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      1 // Copyright 2013 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_FILE_SYSTEM_LOCAL_LOCAL_FILE_CHANGE_TRACKER_H_
      6 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_LOCAL_LOCAL_FILE_CHANGE_TRACKER_H_
      7 
      8 #include <deque>
      9 #include <map>
     10 #include <string>
     11 
     12 #include "base/basictypes.h"
     13 #include "base/compiler_specific.h"
     14 #include "base/files/file_path.h"
     15 #include "base/memory/ref_counted.h"
     16 #include "base/memory/scoped_ptr.h"
     17 #include "base/synchronization/lock.h"
     18 #include "chrome/browser/sync_file_system/file_change.h"
     19 #include "chrome/browser/sync_file_system/sync_status_code.h"
     20 #include "webkit/browser/fileapi/file_observers.h"
     21 #include "webkit/browser/fileapi/file_system_url.h"
     22 
     23 namespace base {
     24 class SequencedTaskRunner;
     25 }
     26 
     27 namespace fileapi {
     28 class FileSystemContext;
     29 class FileSystemURL;
     30 }
     31 
     32 namespace leveldb {
     33 class Env;
     34 }
     35 
     36 namespace sync_file_system {
     37 
     38 // Tracks local file changes for cloud-backed file systems.
     39 // All methods must be called on the file_task_runner given to the constructor.
     40 // Owned by FileSystemContext.
     41 class LocalFileChangeTracker
     42     : public fileapi::FileUpdateObserver,
     43       public fileapi::FileChangeObserver {
     44  public:
     45   // |file_task_runner| must be the one where the observee file operations run.
     46   // (So that we can make sure DB operations are done before actual update
     47   // happens)
     48   LocalFileChangeTracker(const base::FilePath& base_path,
     49                          leveldb::Env* env_override,
     50                          base::SequencedTaskRunner* file_task_runner);
     51   virtual ~LocalFileChangeTracker();
     52 
     53   // FileUpdateObserver overrides.
     54   virtual void OnStartUpdate(const fileapi::FileSystemURL& url) OVERRIDE;
     55   virtual void OnUpdate(
     56       const fileapi::FileSystemURL& url, int64 delta) OVERRIDE {}
     57   virtual void OnEndUpdate(const fileapi::FileSystemURL& url) OVERRIDE;
     58 
     59   // FileChangeObserver overrides.
     60   virtual void OnCreateFile(const fileapi::FileSystemURL& url) OVERRIDE;
     61   virtual void OnCreateFileFrom(const fileapi::FileSystemURL& url,
     62                                 const fileapi::FileSystemURL& src) OVERRIDE;
     63   virtual void OnRemoveFile(const fileapi::FileSystemURL& url) OVERRIDE;
     64   virtual void OnModifyFile(const fileapi::FileSystemURL& url) OVERRIDE;
     65   virtual void OnCreateDirectory(const fileapi::FileSystemURL& url) OVERRIDE;
     66   virtual void OnRemoveDirectory(const fileapi::FileSystemURL& url) OVERRIDE;
     67 
     68   // Retrieves an array of |url| which have more than one pending changes.
     69   // If |max_urls| is non-zero (recommended in production code) this
     70   // returns URLs up to the number from the ones that have smallest
     71   // change_seq numbers (i.e. older changes).
     72   void GetNextChangedURLs(std::deque<fileapi::FileSystemURL>* urls,
     73                           int max_urls);
     74 
     75   // Returns all changes recorded for the given |url|.
     76   // Note that this also returns demoted changes.
     77   // This should be called after writing is disabled.
     78   void GetChangesForURL(const fileapi::FileSystemURL& url,
     79                         FileChangeList* changes);
     80 
     81   // Clears the pending changes recorded in this tracker for |url|.
     82   void ClearChangesForURL(const fileapi::FileSystemURL& url);
     83 
     84   // Creates a fresh (empty) in-memory record for |url|.
     85   // Note that new changes are recorded to the mirror too.
     86   void CreateFreshMirrorForURL(const fileapi::FileSystemURL& url);
     87 
     88   // Removes a mirror for |url|, and commits the change status to database.
     89   void RemoveMirrorAndCommitChangesForURL(const fileapi::FileSystemURL& url);
     90 
     91   // Resets the changes to the ones recorded in mirror for |url|, and
     92   // commits the updated change status to database.
