up to you

[reveman, 2013/05/06 21:36:27]

DCHECK_NE is used in both ways throughout chromium and I would also prefer the
constant as second if EXPECT_EQ and likes didn't prefer it to be the other way
around.

   if (tile->drawing_info().resource_) {
     resource_pool_->ReleaseResource(
         tile->drawing_info().resource_.Pass());
   }
   tile->drawing_info().memory_state_ = NOT_ALLOWED_TO_USE_MEMORY;
 }
 
-bool TileManager::CanDispatchRasterTask(Tile* tile) const {
-  if (pending_tasks_ >= max_pending_tasks_)
-    return false;
-  size_t new_bytes_pending = bytes_pending_upload_;
-  new_bytes_pending += tile->bytes_consumed_if_allocated();
-  return new_bytes_pending <= kMaxPendingUploadBytes &&
-         tiles_with_pending_upload_.size() < kMaxPendingUploads;
-}
+void TileManager::ScheduleTasks() {
+  TRACE_EVENT0("cc", "TileManager::ScheduleTasks");
+  RasterWorkerPool::Task::Queue task_queue;
 
-void TileManager::DispatchMoreTasks() {
-  TileVector tiles_with_image_decoding_tasks;
+  size_t bytes_pending_upload = bytes_pending_upload_;
+  ManagedTileState::PixelRefSet decode_tasks;
 
+  // Build a new task queue containing all task currently needed. Tasks
+  // are added to queue in order of priority, highest priority task first.
+  //
   // Process all tiles in the need_to_be_rasterized queue:
-  // 1. Dispatch image decode tasks.
-  // 2. If the image decode isn't done, save the tile for later processing.
-  // 3. Attempt to dispatch a raster task, or break out of the loop.
-  while (!tiles_that_need_to_be_rasterized_.empty()) {
-    Tile* tile = tiles_that_need_to_be_rasterized_.back();
+  // 1. Queue image decode tasks for tile.
+  // 2. If the image decode is pending, skip tile for later processing.
+  // 3. Attempt to queue a raster task, or break out of the loop.
+  for (TileVector::iterator it = tiles_that_need_to_be_rasterized_.begin();
+       it != tiles_that_need_to_be_rasterized_.end();
+       ++it) {
+    Tile* tile = *it;
 
-    DCHECK(tile->drawing_info().requires_resource());
+    // Skip tile if determined to not require resource.
+    if (!tile->drawing_info().requires_resource())
+      continue;
 
-    if (DispatchImageDecodeTasksForTile(tile)) {
-      tiles_with_image_decoding_tasks.push_back(tile);
-    } else if (!CanDispatchRasterTask(tile)) {
+    // Skip tile if already rasterized.
+    if (tile->drawing_info().resource_)
+      continue;
+
+    bool pending_decode_tasks = false;
+    ManagedTileState& mts = tile->managed_state();
+
+    for (PicturePileImpl::PixelRefIterator iter(tile->content_rect(),

[vmpstr, 2013/05/06 18:05:51]

Is it possible to refactor this loop into a separate function? Something like
UpdateDecodeTasksIfNeeded(tile, &decode_tasks, &task_queue) -> true iff it has
pending decode tasks.

I'm having a bit of trouble keeping decode_tasks, task_queue, and
pending_decode_tasks_ clear in my mind. Maybe this would help

[reveman, 2013/05/06 21:36:27]

Done.

