src/sync/syncable/directory.cc

   1 // Copyright 2013 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/directory.h"
   6
   7 #include <iterator>
   8
   9 #include "base/base64.h"
  10 #include "base/debug/trace_event.h"
  11 #include "base/stl_util.h"
  12 #include "base/strings/string_number_conversions.h"
  13 #include "sync/internal_api/public/base/unique_position.h"
  14 #include "sync/internal_api/public/util/unrecoverable_error_handler.h"
  15 #include "sync/syncable/entry.h"
  16 #include "sync/syncable/entry_kernel.h"
  17 #include "sync/syncable/in_memory_directory_backing_store.h"
  18 #include "sync/syncable/on_disk_directory_backing_store.h"
  19 #include "sync/syncable/scoped_kernel_lock.h"
  20 #include "sync/syncable/scoped_parent_child_index_updater.h"
  21 #include "sync/syncable/syncable-inl.h"
  22 #include "sync/syncable/syncable_base_transaction.h"
  23 #include "sync/syncable/syncable_changes_version.h"
  24 #include "sync/syncable/syncable_read_transaction.h"
  25 #include "sync/syncable/syncable_util.h"
  26 #include "sync/syncable/syncable_write_transaction.h"
  27
  28 using std::string;
  29
  30 namespace syncer {
  31 namespace syncable {
  32
  33 // static
  34 const base::FilePath::CharType Directory::kSyncDatabaseFilename[] =
  35     FILE_PATH_LITERAL("SyncData.sqlite3");
  36
  37 Directory::PersistedKernelInfo::PersistedKernelInfo()
  38     : next_id(0) {
  39   ModelTypeSet protocol_types = ProtocolTypes();
  40   for (ModelTypeSet::Iterator iter = protocol_types.First(); iter.Good();
  41        iter.Inc()) {
  42     reset_download_progress(iter.Get());
  43     transaction_version[iter.Get()] = 0;
  44   }
  45 }
  46
  47 Directory::PersistedKernelInfo::~PersistedKernelInfo() {}
  48
  49 void Directory::PersistedKernelInfo::reset_download_progress(
  50     ModelType model_type) {
  51   download_progress[model_type].set_data_type_id(
  52       GetSpecificsFieldNumberFromModelType(model_type));
  53   // An empty-string token indicates no prior knowledge.
  54   download_progress[model_type].set_token(std::string());
  55 }
  56
  57 Directory::SaveChangesSnapshot::SaveChangesSnapshot()
  58     : kernel_info_status(KERNEL_SHARE_INFO_INVALID) {
  59 }
  60
  61 Directory::SaveChangesSnapshot::~SaveChangesSnapshot() {
  62   STLDeleteElements(&dirty_metas);
  63   STLDeleteElements(&delete_journals);
  64 }
  65
  66 Directory::Kernel::Kernel(
  67     const std::string& name,
  68     const KernelLoadInfo& info, DirectoryChangeDelegate* delegate,
  69     const WeakHandle<TransactionObserver>& transaction_observer)
  70     : next_write_transaction_id(0),
  71       name(name),
  72       info_status(Directory::KERNEL_SHARE_INFO_VALID),
  73       persisted_info(info.kernel_info),
  74       cache_guid(info.cache_guid),
  75       next_metahandle(info.max_metahandle + 1),
  76       delegate(delegate),
  77       transaction_observer(transaction_observer) {
  78   DCHECK(delegate);
  79   DCHECK(transaction_observer.IsInitialized());
  80 }
  81
  82 Directory::Kernel::~Kernel() {
  83   STLDeleteContainerPairSecondPointers(metahandles_map.begin(),
  84                                        metahandles_map.end());
  85 }
  86
  87 Directory::Directory(
  88     DirectoryBackingStore* store,
  89     UnrecoverableErrorHandler* unrecoverable_error_handler,
  90     ReportUnrecoverableErrorFunction report_unrecoverable_error_function,
  91     NigoriHandler* nigori_handler,
  92     Cryptographer* cryptographer)
  93     : kernel_(NULL),
  94       store_(store),
  95       unrecoverable_error_handler_(unrecoverable_error_handler),
  96       report_unrecoverable_error_function_(
  97           report_unrecoverable_error_function),
  98       unrecoverable_error_set_(false),
  99       nigori_handler_(nigori_handler),
 100       cryptographer_(cryptographer),
 101       invariant_check_level_(VERIFY_CHANGES) {
 102 }
 103
 104 Directory::~Directory() {
 105   Close();
 106 }
 107
 108 DirOpenResult Directory::Open(
 109     const string& name,
 110     DirectoryChangeDelegate* delegate,
 111     const WeakHandle<TransactionObserver>& transaction_observer) {
 112   TRACE_EVENT0("sync", "SyncDatabaseOpen");
 113
 114   const DirOpenResult result =
 115       OpenImpl(name, delegate, transaction_observer);
 116
 117   if (OPENED != result)
 118     Close();
 119   return result;
 120 }
 121
 122 void Directory::InitializeIndices(MetahandlesMap* handles_map) {
 123   kernel_->metahandles_map.swap(*handles_map);
 124   for (MetahandlesMap::const_iterator it = kernel_->metahandles_map.begin();
 125        it != kernel_->metahandles_map.end(); ++it) {
 126     EntryKernel* entry = it->second;
 127     if (ParentChildIndex::ShouldInclude(entry))
 128       kernel_->parent_child_index.Insert(entry);
 129     const int64 metahandle = entry->ref(META_HANDLE);
 130     if (entry->ref(IS_UNSYNCED))
 131       kernel_->unsynced_metahandles.insert(metahandle);
 132     if (entry->ref(IS_UNAPPLIED_UPDATE)) {
 133       const ModelType type = entry->GetServerModelType();
 134       kernel_->unapplied_update_metahandles[type].insert(metahandle);
 135     }
 136     if (!entry->ref(UNIQUE_SERVER_TAG).empty()) {
 137       DCHECK(kernel_->server_tags_map.find(entry->ref(UNIQUE_SERVER_TAG)) ==
 138              kernel_->server_tags_map.end())
 139           << "Unexpected duplicate use of client tag";
 140       kernel_->server_tags_map[entry->ref(UNIQUE_SERVER_TAG)] = entry;
 141     }
 142     if (!entry->ref(UNIQUE_CLIENT_TAG).empty()) {
 143       DCHECK(kernel_->server_tags_map.find(entry->ref(UNIQUE_SERVER_TAG)) ==
 144              kernel_->server_tags_map.end())
 145           << "Unexpected duplicate use of server tag";
 146       kernel_->client_tags_map[entry->ref(UNIQUE_CLIENT_TAG)] = entry;
 147     }
 148     DCHECK(kernel_->ids_map.find(entry->ref(ID).value()) ==
 149            kernel_->ids_map.end()) << "Unexpected duplicate use of ID";
 150     kernel_->ids_map[entry->ref(ID).value()] = entry;
 151     DCHECK(!entry->is_dirty());
 152   }
 153 }
 154
 155 DirOpenResult Directory::OpenImpl(
 156     const string& name,
 157     DirectoryChangeDelegate* delegate,
 158     const WeakHandle<TransactionObserver>&
 159         transaction_observer) {
 160   KernelLoadInfo info;
 161   // Temporary indices before kernel_ initialized in case Load fails. We 0(1)
 162   // swap these later.
