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#ifndef CHROME_BROWSER_SYNC_GLUE_TYPED_URL_MODEL_ASSOCIATOR_H_
6#define CHROME_BROWSER_SYNC_GLUE_TYPED_URL_MODEL_ASSOCIATOR_H_
7
8#include <map>
9#include <string>
10#include <utility>
11#include <vector>
12
13#include "base/basictypes.h"
14#include "base/compiler_specific.h"
15#include "base/strings/string16.h"
16#include "chrome/browser/history/history_types.h"
17#include "components/sync_driver/data_type_error_handler.h"
18#include "components/sync_driver/model_associator.h"
19#include "sync/protocol/typed_url_specifics.pb.h"
20
21class GURL;
22class ProfileSyncService;
23
24namespace base {
25class MessageLoop;
26}
27
28namespace history {
29class HistoryBackend;
30class URLRow;
31};
32
33namespace syncer {
34class WriteNode;
35class WriteTransaction;
36};
37
38namespace browser_sync {
39
40// Contains all model association related logic:
41// * Algorithm to associate typed_url model and sync model.
42// * Persisting model associations and loading them back.
43// We do not check if we have local data before this run; we always
44// merge and sync.
45class TypedUrlModelAssociator : public AssociatorInterface {
46 public:
47  typedef std::vector<std::pair<history::URLID, history::URLRow> >
48      TypedUrlUpdateVector;
49  typedef std::vector<std::pair<GURL, std::vector<history::VisitInfo> > >
50      TypedUrlVisitVector;
51
52  static syncer::ModelType model_type() { return syncer::TYPED_URLS; }
53  TypedUrlModelAssociator(ProfileSyncService* sync_service,
54                          history::HistoryBackend* history_backend,
55                          DataTypeErrorHandler* error_handler);
56  virtual ~TypedUrlModelAssociator();
57
58  // AssociatorInterface implementation.
59  //
60  // Iterates through the sync model looking for matched pairs of items.
61  virtual syncer::SyncError AssociateModels(
62      syncer::SyncMergeResult* local_merge_result,
63      syncer::SyncMergeResult* syncer_merge_result) OVERRIDE;
64
65  // Clears all associations.
66  virtual syncer::SyncError DisassociateModels() OVERRIDE;
67
68  // Called from the main thread, to abort the currently active model
69  // association (for example, if we are shutting down).
70  virtual void AbortAssociation() OVERRIDE;
71
72  // The has_nodes out param is true if the sync model has nodes other
73  // than the permanent tagged nodes.
74  virtual bool SyncModelHasUserCreatedNodes(bool* has_nodes) OVERRIDE;
75
76  virtual bool CryptoReadyIfNecessary() OVERRIDE;
77
78  // Delete all typed url nodes.
79  bool DeleteAllNodes(syncer::WriteTransaction* trans);
80
81  void WriteToHistoryBackend(const history::URLRows* new_urls,
82                             const TypedUrlUpdateVector* updated_urls,
83                             const TypedUrlVisitVector* new_visits,
84                             const history::VisitVector* deleted_visits);
85
86  // Given a typed URL in the sync DB, looks for an existing entry in the
87  // local history DB and generates a list of visits to add to the
88  // history DB to bring it up to date (avoiding duplicates).
89  // Updates the passed |visits_to_add| and |visits_to_remove| vectors with the
90  // visits to add to/remove from the history DB, and adds a new entry to either
91  // |updated_urls| or |new_urls| depending on whether the URL already existed
92  // in the history DB.
93  void UpdateFromSyncDB(const sync_pb::TypedUrlSpecifics& typed_url,
94                        TypedUrlVisitVector* visits_to_add,
95                        history::VisitVector* visits_to_remove,
96                        TypedUrlUpdateVector* updated_urls,
97                        history::URLRows* new_urls);
98
99  // Given a TypedUrlSpecifics object, removes all visits that are older than
100  // the current expiration time. Note that this can result in having no visits
101  // at all.
102  sync_pb::TypedUrlSpecifics FilterExpiredVisits(
103      const sync_pb::TypedUrlSpecifics& specifics);
104
105  // Returns the percentage of DB accesses that have resulted in an error.
106  int GetErrorPercentage() const;
107
108  // Bitfield returned from MergeUrls to specify the result of the merge.
