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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_SYNC_SERVICE_BACKEND_MIGRATOR_H_
#define COMPONENTS_SYNC_SERVICE_BACKEND_MIGRATOR_H_
#include <string>
#include "base/compiler_specific.h"
#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "components/sync/base/data_type.h"
#include "components/sync/service/data_type_manager.h"
namespace syncer {
// Interface for anything that wants to know when the migrator's state
// changes.
class MigrationObserver {
public:
virtual void OnMigrationStateChange() = 0;
protected:
virtual ~MigrationObserver();
};
// A class to perform migration of a datatype pursuant to the 'MIGRATION_DONE'
// code in the sync protocol definition (protocol/sync.proto).
class BackendMigrator {
public:
enum State {
IDLE,
WAITING_TO_START, // Waiting for previous configuration to finish.
DISABLING_TYPES, // Exit criteria: OnConfigureDone for enabled types
// _excluding_ `to_migrate_` and empty download progress
// markers for types in `to_migrate_`.
REENABLING_TYPES, // Exit criteria: OnConfigureDone for enabled types.
};
BackendMigrator(const std::string& name,
DataTypeManager* manager,
const base::RepeatingClosure& reconfigure_callback,
const base::RepeatingClosure& migration_done_callback);
BackendMigrator(const BackendMigrator&) = delete;
BackendMigrator& operator=(const BackendMigrator&) = delete;
virtual ~BackendMigrator();
// Starts a sequence of events that will disable and reenable `types`.
void MigrateTypes(DataTypeSet types);
void AddMigrationObserver(MigrationObserver* observer);
void RemoveMigrationObserver(MigrationObserver* observer);
State state() const;
// Called from SyncServiceImpl to notify us of configure done.
// Note: We receive these notifications only when our state is not IDLE.
void OnConfigureDone(const DataTypeManager::ConfigureResult& result);
// Returns the types that are currently pending migration (if any).
DataTypeSet GetPendingMigrationTypesForTest() const;
private:
void ChangeState(State new_state);
// Must be called only in state WAITING_TO_START. If ready to
// start, meaning the data type manager is configured, calls
// RestartMigration() and returns true. Otherwise, does nothing and
// returns false.
bool TryStart();
// Restarts migration, interrupting any existing migration.
void RestartMigration();
// Called by OnConfigureDone().
void OnConfigureDoneImpl(const DataTypeManager::ConfigureResult& result);
const std::string name_;
const raw_ptr<DataTypeManager, DanglingUntriaged> manager_;
const base::RepeatingClosure reconfigure_callback_;
const base::RepeatingClosure migration_done_callback_;
State state_;
base::ObserverList<MigrationObserver>::Unchecked migration_observers_;
DataTypeSet to_migrate_;
base::WeakPtrFactory<BackendMigrator> weak_ptr_factory_{this};
};
} // namespace syncer
#endif // COMPONENTS_SYNC_SERVICE_BACKEND_MIGRATOR_H_
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