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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_HISTORY_ARCHIVED_DATABASE_H_
      6 #define CHROME_BROWSER_HISTORY_ARCHIVED_DATABASE_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "chrome/browser/history/url_database.h"
     10 #include "chrome/browser/history/visit_database.h"
     11 #include "sql/connection.h"
     12 #include "sql/init_status.h"
     13 #include "sql/meta_table.h"
     14 
     15 namespace base {
     16 class FilePath;
     17 }
     18 
     19 namespace history {
     20 
     21 // Encapsulates the database operations for archived history.
     22 //
     23 // IMPORTANT NOTE: The IDs in this system for URLs and visits will be
     24 // different than those in the main database. This is to eliminate the
     25 // dependency between them so we can deal with each one on its own.
     26 class ArchivedDatabase : public URLDatabase,
     27                          public VisitDatabase {
     28  public:
     29   // Must call Init() before using other members.
     30   ArchivedDatabase();
     31   virtual ~ArchivedDatabase();
     32 
     33   // Initializes the database connection. This must return true before any other
     34   // functions on this class are called.
     35   bool Init(const base::FilePath& file_name);
     36 
     37   // Try to trim the cache memory used by the database.  If |aggressively| is
     38   // true try to trim all unused cache, otherwise trim by half.
     39   void TrimMemory(bool aggressively);
     40 
     41   // Transactions on the database. We support nested transactions and only
     42   // commit when the outermost one is committed (sqlite doesn't support true
     43   // nested transactions).
     44   void BeginTransaction();
     45   void CommitTransaction();
     46 
     47   // Returns the current version that we will generate archived databases with.
     48   static int GetCurrentVersion();
     49 
     50  private:
     51   bool InitTables();
     52 
     53   // Implemented for the specialized databases.
     54   virtual sql::Connection& GetDB() OVERRIDE;
     55 
     56   // Makes sure the version is up-to-date, updating if necessary. If the
     57   // database is too old to migrate, the user will be notified. In this case, or
     58   // for other errors, false will be returned. True means it is up-to-date and
     59   // ready for use.
     60   //
     61   // This assumes it is called from the init function inside a transaction. It
     62   // may commit the transaction and start a new one if migration requires it.
     63   sql::InitStatus EnsureCurrentVersion();
     64 
     65   // The database.
     66   sql::Connection db_;
     67   sql::MetaTable meta_table_;
     68 
     69   DISALLOW_COPY_AND_ASSIGN(ArchivedDatabase);
     70 };
     71 
     72 }  // namespace history
     73 
     74 #endif  // CHROME_BROWSER_HISTORY_ARCHIVED_DATABASE_H_
     75