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(tree_priority_);
  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(tree_priority_);
  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 =
  37         a_tile->priority_for_tree_priority(tree_priority_);
  38     const TilePriority& b_priority =
  39         b_tile->priority_for_tree_priority(tree_priority_);
  40     bool prioritize_low_res = tree_priority_ == SMOOTHNESS_TAKES_PRIORITY;
  41
  42     // If the priority bin differs, b is lower priority if it has the higher
  43     // priority bin.
  44     if (a_priority.priority_bin != b_priority.priority_bin)
  45       return b_priority.priority_bin > a_priority.priority_bin;
  46
  47     // Otherwise if the resolution differs, then the order will be determined by
  48     // whether we prioritize low res or not.
  49     // TODO(vmpstr): Remove this when TilePriority is no longer a member of Tile
  50     // class but instead produced by the iterators.
  51     if (b_priority.resolution != a_priority.resolution) {
  52       // Non ideal resolution should be sorted higher than other resolutions.
  53       if (a_priority.resolution == NON_IDEAL_RESOLUTION)
  54         return false;
  55
  56       if (b_priority.resolution == NON_IDEAL_RESOLUTION)
  57         return true;
  58
  59       if (prioritize_low_res)
  60         return a_priority.resolution == LOW_RESOLUTION;
  61       return a_priority.resolution == HIGH_RESOLUTION;
  62     }
  63
  64     // Otherwise if the occlusion differs, b is lower priority if it is
  65     // occluded.
  66     bool a_is_occluded = a_tile->is_occluded_for_tree_priority(tree_priority_);
  67     bool b_is_occluded = b_tile->is_occluded_for_tree_priority(tree_priority_);
  68     if (a_is_occluded != b_is_occluded)
  69       return b_is_occluded;
  70
  71     // b is lower priorty if it is farther from visible.
  72     return b_priority.distance_to_visible > a_priority.distance_to_visible;
  73   }
  74
  75  private:
  76   TreePriority tree_priority_;
  77 };
  78
  79 }  // namespace
  80
  81 EvictionTilePriorityQueue::EvictionTilePriorityQueue() {
  82 }
  83
  84 EvictionTilePriorityQueue::~EvictionTilePriorityQueue() {
  85 }
  86
  87 void EvictionTilePriorityQueue::Build(
  88     const std::vector<PictureLayerImpl::Pair>& paired_layers,
  89     TreePriority tree_priority) {
  90   tree_priority_ = tree_priority;
  91
  92   for (std::vector<PictureLayerImpl::Pair>::const_iterator it =
  93            paired_layers.begin();
  94        it != paired_layers.end();
  95        ++it) {
  96     paired_queues_.push_back(
  97         make_scoped_ptr(new PairedTilingSetQueue(*it, tree_priority_)));
  98   }
  99
 100   paired_queues_.make_heap(EvictionOrderComparator(tree_priority_));
 101 }
 102
 103 bool EvictionTilePriorityQueue::IsEmpty() const {
 104   return paired_queues_.empty() || paired_queues_.front()->IsEmpty();
 105 }
 106
 107 Tile* EvictionTilePriorityQueue::Top() {
 108   DCHECK(!IsEmpty());
 109   return paired_queues_.front()->Top(tree_priority_);
 110 }
 111
 112 void EvictionTilePriorityQueue::Pop() {
 113   DCHECK(!IsEmpty());
 114
 115   paired_queues_.pop_heap(EvictionOrderComparator(tree_priority_));
 116   PairedTilingSetQueue* paired_queue = paired_queues_.back();
 117   paired_queue->Pop(tree_priority_);
 118   paired_queues_.push_heap(EvictionOrderComparator(tree_priority_));
 119 }
 120
 121 EvictionTilePriorityQueue::PairedTilingSetQueue::PairedTilingSetQueue() {
 122 }
 123
 124 EvictionTilePriorityQueue::PairedTilingSetQueue::PairedTilingSetQueue(
