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// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_SYNC_SYNCABLE_SYNCABLE_DELETE_JOURNAL_H_
#define COMPONENTS_SYNC_SYNCABLE_SYNCABLE_DELETE_JOURNAL_H_
#include <stddef.h>
#include <map>
#include <memory>
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/synchronization/lock.h"
#include "components/sync/syncable/entry_kernel.h"
#include "components/sync/syncable/metahandle_set.h"
namespace syncer {
namespace syncable {
class BaseTransaction;
class LessByID {
public:
inline bool operator()(const EntryKernel* a, const EntryKernel* b) const {
return a->ref(ID) < b->ref(ID);
}
};
// This should be |std::set<std::unique_ptr<EntryKernel>, LessByID>|. However,
// DeleteJournal::TakeSnapshotAndClear needs to remove the unique_ptr from the
// set, and std::set::extract is only available in C++17. TODO(avi): Switch to
// using a std::set when Chromium allows C++17 use.
typedef std::map<const EntryKernel*, std::unique_ptr<EntryKernel>, LessByID>
JournalIndex;
// DeleteJournal manages deleted entries that are not in sync directory until
// it's safe to drop them after the deletion is confirmed with native models.
// DeleteJournal is thread-safe and can be accessed on any thread. Has to hold
// a valid transaction object when calling methods of DeleteJournal, thus each
// method requires a non-null |trans| parameter.
class DeleteJournal {
public:
// Initialize |delete_journals_| using |initial_journal|.
explicit DeleteJournal(std::unique_ptr<JournalIndex> initial_journal);
~DeleteJournal();
// For testing only.
size_t GetDeleteJournalSize(BaseTransaction* trans) const;
// Add/remove |entry| to/from |delete_journals_| according to its
// SERVER_IS_DEL field and |was_deleted|. Called on sync thread.
void UpdateDeleteJournalForServerDelete(BaseTransaction* trans,
bool was_deleted,
const EntryKernel& entry);
// Return entries of specified type in |delete_journals_|. This should be
// called ONCE in model association. |deleted_entries| can be used to
// detect deleted sync data that's not persisted in native model to
// prevent back-from-dead problem. |deleted_entries| are only valid during
// lifetime of |trans|. |type| is added to |passive_delete_journal_types_| to
// enable periodically saving/clearing of delete journals of |type| because
// new journals added later are not needed until next model association.
// Can be called on any thread.
void GetDeleteJournals(BaseTransaction* trans,
ModelType type,
EntryKernelSet* deleted_entries);
// Purge entries of specified type in |delete_journals_| if their handles are
// in |to_purge|. This should be called after model association and
// |to_purge| should contain handles of the entries whose deletions are
// confirmed in native model. Can be called on any thread.
void PurgeDeleteJournals(BaseTransaction* trans,
const MetahandleSet& to_purge);
// Move entries in |delete_journals_| whose types are in
// |passive_delete_journal_types_| to |journal_entries|. Move handles in
// |delete_journals_to_purge_| to |journals_to_purge|. Called on sync thread.
void TakeSnapshotAndClear(BaseTransaction* trans,
OwnedEntryKernelSet* journal_entries,
MetahandleSet* journals_to_purge);
// Add |entries| to |delete_journals_| regardless of their SERVER_IS_DEL
// value. This is used to:
// * restore delete journals from snapshot if snapshot failed to save.
// * batch add entries of a data type with unrecoverable error to delete
// journal before purging them.
// Called on sync thread.
void AddJournalBatch(BaseTransaction* trans,
const OwnedEntryKernelSet& entries);
// Return true if delete journals of |type| are maintained.
static bool IsDeleteJournalEnabled(ModelType type);
private:
FRIEND_TEST_ALL_PREFIXES(SyncableDirectoryTest, ManageDeleteJournals);
// Contains deleted entries that may not be persisted in native models. And
// in case of unrecoverable error, all purged entries are moved here for
// bookkeeping to prevent back-from-dead entries that are deleted elsewhere
// when sync's down.
JournalIndex delete_journals_;
// Contains meta handles of deleted entries that have been persisted or
// undeleted, thus can be removed from database.
MetahandleSet delete_journals_to_purge_;
// Delete journals of these types can be cleared from memory after being
// saved to database.
ModelTypeSet passive_delete_journal_types_;
DISALLOW_COPY_AND_ASSIGN(DeleteJournal);
};
} // namespace syncable
} // namespace syncer
#endif // COMPONENTS_SYNC_SYNCABLE_SYNCABLE_DELETE_JOURNAL_H_
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