GDataDB support with leveldb.

chrome/browser/chromeos/gdata/gdata_db.h

+// Copyright (c) 2012 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 CHROME_BROWSER_CHROMEOS_GDATA_GDATA_DB_H_
+#define CHROME_BROWSER_CHROMEOS_GDATA_GDATA_DB_H_
+#pragma once
+
+#include <string>
+
+#include "base/memory/scoped_ptr.h"
+
+class FilePath;
+
+namespace gdata {
+
+class GDataEntry;
+class GDataDBIter;
+
+// GData Database interface class.
+class GDataDB {
+ public:
+  enum Status {
+    DB_OK = 0,
+    DB_NOT_FOUND,

[satorux1, 2012/04/24 18:26:44]

does this mean the db file is not found? or key is not found?

please add some in-line comment.

[achuithb, 2012/04/24 19:43:58]

Done.

+    DB_ERR,

[satorux1, 2012/04/24 18:26:44]

DB_ERROR or DB_FAILED? in favor of less abbreviation.

[achuithb, 2012/04/24 19:43:58]

Done.

+  };
+
+  virtual ~GDataDB() {}
+
+  // Add |entry| to the database.
+  virtual Status Put(const GDataEntry& entry) = 0;
+
+  // Delete a database entry with key |resource_id| or |path| respectively.
+  virtual Status DeleteByResourceId(const std::string& resource_id) = 0;
+  virtual Status DeleteByPath(const FilePath& path) = 0;
+
+  // Fetch a GDataEntry* by key |resource_id| or |path| respectively.
+  virtual Status GetByResourceId(const std::string& resource_id,
+                                 scoped_ptr<GDataEntry>* entry) = 0;
+  virtual Status GetByPath(const FilePath& path,
+                           scoped_ptr<GDataEntry>* entry) = 0;
+
+  // An iterator to fetch all GDataEntry's under |path|.
+  virtual scoped_ptr<GDataDBIter> NewIterator(const FilePath& path) = 0;
+
+ protected:
+  GDataDB() {}
+
+  DISALLOW_COPY_AND_ASSIGN(GDataDB);

[satorux1, 2012/04/24 18:26:44]

nit: In interface class with pure virtual methods, i think we don't put this as
we cannot copy/assign anyway.

[achuithb, 2012/04/24 19:43:58]

Done.

+};
+
+// GData Database Iterator interface class.
+class GDataDBIter {
+ public:
+  virtual ~GDataDBIter() {}
+  virtual scoped_ptr<GDataEntry> GetNext() = 0;

[satorux1, 2012/04/24 18:26:44]

function comment is missing. I expect it'll return NULL when it terminates.
please clarify in the comment.

[achuithb, 2012/04/24 19:43:58]

Done.

+
+ protected:
+  GDataDBIter() {}
+};
+
+}  // namespace gdata
+
+#endif  // CHROME_BROWSER_CHROMEOS_GDATA_GDATA_DB_H_