     93   void ResetToMirrorAndCommitChangesForURL(const fileapi::FileSystemURL& url);
     94 
     95   // Re-inserts changes into the separate demoted_changes_ queue. They won't
     96   // be fetched by GetNextChangedURLs() unless PromoteDemotedChanges() is
     97   // called.
     98   void DemoteChangesForURL(const fileapi::FileSystemURL& url);
     99 
    100   // Promotes all demoted changes to the normal queue. Returns true if it has
    101   // promoted any changes.
    102   bool PromoteDemotedChanges();
    103 
    104   // Called by FileSyncService at the startup time to restore last dirty changes
    105   // left after the last shutdown (if any).
    106   SyncStatusCode Initialize(fileapi::FileSystemContext* file_system_context);
    107 
    108   // Resets all the changes recorded for the given |origin| and |type|.
    109   // TODO(kinuko,nhiroki): Ideally this should be automatically called in
    110   // DeleteFileSystem via QuotaUtil::DeleteOriginDataOnFileThread.
    111   void ResetForFileSystem(const GURL& origin, fileapi::FileSystemType type);
    112 
    113   // This method is (exceptionally) thread-safe.
    114   int64 num_changes() const {
    115     base::AutoLock lock(num_changes_lock_);
    116     return num_changes_;
    117   }
    118 
    119  private:
    120   class TrackerDB;
    121   friend class CannedSyncableFileSystem;
    122   friend class LocalFileChangeTrackerTest;
    123   friend class LocalFileSyncContext;
    124   friend class LocalFileSyncContextTest;
    125   friend class SyncableFileSystemTest;
    126 
    127   struct ChangeInfo {
    128     ChangeInfo();
    129     ~ChangeInfo();
    130     FileChangeList change_list;
    131     int64 change_seq;
    132   };
    133 
    134   typedef std::map<fileapi::FileSystemURL, ChangeInfo,
    135       fileapi::FileSystemURL::Comparator>
    136           FileChangeMap;
    137   typedef std::map<int64, fileapi::FileSystemURL> ChangeSeqMap;
    138 
    139   void UpdateNumChanges();
    140 
    141   // This does mostly same as calling GetNextChangedURLs with max_url=0
    142   // except that it returns urls in set rather than in deque.
    143   // Used only in testings.
    144   void GetAllChangedURLs(fileapi::FileSystemURLSet* urls);
    145 
    146   // Used only in testings.
    147   void DropAllChanges();
    148 
    149   // Database related methods.
    150   SyncStatusCode MarkDirtyOnDatabase(const fileapi::FileSystemURL& url);
    151   SyncStatusCode ClearDirtyOnDatabase(const fileapi::FileSystemURL& url);
    152 
    153   SyncStatusCode CollectLastDirtyChanges(
    154       fileapi::FileSystemContext* file_system_context);
    155   void RecordChange(const fileapi::FileSystemURL& url,
    156                     const FileChange& change);
    157 
    158   static void RecordChangeToChangeMaps(const fileapi::FileSystemURL& url,
    159                                        const FileChange& change,
    160                                        int change_seq,
    161                                        FileChangeMap* changes,
    162                                        ChangeSeqMap* change_seqs);
    163 
    164   bool initialized_;
    165 
    166   scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
    167 
    168   FileChangeMap changes_;
    169   ChangeSeqMap change_seqs_;
    170 
    171   FileChangeMap mirror_changes_;  // For mirrors.
    172   FileChangeMap demoted_changes_;  // For demoted changes.
    173 
    174   scoped_ptr<TrackerDB> tracker_db_;
    175 
    176   // Change sequence number. Briefly gives a hint about the order of changes,
    177   // but they are updated when a new change comes on the same file (as
    178   // well as Drive's changestamps).
    179   int64 current_change_seq_;
    180 
    181   // This can be accessed on any threads (with num_changes_lock_).
    182   int64 num_changes_;
    183   mutable base::Lock num_changes_lock_;
    184 
    185   DISALLOW_COPY_AND_ASSIGN(LocalFileChangeTracker);
    186 };
    187 
    188 }  // namespace sync_file_system
    189 
    190 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_LOCAL_LOCAL_FILE_CHANGE_TRACKER_H_
    191