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      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 #ifndef SYNC_SYNCABLE_DIRECTORY_H_
      6 #define SYNC_SYNCABLE_DIRECTORY_H_
      7 
      8 #include <deque>
      9 #include <set>
     10 #include <string>
     11 #include <vector>
     12 
     13 #include "base/basictypes.h"
     14 #include "base/containers/hash_tables.h"
     15 #include "base/file_util.h"
     16 #include "base/gtest_prod_util.h"
     17 #include "base/values.h"
     18 #include "sync/base/sync_export.h"
     19 #include "sync/internal_api/public/util/report_unrecoverable_error_function.h"
     20 #include "sync/internal_api/public/util/weak_handle.h"
     21 #include "sync/syncable/dir_open_result.h"
     22 #include "sync/syncable/entry.h"
     23 #include "sync/syncable/entry_kernel.h"
     24 #include "sync/syncable/metahandle_set.h"
     25 #include "sync/syncable/parent_child_index.h"
     26 #include "sync/syncable/syncable_delete_journal.h"
     27 
     28 namespace syncer {
     29 
     30 class Cryptographer;
     31 class TestUserShare;
     32 class UnrecoverableErrorHandler;
     33 
     34 namespace syncable {
     35 
     36 class BaseTransaction;
     37 class BaseWriteTransaction;
     38 class DirectoryChangeDelegate;
     39 class DirectoryBackingStore;
     40 class NigoriHandler;
     41 class ScopedKernelLock;
     42 class TransactionObserver;
     43 class WriteTransaction;
     44 
     45 enum InvariantCheckLevel {
     46   OFF = 0,            // No checking.
     47   VERIFY_CHANGES = 1, // Checks only mutated entries.  Does not check hierarchy.
     48   FULL_DB_VERIFICATION = 2 // Check every entry.  This can be expensive.
     49 };
     50 
     51 // Directory stores and manages EntryKernels.
     52 //
     53 // This class is tightly coupled to several other classes (see friends).
     54 class SYNC_EXPORT Directory {
     55   friend class BaseTransaction;
     56   friend class Entry;
     57   friend class ModelNeutralMutableEntry;
     58   friend class MutableEntry;
     59   friend class ReadTransaction;
     60   friend class ScopedKernelLock;
     61   friend class WriteTransaction;
     62   friend class SyncableDirectoryTest;
     63   friend class syncer::TestUserShare;
     64   FRIEND_TEST_ALL_PREFIXES(SyncableDirectoryTest, ManageDeleteJournals);
     65   FRIEND_TEST_ALL_PREFIXES(SyncableDirectoryTest,
     66                            TakeSnapshotGetsAllDirtyHandlesTest);
     67   FRIEND_TEST_ALL_PREFIXES(SyncableDirectoryTest,
     68                            TakeSnapshotGetsOnlyDirtyHandlesTest);
     69   FRIEND_TEST_ALL_PREFIXES(SyncableDirectoryTest,
     70                            TakeSnapshotGetsMetahandlesToPurge);
     71 
     72  public:
     73   typedef std::vector<int64> Metahandles;
     74 
     75   // Be careful when using these hash_map containers.  According to the spec,
     76   // inserting into them may invalidate all iterators.
     77   //
     78   // It gets worse, though.  The Anroid STL library has a bug that means it may
     79   // invalidate all iterators when you erase from the map, too.  That means that
     80   // you can't iterate while erasing.  STLDeleteElements(), std::remove_if(),
     81   // and other similar functions are off-limits too, until this bug is fixed.
     82   //
     83   // See http://sourceforge.net/p/stlport/bugs/239/.
     84   typedef base::hash_map<int64, EntryKernel*> MetahandlesMap;
     85   typedef base::hash_map<std::string, EntryKernel*> IdsMap;
     86   typedef base::hash_map<std::string, EntryKernel*> TagsMap;
     87   typedef std::string AttachmentIdUniqueId;
     88   typedef base::hash_map<AttachmentIdUniqueId, MetahandleSet>
     89       IndexByAttachmentId;
     90 
     91   static const base::FilePath::CharType kSyncDatabaseFilename[];
     92 
     93   // The dirty/clean state of kernel fields backed by the share_info table.
     94   // This is public so it can be used in SaveChangesSnapshot for persistence.
