[Offline Pages] Updated clearing logic in storage manager.

components/offline_pages/offline_page_storage_manager.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_STORAGE_MANAGER_H_
 #define COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_STORAGE_MANAGER_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/time/time.h"
 #include "components/offline_pages/offline_page_types.h"
 
+class PrefService;
 namespace base {
 class Clock;
 }
 
 namespace offline_pages {
 
 class ClientPolicyController;
 
+// Limit of the total storage space occupied by offline pages should be minimal
+// of (50 MB, 10% of available storage space).

[fgorski, 2016/05/17 05:33:29]

where did the second number come from?

[romax, 2016/05/18 02:36:19]

it's from the Offline Page Cache prd. second point under 'Manager Storage'

+static const int64_t kOfflinePageStorageLimit = 50 * (1 << 20);
+static const double kOfflinePageStorageLimitPercentage = 0.1;
+static const base::TimeDelta kClearStorageTimeGap =

[fgorski, 2016/05/17 05:33:29]

kClearStorageInterval

[romax, 2016/05/18 02:36:19]

Done.

+    base::TimeDelta::FromHours(6);
+static const char kOfflinePageStorageLastClearedTime[] =

[fgorski, 2016/05/17 05:33:29]

isn't this defined already?
If unaccessible, this can stay of course.

[romax, 2016/05/18 02:36:20]

yes it was unaccessible. removing since we no longer use it.

+    "offline_page.storage.last_cleared_time";
+
 // This class is used for storage management of offline pages. It provides
 // a ClearPagesIfNeeded method which is used to clear expired offline pages
 // based on last_access_time and lifetime policy of its namespace.
 // It has its own throttle mechanism so calling the method would not be
 // guaranteed to clear the pages immediately.
 //
 // OfflinePageModel should own and control the lifecycle of this manager.
 // And this manager would use OfflinePageModel to get/remove pages.
 class OfflinePageStorageManager {
  public:
   // This interface should have no knowledge of offline page model.
   // This interface should be implemented by clients managed by storage manager.
   class Client {
    public:
     // Asks the client to get all offline pages and invoke |callback|.
     virtual void GetAllPages(
         const MultipleOfflinePageItemCallback& callback) = 0;
 
     // Asks the client to delete pages based on |offline_ids| and invoke
     // |callback|.
     virtual void DeletePagesByOfflineId(const std::vector<int64_t>& offline_ids,
                                         const DeletePageCallback& callback) = 0;
   };
 
+  enum class StorageClearResult {
+    SUCCESS,      // Cleared successfully.
+    UNNECESSARY,  // No expired pages.
+    DELETE_FAIL,  // Deletion failed.

[fgorski, 2016/05/17 05:33:29]

FAILURE?

[romax, 2016/05/18 02:36:20]

Done.

+  };
+
   // Callback used when calling ClearPagesIfNeeded.
   // int: the number of deleted pages.
   // DeletePageResult: result of deleting pages.
-  typedef base::Callback<void(int, DeletePageResult)> ClearPageCallback;
+  typedef base::Callback<void(int, StorageClearResult)> ClearPageCallback;
 
   explicit OfflinePageStorageManager(Client* client,
-                                     ClientPolicyController* policy_controller);
+                                     ClientPolicyController* policy_controller,
+                                     PrefService* prefs);
 
   ~OfflinePageStorageManager();
 
   // The manager would *try* to clear pages when called. It may not delete any
   // pages (if clearing condition wasn't satisfied).
   void ClearPagesIfNeeded(const ClearPageCallback& callback);
 
   // Sets the clock for testing.
   void SetClockForTesting(std::unique_ptr<base::Clock> clock);
 
  private:
+  // Enum indicating how to clear the pages.
+  enum class ClearMode {
+    DEFAULT,    // Using normal expiration logic.
+    CLEAR_ALL,  // Remove all offline pages.
+    NO_NEED,    // No need to remove any page.

[fgorski, 2016/05/17 05:33:29]

Please explain that a bit better.

[romax, 2016/05/18 02:36:20]

Done.

+  };
+
   // Selects and removes pages that need to be expired. Triggered as a callback
   // to |GetAllPages|.
   void ClearExpiredPages(const ClearPageCallback& callback,
                          const MultipleOfflinePageItemResult& pages);
 
   // Gets offline IDs of all expired pages and return in |offline_ids|.
   void GetExpiredPageIds(const MultipleOfflinePageItemResult& pages,
                          std::vector<int64_t>& offline_ids);
 
   // Callback when expired pages has been deleted.
   void OnExpiredPagesDeleted(const ClearPageCallback& callback,
                              int pages_to_clear,
                              DeletePageResult result);
 
   // Determine if manager should clear pages.
-  bool ShouldClearPages();
+  ClearMode ShouldClearPages(const MultipleOfflinePageItemResult& pages);
 
   // Return true if |page| is expired comparing to |now|.
   bool ShouldBeExpired(const base::Time& now, const OfflinePageItem& page);
 
   // Not owned.
   Client* client_;
 
   // Not owned.
   ClientPolicyController* policy_controller_;
 
+  // Not owned, PrefService which is used to store last clear time.
+  PrefService* prefs_;
+
   bool in_progress_;
 
   // Clock for getting time.
   std::unique_ptr<base::Clock> clock_;
 
   base::WeakPtrFactory<OfflinePageStorageManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflinePageStorageManager);
 };
 
 }  // namespace offline_pages
 
 #endif  // COMPONENTS_OFFLINE_PAGES_OFFLINE_PAGE_STORAGE_MANAGER_H_