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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_DOWNLOAD_DOWNLOAD_HISTORY_H_
      6 #define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_HISTORY_H_
      7 
      8 #include <set>
      9 #include <vector>
     10 
     11 #include "base/basictypes.h"
     12 #include "base/callback.h"
     13 #include "base/memory/weak_ptr.h"
     14 #include "base/observer_list.h"
     15 #include "chrome/browser/download/all_download_item_notifier.h"
     16 #include "chrome/browser/history/history_service.h"
     17 #include "content/public/browser/download_item.h"
     18 #include "content/public/browser/download_manager.h"
     19 
     20 namespace history {
     21 struct DownloadRow;
     22 }  // namespace history
     23 
     24 // Observes a single DownloadManager and all its DownloadItems, keeping the
     25 // DownloadDatabase up to date.
     26 class DownloadHistory : public AllDownloadItemNotifier::Observer {
     27  public:
     28   typedef std::set<uint32> IdSet;
     29 
     30   // Caller must guarantee that HistoryService outlives HistoryAdapter.
     31   class HistoryAdapter {
     32    public:
     33     explicit HistoryAdapter(HistoryService* history);
     34     virtual ~HistoryAdapter();
     35 
     36     virtual void QueryDownloads(
     37         const HistoryService::DownloadQueryCallback& callback);
     38 
     39     virtual void CreateDownload(
     40         const history::DownloadRow& info,
     41         const HistoryService::DownloadCreateCallback& callback);
     42 
     43     virtual void UpdateDownload(const history::DownloadRow& data);
     44 
     45     virtual void RemoveDownloads(const std::set<uint32>& ids);
     46 
     47    private:
     48     HistoryService* history_;
     49     DISALLOW_COPY_AND_ASSIGN(HistoryAdapter);
     50   };
     51 
     52   class Observer {
     53    public:
     54     Observer();
     55     virtual ~Observer();
     56 
     57     // Fires when a download is added to or updated in the database, just after
     58     // the task is posted to the history thread.
     59     virtual void OnDownloadStored(content::DownloadItem* item,
     60                                   const history::DownloadRow& info) {}
     61 
     62     // Fires when RemoveDownloads messages are sent to the DB thread.
     63     virtual void OnDownloadsRemoved(const IdSet& ids) {}
     64 
     65     // Fires when the DownloadHistory is being destroyed so that implementors
     66     // can RemoveObserver() and nullify their DownloadHistory*s.
     67     virtual void OnDownloadHistoryDestroyed() {}
     68   };
     69 
     70   // Returns true if the item is persisted.
     71   static bool IsPersisted(content::DownloadItem* item);
     72 
     73   // Neither |manager| nor |history| may be NULL.
     74   // DownloadService creates DownloadHistory some time after DownloadManager is
     75   // created and destroys DownloadHistory as DownloadManager is shutting down.
     76   DownloadHistory(
     77       content::DownloadManager* manager,
     78       scoped_ptr<HistoryAdapter> history);
     79 
     80   virtual ~DownloadHistory();
     81 
     82   void AddObserver(Observer* observer);
     83   void RemoveObserver(Observer* observer);
     84 
     85  private:
     86   typedef std::set<content::DownloadItem*> ItemSet;
     87 
     88   // Callback from |history_| containing all entries in the downloads database
     89   // table.
     90   void QueryCallback(
     91       scoped_ptr<std::vector<history::DownloadRow> > infos);
     92 
     93   // May add |item| to |history_|.
     94   void MaybeAddToHistory(content::DownloadItem* item);
     95 
     96   // Callback from |history_| when an item was successfully inserted into the
     97   // database.
     98   void ItemAdded(uint32 id, bool success);
     99 
    100   // AllDownloadItemNotifier::Observer
    101   virtual void OnDownloadCreated(
    102       content::DownloadManager* manager, content::DownloadItem* item) OVERRIDE;
    103   virtual void OnDownloadUpdated(
    104       content::DownloadManager* manager, content::DownloadItem* item) OVERRIDE;
    105   virtual void OnDownloadOpened(
    106       content::DownloadManager* manager, content::DownloadItem* item) OVERRIDE;
    107   virtual void OnDownloadRemoved(
    108       content::DownloadManager* manager, content::DownloadItem* item) OVERRIDE;
    109 
    110   // Schedule a record to be removed from |history_| the next time
    111   // RemoveDownloadsBatch() runs. Schedule RemoveDownloadsBatch() to be run soon
    112   // if it isn't already scheduled.
    113   void ScheduleRemoveDownload(uint32 download_id);
    114 
    115   // Removes all |removing_ids_| from |history_|.
    116   void RemoveDownloadsBatch();
    117 
    118   AllDownloadItemNotifier notifier_;
    119 
    120   scoped_ptr<HistoryAdapter> history_;
    121 
    122   // Identifier of the item being created in QueryCallback(), matched up with
    123   // created items in OnDownloadCreated() so that the item is not re-added to
    124   // the database.
    125   uint32 loading_id_;
    126 
    127   // Identifiers of items that are scheduled for removal from history, to
    128   // facilitate batching removals together for database efficiency.
    129   IdSet removing_ids_;
    130 
    131   // |GetId()|s of items that were removed while they were being added, so that
    132   // they can be removed when the database finishes adding them.
    133   // TODO(benjhayden) Can this be removed now that it doesn't need to wait for
    134   // the db_handle, and can rely on PostTask sequentiality?
    135   IdSet removed_while_adding_;
    136 
    137   // Count the number of items in the history for UMA.
    138   int64 history_size_;
    139 
    140   ObserverList<Observer> observers_;
    141 
    142   base::WeakPtrFactory<DownloadHistory> weak_ptr_factory_;
    143 
    144   DISALLOW_COPY_AND_ASSIGN(DownloadHistory);
    145 };
    146 
    147 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_HISTORY_H_
    148