 163   Directory::MetahandlesMap tmp_handles_map;
 164   JournalIndex delete_journals;
 165
 166   DirOpenResult result =
 167       store_->Load(&tmp_handles_map, &delete_journals, &info);
 168   if (OPENED != result)
 169     return result;
 170
 171   kernel_ = new Kernel(name, info, delegate, transaction_observer);
 172   delete_journal_.reset(new DeleteJournal(&delete_journals));
 173   InitializeIndices(&tmp_handles_map);
 174
 175   // Write back the share info to reserve some space in 'next_id'.  This will
 176   // prevent local ID reuse in the case of an early crash.  See the comments in
 177   // TakeSnapshotForSaveChanges() or crbug.com/142987 for more information.
 178   kernel_->info_status = KERNEL_SHARE_INFO_DIRTY;
 179   if (!SaveChanges())
 180     return FAILED_INITIAL_WRITE;
 181
 182   return OPENED;
 183 }
 184
 185 DeleteJournal* Directory::delete_journal() {
 186   DCHECK(delete_journal_.get());
 187   return delete_journal_.get();
 188 }
 189
 190 void Directory::Close() {
 191   store_.reset();
 192   if (kernel_) {
 193     delete kernel_;
 194     kernel_ = NULL;
 195   }
 196 }
 197
 198 void Directory::OnUnrecoverableError(const BaseTransaction* trans,
 199                                      const tracked_objects::Location& location,
 200                                      const std::string & message) {
 201   DCHECK(trans != NULL);
 202   unrecoverable_error_set_ = true;
 203   unrecoverable_error_handler_->OnUnrecoverableError(location,
 204                                                      message);
 205 }
 206
 207 EntryKernel* Directory::GetEntryById(const Id& id) {
 208   ScopedKernelLock lock(this);
 209   return GetEntryById(id, &lock);
 210 }
 211
 212 EntryKernel* Directory::GetEntryById(const Id& id,
 213                                      ScopedKernelLock* const lock) {
 214   DCHECK(kernel_);
 215   // Find it in the in memory ID index.
 216   IdsMap::iterator id_found = kernel_->ids_map.find(id.value());
 217   if (id_found != kernel_->ids_map.end()) {
 218     return id_found->second;
 219   }
 220   return NULL;
 221 }
 222
 223 EntryKernel* Directory::GetEntryByClientTag(const string& tag) {
 224   ScopedKernelLock lock(this);
 225   DCHECK(kernel_);
 226
 227   TagsMap::iterator it = kernel_->client_tags_map.find(tag);
 228   if (it != kernel_->client_tags_map.end()) {
 229     return it->second;
 230   }
 231   return NULL;
 232 }
 233
 234 EntryKernel* Directory::GetEntryByServerTag(const string& tag) {
 235   ScopedKernelLock lock(this);
 236   DCHECK(kernel_);
 237   TagsMap::iterator it = kernel_->server_tags_map.find(tag);
 238   if (it != kernel_->server_tags_map.end()) {
 239     return it->second;
 240   }
 241   return NULL;
 242 }
 243
 244 EntryKernel* Directory::GetEntryByHandle(int64 metahandle) {
 245   ScopedKernelLock lock(this);
 246   return GetEntryByHandle(metahandle, &lock);
 247 }
 248
 249 EntryKernel* Directory::GetEntryByHandle(int64 metahandle,
 250                                          ScopedKernelLock* lock) {
 251   // Look up in memory
 252   MetahandlesMap::iterator found =
 253       kernel_->metahandles_map.find(metahandle);
 254   if (found != kernel_->metahandles_map.end()) {
 255     // Found it in memory.  Easy.
 256     return found->second;
 257   }
 258   return NULL;
 259 }
 260
 261 bool Directory::GetChildHandlesById(
 262     BaseTransaction* trans, const Id& parent_id,
 263     Directory::Metahandles* result) {
 264   if (!SyncAssert(this == trans->directory(), FROM_HERE,
 265                   "Directories don't match", trans))
 266     return false;
 267   result->clear();
 268
 269   ScopedKernelLock lock(this);
 270   AppendChildHandles(lock, parent_id, result);
 271   return true;
 272 }
 273
 274 bool Directory::GetChildHandlesByHandle(
 275     BaseTransaction* trans, int64 handle,
 276     Directory::Metahandles* result) {
 277   if (!SyncAssert(this == trans->directory(), FROM_HERE,
 278                   "Directories don't match", trans))
 279     return false;
 280
 281   result->clear();
 282
 283   ScopedKernelLock lock(this);
 284   EntryKernel* kernel = GetEntryByHandle(handle, &lock);
 285   if (!kernel)
 286     return true;
 287
 288   AppendChildHandles(lock, kernel->ref(ID), result);
 289   return true;
 290 }
 291
 292 int Directory::GetTotalNodeCount(
 293     BaseTransaction* trans,
 294     EntryKernel* kernel) const {
 295   if (!SyncAssert(this == trans->directory(), FROM_HERE,
 296                   "Directories don't match", trans))
 297     return false;
 298
 299   int count = 1;
 300   std::deque<const OrderedChildSet*> child_sets;
 301
 302   GetChildSetForKernel(trans, kernel, &child_sets);
 303   while (!child_sets.empty()) {
 304     const OrderedChildSet* set = child_sets.front();
 305     child_sets.pop_front();
 306     for (OrderedChildSet::const_iterator it = set->begin();
 307          it != set->end(); ++it) {
 308       count++;
 309       GetChildSetForKernel(trans, *it, &child_sets);
 310     }
 311   }
 312
 313   return count;
 314 }
 315
 316 void Directory::GetChildSetForKernel(
 317     BaseTransaction* trans,
 318     EntryKernel* kernel,
 319     std::deque<const OrderedChildSet*>* child_sets) const {
 320   if (!kernel->ref(IS_DIR))
 321     return;  // Not a directory => no children.
 322
 323   const OrderedChildSet* descendants =
 324       kernel_->parent_child_index.GetChildren(kernel->ref(ID));
 325   if (!descendants)
 326     return;  // This directory has no children.
 327
 328   // Add our children to the list of items to be traversed.
