[Storage] Blob Storage Refactoring pt 1

storage/common/blob/shareable_file_reference.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 STORAGE_COMMON_BLOB_SHAREABLE_FILE_REFERENCE_H_
-#define STORAGE_COMMON_BLOB_SHAREABLE_FILE_REFERENCE_H_
-
-#include <vector>
-
-#include "storage/common/blob/scoped_file.h"
-
-namespace storage {
-
-// ShareableFileReference allows consumers to share FileReference for the
-// same path if it already exists in its internal map.
-// This class is non-thread-safe and all methods must be called on a single
-// thread.
-class STORAGE_COMMON_EXPORT ShareableFileReference
-    : public base::RefCounted<ShareableFileReference> {
- public:
-  typedef ScopedFile::ScopeOutCallback FinalReleaseCallback;
-
-  enum FinalReleasePolicy {
-    DELETE_ON_FINAL_RELEASE = ScopedFile::DELETE_ON_SCOPE_OUT,
-    DONT_DELETE_ON_FINAL_RELEASE = ScopedFile::DONT_DELETE_ON_SCOPE_OUT,
-  };
-
-  // Returns a ShareableFileReference for the given path, if no reference
-  // for this path exists returns NULL.
-  static scoped_refptr<ShareableFileReference> Get(const base::FilePath& path);
-
-  // Returns a ShareableFileReference for the given path, creating a new
-  // reference if none yet exists. If there's a pre-existing reference for
-  // the path, the policy parameter of this method is ignored.
-  static scoped_refptr<ShareableFileReference> GetOrCreate(
-      const base::FilePath& path,
-      FinalReleasePolicy policy,
-      base::TaskRunner* file_task_runner);
-
-  // Returns a ShareableFileReference for the given path of the |scoped_file|,
-  // creating a new reference if none yet exists. The ownership of |scoped_file|
-  // is passed to this reference.
-  // If there's a pre-existing reference for the path, the scope out policy
-  // and scope-out-callbacks of the given |scoped_file| is ignored.
-  // If the given scoped_file has an empty path (e.g. maybe already
-  // released) this returns NULL reference.
-  //
-  // TODO(kinuko): Make sure if this behavior is ok, we could alternatively
-  // merge callbacks to the existing one.
-  static scoped_refptr<ShareableFileReference> GetOrCreate(
-      ScopedFile scoped_file);
-
-  // The full file path.
-  const base::FilePath& path() const { return scoped_file_.path(); }
-
-  // The |callback| is fired when the final reference of this instance
-  // is released. If release policy is DELETE_ON_FINAL_RELEASE the
-  // callback task(s) is/are posted before the deletion is scheduled.
-  void AddFinalReleaseCallback(const FinalReleaseCallback& callback);
-
- private:
-  friend class base::RefCounted<ShareableFileReference>;
-
-  ShareableFileReference(ScopedFile scoped_file);
-  ~ShareableFileReference();
-
-  ScopedFile scoped_file_;
-
-  DISALLOW_COPY_AND_ASSIGN(ShareableFileReference);
-};
-
-}  // namespace storage
-
-#endif  // STORAGE_COMMON_BLOB_SHAREABLE_FILE_REFERENCE_H_