extensions/browser/value_store/leveldb_value_store.h

   1 // Copyright 2014 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 EXTENSIONS_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_
   6 #define EXTENSIONS_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 "extensions/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   ~LeveldbValueStore() override;
  31
  32   // ValueStore implementation.
  33   size_t GetBytesInUse(const std::string& key) override;
  34   size_t GetBytesInUse(const std::vector<std::string>& keys) override;
  35   size_t GetBytesInUse() override;
  36   ReadResult Get(const std::string& key) override;
  37   ReadResult Get(const std::vector<std::string>& keys) override;
  38   ReadResult Get() override;
  39   WriteResult Set(WriteOptions options,
  40                   const std::string& key,
  41                   const base::Value& value) override;
  42   WriteResult Set(WriteOptions options,
  43                   const base::DictionaryValue& values) override;
  44   WriteResult Remove(const std::string& key) override;
  45   WriteResult Remove(const std::vector<std::string>& keys) override;
  46   WriteResult Clear() override;
  47   bool Restore() override;
  48   bool RestoreKey(const std::string& key) override;
  49
  50   // Write directly to the backing levelDB. Only used for testing to cause
  51   // corruption in the database.
  52   bool WriteToDbForTest(leveldb::WriteBatch* batch);
  53
  54  private:
  55   // Tries to open the database if it hasn't been opened already.
  56   scoped_ptr<ValueStore::Error> EnsureDbIsOpen();
  57
  58   // Reads a setting from the database.
  59   scoped_ptr<ValueStore::Error> ReadFromDb(
  60       leveldb::ReadOptions options,
  61       const std::string& key,
  62       // Will be reset() with the result, if any.
  63       scoped_ptr<base::Value>* setting);
  64
  65   // Adds a setting to a WriteBatch, and logs the change in |changes|. For use
  66   // with WriteToDb.
  67   scoped_ptr<ValueStore::Error> AddToBatch(ValueStore::WriteOptions options,
  68                                            const std::string& key,
  69                                            const base::Value& value,
  70                                            leveldb::WriteBatch* batch,
  71                                            ValueStoreChangeList* changes);
  72
  73   // Commits the changes in |batch| to the database.
  74   scoped_ptr<ValueStore::Error> WriteToDb(leveldb::WriteBatch* batch);
  75
  76   // Converts an error leveldb::Status to a ValueStore::Error. Returns a
  77   // scoped_ptr for convenience; the result will always be non-empty.
  78   scoped_ptr<ValueStore::Error> ToValueStoreError(
  79       const leveldb::Status& status,
  80       scoped_ptr<std::string> key);
  81
  82   // Removes the on-disk database at |db_path_|. Any file system locks should
  83   // be released before calling this method.
  84   void DeleteDbFile();
  85
  86   // Returns whether the database is empty.
  87   bool IsEmpty();
  88
  89   // The location of the leveldb backend.
  90   const base::FilePath db_path_;
  91
  92   // leveldb backend.
  93   scoped_ptr<leveldb::DB> db_;
  94
  95   DISALLOW_COPY_AND_ASSIGN(LeveldbValueStore);
  96 };
  97
  98 #endif  // EXTENSIONS_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_