[Offline pages] Resetting offline page metadata store if initial load fails

components/offline_pages/offline_page_model_impl.cc

Index: components/offline_pages/offline_page_model_impl.cc
diff --git a/components/offline_pages/offline_page_model_impl.cc b/components/offline_pages/offline_page_model_impl.cc
index ce697958ec33545ca0a7f7cfafcfcdca441cddc1..92c4b7b8fbd882140263d37da82a38fc49406948 100644
--- a/components/offline_pages/offline_page_model_impl.cc
+++ b/components/offline_pages/offline_page_model_impl.cc
@@ -305,7 +305,10 @@ void ReportPageHistogramsAfterAccess(const OfflinePageItem& offline_page_item,
 
 // protected
 OfflinePageModelImpl::OfflinePageModelImpl()
-    : OfflinePageModel(), is_loaded_(false), weak_ptr_factory_(this) {}
+    : OfflinePageModel(),
+      is_loaded_(false),
+      store_reset_attempts_left_(3),
+      weak_ptr_factory_(this) {}
 
 OfflinePageModelImpl::OfflinePageModelImpl(
     std::unique_ptr<OfflinePageMetadataStore> store,
@@ -316,6 +319,7 @@ OfflinePageModelImpl::OfflinePageModelImpl(
       is_loaded_(false),
       policy_controller_(new ClientPolicyController()),
       archive_manager_(new ArchiveManager(archives_dir, task_runner)),
+      store_reset_attempts_left_(3),
       testing_clock_(nullptr),
       weak_ptr_factory_(this) {
   archive_manager_->EnsureArchivesDirCreated(
@@ -800,25 +804,35 @@ void OfflinePageModelImpl::OnEnsureArchivesDirCreatedDone(
   UMA_HISTOGRAM_TIMES("OfflinePages.Model.ArchiveDirCreationTime",
                       base::TimeTicks::Now() - start_time);
 
-  store_->GetOfflinePages(base::Bind(&OfflinePageModelImpl::OnLoadDone,
-                                     weak_ptr_factory_.GetWeakPtr(),
-                                     start_time));
+  store_->GetOfflinePages(
+      base::Bind(&OfflinePageModelImpl::OnGetOfflinePagesDoneForInit,
+                 weak_ptr_factory_.GetWeakPtr(), start_time));
 }
 
-void OfflinePageModelImpl::OnLoadDone(
+void OfflinePageModelImpl::OnGetOfflinePagesDoneForInit(
     const base::TimeTicks& start_time,
-    OfflinePageMetadataStore::LoadStatus load_status,
+    StoreState store_state,
     const std::vector<OfflinePageItem>& offline_pages) {
   DCHECK(!is_loaded_);
-  is_loaded_ = true;
+  UMA_HISTOGRAM_ENUMERATION(
+      "OfflinePages.StoreState", static_cast<int32_t>(store_state),
+      static_cast<int32_t>(StoreState::STORE_STATE_COUNT));
 
-  // TODO(jianli): rebuild the store upon failure.
+  if (store_state != StoreState::LOADED) {
+    DVLOG(1) << "Offline pages database loading failed: "
+             << static_cast<int32_t>(store_state);
+  }
 
-  if (load_status == OfflinePageMetadataStore::LOAD_SUCCEEDED)
-    CacheLoadedData(offline_pages);
+  if (store_state == StoreState::FAILED_LOADING && MaybeResetStore(start_time))
+    return;
 
   UMA_HISTOGRAM_TIMES("OfflinePages.Model.ConstructionToLoadedEventTime",
                       base::TimeTicks::Now() - start_time);
+  UMA_HISTOGRAM_COUNTS("OfflinePages.SavedPageCount",

[Mark P, 2016/10/12 16:04:12]

I notice this moved from offline_page_metadata_store_sql.cc.  Is it still
emitted under exactly the same conditions  as before? (including error states)?

[fgorski, 2016/10/12 20:44:09]

Yes, because we are going to be calling the other method more often then simply
initialization in future. This had to be moved to post initialization call. We
would be reporting it far too much otherwise. Thanks for checking on that.

[Mark P, 2016/10/12 22:12:15]

Acknowledged.

+                       static_cast<int32_t>(offline_pages.size()));
+
+  CacheLoadedData(offline_pages);
+  is_loaded_ = true;
 
   // Create Storage Manager.
   storage_manager_.reset(new OfflinePageStorageManager(
@@ -841,6 +855,39 @@ void OfflinePageModelImpl::OnLoadDone(
       kStorageManagerStartingDelay);
 }
 
+bool OfflinePageModelImpl::MaybeResetStore(const base::TimeTicks& start_time) {
+  if (store_reset_attempts_left_ <= 0)
+    return false;
+
+  store_reset_attempts_left_--;
+  store_->Reset(base::Bind(&OfflinePageModelImpl::OnStoreResetDone,
+                           weak_ptr_factory_.GetWeakPtr(), start_time));
+  return true;
+}
+
+void OfflinePageModelImpl::OnStoreResetDone(const base::TimeTicks& start_time,
+                                            bool reset_success) {
+  UMA_HISTOGRAM_ENUMERATION(
+      "OfflinePages.StoreState", static_cast<int32_t>(store_->state()),
+      static_cast<int32_t>(StoreState::STORE_STATE_COUNT));
+
+  if (reset_success) {
+    store_->GetOfflinePages(
+        base::Bind(&OfflinePageModelImpl::OnGetOfflinePagesDoneForInit,
+                   weak_ptr_factory_.GetWeakPtr(), start_time));
+    return;
+  }
+
+  if (store_->state() == StoreState::FAILED_RESET &&
+      MaybeResetStore(start_time)) {
+    return;
+  }
+
+  // Reset failed enough times. Simply initialize the model with no items.
+  OnGetOfflinePagesDoneForInit(start_time, store_->state(),
+                               std::vector<OfflinePageItem>());
+}
+
 void OfflinePageModelImpl::InformSavePageDone(const SavePageCallback& callback,
                                               SavePageResult result,
                                               const ClientId& client_id,