 329   child_sets->push_back(descendants);
 330 }
 331
 332 int Directory::GetPositionIndex(
 333     BaseTransaction* trans,
 334     EntryKernel* kernel) const {
 335   const OrderedChildSet* siblings =
 336       kernel_->parent_child_index.GetChildren(kernel->ref(PARENT_ID));
 337
 338   OrderedChildSet::const_iterator it = siblings->find(kernel);
 339   return std::distance(siblings->begin(), it);
 340 }
 341
 342 EntryKernel* Directory::GetRootEntry() {
 343   return GetEntryById(Id());
 344 }
 345
 346 bool Directory::InsertEntry(BaseWriteTransaction* trans, EntryKernel* entry) {
 347   ScopedKernelLock lock(this);
 348   return InsertEntry(trans, entry, &lock);
 349 }
 350
 351 bool Directory::InsertEntry(BaseWriteTransaction* trans,
 352                             EntryKernel* entry,
 353                             ScopedKernelLock* lock) {
 354   DCHECK(NULL != lock);
 355   if (!SyncAssert(NULL != entry, FROM_HERE, "Entry is null", trans))
 356     return false;
 357
 358   static const char error[] = "Entry already in memory index.";
 359
 360   if (!SyncAssert(
 361           kernel_->metahandles_map.insert(
 362               std::make_pair(entry->ref(META_HANDLE), entry)).second,
 363           FROM_HERE,
 364           error,
 365           trans)) {
 366     return false;
 367   }
 368   if (!SyncAssert(
 369           kernel_->ids_map.insert(
 370               std::make_pair(entry->ref(ID).value(), entry)).second,
 371           FROM_HERE,
 372           error,
 373           trans)) {
 374     return false;
 375   }
 376   if (ParentChildIndex::ShouldInclude(entry)) {
 377     if (!SyncAssert(kernel_->parent_child_index.Insert(entry),
 378                     FROM_HERE,
 379                     error,
 380                     trans)) {
 381       return false;
 382     }
 383   }
 384
 385   // Should NEVER be created with a client tag or server tag.
 386   if (!SyncAssert(entry->ref(UNIQUE_SERVER_TAG).empty(), FROM_HERE,
 387                   "Server tag should be empty", trans)) {
 388     return false;
 389   }
 390   if (!SyncAssert(entry->ref(UNIQUE_CLIENT_TAG).empty(), FROM_HERE,
 391                   "Client tag should be empty", trans))
 392     return false;
 393
 394   return true;
 395 }
 396
 397 bool Directory::ReindexId(BaseWriteTransaction* trans,
 398                           EntryKernel* const entry,
 399                           const Id& new_id) {
 400   ScopedKernelLock lock(this);
 401   if (NULL != GetEntryById(new_id, &lock))
 402     return false;
 403
 404   {
 405     // Update the indices that depend on the ID field.
 406     ScopedParentChildIndexUpdater updater_b(lock, entry,
 407         &kernel_->parent_child_index);
 408     size_t num_erased = kernel_->ids_map.erase(entry->ref(ID).value());
 409     DCHECK_EQ(1U, num_erased);
 410     entry->put(ID, new_id);
 411     kernel_->ids_map[entry->ref(ID).value()] = entry;
 412   }
 413   return true;
 414 }
 415
 416 bool Directory::ReindexParentId(BaseWriteTransaction* trans,
 417                                 EntryKernel* const entry,
 418                                 const Id& new_parent_id) {
 419   ScopedKernelLock lock(this);
 420
 421   {
 422     // Update the indices that depend on the PARENT_ID field.
 423     ScopedParentChildIndexUpdater index_updater(lock, entry,
 424         &kernel_->parent_child_index);
 425     entry->put(PARENT_ID, new_parent_id);
 426   }
 427   return true;
 428 }
 429
 430 bool Directory::unrecoverable_error_set(const BaseTransaction* trans) const {
 431   DCHECK(trans != NULL);
 432   return unrecoverable_error_set_;
 433 }
 434
 435 void Directory::ClearDirtyMetahandles() {
 436   kernel_->transaction_mutex.AssertAcquired();
 437   kernel_->dirty_metahandles.clear();
 438 }
 439
 440 bool Directory::SafeToPurgeFromMemory(WriteTransaction* trans,
 441                                       const EntryKernel* const entry) const {
 442   bool safe = entry->ref(IS_DEL) && !entry->is_dirty() &&
 443       !entry->ref(SYNCING) && !entry->ref(IS_UNAPPLIED_UPDATE) &&
 444       !entry->ref(IS_UNSYNCED);
 445
 446   if (safe) {
 447     int64 handle = entry->ref(META_HANDLE);
 448     const ModelType type = entry->GetServerModelType();
 449     if (!SyncAssert(kernel_->dirty_metahandles.count(handle) == 0U,
 450                     FROM_HERE,
 451                     "Dirty metahandles should be empty", trans))
 452       return false;
 453     // TODO(tim): Bug 49278.
 454     if (!SyncAssert(!kernel_->unsynced_metahandles.count(handle),
 455                     FROM_HERE,
 456                     "Unsynced handles should be empty",
 457                     trans))
 458       return false;
 459     if (!SyncAssert(!kernel_->unapplied_update_metahandles[type].count(handle),
 460                     FROM_HERE,
 461                     "Unapplied metahandles should be empty",
 462                     trans))
 463       return false;
 464   }
 465
 466   return safe;
 467 }
 468
 469 void Directory::TakeSnapshotForSaveChanges(SaveChangesSnapshot* snapshot) {
 470   ReadTransaction trans(FROM_HERE, this);
 471   ScopedKernelLock lock(this);
 472
 473   // If there is an unrecoverable error then just bail out.
 474   if (unrecoverable_error_set(&trans))
 475     return;
 476
 477   // Deep copy dirty entries from kernel_->metahandles_index into snapshot and
 478   // clear dirty flags.
 479   for (MetahandleSet::const_iterator i = kernel_->dirty_metahandles.begin();
 480        i != kernel_->dirty_metahandles.end(); ++i) {
 481     EntryKernel* entry = GetEntryByHandle(*i, &lock);
 482     if (!entry)
 483       continue;
 484     // Skip over false positives; it happens relatively infrequently.
 485     if (!entry->is_dirty())
 486       continue;
 487     snapshot->dirty_metas.insert(snapshot->dirty_metas.end(),
 488                                  new EntryKernel(*entry));
 489     DCHECK_EQ(1U, kernel_->dirty_metahandles.count(*i));
 490     // We don't bother removing from the index here as we blow the entire thing
 491     // in a moment, and it unnecessarily complicates iteration.
 492     entry->clear_dirty(NULL);
 493   }
 494   ClearDirtyMetahandles();
 495
 496   // Set purged handles.
 497   DCHECK(snapshot->metahandles_to_purge.empty());
 498   snapshot->metahandles_to_purge.swap(kernel_->metahandles_to_purge);
 499
 500   // Fill kernel_info_status and kernel_info.
 501   snapshot->kernel_info = kernel_->persisted_info;
 502   // To avoid duplicates when the process crashes, we record the next_id to be
 503   // greater magnitude than could possibly be reached before the next save
 504   // changes.  In other words, it's effectively impossible for the user to
 505   // generate 65536 new bookmarks in 3 seconds.
