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