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// Copyright 2014 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_DRIVER_CHANGE_PROCESSOR_H_
#define COMPONENTS_SYNC_DRIVER_CHANGE_PROCESSOR_H_
#include "components/sync_driver/data_type_error_handler.h"
#include "sync/internal_api/public/base_transaction.h"
#include "sync/internal_api/public/change_record.h"
#include "sync/internal_api/public/user_share.h"
namespace syncer {
class UnrecoverableErrorHandler;
} // namespace syncer
namespace sync_driver {
class ModelAssociator;
// An interface used to apply changes from the sync model to the browser's
// native model. This does not currently distinguish between model data types.
class ChangeProcessor {
public:
explicit ChangeProcessor(DataTypeErrorHandler* error_handler);
virtual ~ChangeProcessor();
// Call when the processor should accept changes from either provided model
// and apply them to the other. Both the native model and sync_api are
// expected to be initialized and loaded. You must have set a valid
// ModelAssociator and UnrecoverableErrorHandler before using this method, and
// the two models should be associated w.r.t the ModelAssociator provided.
void Start(syncer::UserShare* share_handle);
// Changes have been applied to the backend model and are ready to be
// applied to the frontend model.
virtual void ApplyChangesFromSyncModel(
const syncer::BaseTransaction* trans,
int64 model_version,
const syncer::ImmutableChangeRecordList& changes) = 0;
// The changes found in ApplyChangesFromSyncModel may be too slow to be
// performed while holding a [Read/Write]Transaction lock or may interact
// with another thread, which might itself be waiting on the transaction lock,
// putting us at risk of deadlock.
// This function is called once the transactional lock is released and it is
// safe to perform inter-thread or slow I/O operations. Note that not all
// datatypes need this, so we provide an empty default version.
virtual void CommitChangesFromSyncModel();
// This ensures that startobserving gets called after stopobserving even
// if there is an early return in the function.
template <class T>
class ScopedStopObserving {
public:
explicit ScopedStopObserving(T* processor)
: processor_(processor) {
processor_->StopObserving();
}
~ScopedStopObserving() {
processor_->StartObserving();
}
private:
ScopedStopObserving() {}
T* processor_;
};
protected:
// These methods are invoked by Start() and Stop() to do
// implementation-specific work.
virtual void StartImpl() = 0;
DataTypeErrorHandler* error_handler() const;
virtual syncer::UserShare* share_handle() const;
private:
DataTypeErrorHandler* error_handler_; // Guaranteed to outlive us.
// The sync model we are processing changes from.
syncer::UserShare* share_handle_;
DISALLOW_COPY_AND_ASSIGN(ChangeProcessor);
};
} // namespace sync_driver
#endif // COMPONENTS_SYNC_DRIVER_CHANGE_PROCESSOR_H_
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