cc/resources/eviction_tile_priority_queue.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/resources/eviction_tile_priority_queue.h"
   6
   7 namespace cc {
   8
   9 namespace {
  10
  11 class EvictionOrderComparator {
  12  public:
  13   explicit EvictionOrderComparator(TreePriority tree_priority)
  14       : tree_priority_(tree_priority) {}
  15
  16   bool operator()(
  17       const EvictionTilePriorityQueue::PairedTilingSetQueue* a,
  18       const EvictionTilePriorityQueue::PairedTilingSetQueue* b) const {
  19     // Note that in this function, we have to return true if and only if
  20     // b is strictly lower priority than a. Note that for the sake of
  21     // completeness, empty queue is considered to have lowest priority.
  22     if (a->IsEmpty() || b->IsEmpty())
  23       return b->IsEmpty() < a->IsEmpty();
  24
  25     WhichTree a_tree = a->NextTileIteratorTree();
  26     const TilingSetEvictionQueue* a_queue =
  27         a_tree == ACTIVE_TREE ? a->active_queue.get() : a->pending_queue.get();
  28
  29     WhichTree b_tree = b->NextTileIteratorTree();
  30     const TilingSetEvictionQueue* b_queue =
  31         b_tree == ACTIVE_TREE ? b->active_queue.get() : b->pending_queue.get();
  32
  33     const Tile* a_tile = a_queue->Top();
  34     const Tile* b_tile = b_queue->Top();
  35
  36     const TilePriority& a_priority = a_tile->combined_priority();
  37     const TilePriority& b_priority = b_tile->combined_priority();
  38     bool prioritize_low_res = tree_priority_ == SMOOTHNESS_TAKES_PRIORITY;
  39
  40     // If the priority bin differs, b is lower priority if it has the higher
  41     // priority bin.
  42     if (a_priority.priority_bin != b_priority.priority_bin)
  43       return b_priority.priority_bin > a_priority.priority_bin;
  44
  45     // Otherwise if the resolution differs, then the order will be determined by
  46     // whether we prioritize low res or not.
  47     // TODO(vmpstr): Remove this when TilePriority is no longer a member of Tile
  48     // class but instead produced by the iterators.
  49     if (b_priority.resolution != a_priority.resolution) {
  50       // Non ideal resolution should be sorted higher than other resolutions.
  51       if (a_priority.resolution == NON_IDEAL_RESOLUTION)
  52         return false;
  53
  54       if (b_priority.resolution == NON_IDEAL_RESOLUTION)
  55         return true;
  56
  57       if (prioritize_low_res)
  58         return a_priority.resolution == LOW_RESOLUTION;
  59       return a_priority.resolution == HIGH_RESOLUTION;
  60     }
  61
  62     // Otherwise if the occlusion differs, b is lower priority if it is
  63     // occluded.
  64     bool a_is_occluded = a_tile->is_occluded_combined();
  65     bool b_is_occluded = b_tile->is_occluded_combined();
  66     if (a_is_occluded != b_is_occluded)
  67       return b_is_occluded;
  68
  69     // b is lower priorty if it is farther from visible.
  70     return b_priority.distance_to_visible > a_priority.distance_to_visible;
  71   }
  72
  73  private:
  74   TreePriority tree_priority_;
  75 };
  76
  77 }  // namespace
  78
  79 EvictionTilePriorityQueue::EvictionTilePriorityQueue() {
  80 }
  81
  82 EvictionTilePriorityQueue::~EvictionTilePriorityQueue() {
  83 }
  84
  85 void EvictionTilePriorityQueue::Build(
  86     const std::vector<PictureLayerImpl::Pair>& paired_layers,
  87     TreePriority tree_priority) {
  88   tree_priority_ = tree_priority;
  89
  90   for (std::vector<PictureLayerImpl::Pair>::const_iterator it =
  91            paired_layers.begin();
  92        it != paired_layers.end(); ++it) {
  93     paired_queues_.push_back(make_scoped_ptr(new PairedTilingSetQueue(*it)));
  94   }
  95
  96   paired_queues_.make_heap(EvictionOrderComparator(tree_priority_));
  97 }
  98
  99 bool EvictionTilePriorityQueue::IsEmpty() const {
 100   return paired_queues_.empty() || paired_queues_.front()->IsEmpty();
 101 }
 102
