components/webdata/common/web_database_backend.h

   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 COMPONENTS_WEBDATA_COMMON_WEB_DATABASE_BACKEND_H_
   6 #define COMPONENTS_WEBDATA_COMMON_WEB_DATABASE_BACKEND_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/callback_forward.h"
  10 #include "base/compiler_specific.h"
  11 #include "base/files/file_path.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "base/memory/ref_counted_delete_on_message_loop.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "base/memory/scoped_vector.h"
  16 #include "base/single_thread_task_runner.h"
  17 #include "components/webdata/common/web_database_service.h"
  18 #include "components/webdata/common/webdata_export.h"
  19
  20 class WebDatabase;
  21 class WebDatabaseTable;
  22 class WebDataRequest;
  23 class WebDataRequestManager;
  24
  25 namespace tracked_objects {
  26 class Location;
  27 }
  28
  29 // WebDatabaseBackend handles all database tasks posted by
  30 // WebDatabaseService. It is refcounted to allow asynchronous destruction on the
  31 // DB thread.
  32
  33 class WEBDATA_EXPORT WebDatabaseBackend
  34     : public base::RefCountedDeleteOnMessageLoop<WebDatabaseBackend> {
  35  public:
  36   class Delegate {
  37    public:
  38     virtual ~Delegate() {}
  39
  40     // Invoked when the backend has finished loading the db.
  41     virtual void DBLoaded(sql::InitStatus status) = 0;
  42   };
  43
  44   WebDatabaseBackend(
  45       const base::FilePath& path,
  46       Delegate* delegate,
  47       const scoped_refptr<base::SingleThreadTaskRunner>& db_thread);
  48
  49   // Must call only before InitDatabaseWithCallback.
  50   void AddTable(scoped_ptr<WebDatabaseTable> table);
  51
  52   // Initializes the database and notifies caller via callback when complete.
  53   // Callback is called synchronously.
  54   void InitDatabase();
  55
  56   // Opens the database file from the profile path if an init has not yet been
  57   // attempted. Separated from the constructor to ease construction/destruction
  58   // of this object on one thread but database access on the DB thread. Returns
  59   // the status of the database.
  60   sql::InitStatus LoadDatabaseIfNecessary();
  61
  62   // Shuts down the database.
  63   void ShutdownDatabase();
  64
  65   // Task wrappers to update requests and and notify |request_manager_|. These
  66   // are used in cases where the request is being made from the UI thread and an
  67   // asyncronous callback is required to notify the client of |request|'s
  68   // completion.
  69   void DBWriteTaskWrapper(const WebDatabaseService::WriteTask& task,
  70                           scoped_ptr<WebDataRequest> request);
  71   void DBReadTaskWrapper(const WebDatabaseService::ReadTask& task,
  72                          scoped_ptr<WebDataRequest> request);
  73
  74   // Task runners to run database tasks.
  75   void ExecuteWriteTask(const WebDatabaseService::WriteTask& task);
  76   scoped_ptr<WDTypedResult> ExecuteReadTask(
  77       const WebDatabaseService::ReadTask& task);
  78
  79   const scoped_refptr<WebDataRequestManager>& request_manager() {
  80     return request_manager_;
  81   }
  82
  83   WebDatabase* database() { return db_.get(); }
  84
  85  protected:
  86   friend class base::RefCountedDeleteOnMessageLoop<WebDatabaseBackend>;
  87   friend class base::DeleteHelper<WebDatabaseBackend>;
  88
  89   virtual ~WebDatabaseBackend();
  90
  91  private:
  92   // Commit the current transaction.
  93   void Commit();
  94
  95   // Path to database file.
  96   base::FilePath db_path_;
  97
  98   // The tables that participate in managing the database. These are
  99   // owned here but other than that this class does nothing with
 100   // them. Their initialization is in whatever factory creates
 101   // WebDatabaseService, and lookup by type is provided by the
 102   // WebDatabase class. The tables need to be owned by this refcounted
 103   // object, or they themselves would need to be refcounted. Owning
 104   // them here rather than having WebDatabase own them makes for
 105   // easier unit testing of WebDatabase.
 106   ScopedVector<WebDatabaseTable> tables_;
 107
 108   scoped_ptr<WebDatabase> db_;
 109
 110   // Keeps track of all pending requests made to the db.
 111   scoped_refptr<WebDataRequestManager> request_manager_;
 112
 113   // State of database initialization. Used to prevent the executing of tasks
 114   // before the db is ready.
 115   sql::InitStatus init_status_;
 116
 117   // True if an attempt has been made to load the database (even if the attempt
 118   // fails), used to avoid continually trying to reinit if the db init fails.
 119   bool init_complete_;
 120
 121   // Delegate. See the class definition above for more information.
 122   scoped_ptr<Delegate> delegate_;
 123
 124   DISALLOW_COPY_AND_ASSIGN(WebDatabaseBackend);
 125 };
 126
 127 #endif  // COMPONENTS_WEBDATA_COMMON_WEB_DATABASE_BACKEND_H_