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// Copyright (c) 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 CHROME_BROWSER_SYNC_GLUE_CHANGE_PROCESSOR_H_
#define CHROME_BROWSER_SYNC_GLUE_CHANGE_PROCESSOR_H_
#pragma once
#include "chrome/browser/sync/glue/data_type_error_handler.h"
#include "chrome/browser/sync/glue/sync_backend_host.h"
#include "sync/internal_api/change_record.h"
class Profile;
namespace browser_sync {
class ModelAssociator;
class UnrecoverableErrorHandler;
// 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 chrome 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.
// It is safe to call Start again after previously Stop()ing the processor.
// Subclasses can extract their associated chrome model from |profile| in
// |StartImpl|.
void Start(Profile* profile, sync_api::UserShare* share_handle);
void Stop();
virtual bool IsRunning() const;
// Changes have been applied to the backend model and are ready to be
// applied to the frontend model. See syncapi.h for detailed instructions on
// how to interpret and process |changes|.
virtual void ApplyChangesFromSyncModel(
const sync_api::BaseTransaction* trans,
const sync_api::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(Profile* profile) = 0;
virtual void StopImpl() = 0;
bool running() const { return running_; }
DataTypeErrorHandler* error_handler() const;
virtual sync_api::UserShare* share_handle() const;
private:
bool running_; // True if we have been told it is safe to process changes.
DataTypeErrorHandler* error_handler_; // Guaranteed to outlive us.
// The sync model we are processing changes from. Non-NULL when |running_| is
// true.
sync_api::UserShare* share_handle_;
DISALLOW_COPY_AND_ASSIGN(ChangeProcessor);
};
} // namespace browser_sync
#endif // CHROME_BROWSER_SYNC_GLUE_CHANGE_PROCESSOR_H_
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