 506   snapshot->kernel_info.next_id -= 65536;
 507   snapshot->kernel_info_status = kernel_->info_status;
 508   // This one we reset on failure.
 509   kernel_->info_status = KERNEL_SHARE_INFO_VALID;
 510
 511   delete_journal_->TakeSnapshotAndClear(
 512       &trans, &snapshot->delete_journals, &snapshot->delete_journals_to_purge);
 513 }
 514
 515 bool Directory::SaveChanges() {
 516   bool success = false;
 517
 518   base::AutoLock scoped_lock(kernel_->save_changes_mutex);
 519
 520   // Snapshot and save.
 521   SaveChangesSnapshot snapshot;
 522   TakeSnapshotForSaveChanges(&snapshot);
 523   success = store_->SaveChanges(snapshot);
 524
 525   // Handle success or failure.
 526   if (success)
 527     success = VacuumAfterSaveChanges(snapshot);
 528   else
 529     HandleSaveChangesFailure(snapshot);
 530   return success;
 531 }
 532
 533 bool Directory::VacuumAfterSaveChanges(const SaveChangesSnapshot& snapshot) {
 534   if (snapshot.dirty_metas.empty())
 535     return true;
 536
 537   // Need a write transaction as we are about to permanently purge entries.
 538   WriteTransaction trans(FROM_HERE, VACUUM_AFTER_SAVE, this);
 539   ScopedKernelLock lock(this);
 540   // Now drop everything we can out of memory.
 541   for (EntryKernelSet::const_iterator i = snapshot.dirty_metas.begin();
 542        i != snapshot.dirty_metas.end(); ++i) {
 543     MetahandlesMap::iterator found =
 544         kernel_->metahandles_map.find((*i)->ref(META_HANDLE));
 545     EntryKernel* entry = (found == kernel_->metahandles_map.end() ?
 546                           NULL : found->second);
 547     if (entry && SafeToPurgeFromMemory(&trans, entry)) {
 548       // We now drop deleted metahandles that are up to date on both the client
 549       // and the server.
 550       size_t num_erased = 0;
 551       num_erased = kernel_->metahandles_map.erase(entry->ref(META_HANDLE));
 552       DCHECK_EQ(1u, num_erased);
 553       num_erased = kernel_->ids_map.erase(entry->ref(ID).value());
 554       DCHECK_EQ(1u, num_erased);
 555       if (!entry->ref(UNIQUE_SERVER_TAG).empty()) {
 556         num_erased =
 557             kernel_->server_tags_map.erase(entry->ref(UNIQUE_SERVER_TAG));
 558         DCHECK_EQ(1u, num_erased);
 559       }
 560       if (!entry->ref(UNIQUE_CLIENT_TAG).empty()) {
 561         num_erased =
 562             kernel_->client_tags_map.erase(entry->ref(UNIQUE_CLIENT_TAG));
 563         DCHECK_EQ(1u, num_erased);
 564       }
 565       if (!SyncAssert(!kernel_->parent_child_index.Contains(entry),
 566                       FROM_HERE,
 567                       "Deleted entry still present",
 568                       (&trans)))
 569         return false;
 570       delete entry;
 571     }
 572     if (trans.unrecoverable_error_set())
 573       return false;
 574   }
 575   return true;
 576 }
 577
 578 void Directory::UnapplyEntry(EntryKernel* entry) {
 579   int64 handle = entry->ref(META_HANDLE);
 580   ModelType server_type = GetModelTypeFromSpecifics(
 581       entry->ref(SERVER_SPECIFICS));
 582
 583   // Clear enough so that on the next sync cycle all local data will
 584   // be overwritten.
 585   // Note: do not modify the root node in order to preserve the
 586   // initial sync ended bit for this type (else on the next restart
 587   // this type will be treated as disabled and therefore fully purged).
 588   if (IsRealDataType(server_type) &&
 589       ModelTypeToRootTag(server_type) == entry->ref(UNIQUE_SERVER_TAG)) {
 590     return;
 591   }
 592
 593   // Set the unapplied bit if this item has server data.
 594   if (IsRealDataType(server_type) && !entry->ref(IS_UNAPPLIED_UPDATE)) {
 595     entry->put(IS_UNAPPLIED_UPDATE, true);
 596     kernel_->unapplied_update_metahandles[server_type].insert(handle);
 597     entry->mark_dirty(&kernel_->dirty_metahandles);
 598   }
 599
 600   // Unset the unsynced bit.
 601   if (entry->ref(IS_UNSYNCED)) {
 602     kernel_->unsynced_metahandles.erase(handle);
 603     entry->put(IS_UNSYNCED, false);
 604     entry->mark_dirty(&kernel_->dirty_metahandles);
 605   }
 606
 607   // Mark the item as locally deleted. No deleted items are allowed in the
 608   // parent child index.
 609   if (!entry->ref(IS_DEL)) {
 610     kernel_->parent_child_index.Remove(entry);
 611     entry->put(IS_DEL, true);
 612     entry->mark_dirty(&kernel_->dirty_metahandles);
 613   }
 614
 615   // Set the version to the "newly created" version.
 616   if (entry->ref(BASE_VERSION) != CHANGES_VERSION) {
 617     entry->put(BASE_VERSION, CHANGES_VERSION);
 618     entry->mark_dirty(&kernel_->dirty_metahandles);
 619   }
 620
 621   // At this point locally created items that aren't synced will become locally
 622   // deleted items, and purged on the next snapshot. All other items will match
 623   // the state they would have had if they were just created via a server
 624   // update. See MutableEntry::MutableEntry(.., CreateNewUpdateItem, ..).