 103 Tile* EvictionTilePriorityQueue::Top() {
 104   DCHECK(!IsEmpty());
 105   return paired_queues_.front()->Top();
 106 }
 107
 108 void EvictionTilePriorityQueue::Pop() {
 109   DCHECK(!IsEmpty());
 110
 111   paired_queues_.pop_heap(EvictionOrderComparator(tree_priority_));
 112   PairedTilingSetQueue* paired_queue = paired_queues_.back();
 113   paired_queue->Pop();
 114   paired_queues_.push_heap(EvictionOrderComparator(tree_priority_));
 115 }
 116
 117 EvictionTilePriorityQueue::PairedTilingSetQueue::PairedTilingSetQueue() {
 118 }
 119
 120 EvictionTilePriorityQueue::PairedTilingSetQueue::PairedTilingSetQueue(
 121     const PictureLayerImpl::Pair& layer_pair) {
 122   bool skip_shared_out_of_order_tiles = layer_pair.active && layer_pair.pending;
 123   if (layer_pair.active) {
 124     active_queue = make_scoped_ptr(new TilingSetEvictionQueue(
 125         layer_pair.active->picture_layer_tiling_set(),
 126         skip_shared_out_of_order_tiles));
 127   }
 128   if (layer_pair.pending) {
 129     pending_queue = make_scoped_ptr(new TilingSetEvictionQueue(
 130         layer_pair.pending->picture_layer_tiling_set(),
 131         skip_shared_out_of_order_tiles));
 132   }
 133 }
 134
 135 EvictionTilePriorityQueue::PairedTilingSetQueue::~PairedTilingSetQueue() {
 136 }
 137
 138 bool EvictionTilePriorityQueue::PairedTilingSetQueue::IsEmpty() const {
 139   return (!active_queue || active_queue->IsEmpty()) &&
 140          (!pending_queue || pending_queue->IsEmpty());
 141 }
 142
 143 Tile* EvictionTilePriorityQueue::PairedTilingSetQueue::Top() {
 144   DCHECK(!IsEmpty());
 145
 146   WhichTree next_tree = NextTileIteratorTree();
 147   TilingSetEvictionQueue* next_queue =
 148       next_tree == ACTIVE_TREE ? active_queue.get() : pending_queue.get();
 149   DCHECK(next_queue && !next_queue->IsEmpty());
 150
 151   Tile* tile = next_queue->Top();
 152   DCHECK(returned_tiles_for_debug.find(tile) == returned_tiles_for_debug.end());
 153   return tile;
 154 }
 155
 156 void EvictionTilePriorityQueue::PairedTilingSetQueue::Pop() {
 157   DCHECK(!IsEmpty());
 158
 159   WhichTree next_tree = NextTileIteratorTree();
 160   TilingSetEvictionQueue* next_queue =
 161       next_tree == ACTIVE_TREE ? active_queue.get() : pending_queue.get();
 162   DCHECK(next_queue && !next_queue->IsEmpty());
 163   DCHECK(returned_tiles_for_debug.insert(next_queue->Top()).second);
 164   next_queue->Pop();
 165
 166   // If not empty, use Top to DCHECK the next iterator.
 167   DCHECK_IMPLIES(!IsEmpty(), Top());
 168 }
 169
 170 WhichTree
 171 EvictionTilePriorityQueue::PairedTilingSetQueue::NextTileIteratorTree() const {
 172   DCHECK(!IsEmpty());
 173
 174   // If we only have one iterator with tiles, return it.
 175   if (!active_queue || active_queue->IsEmpty())
 176     return PENDING_TREE;
 177   if (!pending_queue || pending_queue->IsEmpty())
 178     return ACTIVE_TREE;
 179
 180   const Tile* active_tile = active_queue->Top();
 181   const Tile* pending_tile = pending_queue->Top();
 182
 183   // If tiles are the same, it doesn't matter which tree we return.
 184   if (active_tile == pending_tile)
 185     return ACTIVE_TREE;
 186
 187   const TilePriority& active_priority = active_tile->combined_priority();
 188   const TilePriority& pending_priority = pending_tile->combined_priority();
 189
 190   // If the bins are the same and activation differs, then return the tree of
 191   // the tile not required for activation.
 192   if (active_priority.priority_bin == pending_priority.priority_bin &&
 193       active_tile->required_for_activation() !=
 194           pending_tile->required_for_activation()) {
 195     return active_tile->required_for_activation() ? PENDING_TREE : ACTIVE_TREE;
 196   }
 197
 198   // Return tile with a lower priority.
 199   if (pending_priority.IsHigherPriorityThan(active_priority))
 200     return ACTIVE_TREE;
 201   return PENDING_TREE;
 202 }
 203
 204 }  // namespace cc