A database to hold mappings from origin identifiers to unique directory names.

webkit/fileapi/file_system_origin_database.h

Index: webkit/fileapi/file_system_origin_database.h
diff --git a/webkit/fileapi/file_system_origin_database.h b/webkit/fileapi/file_system_origin_database.h
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+// Copyright (c) 2011 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 WEBKIT_FILEAPI_FILE_SYSTEM_ORIGIN_DATABASE_H_
+#define WEBKIT_FILEAPI_FILE_SYSTEM_ORIGIN_DATABASE_H_
+
+#include <string>
+#include <utility>
+#include <vector>
+
+#include "base/file_path.h"
+#include "base/scoped_ptr.h"
+#include "third_party/leveldb/include/leveldb/db.h"
+
+namespace fileapi {
+
+// All methods of this class other than the constructor may be used only from
+// the browser's FILE thread.  The constructor may be used on any thread.
+class FileSystemOriginDatabase {
+ public:
+  typedef std::pair<std::string, FilePath> OriginRecord;
+
+  // Only one instance of FileSystemOriginDatabase should exist for a given path
+  // at a given time.
+  FileSystemOriginDatabase(const FilePath& path);
+  ~FileSystemOriginDatabase();
+
+  bool HasOriginPath(const std::string& origin);
+
+  // This will produce a unique path and add it to its database, if it's not
+  // already present.
+  bool GetPathForOrigin(const std::string& origin, FilePath* directory);
+
+  // Also returns success if the origin is not found.
+  bool RemovePathForOrigin(const std::string& origin);
+
+  bool ListAllOrigins(std::vector<OriginRecord>* origins);
+
+  // This will release all database resources in use; call it to save memory.
+  void DropDatabase();
+
+ private:
+  bool Init();
+  void HandleError(leveldb::Status status);
+  bool GetLastPathNumber(int* number);
+
+  std::string path_;
+  scoped_ptr<leveldb::DB> db_;
+  DISALLOW_COPY_AND_ASSIGN(FileSystemOriginDatabase);
+};
+
+}  // namespace fileapi
+
+#endif  // WEBKIT_FILEAPI_FILE_SYSTEM_ORIGIN_DATABASE_H_