     95   enum KernelShareInfoStatus {
     96     KERNEL_SHARE_INFO_INVALID,
     97     KERNEL_SHARE_INFO_VALID,
     98     KERNEL_SHARE_INFO_DIRTY
     99   };
    100 
    101   // Various data that the Directory::Kernel we are backing (persisting data
    102   // for) needs saved across runs of the application.
    103   struct SYNC_EXPORT_PRIVATE PersistedKernelInfo {
    104     PersistedKernelInfo();
    105     ~PersistedKernelInfo();
    106 
    107     // Set the |download_progress| entry for the given model to a
    108     // "first sync" start point.  When such a value is sent to the server,
    109     // a full download of all objects of the model will be initiated.
    110     void ResetDownloadProgress(ModelType model_type);
    111 
    112     // Last sync timestamp fetched from the server.
    113     sync_pb::DataTypeProgressMarker download_progress[MODEL_TYPE_COUNT];
    114     // Sync-side transaction version per data type. Monotonically incremented
    115     // when updating native model. A copy is also saved in native model.
    116     // Later out-of-sync models can be detected and fixed by comparing
    117     // transaction versions of sync model and native model.
    118     // TODO(hatiaol): implement detection and fixing of out-of-sync models.
    119     //                Bug 154858.
    120     int64 transaction_version[MODEL_TYPE_COUNT];
    121     // The store birthday we were given by the server. Contents are opaque to
    122     // the client.
    123     std::string store_birthday;
    124     // The next local ID that has not been used with this cache-GUID.
    125     int64 next_id;
    126     // The serialized bag of chips we were given by the server. Contents are
    127     // opaque to the client. This is the serialization of a message of type
    128     // ChipBag defined in sync.proto. It can contains NULL characters.
    129     std::string bag_of_chips;
    130     // The per-datatype context.
    131     sync_pb::DataTypeContext datatype_context[MODEL_TYPE_COUNT];
    132   };
    133 
    134   // What the Directory needs on initialization to create itself and its Kernel.
    135   // Filled by DirectoryBackingStore::Load.
    136   struct KernelLoadInfo {
    137     PersistedKernelInfo kernel_info;
    138     std::string cache_guid;  // Created on first initialization, never changes.
    139     int64 max_metahandle;    // Computed (using sql MAX aggregate) on init.
    140     KernelLoadInfo() : max_metahandle(0) {
    141     }
    142   };
    143 
    144   // When the Directory is told to SaveChanges, a SaveChangesSnapshot is
    145   // constructed and forms a consistent snapshot of what needs to be sent to
    146   // the backing store.
    147   struct SYNC_EXPORT_PRIVATE SaveChangesSnapshot {
    148     SaveChangesSnapshot();
    149     ~SaveChangesSnapshot();
    150 
    151     KernelShareInfoStatus kernel_info_status;
    152     PersistedKernelInfo kernel_info;
    153     EntryKernelSet dirty_metas;
    154     MetahandleSet metahandles_to_purge;
    155     EntryKernelSet delete_journals;
    156     MetahandleSet delete_journals_to_purge;
    157   };
    158 
    159   // Does not take ownership of |encryptor|.
    160   // |report_unrecoverable_error_function| may be NULL.
    161   // Takes ownership of |store|.
    162   Directory(
    163       DirectoryBackingStore* store,
    164       UnrecoverableErrorHandler* unrecoverable_error_handler,
    165       ReportUnrecoverableErrorFunction
    166           report_unrecoverable_error_function,
    167       NigoriHandler* nigori_handler,
    168       Cryptographer* cryptographer);
    169   virtual ~Directory();
    170 
    171   // Does not take ownership of |delegate|, which must not be NULL.
    172   // Starts sending events to |delegate| if the returned result is
    173   // OPENED.  Note that events to |delegate| may be sent from *any*
    174   // thread.  |transaction_observer| must be initialized.
    175   DirOpenResult Open(const std::string& name,
    176                      DirectoryChangeDelegate* delegate,
    177                      const WeakHandle<TransactionObserver>&
    178                          transaction_observer);
    179 
    180   // Stops sending events to the delegate and the transaction
    181   // observer.
