sync/syncable/parent_child_index.cc

   1 // Copyright (c) 2012 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 "sync/syncable/parent_child_index.h"
   6
   7 #include "base/stl_util.h"
   8
   9 #include "sync/syncable/entry_kernel.h"
  10 #include "sync/syncable/syncable_id.h"
  11
  12 namespace syncer {
  13 namespace syncable {
  14
  15 bool ChildComparator::operator()(const EntryKernel* a,
  16                                  const EntryKernel* b) const {
  17   const UniquePosition& a_pos = a->ref(UNIQUE_POSITION);
  18   const UniquePosition& b_pos = b->ref(UNIQUE_POSITION);
  19
  20   if (a_pos.IsValid() && b_pos.IsValid()) {
  21     // Position is important to this type.
  22     return a_pos.LessThan(b_pos);
  23   } else if (a_pos.IsValid() && !b_pos.IsValid()) {
  24     // TODO(rlarocque): Remove this case.
  25     // An item with valid position as sibling of one with invalid position.
  26     // We should not support this, but the tests rely on it.  For now, just
  27     // move all invalid position items to the right.
  28     return true;
  29   } else if (!a_pos.IsValid() && b_pos.IsValid()) {
  30     // TODO(rlarocque): Remove this case.
  31     // Mirror of the above case.
  32     return false;
  33   } else {
  34     // Position doesn't matter.
  35     DCHECK(!a->ref(UNIQUE_POSITION).IsValid());
  36     DCHECK(!b->ref(UNIQUE_POSITION).IsValid());
  37     // Sort by META_HANDLE to ensure consistent order for testing.
  38     return a->ref(META_HANDLE) < b->ref(META_HANDLE);
  39   }
  40 }
  41
  42 ParentChildIndex::ParentChildIndex() {
  43   // Pre-allocate these two vectors to the number of model types.
  44   model_type_root_ids_.resize(MODEL_TYPE_COUNT);
  45   type_root_child_sets_.resize(MODEL_TYPE_COUNT);
  46 }
  47
  48 ParentChildIndex::~ParentChildIndex() {
  49   for (int i = 0; i < MODEL_TYPE_COUNT; i++) {
  50     // Normally all OrderedChildSet instances in |type_root_child_sets_|
  51     // are shared with |parent_children_map_|. Null out shared instances and
  52     // ScopedVector will take care of the ones that are not shared (if any).
  53     if (!model_type_root_ids_[i].IsNull()) {
  54       DCHECK_EQ(type_root_child_sets_[i],
  55                 parent_children_map_.find(model_type_root_ids_[i])->second);
  56       type_root_child_sets_[i] = nullptr;
  57     }
  58   }
  59
  60   STLDeleteContainerPairSecondPointers(parent_children_map_.begin(),
  61                                        parent_children_map_.end());
  62 }
  63
  64 bool ParentChildIndex::ShouldInclude(const EntryKernel* entry) {
  65   // This index excludes deleted items and the root item.  The root
  66   // item is excluded so that it doesn't show up as a child of itself.
  67   return !entry->ref(IS_DEL) && !entry->ref(ID).IsRoot();
  68 }
  69
  70 bool ParentChildIndex::Insert(EntryKernel* entry) {
  71   DCHECK(ShouldInclude(entry));
  72
  73   OrderedChildSet* siblings = nullptr;
  74   const Id& parent_id = entry->ref(PARENT_ID);
  75   ModelType model_type = entry->GetModelType();
  76
  77   if (ShouldUseParentId(parent_id, model_type)) {
  78     // Hierarchical type, lookup child set in the map.
  79     DCHECK(!parent_id.IsNull());
  80     ParentChildrenMap::iterator it = parent_children_map_.find(parent_id);
  81     if (it != parent_children_map_.end()) {
  82       siblings = it->second;
  83     } else {
  84       siblings = new OrderedChildSet();
  85       parent_children_map_.insert(std::make_pair(parent_id, siblings));
  86     }
  87   } else {
  88     // Non-hierarchical type, return a pre-defined collection by type.
  89     siblings = GetOrCreateModelTypeChildSet(model_type);
  90   }
  91
  92   // If this is one of type root folder for a non-hierarchical type, associate
  93   // its ID with the model type and the type's pre-defined child set with the
  94   // type root ID.
  95   // TODO(stanisc): crbug/438313: Just TypeSupportsHierarchy condition should
  96   // theoretically be sufficient but in practice many tests don't properly
  97   // initialize entries so TypeSupportsHierarchy ends up failing. Consider
  98   // tweaking TypeSupportsHierarchy and fixing all related test code.
  99   if (parent_id.IsRoot() && entry->ref(IS_DIR) &&
 100       syncer::IsRealDataType(model_type) &&
 101       !TypeSupportsHierarchy(model_type)) {
 102     const Id& type_root_id = entry->ref(ID);
 103     // Disassociate the type root child set with the previous ID if any.
 104     const Id& prev_type_root_id = model_type_root_ids_[model_type];
 105     if (!prev_type_root_id.IsNull()) {
 106       ParentChildrenMap::iterator it =
 107           parent_children_map_.find(prev_type_root_id);
 108       if (it != parent_children_map_.end()) {
 109         // If the entry exists in the map it must already have the same
 110         // model type specific child set. This child set will be re-inserted
 111         // in the map under the new ID below so it is safe to simply erase
 112         // the entry here.