 625 }
 626
 627 void Directory::DeleteEntry(bool save_to_journal,
 628                             EntryKernel* entry,
 629                             EntryKernelSet* entries_to_journal) {
 630   int64 handle = entry->ref(META_HANDLE);
 631   ModelType server_type = GetModelTypeFromSpecifics(
 632       entry->ref(SERVER_SPECIFICS));
 633
 634   kernel_->metahandles_to_purge.insert(handle);
 635
 636   size_t num_erased = 0;
 637   num_erased = kernel_->metahandles_map.erase(entry->ref(META_HANDLE));
 638   DCHECK_EQ(1u, num_erased);
 639   num_erased = kernel_->ids_map.erase(entry->ref(ID).value());
 640   DCHECK_EQ(1u, num_erased);
 641   num_erased = kernel_->unsynced_metahandles.erase(handle);
 642   DCHECK_EQ(entry->ref(IS_UNSYNCED), num_erased > 0);
 643   num_erased =
 644       kernel_->unapplied_update_metahandles[server_type].erase(handle);
 645   DCHECK_EQ(entry->ref(IS_UNAPPLIED_UPDATE), num_erased > 0);
 646   if (kernel_->parent_child_index.Contains(entry))
 647     kernel_->parent_child_index.Remove(entry);
 648
 649   if (!entry->ref(UNIQUE_CLIENT_TAG).empty()) {
 650     num_erased =
 651         kernel_->client_tags_map.erase(entry->ref(UNIQUE_CLIENT_TAG));
 652     DCHECK_EQ(1u, num_erased);
 653   }
 654   if (!entry->ref(UNIQUE_SERVER_TAG).empty()) {
 655     num_erased =
 656         kernel_->server_tags_map.erase(entry->ref(UNIQUE_SERVER_TAG));
 657     DCHECK_EQ(1u, num_erased);
 658   }
 659
 660   if (save_to_journal) {
 661     entries_to_journal->insert(entry);
 662   } else {
 663     delete entry;
 664   }
 665 }
 666
 667 bool Directory::PurgeEntriesWithTypeIn(ModelTypeSet disabled_types,
 668                                        ModelTypeSet types_to_journal,
 669                                        ModelTypeSet types_to_unapply) {
 670   disabled_types.RemoveAll(ProxyTypes());
 671
 672   if (disabled_types.Empty())
 673     return true;
 674
 675   {
 676     WriteTransaction trans(FROM_HERE, PURGE_ENTRIES, this);
 677
 678     EntryKernelSet entries_to_journal;
 679     STLElementDeleter<EntryKernelSet> journal_deleter(&entries_to_journal);
 680
 681     {
 682       ScopedKernelLock lock(this);
 683
 684       // We iterate in two passes to avoid a bug in STLport (which is used in
 685       // the Android build).  There are some versions of that library where a
 686       // hash_map's iterators can be invalidated when an item is erased from the
 687       // hash_map.
 688       // See http://sourceforge.net/p/stlport/bugs/239/.
 689
 690       std::set<EntryKernel*> to_purge;
 691       for (MetahandlesMap::iterator it = kernel_->metahandles_map.begin();
 692            it != kernel_->metahandles_map.end(); ++it) {
 693         const sync_pb::EntitySpecifics& local_specifics =
 694             it->second->ref(SPECIFICS);
 695         const sync_pb::EntitySpecifics& server_specifics =
 696             it->second->ref(SERVER_SPECIFICS);
 697         ModelType local_type = GetModelTypeFromSpecifics(local_specifics);
 698         ModelType server_type = GetModelTypeFromSpecifics(server_specifics);
 699
 700         if ((IsRealDataType(local_type) && disabled_types.Has(local_type)) ||
 701             (IsRealDataType(server_type) && disabled_types.Has(server_type))) {
 702           to_purge.insert(it->second);
 703         }
 704       }
 705
 706       for (std::set<EntryKernel*>::iterator it = to_purge.begin();
 707            it != to_purge.end(); ++it) {
 708         EntryKernel* entry = *it;
 709
 710         const sync_pb::EntitySpecifics& local_specifics =
 711             (*it)->ref(SPECIFICS);
 712         const sync_pb::EntitySpecifics& server_specifics =
 713             (*it)->ref(SERVER_SPECIFICS);
 714         ModelType local_type = GetModelTypeFromSpecifics(local_specifics);
 715         ModelType server_type = GetModelTypeFromSpecifics(server_specifics);
 716
 717         if (types_to_unapply.Has(local_type) ||
 718             types_to_unapply.Has(server_type)) {
 719           UnapplyEntry(entry);
 720         } else {
 721           bool save_to_journal =
 722               (types_to_journal.Has(local_type) ||
 723                types_to_journal.Has(server_type)) &&
 724               (delete_journal_->IsDeleteJournalEnabled(local_type) ||
 725                delete_journal_->IsDeleteJournalEnabled(server_type));
 726           DeleteEntry(save_to_journal, entry, &entries_to_journal);
 727         }
 728       }
 729
 730       delete_journal_->AddJournalBatch(&trans, entries_to_journal);
 731
 732       // Ensure meta tracking for these data types reflects the purged state.
 733       for (ModelTypeSet::Iterator it = disabled_types.First();
 734            it.Good(); it.Inc()) {
 735         kernel_->persisted_info.transaction_version[it.Get()] = 0;
 736
 737         // Don't discard progress markers for unapplied types.
 738         if (!types_to_unapply.Has(it.Get()))
 739           kernel_->persisted_info.reset_download_progress(it.Get());
 740       }
 741     }
 742   }
 743   return true;
 744 }
 745
 746 void Directory::HandleSaveChangesFailure(const SaveChangesSnapshot& snapshot) {
 747   WriteTransaction trans(FROM_HERE, HANDLE_SAVE_FAILURE, this);
 748   ScopedKernelLock lock(this);
 749   kernel_->info_status = KERNEL_SHARE_INFO_DIRTY;
 750
 751   // Because we optimistically cleared the dirty bit on the real entries when
 752   // taking the snapshot, we must restore it on failure.  Not doing this could
 753   // cause lost data, if no other changes are made to the in-memory entries
 754   // that would cause the dirty bit to get set again. Setting the bit ensures
 755   // that SaveChanges will at least try again later.
 756   for (EntryKernelSet::const_iterator i = snapshot.dirty_metas.begin();
 757        i != snapshot.dirty_metas.end(); ++i) {
 758     MetahandlesMap::iterator found =
 759         kernel_->metahandles_map.find((*i)->ref(META_HANDLE));
 760     if (found != kernel_->metahandles_map.end()) {
 761       found->second->mark_dirty(&kernel_->dirty_metahandles);
 762     }
 763   }
 764
 765   kernel_->metahandles_to_purge.insert(snapshot.metahandles_to_purge.begin(),
 766                                        snapshot.metahandles_to_purge.end());
 767
 768   // Restore delete journals.