    182   void Close();
    183 
    184   int64 NextMetahandle();
    185   // Returns a negative integer unique to this client.
    186   syncable::Id NextId();
    187 
    188   bool good() const { return NULL != kernel_; }
    189 
    190   // The download progress is an opaque token provided by the sync server
    191   // to indicate the continuation state of the next GetUpdates operation.
    192   void GetDownloadProgress(
    193       ModelType type,
    194       sync_pb::DataTypeProgressMarker* value_out) const;
    195   void GetDownloadProgressAsString(
    196       ModelType type,
    197       std::string* value_out) const;
    198   size_t GetEntriesCount() const;
    199   void SetDownloadProgress(
    200       ModelType type,
    201       const sync_pb::DataTypeProgressMarker& value);
    202 
    203   // Gets/Increments transaction version of a model type. Must be called when
    204   // holding kernel mutex.
    205   int64 GetTransactionVersion(ModelType type) const;
    206   void IncrementTransactionVersion(ModelType type);
    207 
    208   // Getter/setters for the per datatype context.
    209   void GetDataTypeContext(BaseTransaction* trans,
    210                           ModelType type,
    211                           sync_pb::DataTypeContext* context) const;
    212   void SetDataTypeContext(BaseWriteTransaction* trans,
    213                           ModelType type,
    214                           const sync_pb::DataTypeContext& context);
    215 
    216   ModelTypeSet InitialSyncEndedTypes();
    217   bool InitialSyncEndedForType(ModelType type);
    218   bool InitialSyncEndedForType(BaseTransaction* trans, ModelType type);
    219 
    220   const std::string& name() const { return kernel_->name; }
    221 
    222   // (Account) Store birthday is opaque to the client, so we keep it in the
    223   // format it is in the proto buffer in case we switch to a binary birthday
    224   // later.
    225   std::string store_birthday() const;
    226   void set_store_birthday(const std::string& store_birthday);
    227 
    228   // (Account) Bag of chip is an opaque state used by the server to track the
    229   // client.
    230   std::string bag_of_chips() const;
    231   void set_bag_of_chips(const std::string& bag_of_chips);
    232 
    233   // Unique to each account / client pair.
    234   std::string cache_guid() const;
    235 
    236   // Returns a pointer to our Nigori node handler.
    237   NigoriHandler* GetNigoriHandler();
    238 
    239   // Returns a pointer to our cryptographer. Does not transfer ownership.
    240   // Not thread safe, so should only be accessed while holding a transaction.
    241   Cryptographer* GetCryptographer(const BaseTransaction* trans);
    242 
    243   // Returns true if the directory had encountered an unrecoverable error.
    244   // Note: Any function in |Directory| that can be called without holding a
    245   // transaction need to check if the Directory already has an unrecoverable
    246   // error on it.
    247   bool unrecoverable_error_set(const BaseTransaction* trans) const;
    248 
    249   // Called to immediately report an unrecoverable error (but don't
    250   // propagate it up).
    251   void ReportUnrecoverableError() {
    252     if (report_unrecoverable_error_function_) {
    253       report_unrecoverable_error_function_();
    254     }
    255   }
    256 
    257   // Called to set the unrecoverable error on the directory and to propagate
    258   // the error to upper layers.
    259   void OnUnrecoverableError(const BaseTransaction* trans,
    260                             const tracked_objects::Location& location,
    261                             const std::string & message);
    262 
    263   DeleteJournal* delete_journal();
    264 
    265   // Returns the child meta handles (even those for deleted/unlinked
    266   // nodes) for given parent id.  Clears |result| if there are no
    267   // children.
    268   bool GetChildHandlesById(BaseTransaction*, const Id& parent_id,
    269       Metahandles* result);
    270 
    271   // Counts all items under the given node, including the node itself.
    272   int GetTotalNodeCount(BaseTransaction*, EntryKernel* kernel_) const;
    273 
    274   // Returns this item's position within its parent folder.
    275   // The left-most item is 0, second left-most is 1, etc.
    276   int GetPositionIndex(BaseTransaction*, EntryKernel* kernel_) const;
    277 
    278   // Returns true iff |id| has children.
