chrome/browser/value_store/value_store_frontend.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_VALUE_STORE_FRONTEND_H_
   6 #define CHROME_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 "chrome/browser/value_store/value_store.h"
  17
  18 namespace base {
  19 class FilePath;
  20 }
  21
  22 // A frontend for a LeveldbValueStore, for use on the UI thread.
  23 class 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  // CHROME_BROWSER_VALUE_STORE_VALUE_STORE_FRONTEND_H_