 769   delete_journal_->AddJournalBatch(&trans, snapshot.delete_journals);
 770   delete_journal_->PurgeDeleteJournals(&trans,
 771                                        snapshot.delete_journals_to_purge);
 772 }
 773
 774 void Directory::GetDownloadProgress(
 775     ModelType model_type,
 776     sync_pb::DataTypeProgressMarker* value_out) const {
 777   ScopedKernelLock lock(this);
 778   return value_out->CopyFrom(
 779       kernel_->persisted_info.download_progress[model_type]);
 780 }
 781
 782 void Directory::GetDownloadProgressAsString(
 783     ModelType model_type,
 784     std::string* value_out) const {
 785   ScopedKernelLock lock(this);
 786   kernel_->persisted_info.download_progress[model_type].SerializeToString(
 787       value_out);
 788 }
 789
 790 size_t Directory::GetEntriesCount() const {
 791   ScopedKernelLock lock(this);
 792   return kernel_->metahandles_map.size();
 793 }
 794
 795 void Directory::SetDownloadProgress(
 796     ModelType model_type,
 797     const sync_pb::DataTypeProgressMarker& new_progress) {
 798   ScopedKernelLock lock(this);
 799   kernel_->persisted_info.download_progress[model_type].CopyFrom(new_progress);
 800   kernel_->info_status = KERNEL_SHARE_INFO_DIRTY;
 801 }
 802
 803 int64 Directory::GetTransactionVersion(ModelType type) const {
 804   kernel_->transaction_mutex.AssertAcquired();
 805   return kernel_->persisted_info.transaction_version[type];
 806 }
 807
 808 void Directory::IncrementTransactionVersion(ModelType type) {
 809   kernel_->transaction_mutex.AssertAcquired();
 810   kernel_->persisted_info.transaction_version[type]++;
 811 }
 812
 813 ModelTypeSet Directory::InitialSyncEndedTypes() {
 814   syncable::ReadTransaction trans(FROM_HERE, this);
 815   ModelTypeSet protocol_types = ProtocolTypes();
 816   ModelTypeSet initial_sync_ended_types;
 817   for (ModelTypeSet::Iterator i = protocol_types.First(); i.Good(); i.Inc()) {
 818     if (InitialSyncEndedForType(&trans, i.Get())) {
 819       initial_sync_ended_types.Put(i.Get());
 820     }
 821   }
 822   return initial_sync_ended_types;
 823 }
 824
 825 bool Directory::InitialSyncEndedForType(ModelType type) {
 826   syncable::ReadTransaction trans(FROM_HERE, this);
 827   return InitialSyncEndedForType(&trans, type);
 828 }
 829
 830 bool Directory::InitialSyncEndedForType(
 831     BaseTransaction* trans, ModelType type) {
 832   // True iff the type's root node has been received and applied.
 833   syncable::Entry entry(trans,
 834                         syncable::GET_BY_SERVER_TAG,
 835                         ModelTypeToRootTag(type));
 836   return entry.good() && entry.GetBaseVersion() != CHANGES_VERSION;
 837 }
 838
 839 string Directory::store_birthday() const {
 840   ScopedKernelLock lock(this);
 841   return kernel_->persisted_info.store_birthday;
 842 }
 843
 844 void Directory::set_store_birthday(const string& store_birthday) {
 845   ScopedKernelLock lock(this);
 846   if (kernel_->persisted_info.store_birthday == store_birthday)
 847     return;
 848   kernel_->persisted_info.store_birthday = store_birthday;
 849   kernel_->info_status = KERNEL_SHARE_INFO_DIRTY;
 850 }
 851
 852 string Directory::bag_of_chips() const {
 853   ScopedKernelLock lock(this);
 854   return kernel_->persisted_info.bag_of_chips;
 855 }
 856
 857 void Directory::set_bag_of_chips(const string& bag_of_chips) {
 858   ScopedKernelLock lock(this);
 859   if (kernel_->persisted_info.bag_of_chips == bag_of_chips)
 860     return;
 861   kernel_->persisted_info.bag_of_chips = bag_of_chips;
 862   kernel_->info_status = KERNEL_SHARE_INFO_DIRTY;
 863 }
 864
 865
 866 string Directory::cache_guid() const {
 867   // No need to lock since nothing ever writes to it after load.
 868   return kernel_->cache_guid;
 869 }
 870
 871 NigoriHandler* Directory::GetNigoriHandler() {
 872   return nigori_handler_;
 873 }
 874
 875 Cryptographer* Directory::GetCryptographer(const BaseTransaction* trans) {
 876   DCHECK_EQ(this, trans->directory());
 877   return cryptographer_;
 878 }
 879
 880 void Directory::GetAllMetaHandles(BaseTransaction* trans,
 881                                   MetahandleSet* result) {
 882   result->clear();
 883   ScopedKernelLock lock(this);
 884   for (MetahandlesMap::iterator i = kernel_->metahandles_map.begin();
 885        i != kernel_->metahandles_map.end(); ++i) {
 886     result->insert(i->first);
 887   }
 888 }
 889
 890 void Directory::GetAllEntryKernels(BaseTransaction* trans,
 891                                    std::vector<const EntryKernel*>* result) {
 892   result->clear();
 893   ScopedKernelLock lock(this);
 894   for (MetahandlesMap::iterator i = kernel_->metahandles_map.begin();
 895        i != kernel_->metahandles_map.end(); ++i) {
 896     result->push_back(i->second);
 897   }
 898 }
 899
 900 void Directory::GetUnsyncedMetaHandles(BaseTransaction* trans,
 901                                        Metahandles* result) {
 902   result->clear();
 903   ScopedKernelLock lock(this);
 904   copy(kernel_->unsynced_metahandles.begin(),
 905        kernel_->unsynced_metahandles.end(), back_inserter(*result));
 906 }
 907
 908 int64 Directory::unsynced_entity_count() const {
 909   ScopedKernelLock lock(this);
 910   return kernel_->unsynced_metahandles.size();
 911 }
 912
 913 FullModelTypeSet Directory::GetServerTypesWithUnappliedUpdates(
 914     BaseTransaction* trans) const {
 915   FullModelTypeSet server_types;
 916   ScopedKernelLock lock(this);
 917   for (int i = UNSPECIFIED; i < MODEL_TYPE_COUNT; ++i) {
 918     const ModelType type = ModelTypeFromInt(i);
 919     if (!kernel_->unapplied_update_metahandles[type].empty()) {
 920       server_types.Put(type);
 921     }
 922   }
 923   return server_types;
 924 }
 925
 926 void Directory::GetUnappliedUpdateMetaHandles(
 927     BaseTransaction* trans,
 928     FullModelTypeSet server_types,
 929     std::vector<int64>* result) {
 930   result->clear();
 931   ScopedKernelLock lock(this);
 932   for (int i = UNSPECIFIED; i < MODEL_TYPE_COUNT; ++i) {
 933     const ModelType type = ModelTypeFromInt(i);
 934     if (server_types.Has(type)) {
 935       std::copy(kernel_->unapplied_update_metahandles[type].begin(),
 936                 kernel_->unapplied_update_metahandles[type].end(),
 937                 back_inserter(*result));
 938     }
 939   }
 940 }
 941
 942 void Directory::CollectMetaHandleCounts(
 943     std::vector<int>* num_entries_by_type,
 944     std::vector<int>* num_to_delete_entries_by_type) {
 945   syncable::ReadTransaction trans(FROM_HERE, this);
 946   ScopedKernelLock lock(this);
 947
 948   for (MetahandlesMap::iterator it = kernel_->metahandles_map.begin();
 949        it != kernel_->metahandles_map.end(); ++it) {
 950     EntryKernel* entry = it->second;
 951     const ModelType type = GetModelTypeFromSpecifics(entry->ref(SPECIFICS));
 952     (*num_entries_by_type)[type]++;
 953     if (entry->ref(IS_DEL))
 954       (*num_to_delete_entries_by_type)[type]++;
 955   }
 956 }
 957
 958 bool Directory::CheckInvariantsOnTransactionClose(
 959     syncable::BaseTransaction* trans,
 960     const MetahandleSet& modified_handles) {
 961   // NOTE: The trans may be in the process of being destructed.  Be careful if
 962   // you wish to call any of its virtual methods.
