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 namespace base {
  18 class HistogramBase;
  19 }  // namespace base
  20
  21 // Value store area, backed by a leveldb database.
  22 // All methods must be run on the FILE thread.
  23 class LeveldbValueStore : public ValueStore {
  24  public:
  25   // Creates a database bound to |path|. The underlying database won't be
  26   // opened (i.e. may not be created) until one of the get/set/etc methods are
  27   // called - this is because opening the database may fail, and extensions
  28   // need to be notified of that, but we don't want to permanently give up.
  29   //
  30   // Must be created on the FILE thread.
  31   LeveldbValueStore(const std::string& uma_client_name,
  32                     const base::FilePath& path);
  33
  34   // Must be deleted on the FILE thread.
  35   ~LeveldbValueStore() override;
  36
  37   // ValueStore implementation.
  38   size_t GetBytesInUse(const std::string& key) override;
  39   size_t GetBytesInUse(const std::vector<std::string>& keys) override;
  40   size_t GetBytesInUse() override;
  41   ReadResult Get(const std::string& key) override;
  42   ReadResult Get(const std::vector<std::string>& keys) override;
  43   ReadResult Get() override;
  44   WriteResult Set(WriteOptions options,
  45                   const std::string& key,
  46                   const base::Value& value) override;
  47   WriteResult Set(WriteOptions options,
  48                   const base::DictionaryValue& values) override;
  49   WriteResult Remove(const std::string& key) override;
  50   WriteResult Remove(const std::vector<std::string>& keys) override;
  51   WriteResult Clear() override;
  52   bool Restore() override;
  53   bool RestoreKey(const std::string& key) override;
  54
  55   // Write directly to the backing levelDB. Only used for testing to cause
  56   // corruption in the database.
  57   bool WriteToDbForTest(leveldb::WriteBatch* batch);
  58
  59  private:
  60   // Tries to open the database if it hasn't been opened already.
  61   scoped_ptr<ValueStore::Error> EnsureDbIsOpen();
  62
  63   // Reads a setting from the database.
  64   scoped_ptr<ValueStore::Error> ReadFromDb(
  65       leveldb::ReadOptions options,
  66       const std::string& key,
  67       // Will be reset() with the result, if any.
  68       scoped_ptr<base::Value>* setting);
  69
  70   // Adds a setting to a WriteBatch, and logs the change in |changes|. For use
  71   // with WriteToDb.
  72   scoped_ptr<ValueStore::Error> AddToBatch(ValueStore::WriteOptions options,
  73                                            const std::string& key,
  74                                            const base::Value& value,
  75                                            leveldb::WriteBatch* batch,
  76                                            ValueStoreChangeList* changes);
  77
  78   // Commits the changes in |batch| to the database.
  79   scoped_ptr<ValueStore::Error> WriteToDb(leveldb::WriteBatch* batch);
  80
  81   // Converts an error leveldb::Status to a ValueStore::Error. Returns a
  82   // scoped_ptr for convenience; the result will always be non-empty.
  83   scoped_ptr<ValueStore::Error> ToValueStoreError(
  84       const leveldb::Status& status,
  85       scoped_ptr<std::string> key);
  86
  87   // Removes the on-disk database at |db_path_|. Any file system locks should
  88   // be released before calling this method.
  89   void DeleteDbFile();
  90
  91   // Returns whether the database is empty.
  92   bool IsEmpty();
  93
  94   // The location of the leveldb backend.
  95   const base::FilePath db_path_;
  96
  97   // leveldb backend.
  98   scoped_ptr<leveldb::DB> db_;
  99   base::HistogramBase* open_histogram_;
 100
 101   DISALLOW_COPY_AND_ASSIGN(LeveldbValueStore);
 102 };
 103
 104 #endif  // EXTENSIONS_BROWSER_VALUE_STORE_LEVELDB_VALUE_STORE_H_