chrome/browser/download/download_history.h

   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 "components/history/core/browser/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(history::HistoryService* history);
  34     virtual ~HistoryAdapter();
  35
  36     virtual void QueryDownloads(
  37         const history::HistoryService::DownloadQueryCallback& callback);
  38
  39     virtual void CreateDownload(
  40         const history::DownloadRow& info,
  41         const history::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     history::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 download is persisted. Not reliable when called from
  71   // within a DownloadManager::Observer::OnDownloadCreated handler since the
  72   // persisted state may not yet have been updated for a download that was
  73   // restored from history.
  74   static bool IsPersisted(const content::DownloadItem* item);
  75
  76   // Neither |manager| nor |history| may be NULL.
  77   // DownloadService creates DownloadHistory some time after DownloadManager is
  78   // created and destroys DownloadHistory as DownloadManager is shutting down.
  79   DownloadHistory(
  80       content::DownloadManager* manager,
  81       scoped_ptr<HistoryAdapter> history);
  82
  83   ~DownloadHistory() override;
  84
  85   void AddObserver(Observer* observer);
  86   void RemoveObserver(Observer* observer);
  87
  88   // Returns true if the download was restored from history. Safe to call from
  89   // within a DownloadManager::Observer::OnDownloadCreated handler and can be
  90   // used to distinguish between downloads that were created due to new requests
  91   // vs. downloads that were created due to being restored from history. Note
  92   // that the return value is only reliable for downloads that were restored by
  93   // this specific DownloadHistory instance.
  94   bool WasRestoredFromHistory(const content::DownloadItem* item) const;
  95
  96  private:
  97   typedef std::set<content::DownloadItem*> ItemSet;
  98
  99   // Callback from |history_| containing all entries in the downloads database
 100   // table.
 101   void QueryCallback(
 102       scoped_ptr<std::vector<history::DownloadRow> > infos);
 103
 104   // May add |item| to |history_|.
 105   void MaybeAddToHistory(content::DownloadItem* item);
 106
 107   // Callback from |history_| when an item was successfully inserted into the
 108   // database.
 109   void ItemAdded(uint32 id, bool success);
 110
 111   // AllDownloadItemNotifier::Observer
 112   void OnDownloadCreated(content::DownloadManager* manager,
 113                          content::DownloadItem* item) override;
 114   void OnDownloadUpdated(content::DownloadManager* manager,
 115                          content::DownloadItem* item) override;
 116   void OnDownloadOpened(content::DownloadManager* manager,
 117                         content::DownloadItem* item) override;
 118   void OnDownloadRemoved(content::DownloadManager* manager,
 119                          content::DownloadItem* item) override;
 120
 121   // Schedule a record to be removed from |history_| the next time
 122   // RemoveDownloadsBatch() runs. Schedule RemoveDownloadsBatch() to be run soon
 123   // if it isn't already scheduled.
 124   void ScheduleRemoveDownload(uint32 download_id);
 125
 126   // Removes all |removing_ids_| from |history_|.
 127   void RemoveDownloadsBatch();
 128
 129   AllDownloadItemNotifier notifier_;
 130
 131   scoped_ptr<HistoryAdapter> history_;
 132
 133   // Identifier of the item being created in QueryCallback(), matched up with
 134   // created items in OnDownloadCreated() so that the item is not re-added to
 135   // the database.
 136   uint32 loading_id_;
 137
 138   // Identifiers of items that are scheduled for removal from history, to
 139   // facilitate batching removals together for database efficiency.
 140   IdSet removing_ids_;
 141
 142   // |GetId()|s of items that were removed while they were being added, so that
 143   // they can be removed when the database finishes adding them.
 144   // TODO(benjhayden) Can this be removed now that it doesn't need to wait for
 145   // the db_handle, and can rely on PostTask sequentiality?
 146   IdSet removed_while_adding_;
 147
 148   // Count the number of items in the history for UMA.
 149   int64 history_size_;
 150
 151   base::ObserverList<Observer> observers_;
 152
 153   base::WeakPtrFactory<DownloadHistory> weak_ptr_factory_;
 154
 155   DISALLOW_COPY_AND_ASSIGN(DownloadHistory);
 156 };
 157
 158 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_HISTORY_H_