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();
  93        ++it) {
  94     paired_queues_.push_back(
  95         make_scoped_ptr(new PairedTilingSetQueue(*it, tree_priority_)));
  96   }
  97
  98   paired_queues_.make_heap(EvictionOrderComparator(tree_priority_));
  99 }
 100
 101 bool EvictionTilePriorityQueue::IsEmpty() const {
 102   return paired_queues_.empty() || paired_queues_.front()->IsEmpty();
 103 }
 104
 105 Tile* EvictionTilePriorityQueue::Top() {
 106   DCHECK(!IsEmpty());
 107   return paired_queues_.front()->Top();
 108 }
 109
 110 void EvictionTilePriorityQueue::Pop() {
 111   DCHECK(!IsEmpty());
 112
 113   paired_queues_.pop_heap(EvictionOrderComparator(tree_priority_));
 114   PairedTilingSetQueue* paired_queue = paired_queues_.back();
 115   paired_queue->Pop();
 116   paired_queues_.push_heap(EvictionOrderComparator(tree_priority_));
 117 }
 118
 119 EvictionTilePriorityQueue::PairedTilingSetQueue::PairedTilingSetQueue() {
 120 }
 121
 122 EvictionTilePriorityQueue::PairedTilingSetQueue::PairedTilingSetQueue(
 123     const PictureLayerImpl::Pair& layer_pair,
 124     TreePriority tree_priority) {
 125   bool skip_shared_out_of_order_tiles = layer_pair.active && layer_pair.pending;
 126   if (layer_pair.active) {
 127     active_queue = make_scoped_ptr(new TilingSetEvictionQueue(
 128         layer_pair.active->picture_layer_tiling_set(), tree_priority,
 129         skip_shared_out_of_order_tiles));
 130   }
 131   if (layer_pair.pending) {
 132     pending_queue = make_scoped_ptr(new TilingSetEvictionQueue(
 133         layer_pair.pending->picture_layer_tiling_set(), tree_priority,
 134         skip_shared_out_of_order_tiles));
 135   }
 136 }
 137
 138 EvictionTilePriorityQueue::PairedTilingSetQueue::~PairedTilingSetQueue() {
 139 }
 140
 141 bool EvictionTilePriorityQueue::PairedTilingSetQueue::IsEmpty() const {
 142   return (!active_queue || active_queue->IsEmpty()) &&
 143          (!pending_queue || pending_queue->IsEmpty());
 144 }
 145
 146 Tile* EvictionTilePriorityQueue::PairedTilingSetQueue::Top() {
 147   DCHECK(!IsEmpty());
 148
 149   WhichTree next_tree = NextTileIteratorTree();
 150   TilingSetEvictionQueue* next_queue =
 151       next_tree == ACTIVE_TREE ? active_queue.get() : pending_queue.get();
 152   DCHECK(next_queue && !next_queue->IsEmpty());
 153
 154   Tile* tile = next_queue->Top();
 155   DCHECK(returned_tiles_for_debug.find(tile) == returned_tiles_for_debug.end());
 156   return tile;
 157 }
 158
 159 void EvictionTilePriorityQueue::PairedTilingSetQueue::Pop() {
 160   DCHECK(!IsEmpty());
 161
 162   WhichTree next_tree = NextTileIteratorTree();
 163   TilingSetEvictionQueue* next_queue =
 164       next_tree == ACTIVE_TREE ? active_queue.get() : pending_queue.get();
 165   DCHECK(next_queue && !next_queue->IsEmpty());
 166   DCHECK(returned_tiles_for_debug.insert(next_queue->Top()).second);
 167   next_queue->Pop();
 168
 169   // If not empty, use Top to DCHECK the next iterator.
 170   DCHECK_IMPLIES(!IsEmpty(), Top());
 171 }
 172
 173 WhichTree
 174 EvictionTilePriorityQueue::PairedTilingSetQueue::NextTileIteratorTree() const {
 175   DCHECK(!IsEmpty());
 176
 177   // If we only have one iterator with tiles, return it.
 178   if (!active_queue || active_queue->IsEmpty())
 179     return PENDING_TREE;
 180   if (!pending_queue || pending_queue->IsEmpty())
 181     return ACTIVE_TREE;
 182
 183   const Tile* active_tile = active_queue->Top();
 184   const Tile* pending_tile = pending_queue->Top();
 185
 186   // If tiles are the same, it doesn't matter which tree we return.
 187   if (active_tile == pending_tile)
 188     return ACTIVE_TREE;
 189
 190   const TilePriority& active_priority = active_tile->combined_priority();
 191   const TilePriority& pending_priority = pending_tile->combined_priority();
 192
 193   // If the bins are the same and activation differs, then return the tree of
 194   // the tile not required for activation.
 195   if (active_priority.priority_bin == pending_priority.priority_bin &&
 196       active_tile->required_for_activation() !=
 197           pending_tile->required_for_activation()) {
 198     return active_tile->required_for_activation() ? PENDING_TREE : ACTIVE_TREE;
 199   }
 200
 201   // Return tile with a lower priority.
 202   if (pending_priority.IsHigherPriorityThan(active_priority))
 203     return ACTIVE_TREE;
 204   return PENDING_TREE;
 205 }
 206
 207 }  // namespace cc