1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 // 5 // Defines ChangeReorderBuffer, which can be used to sort a list of item 6 // actions to achieve the ordering constraint required by the SyncObserver 7 // interface of the SyncAPI. 8 9 #ifndef CHROME_BROWSER_SYNC_ENGINE_CHANGE_REORDER_BUFFER_H_ 10 #define CHROME_BROWSER_SYNC_ENGINE_CHANGE_REORDER_BUFFER_H_ 11 #pragma once 12 13 #include <map> 14 #include <vector> 15 16 #include "base/memory/linked_ptr.h" 17 #include "chrome/browser/sync/engine/syncapi.h" 18 #include "chrome/browser/sync/protocol/sync.pb.h" 19 20 namespace sync_api { 21 22 // ChangeReorderBuffer is a utility type which accepts an unordered set 23 // of changes (via its Push methods), and yields a vector of ChangeRecords 24 // (via the GetAllChangesInTreeOrder method) that are in the order that 25 // the SyncObserver expects them to be. A buffer is initially empty. 26 // 27 // The ordering produced by ChangeReorderBuffer is as follows: 28 // (a) All Deleted items appear first. 29 // (b) For Updated and/or Added items, parents appear before their children. 30 // (c) When there are changes to the sibling order (this means Added items, 31 // or Updated items with the |position_changed| parameter set to true), 32 // all siblings under a parent will appear in the output, even if they 33 // are not explicitly pushed. The sibling order will be preserved in 34 // the output list -- items will appear before their sibling-order 35 // successors. 36 // (d) When there are no changes to the sibling order under a parent node, 37 // the sibling order is not necessarily preserved in the output for 38 // its children. 39 class ChangeReorderBuffer { 40 public: 41 typedef SyncManager::ChangeRecord ChangeRecord; 42 typedef SyncManager::ExtraPasswordChangeRecordData ExtraChangeRecordData; 43 44 ChangeReorderBuffer(); 45 ~ChangeReorderBuffer(); 46 47 // Insert an item, identified by the metahandle |id|, into the reorder 48 // buffer. This item will appear in the output list as an ACTION_ADD 49 // ChangeRecord. PushAddedItem(int64 id)50 void PushAddedItem(int64 id) { 51 operations_[id] = OP_ADD; 52 } 53 54 // Insert an item, identified by the metahandle |id|, into the reorder 55 // buffer. This item will appear in the output list as an ACTION_DELETE 56 // ChangeRecord. PushDeletedItem(int64 id)57 void PushDeletedItem(int64 id) { 58 operations_[id] = OP_DELETE; 59 } 60 61 // Insert an item, identified by the metahandle |id|, into the reorder 62 // buffer. This item will appear in the output list as an ACTION_UPDATE 63 // ChangeRecord. Also, if |position_changed| is true, all siblings of this 64 // item will appear in the output list as well; if it wasn't explicitly 65 // pushed, the siblings will have an ACTION_UPDATE ChangeRecord. PushUpdatedItem(int64 id,bool position_changed)66 void PushUpdatedItem(int64 id, bool position_changed) { 67 operations_[id] = position_changed ? OP_UPDATE_POSITION_AND_PROPERTIES : 68 OP_UPDATE_PROPERTIES_ONLY; 69 } 70 SetExtraDataForId(int64 id,ExtraChangeRecordData * extra)71 void SetExtraDataForId(int64 id, ExtraChangeRecordData* extra) { 72 extra_data_[id] = make_linked_ptr<ExtraChangeRecordData>(extra); 73 } 74 SetSpecificsForId(int64 id,const sync_pb::EntitySpecifics & specifics)75 void SetSpecificsForId(int64 id, const sync_pb::EntitySpecifics& specifics) { 76 specifics_[id] = specifics; 77 } 78 79 // Reset the buffer, forgetting any pushed items, so that it can be used 80 // again to reorder a new set of changes. Clear()81 void Clear() { 82 operations_.clear(); 83 } 84 IsEmpty()85 bool IsEmpty() const { 86 return operations_.empty(); 87 } 88 89 // Output a reordered list of changes to |changelist| using the items that 90 // were pushed into the reorder buffer. |sync_trans| is used to determine the 91 // ordering. 92 void GetAllChangesInTreeOrder(const BaseTransaction* sync_trans, 93 std::vector<ChangeRecord>* changelist); 94 95 private: 96 class Traversal; 97 enum Operation { 98 OP_ADD, // AddedItem. 99 OP_DELETE, // DeletedItem. 100 OP_UPDATE_PROPERTIES_ONLY, // UpdatedItem with position_changed=0. 101 OP_UPDATE_POSITION_AND_PROPERTIES, // UpdatedItem with position_changed=1. 102 }; 103 typedef std::map<int64, Operation> OperationMap; 104 typedef std::map<int64, sync_pb::EntitySpecifics> SpecificsMap; 105 typedef std::map<int64, linked_ptr<ExtraChangeRecordData> > ExtraDataMap; 106 107 // Stores the items that have been pushed into the buffer, and the type of 108 // operation that was associated with them. 109 OperationMap operations_; 110 111 // Stores entity-specific ChangeRecord data per-ID. 112 SpecificsMap specifics_; 113 114 // Stores type-specific extra data per-ID. 115 ExtraDataMap extra_data_; 116 117 DISALLOW_COPY_AND_ASSIGN(ChangeReorderBuffer); 118 }; 119 120 } // namespace sync_api 121 122 #endif // CHROME_BROWSER_SYNC_ENGINE_CHANGE_REORDER_BUFFER_H_ 123