sync/syncable/syncable_delete_journal.h

   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_SYNCABLE_DELETE_JOURNAL_H_
   6 #define SYNC_SYNCABLE_SYNCABLE_DELETE_JOURNAL_H_
   7
   8 #include <set>
   9
  10 #include "base/gtest_prod_util.h"
  11 #include "base/synchronization/lock.h"
  12 #include "sync/base/sync_export.h"
  13 #include "sync/syncable/metahandle_set.h"
  14 #include "sync/syncable/syncable-inl.h"
  15
  16 namespace syncer {
  17 namespace syncable {
  18
  19 class BaseTransaction;
  20 struct EntryKernel;
  21
  22 typedef std::set<const EntryKernel*, LessField<IdField, ID> > JournalIndex;
  23
  24 // DeleteJournal manages deleted entries that are not in sync directory until
  25 // it's safe to drop them after the deletion is confirmed with native models.
  26 // DeleteJournal is thread-safe and can be accessed on any thread. Has to hold
  27 // a valid transaction object when calling methods of DeleteJournal, thus each
  28 // method requires a non-null |trans| parameter.
  29 class SYNC_EXPORT_PRIVATE DeleteJournal {
  30  public:
  31   FRIEND_TEST_ALL_PREFIXES(SyncableDirectoryTest, ManageDeleteJournals);
  32
  33   // Initialize |delete_journals_| using |intitial_journal|, whose content is
  34   // destroyed during initialization.
  35   explicit DeleteJournal(JournalIndex* initial_journal);
  36   ~DeleteJournal();
  37
  38   // For testing only.
  39   size_t GetDeleteJournalSize(BaseTransaction* trans) const;
  40
  41   // Add/remove |entry| to/from |delete_journals_| according to its
  42   // SERVER_IS_DEL field and |was_deleted|. Called on sync thread.
  43   void UpdateDeleteJournalForServerDelete(BaseTransaction* trans,
  44                                           bool was_deleted,
  45                                           const EntryKernel& entry);
  46
  47   // Return entries of specified type in |delete_journals_|. This should be
  48   // called ONCE in model association. |deleted_entries| can be used to
  49   // detect deleted sync data that's not persisted in native model to
  50   // prevent back-from-dead problem. |deleted_entries| are only valid during
  51   // lifetime of |trans|. |type| is added to |passive_delete_journal_types_| to
  52   // enable periodically saving/clearing of delete journals of |type| because
  53   // new journals added later are not needed until next model association.
  54   // Can be called on any thread.
  55   void GetDeleteJournals(BaseTransaction* trans, ModelType type,
  56                          EntryKernelSet* deleted_entries);
  57
  58   // Purge entries of specified type in |delete_journals_| if their handles are
  59   // in |to_purge|. This should be called after model association and
  60   // |to_purge| should contain handles of the entries whose deletions are
  61   // confirmed in native model. Can be called on any thread.
  62   void PurgeDeleteJournals(BaseTransaction* trans,
  63                            const MetahandleSet& to_purge);
  64
  65   // Move entries in |delete_journals_| whose types are in
  66   // |passive_delete_journal_types_| to |journal_entries|. Move handles in
  67   // |delete_journals_to_purge_| to |journals_to_purge|. Called on sync thread.
  68   void TakeSnapshotAndClear(BaseTransaction* trans,
  69                             EntryKernelSet* journal_entries,
  70                             MetahandleSet* journals_to_purge);
  71
  72   // Add |entries| to |delete_journals_| regardless of their SERVER_IS_DEL
  73   // value. This is used to:
  74   // * restore delete journals from snapshot if snapshot failed to save.
  75   // * batch add entries of a data type with unrecoverable error to delete
  76   //   journal before purging them.
  77   // Called on sync thread.
  78   void AddJournalBatch(BaseTransaction* trans, const EntryKernelSet& entries);
  79
  80   // Return true if delete journals of |type| are maintained.
  81   static bool IsDeleteJournalEnabled(ModelType type);
  82
  83  private:
  84   // Contains deleted entries that may not be persisted in native models. And
  85   // in case of unrecoverable error, all purged entries are moved here for
  86   // bookkeeping to prevent back-from-dead entries that are deleted elsewhere
  87   // when sync's down.
  88   JournalIndex delete_journals_;
  89
  90   // Contains meta handles of deleted entries that have been persisted or
  91   // undeleted, thus can be removed from database.
  92   MetahandleSet delete_journals_to_purge_;
  93
  94   // Delete journals of these types can be cleared from memory after being
  95   // saved to database.
  96   ModelTypeSet passive_delete_journal_types_;
  97
  98   DISALLOW_COPY_AND_ASSIGN(DeleteJournal);
  99 };
 100
 101 }  // namespace syncable
 102 }  // namespace syncer
 103
 104 #endif  // SYNC_SYNCABLE_SYNCABLE_DELETE_JOURNAL_H_