+                                                tile->contents_scale(),
+                                                tile->picture_pile());
+         iter; ++iter) {
+      skia::LazyPixelRef* pixel_ref = *iter;
+      uint32_t id = pixel_ref->getGenerationID();
+
+      // Check if image has already been decoded for this tile.
+      if (mts.decoded_pixel_refs.find(id) != mts.decoded_pixel_refs.end())
+        continue;
+
+      // TODO(qinmin): passing correct image size to PrepareToDecode().
+      if (pixel_ref->PrepareToDecode(skia::LazyPixelRef::PrepareParams())) {
+        rendering_stats_instrumentation_->IncrementDeferredImageCacheHitCount();
+        mts.decoded_pixel_refs.insert(id);
+        continue;
+      }
+
+      pending_decode_tasks = true;
+
+      // TODO(reveman): Remove max pending tasks throttling.
+      if (task_queue.size() >= max_pending_tasks_)
         break;
-    } else {
-      DispatchOneRasterTask(tile);
+
+      // Check if already added to |task_queue|. There should only be
+      // one task per pixel ref.
+      if (decode_tasks.find(id) != decode_tasks.end())
+        continue;
+      decode_tasks.insert(id);
+
+      // Queue existing task if available.
+      PixelRefMap::iterator decode_task_it = pending_decode_tasks_.find(id);
+      if (decode_task_it != pending_decode_tasks_.end()) {
+        task_queue.Append(decode_task_it->second);
+        continue;
+      }
+
+      // Create and queue new image decode task for this pixel ref.
+      RasterWorkerPool::Task decode_task = CreateImageDecodeTask(
+          tile, pixel_ref);
+      task_queue.Append(decode_task);
+      pending_decode_tasks_[id] = decode_task;
     }
-    tiles_that_need_to_be_rasterized_.pop_back();
+
+    // Skip tile if image decode is pending.
+    if (pending_decode_tasks)
+      continue;
+
+    // TODO(reveman): Remove throttling based on max pending tasks.
+    if (task_queue.size() >= max_pending_tasks_)
+      break;
+
+    // TODO(reveman): Remove throttling based on max pending uploads.
+    if (tiles_with_pending_upload_.size() >= kMaxPendingUploads)
+      break;
+
+    // TODO(reveman): Throttle based on shared memory usage rather
+    // than bytes pending upload.
+    size_t new_bytes_pending = bytes_pending_upload;
+    new_bytes_pending += tile->bytes_consumed_if_allocated();
+    if (new_bytes_pending > kMaxPendingUploadBytes)
+      break;
+    bytes_pending_upload = new_bytes_pending;
+
+    // Create raster task for this tile if necessary.
+    if (mts.raster_task.is_null())
+      mts.raster_task = CreateRasterTask(tile);
+
+    // Finally queue raster task for tile.
+    task_queue.Append(mts.raster_task);
   }
 
-  // Put the saved tiles back into the queue. The order is reversed
-  // to preserve original ordering.
-  tiles_that_need_to_be_rasterized_.insert(
-      tiles_that_need_to_be_rasterized_.end(),
-      tiles_with_image_decoding_tasks.rbegin(),
-      tiles_with_image_decoding_tasks.rend());
+  // Schedule running of tasks in |task_queue|. This replaces any
+  // previously scheduled tasks and effectively cancels any tasks

[vmpstr, 2013/05/06 18:05:51]

How do we cancel an upload? (or ensure upload continues?)

[reveman, 2013/05/06 21:36:27]

We can't cancel an upload at the moment but that's a separate issue that I
intend to solve later (requires command buffer API changes).

We already avoid to issue an upload if |was_cancelled| is true in
OnRasterTaskCompleted().

+  // not present in |task_queue|.
+  raster_worker_pool_->ScheduleTasks(&task_queue);
 
   if (did_initialize_visible_tile_) {
     did_initialize_visible_tile_ = false;
     client_->DidInitializeVisibleTile();
   }
 }
 
-bool TileManager::DispatchImageDecodeTasksForTile(Tile* tile) {

[vmpstr, 2013/05/06 18:05:51]

I guess my earlier comment is asking to just rename this function, instead of
inlining it

[reveman, 2013/05/06 21:36:27]

Done.

-  TRACE_EVENT0("cc", "TileManager::DispatchImageDecodeTasksForTile");
-  ManagedTileState& mts = tile->managed_state();
-  bool pending_decode_tasks = false;
+RasterWorkerPool::Task TileManager::CreateImageDecodeTask(
+    Tile* tile, skia::LazyPixelRef* pixel_ref) {
+  TRACE_EVENT0("cc", "TileManager::CreateImageDecodeTask");
 