    279   bool HasChildren(BaseTransaction* trans, const Id& id);
    280 
    281   // Find the first child in the positional ordering under a parent,
    282   // and fill in |*first_child_id| with its id.  Fills in a root Id if
    283   // parent has no children.  Returns true if the first child was
    284   // successfully found, or false if an error was encountered.
    285   Id GetFirstChildId(BaseTransaction* trans, const EntryKernel* parent);
    286 
    287   // These functions allow one to fetch the next or previous item under
    288   // the same folder.  Returns the "root" ID if there is no predecessor
    289   // or successor.
    290   //
    291   // TODO(rlarocque): These functions are used mainly for tree traversal.  We
    292   // should replace these with an iterator API.  See crbug.com/178275.
    293   syncable::Id GetPredecessorId(EntryKernel*);
    294   syncable::Id GetSuccessorId(EntryKernel*);
    295 
    296   // Places |e| as a successor to |predecessor|.  If |predecessor| is NULL,
    297   // |e| will be placed as the left-most item in its folder.
    298   //
    299   // Both |e| and |predecessor| must be valid entries under the same parent.
    300   //
    301   // TODO(rlarocque): This function includes limited support for placing items
    302   // with valid positions (ie. Bookmarks) as siblings of items that have no set
    303   // ordering (ie. Autofill items).  This support is required only for tests,
    304   // and should be removed.  See crbug.com/178282.
    305   void PutPredecessor(EntryKernel* e, EntryKernel* predecessor);
    306 
    307   // SaveChanges works by taking a consistent snapshot of the current Directory
    308   // state and indices (by deep copy) under a ReadTransaction, passing this
    309   // snapshot to the backing store under no transaction, and finally cleaning
    310   // up by either purging entries no longer needed (this part done under a
    311   // WriteTransaction) or rolling back the dirty bits.  It also uses
    312   // internal locking to enforce SaveChanges operations are mutually exclusive.
    313   //
    314   // WARNING: THIS METHOD PERFORMS SYNCHRONOUS I/O VIA SQLITE.
    315   bool SaveChanges();
    316 
    317   // Returns the number of entities with the unsynced bit set.
    318   int64 unsynced_entity_count() const;
    319 
    320   // Get GetUnsyncedMetaHandles should only be called after SaveChanges and
    321   // before any new entries have been created. The intention is that the
    322   // syncer should call it from its PerformSyncQueries member.
    323   void GetUnsyncedMetaHandles(BaseTransaction* trans,
    324                               Metahandles* result);
    325 
    326   // Returns whether or not this |type| has unapplied updates.
    327   bool TypeHasUnappliedUpdates(ModelType type);
    328 
    329   // Get all the metahandles for unapplied updates for a given set of
    330   // server types.
    331   void GetUnappliedUpdateMetaHandles(BaseTransaction* trans,
    332                                      FullModelTypeSet server_types,
    333                                      std::vector<int64>* result);
    334 
    335   // Get all the metahandles of entries of |type|.
    336   void GetMetaHandlesOfType(BaseTransaction* trans,
    337                             ModelType type,
    338                             Metahandles* result);
    339 
    340   // Get metahandle counts for various criteria to show on the
    341   // about:sync page. The information is computed on the fly
    342   // each time. If this results in a significant performance hit,
    343   // additional data structures can be added to cache results.
    344   void CollectMetaHandleCounts(std::vector<int>* num_entries_by_type,
    345                                std::vector<int>* num_to_delete_entries_by_type);
    346 
    347   // Returns a ListValue serialization of all nodes for the given type.
    348   scoped_ptr<base::ListValue> GetNodeDetailsForType(
    349       BaseTransaction* trans,
    350       ModelType type);
    351 
    352   // Sets the level of invariant checking performed after transactions.
    353   void SetInvariantCheckLevel(InvariantCheckLevel check_level);
    354 
    355   // Checks tree metadata consistency following a transaction.  It is intended
    356   // to provide a reasonable tradeoff between performance and comprehensiveness
    357   // and may be used in release code.
    358   bool CheckInvariantsOnTransactionClose(
    359       syncable::BaseTransaction* trans,
    360       const MetahandleSet& modified_handles);
    361 
    362   // Forces a full check of the directory.  This operation may be slow and
    363   // should not be invoked outside of tests.