 963   switch (invariant_check_level_) {
 964     case FULL_DB_VERIFICATION: {
 965       MetahandleSet all_handles;
 966       GetAllMetaHandles(trans, &all_handles);
 967       return CheckTreeInvariants(trans, all_handles);
 968     }
 969     case VERIFY_CHANGES: {
 970       return CheckTreeInvariants(trans, modified_handles);
 971     }
 972     case OFF: {
 973       return true;
 974     }
 975   }
 976   NOTREACHED();
 977   return false;
 978 }
 979
 980 bool Directory::FullyCheckTreeInvariants(syncable::BaseTransaction* trans) {
 981   MetahandleSet handles;
 982   GetAllMetaHandles(trans, &handles);
 983   return CheckTreeInvariants(trans, handles);
 984 }
 985
 986 bool Directory::CheckTreeInvariants(syncable::BaseTransaction* trans,
 987                                     const MetahandleSet& handles) {
 988   MetahandleSet::const_iterator i;
 989   for (i = handles.begin() ; i != handles.end() ; ++i) {
 990     int64 metahandle = *i;
 991     Entry e(trans, GET_BY_HANDLE, metahandle);
 992     if (!SyncAssert(e.good(), FROM_HERE, "Entry is bad", trans))
 993       return false;
 994     syncable::Id id = e.GetId();
 995     syncable::Id parentid = e.GetParentId();
 996
 997     if (id.IsRoot()) {
 998       if (!SyncAssert(e.GetIsDir(), FROM_HERE,
 999                       "Entry should be a directory",
1000                       trans))
1001         return false;
1002       if (!SyncAssert(parentid.IsRoot(), FROM_HERE,
1003                       "Entry should be root",
1004                       trans))
1005          return false;
1006       if (!SyncAssert(!e.GetIsUnsynced(), FROM_HERE,
1007                       "Entry should be sycned",
1008                       trans))
1009          return false;
1010       continue;
1011     }
1012
1013     if (!e.GetIsDel()) {
1014       if (!SyncAssert(id != parentid, FROM_HERE,
1015                       "Id should be different from parent id.",
1016                       trans))
1017          return false;
1018       if (!SyncAssert(!e.GetNonUniqueName().empty(), FROM_HERE,
1019                       "Non unique name should not be empty.",
1020                       trans))
1021         return false;
1022       int safety_count = handles.size() + 1;
1023       while (!parentid.IsRoot()) {
1024         Entry parent(trans, GET_BY_ID, parentid);
1025         if (!SyncAssert(parent.good(), FROM_HERE,
1026                         "Parent entry is not valid.",
1027                         trans))
1028           return false;
1029         if (handles.end() == handles.find(parent.GetMetahandle()))
1030             break; // Skip further checking if parent was unmodified.
1031         if (!SyncAssert(parent.GetIsDir(), FROM_HERE,
1032                         "Parent should be a directory",
1033                         trans))
1034           return false;
1035         if (!SyncAssert(!parent.GetIsDel(), FROM_HERE,
1036                         "Parent should not have been marked for deletion.",
1037                         trans))
1038           return false;
1039         if (!SyncAssert(handles.end() != handles.find(parent.GetMetahandle()),
1040                         FROM_HERE,
1041                         "Parent should be in the index.",
1042                         trans))
1043           return false;
1044         parentid = parent.GetParentId();
1045         if (!SyncAssert(--safety_count > 0, FROM_HERE,
1046                         "Count should be greater than zero.",
1047                         trans))
1048           return false;
1049       }
1050     }
1051     int64 base_version = e.GetBaseVersion();
1052     int64 server_version = e.GetServerVersion();
1053     bool using_unique_client_tag = !e.GetUniqueClientTag().empty();
1054     if (CHANGES_VERSION == base_version || 0 == base_version) {
1055       if (e.GetIsUnappliedUpdate()) {
1056         // Must be a new item, or a de-duplicated unique client tag
1057         // that was created both locally and remotely.
1058         if (!using_unique_client_tag) {
1059           if (!SyncAssert(e.GetIsDel(), FROM_HERE,
1060                           "The entry should not have been deleted.",
1061                           trans))
1062             return false;
1063         }
1064         // It came from the server, so it must have a server ID.
1065         if (!SyncAssert(id.ServerKnows(), FROM_HERE,
1066                         "The id should be from a server.",
1067                         trans))
1068           return false;
1069       } else {
1070         if (e.GetIsDir()) {
1071           // TODO(chron): Implement this mode if clients ever need it.
1072           // For now, you can't combine a client tag and a directory.
1073           if (!SyncAssert(!using_unique_client_tag, FROM_HERE,
1074                           "Directory cannot have a client tag.",
1075                           trans))
1076             return false;
1077         }
1078         // Should be an uncomitted item, or a successfully deleted one.
1079         if (!e.GetIsDel()) {
1080           if (!SyncAssert(e.GetIsUnsynced(), FROM_HERE,
1081                           "The item should be unsynced.",
1082                           trans))
1083             return false;
1084         }
1085         // If the next check failed, it would imply that an item exists
1086         // on the server, isn't waiting for application locally, but either
1087         // is an unsynced create or a sucessful delete in the local copy.
1088         // Either way, that's a mismatch.
1089         if (!SyncAssert(0 == server_version, FROM_HERE,
1090                         "Server version should be zero.",
1091                         trans))
1092           return false;
1093         // Items that aren't using the unique client tag should have a zero
1094         // base version only if they have a local ID.  Items with unique client
1095         // tags are allowed to use the zero base version for undeletion and
1096         // de-duplication; the unique client tag trumps the server ID.
1097         if (!using_unique_client_tag) {
1098           if (!SyncAssert(!id.ServerKnows(), FROM_HERE,
1099                           "Should be a client only id.",
1100                           trans))
1101             return false;
1102         }
1103       }
1104     } else {
1105       if (!SyncAssert(id.ServerKnows(),
1106                       FROM_HERE,
1107                       "Should be a server id.",
1108                       trans))
1109         return false;
1110     }
1111     // Server-unknown items that are locally deleted should not be sent up to
1112     // the server.  They must be !IS_UNSYNCED.
1113     if (!SyncAssert(!(!id.ServerKnows() && e.GetIsDel() && e.GetIsUnsynced()),
1114                     FROM_HERE,
1115                     "Locally deleted item must not be unsynced.",
1116                     trans)) {
1117       return false;
1118     }
1119   }
1120   return true;
1121 }
1122
1123 void Directory::SetInvariantCheckLevel(InvariantCheckLevel check_level) {
1124   invariant_check_level_ = check_level;
1125 }
1126
1127 int64 Directory::NextMetahandle() {
1128   ScopedKernelLock lock(this);
1129   int64 metahandle = (kernel_->next_metahandle)++;
1130   return metahandle;
1131 }
1132
1133 // Always returns a client ID that is the string representation of a negative
1134 // number.
