Propagate more information about ValueStore errors to callers, notably an

chrome/browser/value_store/leveldb_value_store.h

 // Copyright (c) 2012 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 CHROME_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_
 #define CHROME_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 29 matching lines @@
       WriteOptions options,
       const std::string& key,
       const Value& value) OVERRIDE;
   virtual WriteResult Set(
       WriteOptions options, const DictionaryValue& values) OVERRIDE;
   virtual WriteResult Remove(const std::string& key) OVERRIDE;
   virtual WriteResult Remove(const std::vector<std::string>& keys) OVERRIDE;
   virtual WriteResult Clear() OVERRIDE;
 
  private:
-  // Tries to open the database if it hasn't been opened already.  Returns the
-  // error message on failure, or "" on success (guaranteeding that |db_| is
-  // non-NULL),
-  std::string EnsureDbIsOpen();
+  // Tries to open the database if it hasn't been opened already.
+  scoped_ptr<ValueStore::Error> EnsureDbIsOpen();
 
-  // Reads a setting from the database. Returns the error message on failure,
-  // or "" on success in which case |setting| will be reset to the Value read
-  // from the database. This value may be NULL.
-  std::string ReadFromDb(
+  // Reads a setting from the database.
+  scoped_ptr<ValueStore::Error> ReadFromDb(
       leveldb::ReadOptions options,
       const std::string& key,
       // Will be reset() with the result, if any.
       scoped_ptr<Value>* setting);
 
   // Adds a setting to a WriteBatch, and logs the change in |changes|. For use
-  // with WriteToDb. Returns the error message on failure, or "" on success.
-  std::string AddToBatch(
-      ValueStore::WriteOptions options,
-      const std::string& key,
-      const base::Value& value,
-      leveldb::WriteBatch* batch,
-      ValueStoreChangeList* changes);
+  // with WriteToDb.
+  scoped_ptr<ValueStore::Error> AddToBatch(ValueStore::WriteOptions options,
+                                           const std::string& key,
+                                           const base::Value& value,
+                                           leveldb::WriteBatch* batch,
+                                           ValueStoreChangeList* changes);
 
-  // Commits the changes in |batch| to the database, returning the error message
-  // on failure or "" on success.
-  std::string WriteToDb(leveldb::WriteBatch* batch);
+  // Commits the changes in |batch| to the database.
+  scoped_ptr<ValueStore::Error> WriteToDb(leveldb::WriteBatch* batch);
+
+  // Converts an error leveldb::Status to a ValueStore::Error. Returns a
+  // scoped_ptr for convenience; the result will always be non-empty.
+  scoped_ptr<ValueStore::Error> ToValueStoreError(
+      const leveldb::Status& status,
+      scoped_ptr<std::string> key);
+
+  // Removes the on-disk database at |db_path_|. Any file system locks should
+  // be released before calling this method.
+  void DeleteDbFile();
 
   // Returns whether the database is empty.
   bool IsEmpty();
 
   // The location of the leveldb backend.
   const base::FilePath db_path_;
 
   // leveldb backend.
   scoped_ptr<leveldb::DB> db_;
 
   DISALLOW_COPY_AND_ASSIGN(LeveldbValueStore);
 };
 
 #endif  // CHROME_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_