-  for (PicturePileImpl::PixelRefIterator iter(tile->content_rect(),
-                                              tile->contents_scale(),
-                                              tile->picture_pile());
-       iter; ++iter) {
-    skia::LazyPixelRef* pixel_ref = *iter;
-    uint32_t id = pixel_ref->getGenerationID();
-
-    // Check if image has already been decoded.
-    if (mts.decoded_pixel_refs.find(id) != mts.decoded_pixel_refs.end())
-      continue;
-
-    // Check if decode task is already pending.
-    if (pending_decode_tasks_.find(id) != pending_decode_tasks_.end()) {
-      pending_decode_tasks = true;
-      continue;
-    }
-
-    // TODO(qinmin): passing correct image size to PrepareToDecode().
-    if (pixel_ref->PrepareToDecode(skia::LazyPixelRef::PrepareParams())) {
-      rendering_stats_instrumentation_->IncrementDeferredImageCacheHitCount();
-      mts.decoded_pixel_refs.insert(id);
-      continue;
-    }
-
-    if (pending_tasks_ >= max_pending_tasks_)
-      break;
-
-    DispatchOneImageDecodeTask(tile, pixel_ref);
-    pending_decode_tasks = true;
-  }
-
-  return pending_decode_tasks;
-}
-
-void TileManager::DispatchOneImageDecodeTask(
-    scoped_refptr<Tile> tile, skia::LazyPixelRef* pixel_ref) {
-  TRACE_EVENT0("cc", "TileManager::DispatchOneImageDecodeTask");
-  uint32_t pixel_ref_id = pixel_ref->getGenerationID();
-  DCHECK(pending_decode_tasks_.end() ==
-      pending_decode_tasks_.find(pixel_ref_id));
-  pending_decode_tasks_.insert(pixel_ref_id);
-
-  raster_worker_pool_->PostTaskAndReply(
+  return RasterWorkerPool::Task(
       base::Bind(&TileManager::RunImageDecodeTask,
                  pixel_ref,
                  rendering_stats_instrumentation_),
       base::Bind(&TileManager::OnImageDecodeTaskCompleted,
                  base::Unretained(this),
-                 tile,
-                 pixel_ref_id));
-  pending_tasks_++;
+                 make_scoped_refptr(tile),
+                 pixel_ref->getGenerationID()));
 }
 
-void TileManager::OnImageDecodeTaskCompleted(
-    scoped_refptr<Tile> tile, uint32_t pixel_ref_id) {
+void TileManager::OnImageDecodeTaskCompleted(scoped_refptr<Tile> tile,
+                                             uint32_t pixel_ref_id,
+                                             bool was_cancelled) {
   TRACE_EVENT0("cc", "TileManager::OnImageDecodeTaskCompleted");
+  DCHECK(pending_decode_tasks_.find(pixel_ref_id) !=
+         pending_decode_tasks_.end());
+  pending_decode_tasks_.erase(pixel_ref_id);
+  if (was_cancelled)
+    return;
   ManagedTileState& mts = tile->managed_state();
+  // Note: |decoded_pixel_refs| might already contain |pixel_ref_id| as
+  // the PrepareToDecode() check in ScheduleTasks() could have added it.
   mts.decoded_pixel_refs.insert(pixel_ref_id);
-  pending_decode_tasks_.erase(pixel_ref_id);
-  pending_tasks_--;
 }
 
-scoped_ptr<ResourcePool::Resource> TileManager::PrepareTileForRaster(
-    Tile* tile) {
-  scoped_ptr<ResourcePool::Resource> resource = resource_pool_->AcquireResource(
-      tile->tile_size_.size(),
-      tile->drawing_info().resource_format_);
+RasterWorkerPool::Task TileManager::CreateRasterTask(Tile* tile) {
+  TRACE_EVENT0("cc", "TileManager::CreateRasterTask");
+
+  scoped_ptr<ResourcePool::Resource> resource =
+      resource_pool_->AcquireResource(
+          tile->tile_size_.size(),
+          tile->drawing_info().resource_format_);
   resource_pool_->resource_provider()->AcquirePixelBuffer(resource->id());
 
+  DCHECK_EQ(CAN_USE_MEMORY, tile->drawing_info().memory_state_);
   tile->drawing_info().memory_state_ = USING_UNRELEASABLE_MEMORY;
 
-  return resource.Pass();
-}
-
-void TileManager::DispatchOneRasterTask(scoped_refptr<Tile> tile) {
-  TRACE_EVENT0("cc", "TileManager::DispatchOneRasterTask");
-  scoped_ptr<ResourcePool::Resource> resource = PrepareTileForRaster(tile);
-  ResourceProvider::ResourceId resource_id = resource->id();
   PicturePileImpl::Analysis* analysis = new PicturePileImpl::Analysis;
 
   // MapPixelBuffer() returns NULL if context was lost at the time
   // AcquirePixelBuffer() was called. For simplicity we still post
   // a raster task that is essentially a noop in these situations.
   uint8* buffer = resource_pool_->resource_provider()->MapPixelBuffer(
-      resource_id);
+      resource->id());
 
   // skia requires that our buffer be 4-byte aligned
   CHECK(!(reinterpret_cast<intptr_t>(buffer) & 3));

[vmpstr, 2013/05/06 18:05:51]

I would vote that this moves into MapPixelBuffer, but that's unrelated to this
change.

[reveman, 2013/05/06 21:36:27]

I agree. Moving it RP and closer to the source as part of this CL.