 113         DCHECK_EQ(it->second, GetModelTypeChildSet(model_type));
 114         parent_children_map_.erase(it);
 115       }
 116     }
 117     // Store the new type root ID and associate the child set.
 118     // Note that the child set isn't owned by the map in this case.
 119     model_type_root_ids_[model_type] = type_root_id;
 120     parent_children_map_.insert(
 121         std::make_pair(type_root_id, GetOrCreateModelTypeChildSet(model_type)));
 122   }
 123
 124   // Finally, insert the entry in the child set.
 125   return siblings->insert(entry).second;
 126 }
 127
 128 // Like the other containers used to help support the syncable::Directory, this
 129 // one does not own any EntryKernels.  This function removes references to the
 130 // given EntryKernel but does not delete it.
 131 void ParentChildIndex::Remove(EntryKernel* e) {
 132   OrderedChildSet* siblings = nullptr;
 133   ModelType model_type = e->GetModelType();
 134   const Id& parent_id = e->ref(PARENT_ID);
 135   bool should_erase = false;
 136   ParentChildrenMap::iterator it;
 137
 138   if (ShouldUseParentId(parent_id, model_type)) {
 139     // Hierarchical type, lookup child set in the map.
 140     DCHECK(!parent_id.IsNull());
 141     it = parent_children_map_.find(parent_id);
 142     DCHECK(it != parent_children_map_.end());
 143     siblings = it->second;
 144     should_erase = true;
 145   } else {
 146     // Non-hierarchical type, return a pre-defined child set by type.
 147     siblings = type_root_child_sets_[model_type];
 148   }
 149
 150   OrderedChildSet::iterator j = siblings->find(e);
 151   DCHECK(j != siblings->end());
 152
 153   // Erase the entry from the child set.
 154   siblings->erase(j);
 155   // If the set is now empty and isn't shareable with |type_root_child_sets_|,
 156   // erase it from the map.
 157   if (siblings->empty() && should_erase) {
 158     delete siblings;
 159     parent_children_map_.erase(it);
 160   }
 161 }
 162
 163 bool ParentChildIndex::Contains(EntryKernel *e) const {
 164   const OrderedChildSet* siblings = GetChildSet(e);
 165   return siblings && siblings->count(e) > 0;
 166 }
 167
 168 const OrderedChildSet* ParentChildIndex::GetChildren(const Id& id) const {
 169   DCHECK(!id.IsNull());
 170
 171   ParentChildrenMap::const_iterator parent = parent_children_map_.find(id);
 172   if (parent == parent_children_map_.end()) {
 173     return nullptr;
 174   }
 175
 176   OrderedChildSet* children = parent->second;
 177   // The expectation is that the function returns nullptr instead of an empty
 178   // child set
 179   if (children && children->empty())
 180     children = nullptr;
 181   return children;
 182 }
 183
 184 const OrderedChildSet* ParentChildIndex::GetChildren(EntryKernel* e) const {
 185   return GetChildren(e->ref(ID));
 186 }
 187
 188 const OrderedChildSet* ParentChildIndex::GetSiblings(EntryKernel* e) const {
 189   // This implies the entry is in the index.
 190   DCHECK(Contains(e));
 191   const OrderedChildSet* siblings = GetChildSet(e);
 192   DCHECK(siblings && !siblings->empty());
 193   return siblings;
 194 }
 195
 196 /* static */
 197 bool ParentChildIndex::ShouldUseParentId(const Id& parent_id,
 198                                          ModelType model_type) {
 199   // For compatibility with legacy unit tests, in addition to hierarchical
 200   // entries, this returns true any entries directly under root and for entries
 201   // of UNSPECIFIED model type.
 202   return parent_id.IsRoot() || TypeSupportsHierarchy(model_type) ||
 203          !syncer::IsRealDataType(model_type);
 204 }
 205
 206 const OrderedChildSet* ParentChildIndex::GetChildSet(EntryKernel* e) const {
 207   ModelType model_type = e->GetModelType();
 208
 209   const Id& parent_id = e->ref(PARENT_ID);
 210   if (ShouldUseParentId(parent_id, model_type)) {
 211     // Hierarchical type, lookup child set in the map.
 212     ParentChildrenMap::const_iterator it = parent_children_map_.find(parent_id);
 213     if (it == parent_children_map_.end())
 214       return nullptr;
 215     return it->second;
 216   }
 217
 218   // Non-hierarchical type, return a collection indexed by type.
 219   return GetModelTypeChildSet(model_type);
 220 }
 221
 222 const OrderedChildSet* ParentChildIndex::GetModelTypeChildSet(
 223     ModelType model_type) const {
 224   return type_root_child_sets_[model_type];
 225 }
 226
 227 OrderedChildSet* ParentChildIndex::GetOrCreateModelTypeChildSet(
 228     ModelType model_type) {
 229   if (!type_root_child_sets_[model_type])
 230     type_root_child_sets_[model_type] = new OrderedChildSet();
 231   return type_root_child_sets_[model_type];
 232 }
 233
 234 const Id& ParentChildIndex::GetModelTypeRootId(ModelType model_type) const {
 235   return model_type_root_ids_[model_type];
 236 }
 237
 238 }  // namespace syncable
 239 }  // namespace syncer