109  typedef uint32 MergeResult;
110  static const MergeResult DIFF_NONE                = 0;
111  static const MergeResult DIFF_UPDATE_NODE         = 1 << 0;
112  static const MergeResult DIFF_LOCAL_ROW_CHANGED   = 1 << 1;
113  static const MergeResult DIFF_LOCAL_VISITS_ADDED  = 1 << 2;
114
115  // Merges the URL information in |typed_url| with the URL information from the
116  // history database in |url| and |visits|, and returns a bitmask with the
117  // results of the merge:
118  // DIFF_UPDATE_NODE - changes have been made to |new_url| and |visits| which
119  //   should be persisted to the sync node.
120  // DIFF_LOCAL_ROW_CHANGED - The history data in |new_url| should be persisted
121  //   to the history DB.
122  // DIFF_LOCAL_VISITS_ADDED - |new_visits| contains a list of visits that
123  //   should be written to the history DB for this URL. Deletions are not
124  //   written to the DB - each client is left to age out visits on their own.
125  static MergeResult MergeUrls(const sync_pb::TypedUrlSpecifics& typed_url,
126                               const history::URLRow& url,
127                               history::VisitVector* visits,
128                               history::URLRow* new_url,
129                               std::vector<history::VisitInfo>* new_visits);
130  static void WriteToSyncNode(const history::URLRow& url,
131                              const history::VisitVector& visits,
132                              syncer::WriteNode* node);
133
134  // Diffs the set of visits between the history DB and the sync DB, using the
135  // sync DB as the canonical copy. Result is the set of |new_visits| and
136  // |removed_visits| that can be applied to the history DB to make it match
137  // the sync DB version. |removed_visits| can be null if the caller does not
138  // care about which visits to remove.
139  static void DiffVisits(const history::VisitVector& old_visits,
140                         const sync_pb::TypedUrlSpecifics& new_url,
141                         std::vector<history::VisitInfo>* new_visits,
142                         history::VisitVector* removed_visits);
143
144  // Converts the passed URL information to a TypedUrlSpecifics structure for
145  // writing to the sync DB
146  static void WriteToTypedUrlSpecifics(const history::URLRow& url,
147                                       const history::VisitVector& visits,
148                                       sync_pb::TypedUrlSpecifics* specifics);
149
150  // Fetches visits from the history DB corresponding to the passed URL. This
151  // function compensates for the fact that the history DB has rather poor data
152  // integrity (duplicate visits, visit timestamps that don't match the
153  // last_visit timestamp, huge data sets that exhaust memory when fetched,
154  // etc) by modifying the passed |url| object and |visits| vector.
155  // Returns false if we could not fetch the visits for the passed URL, and
156  // tracks DB error statistics internally for reporting via UMA.
157  bool FixupURLAndGetVisits(history::URLRow* url,
158                            history::VisitVector* visits);
159
160  // Updates the passed |url_row| based on the values in |specifics|. Fields
161  // that are not contained in |specifics| (such as typed_count) are left
162  // unchanged.
163  static void UpdateURLRowFromTypedUrlSpecifics(
164      const sync_pb::TypedUrlSpecifics& specifics, history::URLRow* url_row);
165
166  // Helper function that determines if we should ignore a URL for the purposes
167  // of sync, because it contains invalid data.
168  bool ShouldIgnoreUrl(const GURL& url);
169
170 protected:
171  // Helper function that clears our error counters (used to reset stats after
172  // model association so we can track model association errors separately).
173  // Overridden by tests.
174  virtual void ClearErrorStats();
175
176 private:
177
178  // Helper routine that actually does the work of associating models.
179  syncer::SyncError DoAssociateModels();
180
181  // Helper function that determines if we should ignore a URL for the purposes
182  // of sync, based on the visits the URL had.
183  bool ShouldIgnoreVisits(const history::VisitVector& visits);
184
185  ProfileSyncService* sync_service_;
186  history::HistoryBackend* history_backend_;
187
188  base::MessageLoop* expected_loop_;
189
190  bool abort_requested_;
191  base::Lock abort_lock_;
192
193  DataTypeErrorHandler* error_handler_; // Guaranteed to outlive datatypes.
194
195  // Statistics for the purposes of tracking the percentage of DB accesses that
196  // fail for each client via UMA.
197  int num_db_accesses_;
198  int num_db_errors_;
199
200  DISALLOW_COPY_AND_ASSIGN(TypedUrlModelAssociator);
201};
202
203}  // namespace browser_sync
204
205#endif  // CHROME_BROWSER_SYNC_GLUE_TYPED_URL_MODEL_ASSOCIATOR_H_
206