 
-  raster_worker_pool_->PostRasterTaskAndReply(
+  return RasterWorkerPool::PictureTask(
       tile->picture_pile(),
       base::Bind(&TileManager::RunAnalyzeAndRasterTask,
                  base::Bind(&TileManager::RunAnalyzeTask,
                             analysis,
                             tile->content_rect(),
                             tile->contents_scale(),
                             use_color_estimator_,
                             GetRasterTaskMetadata(*tile),
                             rendering_stats_instrumentation_),
                  base::Bind(&TileManager::RunRasterTask,
                             buffer,
                             analysis,
                             tile->content_rect(),
                             tile->contents_scale(),
                             GetRasterTaskMetadata(*tile),
                             rendering_stats_instrumentation_)),
       base::Bind(&TileManager::OnRasterTaskCompleted,
                  base::Unretained(this),
-                 tile,
+                 make_scoped_refptr(tile),
                  base::Passed(&resource),
-                 base::Owned(analysis),
-                 manage_tiles_call_count_));
-  pending_tasks_++;
+                 base::Owned(analysis)));
 }
 
 TileManager::RasterTaskMetadata TileManager::GetRasterTaskMetadata(
     const Tile& tile) const {
   RasterTaskMetadata metadata;
   const ManagedTileState& mts = tile.managed_state();
   metadata.prediction_benchmarking = prediction_benchmarking_;
   metadata.is_tile_in_pending_tree_now_bin =
       mts.tree_bin[PENDING_TREE] == NOW_BIN;
   metadata.tile_resolution = mts.resolution;
   metadata.layer_id = tile.layer_id();
   return metadata;
 }
 
 void TileManager::OnRasterTaskCompleted(
     scoped_refptr<Tile> tile,
     scoped_ptr<ResourcePool::Resource> resource,
     PicturePileImpl::Analysis* analysis,
-    int manage_tiles_call_count_when_dispatched) {
+    bool was_cancelled) {
   TRACE_EVENT0("cc", "TileManager::OnRasterTaskCompleted");
 
-  pending_tasks_--;
+  ManagedTileState& mts = tile->managed_state();
+  DCHECK(!mts.raster_task.is_null());
+  mts.raster_task.Reset();
+
+  // Tile resources can't be freed until upload has completed.
+  DCHECK_EQ(USING_UNRELEASABLE_MEMORY, tile->drawing_info().memory_state_);
 
   // Release raster resources.
   resource_pool_->resource_provider()->UnmapPixelBuffer(resource->id());
 
-  tile->drawing_info().memory_state_ = USING_RELEASABLE_MEMORY;
+  if (was_cancelled) {
+    tile->drawing_info().memory_state_ = CAN_USE_MEMORY;

[vmpstr, 2013/05/06 18:05:51]

Why can use memory? I would think that if it was cancelled, then it would go
into NOT_ALLOWED_TO_USE_MEMORY, unless AssignGpuMemory decides to allocate
memory to it again

[reveman, 2013/05/06 21:36:27]

The tile will always be allowed to use memory at the time
OnRasterTaskCompleted() is called. AssignGpuMemory needs to be called for that
to change. Setting it to  NOT_ALLOWED_TO_USE_MEMORY can cause incorrect behavior
in ScheduleTasks() when tile was cancelled because of throttling.

I just realized a minor issue in the current implementation. If we're OOM and a
tile previously using unreleasable memory transitions to CAN_USE_MEMORY or
USING_RELEASABLE_MEMORY, AssignGpuMemory needs to be called to ensure that
memory is accurately assigned to tiles. That's not a new issue though. And it
probably doesn't have a significant impact.

+    resource_pool_->resource_provider()->ReleasePixelBuffer(resource->id());
+    resource_pool_->ReleaseResource(resource.Pass());
+    return;
+  }
 
-  ManagedTileState& managed_tile_state = tile->managed_state();
-  managed_tile_state.picture_pile_analysis = *analysis;
-  managed_tile_state.picture_pile_analyzed = true;
+  mts.picture_pile_analysis = *analysis;
+  mts.picture_pile_analyzed = true;
 
   if (analysis->is_solid_color) {
     tile->drawing_info().set_solid_color(analysis->solid_color);
     resource_pool_->resource_provider()->ReleasePixelBuffer(resource->id());
     resource_pool_->ReleaseResource(resource.Pass());
     DidFinishTileInitialization(tile);
     return;
   }
 
-  // Tile can be freed after the completion of the raster task. Call
-  // AssignGpuMemoryToTiles() to re-assign gpu memory to highest priority
-  // tiles if ManageTiles() was called since task was dispatched. The result
-  // of this could be that this tile is no longer allowed to use gpu
-  // memory and in that case we need to abort initialization and free all
-  // associated resources before calling DispatchMoreTasks().
-  if (manage_tiles_call_count_when_dispatched != manage_tiles_call_count_)
-    AssignGpuMemoryToTiles();
+  resource_pool_->resource_provider()->BeginSetPixels(resource->id());
+  has_performed_uploads_since_last_flush_ = true;
 
