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// Copyright 2012 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 SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_
#define SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_
#include <string>
#include "base/memory/scoped_ptr.h"
#include "base/threading/non_thread_safe.h"
#include "sql/connection.h"
#include "sql/statement.h"
#include "sync/base/sync_export.h"
#include "sync/internal_api/public/base/model_type.h"
#include "sync/syncable/dir_open_result.h"
#include "sync/syncable/directory.h"
#include "sync/syncable/metahandle_set.h"
namespace sync_pb {
class EntitySpecifics;
}
namespace syncer {
namespace syncable {
SYNC_EXPORT_PRIVATE extern const int32 kCurrentDBVersion;
struct ColumnSpec;
// Interface that provides persistence for a syncable::Directory object. You can
// load all the persisted data to prime a syncable::Directory on startup by
// invoking Load. The only other thing you (or more correctly, a Directory) can
// do here is save any changes that have occurred since calling Load, which can
// be done periodically as often as desired.
//
// The DirectoryBackingStore will own an sqlite lock on its database for most of
// its lifetime. You must not have two DirectoryBackingStore objects accessing
// the database simultaneously. Because the lock exists at the database level,
// not even two separate browser instances would be able to acquire it
// simultaneously.
//
// This class is abstract so that we can extend it in interesting ways for use
// in tests. The concrete class used in non-test scenarios is
// OnDiskDirectoryBackingStore.
class SYNC_EXPORT_PRIVATE DirectoryBackingStore : public base::NonThreadSafe {
friend class DirectoryBackingStoreTest;
FRIEND_TEST_ALL_PREFIXES(DirectoryBackingStoreTest,
IncreaseDatabasePageSizeFrom4KTo32K);
public:
explicit DirectoryBackingStore(const std::string& dir_name);
virtual ~DirectoryBackingStore();
// Loads and drops all currently persisted meta entries into |handles_map|
// and loads appropriate persisted kernel info into |kernel_load_info|.
// The function determines which entries can be safely dropped and inserts
// their keys into |metahandles_to_purge|. It is up to the caller to
// perform the actual cleanup.
//
// This function will migrate to the latest database version.
//
// NOTE: On success (return value of OPENED), the buckets are populated with
// newly allocated items, meaning ownership is bestowed upon the caller.
virtual DirOpenResult Load(Directory::MetahandlesMap* handles_map,
JournalIndex* delete_journals,
MetahandleSet* metahandles_to_purge,
Directory::KernelLoadInfo* kernel_load_info) = 0;
// Updates the on-disk store with the input |snapshot| as a database
// transaction. Does NOT open any syncable transactions as this would cause
// opening transactions elsewhere to block on synchronous I/O.
// DO NOT CALL THIS FROM MORE THAN ONE THREAD EVER. Also, whichever thread
// calls SaveChanges *must* be the thread that owns/destroys |this|.
virtual bool SaveChanges(const Directory::SaveChangesSnapshot& snapshot);
protected:
// For test classes.
DirectoryBackingStore(const std::string& dir_name,
sql::Connection* connection);
// General Directory initialization and load helpers.
bool InitializeTables();
bool CreateTables();
// Create 'share_info' or 'temp_share_info' depending on value of
// is_temporary. Returns an sqlite
bool CreateShareInfoTable(bool is_temporary);
bool CreateShareInfoTableVersion71(bool is_temporary);
// Create 'metas' or 'temp_metas' depending on value of is_temporary. Also
// create a 'deleted_metas' table using same schema.
bool CreateMetasTable(bool is_temporary);
bool CreateModelsTable();
bool CreateV71ModelsTable();
bool CreateV75ModelsTable();
bool CreateV81ModelsTable();
// Drops a table if it exists, harmless if the table did not already exist.
bool SafeDropTable(const char* table_name);
// Load helpers for entries and attributes.
bool LoadEntries(Directory::MetahandlesMap* handles_map,
MetahandleSet* metahandles_to_purge);
bool LoadDeleteJournals(JournalIndex* delete_journals);
bool LoadInfo(Directory::KernelLoadInfo* info);
bool SafeToPurgeOnLoading(const EntryKernel& entry) const;
// Save/update helpers for entries. Return false if sqlite commit fails.
static bool SaveEntryToDB(sql::Statement* save_statement,
const EntryKernel& entry);
bool SaveNewEntryToDB(const EntryKernel& entry);
bool UpdateEntryToDB(const EntryKernel& entry);
// Close save_dbhandle_. Broken out for testing.
void EndSave();
enum EntryTable {
METAS_TABLE,
DELETE_JOURNAL_TABLE,
};
// Removes each entry whose metahandle is in |handles| from the table
// specified by |from| table. Does synchronous I/O. Returns false on error.
bool DeleteEntries(EntryTable from, const MetahandleSet& handles);
// Drop all tables in preparation for reinitialization.
void DropAllTables();
// Serialization helpers for ModelType. These convert between
// the ModelType enum and the values we persist in the database to identify
// a model. We persist a default instance of the specifics protobuf as the
// ID, rather than the enum value.
static ModelType ModelIdToModelTypeEnum(const void* data, int length);
static std::string ModelTypeEnumToModelId(ModelType model_type);
static std::string GenerateCacheGUID();
// Runs an integrity check on the current database. If the
// integrity check fails, false is returned and error is populated
// with an error message.
bool CheckIntegrity(sqlite3* handle, std::string* error) const;
// Checks that the references between sync nodes is consistent.
static bool VerifyReferenceIntegrity(
const Directory::MetahandlesMap* handles_map);
// Migration utilities.
bool RefreshColumns();
bool SetVersion(int version);
int GetVersion();
bool MigrateToSpecifics(const char* old_columns,
const char* specifics_column,
void(*handler_function) (
sql::Statement* old_value_query,
int old_value_column,
sync_pb::EntitySpecifics* mutable_new_value));
// Individual version migrations.
bool MigrateVersion67To68();
bool MigrateVersion68To69();
bool MigrateVersion69To70();
bool MigrateVersion70To71();
bool MigrateVersion71To72();
bool MigrateVersion72To73();
bool MigrateVersion73To74();
bool MigrateVersion74To75();
bool MigrateVersion75To76();
bool MigrateVersion76To77();
bool MigrateVersion77To78();
bool MigrateVersion78To79();
bool MigrateVersion79To80();
bool MigrateVersion80To81();
bool MigrateVersion81To82();
bool MigrateVersion82To83();
bool MigrateVersion83To84();
bool MigrateVersion84To85();
bool MigrateVersion85To86();
bool MigrateVersion86To87();
bool MigrateVersion87To88();
bool MigrateVersion88To89();
// Accessor for needs_column_refresh_. Used in tests.
bool needs_column_refresh() const;
// Destroys the existing Connection and creates a new one.
void ResetAndCreateConnection();
scoped_ptr<sql::Connection> db_;
private:
bool Vacuum();
bool IncreasePageSizeTo32K();
bool GetDatabasePageSize(int* page_size);
// Prepares |save_statement| for saving entries in |table|.
void PrepareSaveEntryStatement(EntryTable table,
sql::Statement* save_statement);
const std::string dir_name_;
const int database_page_size_;
sql::Statement save_meta_statement_;
sql::Statement save_delete_journal_statement_;
// Set to true if migration left some old columns around that need to be
// discarded.
bool needs_column_refresh_;
DISALLOW_COPY_AND_ASSIGN(DirectoryBackingStore);
};
} // namespace syncable
} // namespace syncer
#endif // SYNC_SYNCABLE_DIRECTORY_BACKING_STORE_H_