1135 Id Directory::NextId() {
1136   int64 result;
1137   {
1138     ScopedKernelLock lock(this);
1139     result = (kernel_->persisted_info.next_id)--;
1140     kernel_->info_status = KERNEL_SHARE_INFO_DIRTY;
1141   }
1142   DCHECK_LT(result, 0);
1143   return Id::CreateFromClientString(base::Int64ToString(result));
1144 }
1145
1146 bool Directory::HasChildren(BaseTransaction* trans, const Id& id) {
1147   ScopedKernelLock lock(this);
1148   return kernel_->parent_child_index.GetChildren(id) != NULL;
1149 }
1150
1151 Id Directory::GetFirstChildId(BaseTransaction* trans,
1152                               const EntryKernel* parent) {
1153   DCHECK(parent);
1154   DCHECK(parent->ref(IS_DIR));
1155
1156   ScopedKernelLock lock(this);
1157   const OrderedChildSet* children =
1158       kernel_->parent_child_index.GetChildren(parent->ref(ID));
1159
1160   // We're expected to return root if there are no children.
1161   if (!children)
1162     return Id();
1163
1164   return (*children->begin())->ref(ID);
1165 }
1166
1167 syncable::Id Directory::GetPredecessorId(EntryKernel* e) {
1168   ScopedKernelLock lock(this);
1169
1170   DCHECK(ParentChildIndex::ShouldInclude(e));
1171   const OrderedChildSet* children =
1172       kernel_->parent_child_index.GetChildren(e->ref(PARENT_ID));
1173   DCHECK(children && !children->empty());
1174   OrderedChildSet::const_iterator i = children->find(e);
1175   DCHECK(i != children->end());
1176
1177   if (i == children->begin()) {
1178     return Id();
1179   } else {
1180     i--;
1181     return (*i)->ref(ID);
1182   }
1183 }
1184
1185 syncable::Id Directory::GetSuccessorId(EntryKernel* e) {
1186   ScopedKernelLock lock(this);
1187
1188   DCHECK(ParentChildIndex::ShouldInclude(e));
1189   const OrderedChildSet* children =
1190       kernel_->parent_child_index.GetChildren(e->ref(PARENT_ID));
1191   DCHECK(children && !children->empty());
1192   OrderedChildSet::const_iterator i = children->find(e);
1193   DCHECK(i != children->end());
1194
1195   i++;
1196   if (i == children->end()) {
1197     return Id();
1198   } else {
1199     return (*i)->ref(ID);
1200   }
1201 }
1202
1203 // TODO(rlarocque): Remove all support for placing ShouldMaintainPosition()
1204 // items as siblings of items that do not maintain postions.  It is required
1205 // only for tests.  See crbug.com/178282.
1206 void Directory::PutPredecessor(EntryKernel* e, EntryKernel* predecessor) {
1207   DCHECK(!e->ref(IS_DEL));
1208   if (!e->ShouldMaintainPosition()) {
1209     DCHECK(!e->ref(UNIQUE_POSITION).IsValid());
1210     return;
1211   }
1212   std::string suffix = e->ref(UNIQUE_BOOKMARK_TAG);
1213   DCHECK(!suffix.empty());
1214
1215   // Remove our item from the ParentChildIndex and remember to re-add it later.
1216   ScopedKernelLock lock(this);
1217   ScopedParentChildIndexUpdater updater(lock, e, &kernel_->parent_child_index);
1218
1219   // Note: The ScopedParentChildIndexUpdater will update this set for us as we
1220   // leave this function.
1221   const OrderedChildSet* siblings =
1222       kernel_->parent_child_index.GetChildren(e->ref(PARENT_ID));
1223
1224   if (!siblings) {
1225     // This parent currently has no other children.
1226     DCHECK(predecessor->ref(ID).IsRoot());
1227     UniquePosition pos = UniquePosition::InitialPosition(suffix);
1228     e->put(UNIQUE_POSITION, pos);
1229     return;
1230   }
1231
1232   if (predecessor->ref(ID).IsRoot()) {
1233     // We have at least one sibling, and we're inserting to the left of them.
1234     UniquePosition successor_pos = (*siblings->begin())->ref(UNIQUE_POSITION);
1235
1236     UniquePosition pos;
1237     if (!successor_pos.IsValid()) {
1238       // If all our successors are of non-positionable types, just create an
1239       // initial position.  We arbitrarily choose to sort invalid positions to
1240       // the right of the valid positions.
1241       //
1242       // We really shouldn't need to support this.  See TODO above.
1243       pos = UniquePosition::InitialPosition(suffix);
1244     } else  {
1245       DCHECK(!siblings->empty());
1246       pos = UniquePosition::Before(successor_pos, suffix);
1247     }
1248
1249     e->put(UNIQUE_POSITION, pos);
1250     return;
1251   }
1252
1253   // We can't support placing an item after an invalid position.  Fortunately,
1254   // the tests don't exercise this particular case.  We should not support
1255   // siblings with invalid positions at all.  See TODO above.
1256   DCHECK(predecessor->ref(UNIQUE_POSITION).IsValid());
1257
1258   OrderedChildSet::const_iterator neighbour = siblings->find(predecessor);
1259   DCHECK(neighbour != siblings->end());
1260
1261   ++neighbour;
1262   if (neighbour == siblings->end()) {
1263     // Inserting at the end of the list.
1264     UniquePosition pos = UniquePosition::After(
1265         predecessor->ref(UNIQUE_POSITION),
1266         suffix);
1267     e->put(UNIQUE_POSITION, pos);
1268     return;
1269   }
1270
1271   EntryKernel* successor = *neighbour;
1272
1273   // Another mixed valid and invalid position case.  This one could be supported
1274   // in theory, but we're trying to deprecate support for siblings with and
1275   // without valid positions.  See TODO above.
1276   DCHECK(successor->ref(UNIQUE_POSITION).IsValid());
1277
1278   // Finally, the normal case: inserting between two elements.
1279   UniquePosition pos = UniquePosition::Between(
1280       predecessor->ref(UNIQUE_POSITION),
1281       successor->ref(UNIQUE_POSITION),
1282       suffix);
1283   e->put(UNIQUE_POSITION, pos);
1284   return;
1285 }
1286
1287 // TODO(rlarocque): Avoid this indirection.  Just return the set.
1288 void Directory::AppendChildHandles(const ScopedKernelLock& lock,
1289                                    const Id& parent_id,
1290                                    Directory::Metahandles* result) {
1291   const OrderedChildSet* children =
1292       kernel_->parent_child_index.GetChildren(parent_id);
1293   if (!children)
1294     return;
1295
1296   for (OrderedChildSet::const_iterator i = children->begin();
1297        i != children->end(); ++i) {
1298     DCHECK_EQ(parent_id, (*i)->ref(PARENT_ID));
1299     result->push_back((*i)->ref(META_HANDLE));
1300   }
1301 }
1302
1303 }  // namespace syncable
1304 }  // namespace syncer