[NTP Snippets] Shut down the service on database failure

components/ntp_snippets/ntp_snippets_database.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_NTP_SNIPPETS_NTP_SNIPPETS_DATABASE_H_
 #define COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_DATABASE_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 23 matching lines @@
   NTPSnippetsDatabase(
       const base::FilePath& database_dir,
       scoped_refptr<base::SequencedTaskRunner> file_task_runner);
   ~NTPSnippetsDatabase();
 
   // Returns whether the database has finished initialization. While this is
   // false, loads may already be started (they'll be serviced after
   // initialization finishes), but no updates are allowed.
   bool IsInitialized() const;
 
+  // Returns whether the database is in an (unrecoverable) error state. If this
+  // is true, the database must not be used anymore
+  bool IsErrorState() const;
+
+  // Set a callback to be called when the database enters an error state.
+  void SetErrorCallback(const base::Closure& error_callback);
+
   // Loads all snippets from storage and passes them to |callback|.
   void LoadSnippets(const SnippetsCallback& callback);
 
   // Adds or updates the given snippet.
   void SaveSnippet(const NTPSnippet& snippet);
   // Adds or updates all the given snippets.
   void SaveSnippets(const NTPSnippet::PtrVector& snippets);
 
   // Deletes the snippet with the given ID, and its image.
   void DeleteSnippet(const std::string& snippet_id);
@@ skipping 27 matching lines @@
                         std::unique_ptr<std::vector<SnippetProto>> entries);
   void OnDatabaseSaved(bool success);
 
   // Callbacks for ProtoDatabase<SnippetImageProto> operations.
   void OnImageDatabaseInited(bool success);
   void OnImageDatabaseLoaded(const SnippetImageCallback& callback,
                              bool success,
                              std::unique_ptr<SnippetImageProto> entry);
   void OnImageDatabaseSaved(bool success);
 
+  void OnDatabaseError();
+
   void ProcessPendingLoads();
 
   void LoadSnippetsImpl(const SnippetsCallback& callback);
   void SaveSnippetsImpl(std::unique_ptr<KeyEntryVector> entries_to_save);
   void DeleteSnippetsImpl(
       std::unique_ptr<std::vector<std::string>> keys_to_remove);
 
   void LoadImageImpl(const std::string& snippet_id,
                      const SnippetImageCallback& callback);
   void DeleteImagesImpl(
       std::unique_ptr<std::vector<std::string>> keys_to_remove);
 
-  void ResetDatabases();
-
   std::unique_ptr<leveldb_proto::ProtoDatabase<SnippetProto>> database_;
   bool database_initialized_;
   std::vector<SnippetsCallback> pending_snippets_callbacks_;
 
   std::unique_ptr<leveldb_proto::ProtoDatabase<SnippetImageProto>>
       image_database_;
   bool image_database_initialized_;
   std::vector<std::pair<std::string, SnippetImageCallback>>
       pending_image_callbacks_;
 
+  base::Closure error_callback_;

[Bernhard Bauer, 2016/06/20 17:37:46]

At some point you could think about switching to a client interface instead of
having multiple callbacks and lists thereof.

[Marc Treib, 2016/06/21 08:27:48]

Hm, true. I generally like explicit callbacks because it's often convenient for
the client to bind their own parameters to them, but maybe the point has come to
switch over to a client interface here...

+
   base::WeakPtrFactory<NTPSnippetsDatabase> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NTPSnippetsDatabase);
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_DATABASE_H_