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_VALUE_STORE_FRONTEND_H_
6#define EXTENSIONS_BROWSER_VALUE_STORE_VALUE_STORE_FRONTEND_H_
7
8#include <string>
9
10#include "base/callback.h"
11#include "base/memory/ref_counted.h"
12#include "base/memory/scoped_ptr.h"
13#include "base/memory/weak_ptr.h"
14#include "base/threading/non_thread_safe.h"
15#include "base/values.h"
16#include "extensions/browser/value_store/value_store.h"
17
18namespace base {
19class FilePath;
20}
21
22// A frontend for a LeveldbValueStore, for use on the UI thread.
23class ValueStoreFrontend
24    : public base::SupportsWeakPtr<ValueStoreFrontend>,
25      public base::NonThreadSafe {
26 public:
27  typedef base::Callback<void(scoped_ptr<base::Value>)> ReadCallback;
28
29  ValueStoreFrontend();
30  explicit ValueStoreFrontend(const base::FilePath& db_path);
31  // This variant is useful for testing (using a mock ValueStore).
32  explicit ValueStoreFrontend(scoped_ptr<ValueStore> value_store);
33  ~ValueStoreFrontend();
34
35  void Init(const base::FilePath& db_path);
36
37  // Retrieves a value from the database asynchronously, passing a copy to
38  // |callback| when ready. NULL is passed if no matching entry is found.
39  void Get(const std::string& key, const ReadCallback& callback);
40
41  // Sets a value with the given key.
42  void Set(const std::string& key, scoped_ptr<base::Value> value);
43
44  // Removes the value with the given key.
45  void Remove(const std::string& key);
46
47 private:
48  class Backend;
49
50  // A helper class to manage lifetime of the backing ValueStore, which lives
51  // on the FILE thread.
52  scoped_refptr<Backend> backend_;
53
54  DISALLOW_COPY_AND_ASSIGN(ValueStoreFrontend);
55};
56
57#endif  // EXTENSIONS_BROWSER_VALUE_STORE_VALUE_STORE_FRONTEND_H_
58