    364   bool FullyCheckTreeInvariants(BaseTransaction *trans);
    365 
    366   // Purges data associated with any entries whose ModelType or ServerModelType
    367   // is found in |disabled_types|, from sync directory _both_ in memory and on
    368   // disk. Only valid, "real" model types are allowed in |disabled_types| (see
    369   // model_type.h for definitions).
    370   // 1. Data associated with |types_to_journal| is saved in the delete journal
    371   // to help prevent back-from-dead problem due to offline delete in the next
    372   // sync session. |types_to_journal| must be a subset of |disabled_types|.
    373   // 2. Data associated with |types_to_unapply| is reset to an "unapplied"
    374   // state, wherein all local data is deleted and IS_UNAPPLIED is set to true.
    375   // This is useful when there's no benefit in discarding the currently
    376   // downloaded state, such as when there are cryptographer errors.
    377   // |types_to_unapply| must be a subset of |disabled_types|.
    378   // 3. All other data is purged entirely.
    379   // Note: "Purge" is just meant to distinguish from "deleting" entries, which
    380   // means something different in the syncable namespace.
    381   // WARNING! This can be real slow, as it iterates over all entries.
    382   // WARNING! Performs synchronous I/O.
    383   // Returns: true on success, false if an error was encountered.
    384   virtual bool PurgeEntriesWithTypeIn(ModelTypeSet disabled_types,
    385                                       ModelTypeSet types_to_journal,
    386                                       ModelTypeSet types_to_unapply);
    387 
    388   // Resets the base_versions and server_versions of all synced entities
    389   // associated with |type| to 1.
    390   // WARNING! This can be slow, as it iterates over all entries for a type.
    391   bool ResetVersionsForType(BaseWriteTransaction* trans, ModelType type);
    392 
    393   // Returns true iff the attachment identified by |attachment_id_proto| is
    394   // linked to an entry.
    395   //
    396   // An attachment linked to a deleted entry is still considered linked if the
    397   // entry hasn't yet been purged.
    398   bool IsAttachmentLinked(
    399       const sync_pb::AttachmentIdProto& attachment_id_proto) const;
    400 
    401   // Given attachment id return metahandles to all entries that reference this
    402   // attachment.
    403   void GetMetahandlesByAttachmentId(
    404       BaseTransaction* trans,
    405       const sync_pb::AttachmentIdProto& attachment_id_proto,
    406       Metahandles* result);
    407 
    408   // Change entry to not dirty. Used in special case when we don't want to
    409   // persist modified entry on disk. e.g. SyncBackupManager uses this to
    410   // preserve sync preferences in DB on disk.
    411   void UnmarkDirtyEntry(WriteTransaction* trans, Entry* entry);
    412 
    413  protected:  // for friends, mainly used by Entry constructors
    414   virtual EntryKernel* GetEntryByHandle(int64 handle);
    415   virtual EntryKernel* GetEntryByHandle(int64 metahandle,
    416       ScopedKernelLock* lock);
    417   virtual EntryKernel* GetEntryById(const Id& id);
    418   EntryKernel* GetEntryByServerTag(const std::string& tag);
    419   virtual EntryKernel* GetEntryByClientTag(const std::string& tag);
    420   bool ReindexId(BaseWriteTransaction* trans, EntryKernel* const entry,
    421                  const Id& new_id);
    422   bool ReindexParentId(BaseWriteTransaction* trans, EntryKernel* const entry,
    423                        const Id& new_parent_id);
    424   // Update the attachment index for |metahandle| removing it from the index
    425   // under |old_metadata| entries and add it under |new_metadata| entries.
    426   void UpdateAttachmentIndex(const int64 metahandle,
    427                              const sync_pb::AttachmentMetadata& old_metadata,
    428                              const sync_pb::AttachmentMetadata& new_metadata);
    429   void ClearDirtyMetahandles();
    430 
    431   DirOpenResult OpenImpl(
    432       const std::string& name,
    433       DirectoryChangeDelegate* delegate,
    434       const WeakHandle<TransactionObserver>& transaction_observer);
    435 
    436  private:
    437   struct Kernel {
    438     // |delegate| must not be NULL.  |transaction_observer| must be
    439     // initialized.
