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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 COMPONENTS_SYNC_MODEL_SYNC_CHANGE_PROCESSOR_H_
#define COMPONENTS_SYNC_MODEL_SYNC_CHANGE_PROCESSOR_H_
#include <string>
#include <vector>
#include "components/sync/base/model_type.h"
#include "components/sync/model/sync_data.h"
#include "components/sync/model/sync_error.h"
namespace tracked_objects {
class Location;
} // namespace tracked_objects
namespace syncer {
class SyncChange;
class LocalChangeObserver;
typedef std::vector<SyncChange> SyncChangeList;
// An interface for services that handle receiving SyncChanges.
class SyncChangeProcessor {
public:
// Whether a context change should force a datatype refresh or not.
enum ContextRefreshStatus { NO_REFRESH, REFRESH_NEEDED };
typedef base::Callback<void(const SyncData&)> GetSyncDataCallback;
SyncChangeProcessor();
virtual ~SyncChangeProcessor();
// Process a list of SyncChanges.
// Returns: A default SyncError (IsSet() == false) if no errors were
// encountered, and a filled SyncError (IsSet() == true)
// otherwise.
// Inputs:
// |from_here|: allows tracking of where sync changes originate.
// |change_list|: is the list of sync changes in need of processing.
virtual SyncError ProcessSyncChanges(
const tracked_objects::Location& from_here,
const SyncChangeList& change_list) = 0;
// Fills a list of SyncData. This should create an up to date representation
// of all the data known to the ChangeProcessor for |datatype|, and
// should match/be a subset of the server's view of that datatype.
//
// WARNING: This can be a potentially slow & memory intensive operation and
// should only be used when absolutely necessary / sparingly.
virtual SyncDataList GetAllSyncData(ModelType type) const = 0;
// Retrieves the SyncData identified by |type| and |sync_tag| and invokes
// |callback| asynchronously. If no such SyncData exists locally, IsValid on
// the SyncData passed to |callback| will return false.
//
// This is an asynchronous local operation that may result in disk IO.
//
// Refer to sync_data.h for a description of |sync_tag|.
//
// TODO(maniscalco): N.B. this method should really be pure virtual. An
// implentation is provided here just to verify that everything compiles.
// Update this method to be pure virtual (bug 353300).
virtual void GetSyncData(const ModelType& type,
const std::string& sync_tag,
const GetSyncDataCallback& callback) const {}
// Updates the context for |type|, triggering an optional context refresh.
// Default implementation does nothing. A type's context is a per-client blob
// that can affect all SyncData sent to/from the server, much like a cookie.
// TODO(zea): consider pulling the refresh logic into a separate method
// unrelated to datatype implementations.
virtual SyncError UpdateDataTypeContext(ModelType type,
ContextRefreshStatus refresh_status,
const std::string& context);
// Adds an observer of local sync changes. This observer is notified when
// local sync changes are applied by GenericChangeProcessor. observer is
// not owned by the SyncChangeProcessor.
virtual void AddLocalChangeObserver(LocalChangeObserver* observer);
virtual void RemoveLocalChangeObserver(LocalChangeObserver* observer);
};
} // namespace syncer
#endif // COMPONENTS_SYNC_MODEL_SYNC_CHANGE_PROCESSOR_H_
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