[Offline Pages] Two-step expiration in storage manager.

components/offline_pages/offline_page_storage_manager.h

Index: components/offline_pages/offline_page_storage_manager.h
diff --git a/components/offline_pages/offline_page_storage_manager.h b/components/offline_pages/offline_page_storage_manager.h
index 47f560120d929cfe10b80358f35b631c65796aae..254cc25bbbbf633cc7836375263fe8f20eda3f54 100644
--- a/components/offline_pages/offline_page_storage_manager.h
+++ b/components/offline_pages/offline_page_storage_manager.h
@@ -22,12 +22,17 @@ class Clock;
 
 namespace offline_pages {
 
-// Limit of the total storage space occupied by offline pages should be 30% of
-// available storage. And we clear storage when it is over the threshold,
-// reducing the usage below threshold.
+// Maximum % of total available storage that will be occupied by offline pages
+// before a storage clearing.

[jianli, 2016/05/26 21:59:31]

nit: storage clearing => storage cleanup

[romax, 2016/05/27 00:41:38]

Done.

 const double kOfflinePageStorageLimit = 0.3;

[jianli, 2016/05/26 21:59:32]

If these constants are only needed in .cc file, please move them over.

[romax, 2016/05/27 00:41:38]

per discussion I'm leaving them here.

+// The target % of storage usage we try to reach below when expiring pages.
 const double kOfflinePageStorageClearThreshold = 0.1;
+// Storage manager will clear storage if it has been longer than this interval

[jianli, 2016/05/26 21:59:31]

nit: The time that the storage cleanup will be triggered again since the last
cleanup.

[romax, 2016/05/27 00:41:38]

Done.

+// since last clearing.
 const base::TimeDelta kClearStorageInterval = base::TimeDelta::FromMinutes(10);
+// Storage manager will remove a page from metadata store once the page has been

[jianli, 2016/05/26 21:59:32]

nit: The time that the page record will be removed from the store since the page
has been expired.

[romax, 2016/05/27 00:41:38]

Done.

+// expired longer than this interval.
+const base::TimeDelta kRemovePageItemInterval = base::TimeDelta::FromDays(21);
 
 class ArchiveManager;
 class ClientPolicyController;
@@ -48,26 +53,33 @@ class OfflinePageStorageManager {
    public:
     virtual ~Client() {}
 
+    // Asks the client to delete pages based on |ofline_ids| and invoke

[jianli, 2016/05/26 21:59:32]

nit: invoke => invokes
also consider adding "upon completion" after |callback|.

[romax, 2016/05/27 00:41:38]

Done.

+    // |callback|.
+    virtual void DeletePagesByOfflineId(const std::vector<int64_t>& offline_ids,
+                                        const DeletePageCallback& callback) = 0;
+
     // 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;
+    // Asks the client to mark pages with |offline_ids| as expired and the

[jianli, 2016/05/26 21:59:32]

nit: add "deletes" after "and".

[romax, 2016/05/27 00:41:38]

Done.

+    // associated archive files.
+    virtual void ExpirePages(const std::vector<int64_t>& offline_ids,
+                             const base::Time& expiration_time,
+                             const base::Callback<void(bool)>& callback) = 0;
   };
 
   enum class ClearStorageResult {
     SUCCESS,         // Cleared successfully.
     UNNECESSARY,     // No expired pages.
+    EXPIRE_FAILURE,  // Expiration failed.
     DELETE_FAILURE,  // Deletion failed.
   };
 
   // Callback used when calling ClearPagesIfNeeded.
-  // int: the number of expired pages.
+  // size_t: the number of expired pages.
   // ClearStorageResult: result of expiring pages in storage.
-  typedef base::Callback<void(int, ClearStorageResult)> ClearPagesCallback;
+  typedef base::Callback<void(size_t, ClearStorageResult)> ClearPagesCallback;
 
   explicit OfflinePageStorageManager(Client* client,
                                      ClientPolicyController* policy_controller,
@@ -103,20 +115,34 @@ class OfflinePageStorageManager {
   // Callback called after getting all pages from client done.
   void OnGetAllPagesDone(const ClearPagesCallback& callback,
                          const ArchiveManager::StorageStats& storage_stats,
+                         const base::Time& now,
                          const MultipleOfflinePageItemResult& pages);
 
   // Callback called after expired pages have been deleted.
-  void OnExpiredPagesDeleted(const ClearPagesCallback& callback,
-                             int pages_to_clear,
-                             DeletePageResult result);
-
-  // Gets offline IDs of all expired pages and return in |offline_ids|.
-  void GetExpiredPageIds(const MultipleOfflinePageItemResult& pages,
+  void OnPagesExpired(const ClearPagesCallback& callback,
+                      size_t pages_to_clear,
+                      std::vector<int64_t>* page_ids_to_remove,
+                      bool success);
+
+  // Callback called after clearing outdated pages from client.
+  void OnDeadPagesCleared(const ClearPagesCallback& callback,

[jianli, 2016/05/26 21:59:32]

replace Dead with Outdated

[romax, 2016/05/27 00:41:38]

Done.

+                          size_t pages_cleared,
+                          bool success,
+                          DeletePageResult result);
+
+  // Gets offline IDs of both pages that should be expired and the ones that
+  // need to be removed from metadata store. |page_ids_to_expire| will have
+  // the pages to be expired, |page_ids_to_remove| will have the pages to be
+  // removed. |now| is used to keep the time consistecy with other operations.
+  void GetPageIdsToClear(const MultipleOfflinePageItemResult& pages,
                          const ArchiveManager::StorageStats& stats,
-                         std::vector<int64_t>& offline_ids);
+                         const base::Time& now,
+                         std::vector<int64_t>* page_ids_to_expire,
+                         std::vector<int64_t>* page_ids_to_remove);
 
   // Determine if manager should clear pages.
-  ClearMode ShouldClearPages(const ArchiveManager::StorageStats& storage_stats);
+  ClearMode ShouldClearPages(const ArchiveManager::StorageStats& storage_stats,
+                             const base::Time& now);
 
   // Return true if |page| is expired comparing to |now|.
   bool ShouldBeExpired(const base::Time& now, const OfflinePageItem& page);