cc/trees/tree_synchronizer.cc

// Copyright 2011 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/trees/tree_synchronizer.h"

#include <stddef.h>

#include <set>

#include "base/containers/flat_set.h"
#include "base/debug/crash_logging.h"
#include "base/debug/dump_without_crashing.h"
#include "base/logging.h"
#include "base/stl_util.h"
#include "base/trace_event/trace_event.h"
#include "cc/layers/layer.h"
#include "cc/layers/layer_collections.h"
#include "cc/layers/layer_impl.h"
#include "cc/trees/layer_tree_host.h"
#include "cc/trees/layer_tree_impl.h"

namespace cc {
namespace {
#if DCHECK_IS_ON()
template <typename LayerType>
static void AssertValidPropertyTreeIndices(LayerType* layer) {
  DCHECK(layer);
  DCHECK_NE(layer->transform_tree_index(), TransformTree::kInvalidNodeId);
  DCHECK_NE(layer->effect_tree_index(), EffectTree::kInvalidNodeId);
  DCHECK_NE(layer->clip_tree_index(), ClipTree::kInvalidNodeId);
  DCHECK_NE(layer->scroll_tree_index(), ScrollTree::kInvalidNodeId);
}

static bool LayerHasValidPropertyTreeIndices(LayerImpl* layer) {
  DCHECK(layer);
  return layer->transform_tree_index() != TransformTree::kInvalidNodeId &&
         layer->effect_tree_index() != EffectTree::kInvalidNodeId &&
         layer->clip_tree_index() != ClipTree::kInvalidNodeId &&
         layer->scroll_tree_index() != ScrollTree::kInvalidNodeId;
}

static bool LayerWillPushProperties(LayerTreeHost* host, Layer* layer) {
  return base::ContainsKey(host->LayersThatShouldPushProperties(), layer);
}

static bool LayerWillPushProperties(LayerTreeImpl* tree, LayerImpl* layer) {
  return base::ContainsKey(tree->LayersThatShouldPushProperties(), layer) ||
         // TODO(crbug.com/303943): Stop always pushing PictureLayerImpl
         // properties.
         base::ContainsValue(tree->picture_layers(), layer);
}
#endif

template <typename LayerType>
std::unique_ptr<LayerImpl> ReuseOrCreateLayerImpl(OwnedLayerImplMap* old_layers,
                                                  LayerType* layer,
                                                  LayerTreeImpl* tree_impl) {
  if (!layer)
    return nullptr;
  std::unique_ptr<LayerImpl> layer_impl = std::move((*old_layers)[layer->id()]);
  if (!layer_impl)
    layer_impl = layer->CreateLayerImpl(tree_impl);
  return layer_impl;
}

template <typename LayerTreeType>
void PushLayerList(OwnedLayerImplMap* old_layers,
                   LayerTreeType* host,
                   LayerTreeImpl* tree_impl) {
  tree_impl->ClearLayerList();
  for (auto* layer : *host) {
    std::unique_ptr<LayerImpl> layer_impl(
        ReuseOrCreateLayerImpl(old_layers, layer, tree_impl));

#if DCHECK_IS_ON()
    // Every layer should have valid property tree indices
    AssertValidPropertyTreeIndices(layer);
    // Every layer_impl should either have valid property tree indices already
    // or the corresponding layer should push them onto layer_impl.
    DCHECK(LayerHasValidPropertyTreeIndices(layer_impl.get()) ||
           LayerWillPushProperties(host, layer));
#endif

    tree_impl->AddToLayerList(layer_impl.get());
    tree_impl->AddLayer(std::move(layer_impl));
  }
  tree_impl->OnCanDrawStateChangedForTree();
}

template <typename LayerTreeType>
void PushElementsInPropertyTreesTo(LayerTreeType* host,
                                   LayerTreeImpl* tree_impl) {
  for (auto id_iter = tree_impl->elements_in_property_trees().begin();
       id_iter != tree_impl->elements_in_property_trees().end();) {
    const auto& id = *(id_iter++);
    if (!host->elements_in_property_trees().count(id))
      tree_impl->RemoveFromElementPropertyTreeList(id);
  }

  for (const auto& id : host->elements_in_property_trees()) {
    if (!tree_impl->IsElementInPropertyTree(id)) {
      // TODO(flackr): We should expose adding element ids without a
      // layer pointer.
      tree_impl->AddToElementPropertyTreeList(id);
    }
  }
}

template <typename LayerTreeType>
void SynchronizeTreesInternal(LayerTreeType* source_tree,
                              LayerTreeImpl* tree_impl,
                              PropertyTrees* property_trees) {
  DCHECK(tree_impl);

  TRACE_EVENT0("cc", "TreeSynchronizer::SynchronizeTrees");
  std::unique_ptr<OwnedLayerImplList> old_layers(tree_impl->DetachLayers());

  OwnedLayerImplMap old_layer_map;
  for (auto& it : *old_layers) {
    DCHECK(it);
    old_layer_map[it->id()] = std::move(it);
  }