    440     Kernel(const std::string& name, const KernelLoadInfo& info,
    441            DirectoryChangeDelegate* delegate,
    442            const WeakHandle<TransactionObserver>& transaction_observer);
    443 
    444     ~Kernel();
    445 
    446     // Implements ReadTransaction / WriteTransaction using a simple lock.
    447     base::Lock transaction_mutex;
    448 
    449     // Protected by transaction_mutex.  Used by WriteTransactions.
    450     int64 next_write_transaction_id;
    451 
    452     // The name of this directory.
    453     std::string const name;
    454 
    455     // Protects all members below.
    456     // The mutex effectively protects all the indices, but not the
    457     // entries themselves.  So once a pointer to an entry is pulled
    458     // from the index, the mutex can be unlocked and entry read or written.
    459     //
    460     // Never hold the mutex and do anything with the database or any
    461     // other buffered IO.  Violating this rule will result in deadlock.
    462     base::Lock mutex;
    463 
    464     // Entries indexed by metahandle.  This container is considered to be the
    465     // owner of all EntryKernels, which may be referened by the other
    466     // containers.  If you remove an EntryKernel from this map, you probably
    467     // want to remove it from all other containers and delete it, too.
    468     MetahandlesMap metahandles_map;
    469 
    470     // Entries indexed by id
    471     IdsMap ids_map;
    472 
    473     // Entries indexed by server tag.
    474     // This map does not include any entries with non-existent server tags.
    475     TagsMap server_tags_map;
    476 
    477     // Entries indexed by client tag.
    478     // This map does not include any entries with non-existent client tags.
    479     // IS_DEL items are included.
    480     TagsMap client_tags_map;
    481 
    482     // Contains non-deleted items, indexed according to parent and position
    483     // within parent.  Protected by the ScopedKernelLock.
    484     ParentChildIndex parent_child_index;
    485 
    486     // This index keeps track of which metahandles refer to a given attachment.
    487     // Think of it as the inverse of EntryKernel's AttachmentMetadata Records.
    488     //
    489     // Because entries can be undeleted (e.g. PutIsDel(false)), entries should
    490     // not removed from the index until they are actually deleted from memory.
    491     //
    492     // All access should go through IsAttachmentLinked,
    493     // RemoveFromAttachmentIndex, AddToAttachmentIndex, and
    494     // UpdateAttachmentIndex methods to avoid iterator invalidation errors.
    495     IndexByAttachmentId index_by_attachment_id;
    496 
    497     // 3 in-memory indices on bits used extremely frequently by the syncer.
    498     // |unapplied_update_metahandles| is keyed by the server model type.
    499     MetahandleSet unapplied_update_metahandles[MODEL_TYPE_COUNT];
    500     MetahandleSet unsynced_metahandles;
    501     // Contains metahandles that are most likely dirty (though not
    502     // necessarily).  Dirtyness is confirmed in TakeSnapshotForSaveChanges().
    503     MetahandleSet dirty_metahandles;
    504 
    505     // When a purge takes place, we remove items from all our indices and stash
    506     // them in here so that SaveChanges can persist their permanent deletion.
    507     MetahandleSet metahandles_to_purge;
    508 
    509     KernelShareInfoStatus info_status;
    510 
    511     // These 3 members are backed in the share_info table, and
    512     // their state is marked by the flag above.
    513 
    514     // A structure containing the Directory state that is written back into the
    515     // database on SaveChanges.
    516     PersistedKernelInfo persisted_info;
    517 
    518     // A unique identifier for this account's cache db, used to generate
    519     // unique server IDs. No need to lock, only written at init time.
    520     const std::string cache_guid;
    521 
    522     // It doesn't make sense for two threads to run SaveChanges at the same
    523     // time; this mutex protects that activity.
    524     base::Lock save_changes_mutex;
    525 
    526     // The next metahandle is protected by kernel mutex.
    527     int64 next_metahandle;
    528 
    529     // The delegate for directory change events.  Must not be NULL.
    530     DirectoryChangeDelegate* const delegate;
    531 
    532     // The transaction observer.
    533     const WeakHandle<TransactionObserver> transaction_observer;
    534   };
    535 
    536   // These private versions expect the kernel lock to already be held
    537   // before calling.
    538   EntryKernel* GetEntryById(const Id& id, ScopedKernelLock* const lock);
    539 
    540   // A helper that implements the logic of checking tree invariants.