-  // Finish resource initialization we're still using memory.
-  if (tile->drawing_info().memory_state_ == USING_RELEASABLE_MEMORY) {
-    // Tile resources can't be freed until upload has completed.
-    tile->drawing_info().memory_state_ = USING_UNRELEASABLE_MEMORY;
+  tile->drawing_info().resource_ = resource.Pass();
 
-    resource_pool_->resource_provider()->BeginSetPixels(resource->id());
-    has_performed_uploads_since_last_flush_ = true;
-
-    tile->drawing_info().resource_ = resource.Pass();
-
-    bytes_pending_upload_ += tile->bytes_consumed_if_allocated();
-    tiles_with_pending_upload_.push(tile);
-  } else {
-    resource_pool_->resource_provider()->ReleasePixelBuffer(resource->id());
-    resource_pool_->ReleaseResource(resource.Pass());
-  }
+  bytes_pending_upload_ += tile->bytes_consumed_if_allocated();
+  tiles_with_pending_upload_.push(tile);
 }
 
 void TileManager::DidFinishTileInitialization(Tile* tile) {
   if (tile->priority(ACTIVE_TREE).distance_to_visible_in_pixels == 0)
     did_initialize_visible_tile_ = true;
 }
 
 void TileManager::DidTileTreeBinChange(Tile* tile,
                                        TileManagerBin new_tree_bin,
                                        WhichTree tree) {
   ManagedTileState& mts = tile->managed_state();
   mts.tree_bin[tree] = new_tree_bin;
 }
 
 // static
+void TileManager::RunImageDecodeTask(
+    skia::LazyPixelRef* pixel_ref,
+    RenderingStatsInstrumentation* stats_instrumentation) {
+  TRACE_EVENT0("cc", "TileManager::RunImageDecodeTask");
+  base::TimeTicks start_time = stats_instrumentation->StartRecording();
+  pixel_ref->Decode();
+  base::TimeDelta duration = stats_instrumentation->EndRecording(start_time);
+  stats_instrumentation->AddDeferredImageDecode(duration);
+}
+
+// static
 void TileManager::RunAnalyzeAndRasterTask(
-    const RasterWorkerPool::RasterCallback& analyze_task,
-    const RasterWorkerPool::RasterCallback& raster_task,
+    const RasterWorkerPool::PictureTask::Callback& analyze_task,
+    const RasterWorkerPool::PictureTask::Callback& raster_task,
     PicturePileImpl* picture_pile) {
   analyze_task.Run(picture_pile);
   raster_task.Run(picture_pile);
 }
 
 // static
 void TileManager::RunAnalyzeTask(
     PicturePileImpl::Analysis* analysis,
     gfx::Rect rect,
     float contents_scale,
@@ skipping 81 matching lines @@
         raster_stats.total_rasterize_time.InMicroseconds(),
         0,
         100000,
         100);
   } else {
     picture_pile->Raster(&canvas, rect, contents_scale, NULL);
   }
 }
 
 // static
-void TileManager::RunImageDecodeTask(
-    skia::LazyPixelRef* pixel_ref,
-    RenderingStatsInstrumentation* stats_instrumentation) {
-  TRACE_EVENT0("cc", "TileManager::RunImageDecodeTask");
-  base::TimeTicks start_time = stats_instrumentation->StartRecording();
-  pixel_ref->Decode();
-  base::TimeDelta duration = stats_instrumentation->EndRecording(start_time);
-  stats_instrumentation->AddDeferredImageDecode(duration);
-}
-
-// static
 void TileManager::RecordSolidColorPredictorResults(
     const SkPMColor* actual_colors,
     size_t color_count,
     bool is_predicted_solid,
     SkPMColor predicted_color) {
   DCHECK_GT(color_count, 0u);
 
   bool is_actually_solid = true;
 
   SkPMColor actual_color = *actual_colors;
@@ skipping 14 matching lines @@
                     is_predicted_solid && predicted_color != actual_color);
   HISTOGRAM_BOOLEAN("Renderer4.ColorPredictor.Accuracy",
                     is_predicted_solid == is_actually_solid &&
                     (!is_predicted_solid || predicted_color == actual_color));
   HISTOGRAM_BOOLEAN("Renderer4.ColorPredictor.IsCorrectSolid",
                     is_predicted_solid == is_actually_solid &&
                     (is_predicted_solid && predicted_color == actual_color));
 }
 
 }  // namespace cc