 125     const PictureLayerImpl::Pair& layer_pair,
 126     TreePriority tree_priority) {
 127   bool skip_shared_out_of_order_tiles = layer_pair.active && layer_pair.pending;
 128   if (layer_pair.active) {
 129     active_queue = make_scoped_ptr(new TilingSetEvictionQueue(
 130         layer_pair.active->picture_layer_tiling_set(), tree_priority,
 131         skip_shared_out_of_order_tiles));
 132   }
 133   if (layer_pair.pending) {
 134     pending_queue = make_scoped_ptr(new TilingSetEvictionQueue(
 135         layer_pair.pending->picture_layer_tiling_set(), tree_priority,
 136         skip_shared_out_of_order_tiles));
 137   }
 138 }
 139
 140 EvictionTilePriorityQueue::PairedTilingSetQueue::~PairedTilingSetQueue() {
 141 }
 142
 143 bool EvictionTilePriorityQueue::PairedTilingSetQueue::IsEmpty() const {
 144   return (!active_queue || active_queue->IsEmpty()) &&
 145          (!pending_queue || pending_queue->IsEmpty());
 146 }
 147
 148 Tile* EvictionTilePriorityQueue::PairedTilingSetQueue::Top(
 149     TreePriority tree_priority) {
 150   DCHECK(!IsEmpty());
 151
 152   WhichTree next_tree = NextTileIteratorTree(tree_priority);
 153   TilingSetEvictionQueue* next_queue =
 154       next_tree == ACTIVE_TREE ? active_queue.get() : pending_queue.get();
 155   DCHECK(next_queue && !next_queue->IsEmpty());
 156
 157   Tile* tile = next_queue->Top();
 158   DCHECK(returned_tiles_for_debug.find(tile) == returned_tiles_for_debug.end());
 159   return tile;
 160 }
 161
 162 void EvictionTilePriorityQueue::PairedTilingSetQueue::Pop(
 163     TreePriority tree_priority) {
 164   DCHECK(!IsEmpty());
 165
 166   WhichTree next_tree = NextTileIteratorTree(tree_priority);
 167   TilingSetEvictionQueue* next_queue =
 168       next_tree == ACTIVE_TREE ? active_queue.get() : pending_queue.get();
 169   DCHECK(next_queue && !next_queue->IsEmpty());
 170   DCHECK(returned_tiles_for_debug.insert(next_queue->Top()).second);
 171   next_queue->Pop();
 172
 173   // If not empty, use Top to DCHECK the next iterator.
 174   DCHECK_IMPLIES(!IsEmpty(), Top(tree_priority));
 175 }
 176
 177 WhichTree
 178 EvictionTilePriorityQueue::PairedTilingSetQueue::NextTileIteratorTree(
 179     TreePriority tree_priority) const {
 180   DCHECK(!IsEmpty());
 181
 182   // If we only have one iterator with tiles, return it.
 183   if (!active_queue || active_queue->IsEmpty())
 184     return PENDING_TREE;
 185   if (!pending_queue || pending_queue->IsEmpty())
 186     return ACTIVE_TREE;
 187
 188   const Tile* active_tile = active_queue->Top();
 189   const Tile* pending_tile = pending_queue->Top();
 190
 191   // If tiles are the same, it doesn't matter which tree we return.
 192   if (active_tile == pending_tile)
 193     return ACTIVE_TREE;
 194
 195   const TilePriority& active_priority =
 196       active_tile->priority_for_tree_priority(tree_priority);
 197   const TilePriority& pending_priority =
 198       pending_tile->priority_for_tree_priority(tree_priority);
 199
 200   // If the bins are the same and activation differs, then return the tree of
 201   // the tile not required for activation.
 202   if (active_priority.priority_bin == pending_priority.priority_bin &&
 203       active_tile->required_for_activation() !=
 204           pending_tile->required_for_activation()) {
 205     return active_tile->required_for_activation() ? PENDING_TREE : ACTIVE_TREE;
 206   }
 207
 208   // Return tile with a lower priority.
 209   if (pending_priority.IsHigherPriorityThan(active_priority))
 210     return ACTIVE_TREE;
 211   return PENDING_TREE;
 212 }
 213
 214 }  // namespace cc