    541   bool CheckTreeInvariants(syncable::BaseTransaction* trans,
    542                            const MetahandleSet& handles);
    543 
    544   // Helper to prime metahandles_map, ids_map, parent_child_index,
    545   // unsynced_metahandles, unapplied_update_metahandles, server_tags_map and
    546   // client_tags_map from metahandles_index.  The input |handles_map| will be
    547   // cleared during the initialization process.
    548   void InitializeIndices(MetahandlesMap* handles_map);
    549 
    550   // Constructs a consistent snapshot of the current Directory state and
    551   // indices (by deep copy) under a ReadTransaction for use in |snapshot|.
    552   // See SaveChanges() for more information.
    553   void TakeSnapshotForSaveChanges(SaveChangesSnapshot* snapshot);
    554 
    555   // Purges from memory any unused, safe to remove entries that were
    556   // successfully deleted on disk as a result of the SaveChanges that processed
    557   // |snapshot|.  See SaveChanges() for more information.
    558   bool VacuumAfterSaveChanges(const SaveChangesSnapshot& snapshot);
    559 
    560   // Rolls back dirty bits in the event that the SaveChanges that
    561   // processed |snapshot| failed, for example, due to no disk space.
    562   void HandleSaveChangesFailure(const SaveChangesSnapshot& snapshot);
    563 
    564   // For new entry creation only
    565   bool InsertEntry(BaseWriteTransaction* trans,
    566                    EntryKernel* entry, ScopedKernelLock* lock);
    567   bool InsertEntry(BaseWriteTransaction* trans, EntryKernel* entry);
    568 
    569   // Used by CheckTreeInvariants
    570   void GetAllMetaHandles(BaseTransaction* trans, MetahandleSet* result);
    571   bool SafeToPurgeFromMemory(WriteTransaction* trans,
    572                              const EntryKernel* const entry) const;
    573 
    574   // A helper used by GetTotalNodeCount.
    575   void GetChildSetForKernel(
    576       BaseTransaction*,
    577       EntryKernel* kernel_,
    578       std::deque<const OrderedChildSet*>* child_sets) const;
    579 
    580   // Append the handles of the children of |parent_id| to |result|.
    581   void AppendChildHandles(
    582       const ScopedKernelLock& lock,
    583       const Id& parent_id, Directory::Metahandles* result);
    584 
    585   // Helper methods used by PurgeDisabledTypes.
    586   void UnapplyEntry(EntryKernel* entry);
    587   void DeleteEntry(bool save_to_journal,
    588                    EntryKernel* entry,
    589                    EntryKernelSet* entries_to_journal,
    590                    const ScopedKernelLock& lock);
    591 
    592   // Remove each of |metahandle|'s attachment ids from index_by_attachment_id.
    593   void RemoveFromAttachmentIndex(
    594       const int64 metahandle,
    595       const sync_pb::AttachmentMetadata& attachment_metadata,
    596       const ScopedKernelLock& lock);
    597   // Add each of |metahandle|'s attachment ids to the index_by_attachment_id.
    598   void AddToAttachmentIndex(
    599       const int64 metahandle,
    600       const sync_pb::AttachmentMetadata& attachment_metadata,
    601       const ScopedKernelLock& lock);
    602 
    603   Kernel* kernel_;
    604 
    605   scoped_ptr<DirectoryBackingStore> store_;
    606 
    607   UnrecoverableErrorHandler* const unrecoverable_error_handler_;
    608   const ReportUnrecoverableErrorFunction report_unrecoverable_error_function_;
    609   bool unrecoverable_error_set_;
    610 
    611   // Not owned.
    612   NigoriHandler* const nigori_handler_;
    613   Cryptographer* const cryptographer_;
    614 
    615   InvariantCheckLevel invariant_check_level_;
    616 
    617   // Maintain deleted entries not in |kernel_| until it's verified that they
    618   // are deleted in native models as well.
    619   scoped_ptr<DeleteJournal> delete_journal_;
    620 
    621   DISALLOW_COPY_AND_ASSIGN(Directory);
    622 };
    623 
    624 }  // namespace syncable
    625 }  // namespace syncer
    626 
    627 #endif // SYNC_SYNCABLE_DIRECTORY_H_
    628