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1 // Copyright (c) 2012 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_INTERNAL_API_CHANGE_REORDER_BUFFER_H_ | |
10 #define CHROME_BROWSER_SYNC_INTERNAL_API_CHANGE_REORDER_BUFFER_H_ | |
11 #pragma once | |
12 | |
13 #include <map> | |
14 #include <vector> | |
15 | |
16 #include "base/compiler_specific.h" | |
17 #include "base/memory/linked_ptr.h" | |
18 #include "chrome/browser/sync/internal_api/base_transaction.h" | |
19 #include "chrome/browser/sync/internal_api/change_record.h" | |
20 #include "sync/protocol/sync.pb.h" | |
21 | |
22 namespace sync_api { | |
23 | |
24 // ChangeReorderBuffer is a utility type which accepts an unordered set | |
25 // of changes (via its Push methods), and yields an ImmutableChangeRecordList | |
26 // (via the GetAllChangesInTreeOrder method) that are in the order that | |
27 // the SyncObserver expects them to be. A buffer is initially empty. | |
28 // | |
29 // The ordering produced by ChangeReorderBuffer is as follows: | |
30 // (a) All Deleted items appear first. | |
31 // (b) For Updated and/or Added items, parents appear before their children. | |
32 // (c) When there are changes to the sibling order (this means Added items, | |
33 // or Updated items with the |position_changed| parameter set to true), | |
34 // all siblings under a parent will appear in the output, even if they | |
35 // are not explicitly pushed. The sibling order will be preserved in | |
36 // the output list -- items will appear before their sibling-order | |
37 // successors. | |
38 // (d) When there are no changes to the sibling order under a parent node, | |
39 // the sibling order is not necessarily preserved in the output for | |
40 // its children. | |
41 class ChangeReorderBuffer { | |
42 public: | |
43 ChangeReorderBuffer(); | |
44 ~ChangeReorderBuffer(); | |
45 | |
46 // Insert an item, identified by the metahandle |id|, into the reorder | |
47 // buffer. This item will appear in the output list as an ACTION_ADD | |
48 // ChangeRecord. | |
49 void PushAddedItem(int64 id) { | |
50 operations_[id] = OP_ADD; | |
51 } | |
52 | |
53 // Insert an item, identified by the metahandle |id|, into the reorder | |
54 // buffer. This item will appear in the output list as an ACTION_DELETE | |
55 // ChangeRecord. | |
56 void PushDeletedItem(int64 id) { | |
57 operations_[id] = OP_DELETE; | |
58 } | |
59 | |
60 // Insert an item, identified by the metahandle |id|, into the reorder | |
61 // buffer. This item will appear in the output list as an ACTION_UPDATE | |
62 // ChangeRecord. Also, if |position_changed| is true, all siblings of this | |
63 // item will appear in the output list as well; if it wasn't explicitly | |
64 // pushed, the siblings will have an ACTION_UPDATE ChangeRecord. | |
65 void PushUpdatedItem(int64 id, bool position_changed) { | |
66 operations_[id] = position_changed ? OP_UPDATE_POSITION_AND_PROPERTIES : | |
67 OP_UPDATE_PROPERTIES_ONLY; | |
68 } | |
69 | |
70 void SetExtraDataForId(int64 id, ExtraPasswordChangeRecordData* extra) { | |
71 extra_data_[id] = make_linked_ptr<ExtraPasswordChangeRecordData>(extra); | |
72 } | |
73 | |
74 void SetSpecificsForId(int64 id, const sync_pb::EntitySpecifics& specifics) { | |
75 specifics_[id] = specifics; | |
76 } | |
77 | |
78 // Reset the buffer, forgetting any pushed items, so that it can be used | |
79 // again to reorder a new set of changes. | |
80 void Clear() { | |
81 operations_.clear(); | |
82 } | |
83 | |
84 bool IsEmpty() const { | |
85 return operations_.empty(); | |
86 } | |
87 | |
88 // Output a reordered list of changes to |changes| using the items | |
89 // that were pushed into the reorder buffer. |sync_trans| is used to | |
90 // determine the ordering. Returns true if successful, or false if | |
91 // an error was encountered. | |
92 bool GetAllChangesInTreeOrder( | |
93 const BaseTransaction* sync_trans, | |
94 ImmutableChangeRecordList* changes) WARN_UNUSED_RESULT; | |
95 | |
96 private: | |
97 class Traversal; | |
98 enum Operation { | |
99 OP_ADD, // AddedItem. | |
100 OP_DELETE, // DeletedItem. | |
101 OP_UPDATE_PROPERTIES_ONLY, // UpdatedItem with position_changed=0. | |
102 OP_UPDATE_POSITION_AND_PROPERTIES, // UpdatedItem with position_changed=1. | |
103 }; | |
104 typedef std::map<int64, Operation> OperationMap; | |
105 typedef std::map<int64, sync_pb::EntitySpecifics> SpecificsMap; | |
106 typedef std::map<int64, linked_ptr<ExtraPasswordChangeRecordData> > | |
107 ExtraDataMap; | |
108 | |
109 // Stores the items that have been pushed into the buffer, and the type of | |
110 // operation that was associated with them. | |
111 OperationMap operations_; | |
112 | |
113 // Stores entity-specific ChangeRecord data per-ID. | |
114 SpecificsMap specifics_; | |
115 | |
116 // Stores type-specific extra data per-ID. | |
117 ExtraDataMap extra_data_; | |
118 | |
119 DISALLOW_COPY_AND_ASSIGN(ChangeReorderBuffer); | |
120 }; | |
121 | |
122 } // namespace sync_api | |
123 | |
124 #endif // CHROME_BROWSER_SYNC_INTERNAL_API_CHANGE_REORDER_BUFFER_H_ | |
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