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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.
//
// Defines ChangeReorderBuffer, which can be used to sort a list of item
// actions to achieve the ordering constraint required by the SyncObserver
// interface of the SyncAPI.
#ifndef SYNC_INTERNAL_API_CHANGE_REORDER_BUFFER_H_
#define SYNC_INTERNAL_API_CHANGE_REORDER_BUFFER_H_
#include <map>
#include <vector>
#include "base/compiler_specific.h"
#include "base/memory/linked_ptr.h"
#include "sync/internal_api/public/change_record.h"
#include "sync/protocol/sync.pb.h"
namespace syncer {
class BaseTransaction;
// ChangeReorderBuffer is a utility type which accepts an unordered set
// of changes (via its Push methods), and yields an ImmutableChangeRecordList
// (via the GetAllChangesInTreeOrder method) that are in the order that
// the SyncObserver expects them to be. A buffer is initially empty.
//
// The ordering produced by ChangeReorderBuffer is as follows:
// (a) All Deleted items appear first.
// (b) For Updated and/or Added items, parents appear before their children.
//
// The sibling order is not necessarily preserved.
class ChangeReorderBuffer {
public:
ChangeReorderBuffer();
~ChangeReorderBuffer();
// Insert an item, identified by the metahandle |id|, into the reorder buffer.
// This item will appear in the output list as an ACTION_ADD ChangeRecord.
void PushAddedItem(int64 id);
// Insert an item, identified by the metahandle |id|, into the reorder buffer.
// This item will appear in the output list as an ACTION_DELETE ChangeRecord.
void PushDeletedItem(int64 id);
// Insert an item, identified by the metahandle |id|, into the reorder buffer.
// This item will appear in the output list as an ACTION_UPDATE ChangeRecord.
void PushUpdatedItem(int64 id);
void SetExtraDataForId(int64 id, ExtraPasswordChangeRecordData* extra);
void SetSpecificsForId(int64 id, const sync_pb::EntitySpecifics& specifics);
// Reset the buffer, forgetting any pushed items, so that it can be used again
// to reorder a new set of changes.
void Clear();
bool IsEmpty() const;
// Output a reordered list of changes to |changes| using the items
// that were pushed into the reorder buffer. |sync_trans| is used to
// determine the ordering. Returns true if successful, or false if
// an error was encountered.
bool GetAllChangesInTreeOrder(
const BaseTransaction* sync_trans,
ImmutableChangeRecordList* changes) WARN_UNUSED_RESULT;
private:
class Traversal;
typedef std::map<int64, ChangeRecord::Action> OperationMap;
typedef std::map<int64, sync_pb::EntitySpecifics> SpecificsMap;
typedef std::map<int64, linked_ptr<ExtraPasswordChangeRecordData> >
ExtraDataMap;
// Stores the items that have been pushed into the buffer, and the type of
// operation that was associated with them.
OperationMap operations_;
// Stores entity-specific ChangeRecord data per-ID.
SpecificsMap specifics_;
// Stores type-specific extra data per-ID.
ExtraDataMap extra_data_;
DISALLOW_COPY_AND_ASSIGN(ChangeReorderBuffer);
};
} // namespace syncer
#endif // SYNC_INTERNAL_API_CHANGE_REORDER_BUFFER_H_
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