chrome/browser/value_store/leveldb_value_store.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_
   6 #define CHROME_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/compiler_specific.h"
  12 #include "base/files/file_path.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "chrome/browser/value_store/value_store.h"
  15 #include "third_party/leveldatabase/src/include/leveldb/db.h"
  16
  17 // Value store area, backed by a leveldb database.
  18 // All methods must be run on the FILE thread.
  19 class LeveldbValueStore : public ValueStore {
  20  public:
  21   // Creates a database bound to |path|. The underlying database won't be
  22   // opened (i.e. may not be created) until one of the get/set/etc methods are
  23   // called - this is because opening the database may fail, and extensions
  24   // need to be notified of that, but we don't want to permanently give up.
  25   //
  26   // Must be created on the FILE thread.
  27   explicit LeveldbValueStore(const base::FilePath& path);
  28
  29   // Must be deleted on the FILE thread.
  30   virtual ~LeveldbValueStore();
  31
  32   // ValueStore implementation.
  33   virtual size_t GetBytesInUse(const std::string& key) OVERRIDE;
  34   virtual size_t GetBytesInUse(const std::vector<std::string>& keys) OVERRIDE;
  35   virtual size_t GetBytesInUse() OVERRIDE;
  36   virtual ReadResult Get(const std::string& key) OVERRIDE;
  37   virtual ReadResult Get(const std::vector<std::string>& keys) OVERRIDE;
  38   virtual ReadResult Get() OVERRIDE;
  39   virtual WriteResult Set(
  40       WriteOptions options,
  41       const std::string& key,
  42       const base::Value& value) OVERRIDE;
  43   virtual WriteResult Set(
  44       WriteOptions options, const base::DictionaryValue& values) OVERRIDE;
  45   virtual WriteResult Remove(const std::string& key) OVERRIDE;
  46   virtual WriteResult Remove(const std::vector<std::string>& keys) OVERRIDE;
  47   virtual WriteResult Clear() OVERRIDE;
  48
  49  private:
  50   // Tries to open the database if it hasn't been opened already.
  51   scoped_ptr<ValueStore::Error> EnsureDbIsOpen();
  52
  53   // Reads a setting from the database.
  54   scoped_ptr<ValueStore::Error> ReadFromDb(
  55       leveldb::ReadOptions options,
  56       const std::string& key,
  57       // Will be reset() with the result, if any.
  58       scoped_ptr<base::Value>* setting);
  59
  60   // Adds a setting to a WriteBatch, and logs the change in |changes|. For use
  61   // with WriteToDb.
  62   scoped_ptr<ValueStore::Error> AddToBatch(ValueStore::WriteOptions options,
  63                                            const std::string& key,
  64                                            const base::Value& value,
  65                                            leveldb::WriteBatch* batch,
  66                                            ValueStoreChangeList* changes);
  67
  68   // Commits the changes in |batch| to the database.
  69   scoped_ptr<ValueStore::Error> WriteToDb(leveldb::WriteBatch* batch);
  70
  71   // Converts an error leveldb::Status to a ValueStore::Error. Returns a
  72   // scoped_ptr for convenience; the result will always be non-empty.
  73   scoped_ptr<ValueStore::Error> ToValueStoreError(
  74       const leveldb::Status& status,
  75       scoped_ptr<std::string> key);
  76
  77   // Removes the on-disk database at |db_path_|. Any file system locks should
  78   // be released before calling this method.
  79   void DeleteDbFile();
  80
  81   // Returns whether the database is empty.
  82   bool IsEmpty();
  83
  84   // The location of the leveldb backend.
  85   const base::FilePath db_path_;
  86
  87   // leveldb backend.
  88   scoped_ptr<leveldb::DB> db_;
  89
  90   DISALLOW_COPY_AND_ASSIGN(LeveldbValueStore);
  91 };
  92
  93 #endif  // CHROME_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_