  PushLayerList(&old_layer_map, source_tree, tree_impl);

  for (int id : property_trees->effect_tree.mask_layer_ids()) {
    std::unique_ptr<LayerImpl> layer_impl(ReuseOrCreateLayerImpl(
        &old_layer_map, source_tree->LayerById(id), tree_impl));
    tree_impl->AddLayer(std::move(layer_impl));
  }
}

}  // namespace

void TreeSynchronizer::SynchronizeTrees(Layer* layer_root,
                                        LayerTreeImpl* tree_impl) {
  if (!layer_root) {
    tree_impl->DetachLayers();
  } else {
    SynchronizeTreesInternal(layer_root->layer_tree_host(), tree_impl,
                             layer_root->layer_tree_host()->property_trees());
  }
}

void TreeSynchronizer::SynchronizeTrees(LayerTreeImpl* pending_tree,
                                        LayerTreeImpl* active_tree) {
  if (pending_tree->LayerListIsEmpty()) {
    active_tree->DetachLayers();
  } else {
    SynchronizeTreesInternal(pending_tree, active_tree,
                             pending_tree->property_trees());
  }
}

template <typename Iterator>
static void PushLayerPropertiesInternal(Iterator source_layers_begin,
                                        Iterator source_layers_end,
                                        LayerTreeHost* host_tree,
                                        LayerTreeImpl* target_impl_tree) {
  for (Iterator it = source_layers_begin; it != source_layers_end; ++it) {
    auto* source_layer = *it;
    LayerImpl* target_layer = target_impl_tree->LayerById(source_layer->id());
    DCHECK(target_layer);
    // TODO(enne): http://crbug.com/918126 debugging
    CHECK(source_layer);
    if (!target_layer) {
      bool host_set_on_source = source_layer->layer_tree_host() == host_tree;

      bool source_found_by_iterator = false;
      for (auto it = host_tree->begin(); it != host_tree->end(); ++it) {
        if (*it == source_layer) {
          source_found_by_iterator = true;
          break;
        }
      }

      bool root_layer_valid = !!host_tree->root_layer();
      bool found_root = false;
      Layer* layer = source_layer;
      while (layer) {
        if (layer == host_tree->root_layer()) {
          found_root = true;
          break;
        }
        layer = layer->parent();
      }

      auto str = base::StringPrintf(
          "hs: %d, sf: %d, rlv: %d, fr: %d", host_set_on_source,
          source_found_by_iterator, root_layer_valid, found_root);
      static auto* crash_key = base::debug::AllocateCrashKeyString(
          "cc_null_layer_sync", base::debug::CrashKeySize::Size32);
      base::debug::SetCrashKeyString(crash_key, str);
      base::debug::DumpWithoutCrashing();
    }
    source_layer->PushPropertiesTo(target_layer);
  }
}

template <typename Iterator>
static void PushLayerPropertiesInternal(Iterator source_layers_begin,
                                        Iterator source_layers_end,
                                        LayerTreeImpl* target_impl_tree) {
  for (Iterator it = source_layers_begin; it != source_layers_end; ++it) {
    auto* source_layer = *it;
    LayerImpl* target_layer = target_impl_tree->LayerById(source_layer->id());
    DCHECK(target_layer);
    source_layer->PushPropertiesTo(target_layer);
  }
}

void TreeSynchronizer::PushLayerProperties(LayerTreeImpl* pending_tree,
                                           LayerTreeImpl* active_tree) {
  const auto& layers = pending_tree->LayersThatShouldPushProperties();
  // TODO(crbug.com/303943): Stop always pushing PictureLayerImpl properties.
  const auto& picture_layers = pending_tree->picture_layers();
  TRACE_EVENT1("cc", "TreeSynchronizer::PushLayerPropertiesTo.Impl",
               "layer_count", layers.size() + picture_layers.size());
  PushLayerPropertiesInternal(layers.begin(), layers.end(), active_tree);
  PushLayerPropertiesInternal(picture_layers.begin(), picture_layers.end(),
                              active_tree);
  if (pending_tree->settings().use_layer_lists)
    PushElementsInPropertyTreesTo(pending_tree, active_tree);
  pending_tree->ClearLayersThatShouldPushProperties();
}

void TreeSynchronizer::PushLayerProperties(LayerTreeHost* host_tree,
                                           LayerTreeImpl* impl_tree) {
  auto layers = host_tree->LayersThatShouldPushProperties();
  TRACE_EVENT1("cc", "TreeSynchronizer::PushLayerPropertiesTo.Main",
               "layer_count", layers.size());
  PushLayerPropertiesInternal(layers.begin(), layers.end(), host_tree,
                              impl_tree);
  // When using layer lists, we may not have layers for all property tree
  // node ids and need to synchronize the registered id list.
  if (host_tree->IsUsingLayerLists())
    PushElementsInPropertyTreesTo(host_tree, impl_tree);
  host_tree->ClearLayersThatShouldPushProperties();
}

}  // namespace cc