Extract protobuf database into a new 'leveldb_proto' component

components/dom_distiller/core/dom_distiller_database.h

-// Copyright 2013 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_DATABASE_H_
-#define COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_DATABASE_H_
-
-#include <string>
-#include <vector>
-
-#include "base/callback.h"
-#include "base/files/file_path.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/memory/scoped_vector.h"
-#include "base/memory/weak_ptr.h"
-#include "base/threading/thread_checker.h"
-#include "base/threading/thread_collision_warner.h"
-#include "components/dom_distiller/core/article_entry.h"
-
-namespace base {
-class SequencedTaskRunner;
-class MessageLoop;
-}
-
-namespace leveldb {
-class DB;
-}
-
-namespace dom_distiller {
-
-typedef std::vector<ArticleEntry> EntryVector;
-
-// Interface for classes providing persistent storage of DomDistiller entries.
-class DomDistillerDatabaseInterface {
- public:
-  typedef std::vector<std::string> ArticleEntryIds;
-  typedef base::Callback<void(bool success)> InitCallback;
-  typedef base::Callback<void(bool success)> UpdateCallback;
-  typedef base::Callback<void(bool success, scoped_ptr<EntryVector>)>
-      LoadCallback;
-
-  virtual ~DomDistillerDatabaseInterface() {}
-
-  // Asynchronously initializes the object. |callback| will be invoked on the UI
-  // thread when complete.
-  virtual void Init(const base::FilePath& database_dir,
-                    InitCallback callback) = 0;
-
-  // Asynchronously saves |entries_to_save| and deletes entries from
-  // |entries_to_remove| from the database. |callback| will be invoked on the UI
-  // thread when complete.
-  virtual void UpdateEntries(scoped_ptr<EntryVector> entries_to_save,
-                             scoped_ptr<EntryVector> entries_to_remove,
-                             UpdateCallback callback) = 0;
-
-  // Asynchronously loads all entries from the database and invokes |callback|
-  // when complete.
-  virtual void LoadEntries(LoadCallback callback) = 0;
-};
-
-// When the DomDistillerDatabase instance is deleted, in-progress asynchronous
-// operations will be completed and the corresponding callbacks will be called.
-class DomDistillerDatabase
-    : public DomDistillerDatabaseInterface {
- public:
-  // The underlying database. Calls to this type may be blocking.
-  class Database {
-   public:
-    virtual bool Init(const base::FilePath& database_dir) = 0;
-    virtual bool Save(const EntryVector& entries_to_save,
-                      const EntryVector& entries_to_remove) = 0;
-    virtual bool Load(EntryVector* entries) = 0;
-    virtual ~Database() {}
-  };
-
-  // Once constructed, function calls and destruction should all occur on the
-  // same thread (not necessarily the same as the constructor).
-  class LevelDB : public Database {
-   public:
-    LevelDB();
-    virtual ~LevelDB();
-    virtual bool Init(const base::FilePath& database_dir) OVERRIDE;
-    virtual bool Save(const EntryVector& entries_to_save,
-                      const EntryVector& entries_to_remove) OVERRIDE;
-    virtual bool Load(EntryVector* entries) OVERRIDE;
-
-   private:
-    DFAKE_MUTEX(thread_checker_);
-    scoped_ptr<leveldb::DB> db_;
-  };
-
-  explicit DomDistillerDatabase(
-      scoped_refptr<base::SequencedTaskRunner> task_runner);
-
-  virtual ~DomDistillerDatabase();
-
-  // DomDistillerDatabaseInterface implementation.
-  virtual void Init(const base::FilePath& database_dir,
-                    InitCallback callback) OVERRIDE;
-  virtual void UpdateEntries(scoped_ptr<EntryVector> entries_to_save,
-                           scoped_ptr<EntryVector> entries_to_remove,
-                           UpdateCallback callback) OVERRIDE;
-  virtual void LoadEntries(LoadCallback callback) OVERRIDE;
-
-  // Allow callers to provide their own Database implementation.
-  void InitWithDatabase(scoped_ptr<Database> database,
-                        const base::FilePath& database_dir,
-                        InitCallback callback);
-
- private:
-  base::ThreadChecker thread_checker_;
-
-  // Used to run blocking tasks in-order.
-  scoped_refptr<base::SequencedTaskRunner> task_runner_;
-
-  scoped_ptr<Database> db_;
-
-  DISALLOW_COPY_AND_ASSIGN(DomDistillerDatabase);
-};
-
-}  // namespace dom_distiller
-
-#endif  // COMPONENTS_DOM_DISTILLER_CORE_DOM_DISTILLER_DATABASE_H_