storage/browser/blob/shareable_blob_data_item.h

   1 // Copyright 2015 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 STORAGE_BROWSER_BLOB_SHAREABLE_BLOB_DATA_ITEM_H_
   6 #define STORAGE_BROWSER_BLOB_SHAREABLE_BLOB_DATA_ITEM_H_
   7
   8 #include "base/containers/hash_tables.h"
   9 #include "base/hash.h"
  10 #include "base/macros.h"
  11 #include "base/memory/ref_counted.h"
  12 #include "storage/common/data_element.h"
  13
  14 namespace storage {
  15
  16 class BlobDataItem;
  17
  18 // This class allows blob items to be shared between blobs, and is only used by
  19 // BlobStorageContext. This class contains both the blob data item and the uuids
  20 // of all the blobs using this item.
  21 // The data in this class (the item) is immutable, but the item itself can be
  22 // swapped out with an item with the same data but a different backing (think
  23 // RAM vs file backed).
  24 class ShareableBlobDataItem : public base::RefCounted<ShareableBlobDataItem> {
  25  public:
  26   ShareableBlobDataItem(const std::string& blob_uuid,
  27                         const scoped_refptr<BlobDataItem>& item);
  28
  29   const scoped_refptr<BlobDataItem>& item();
  30
  31   base::hash_set<std::string>& referencing_blobs() {
  32     return referencing_blobs_;
  33   }
  34
  35  private:
  36   friend class base::RefCounted<ShareableBlobDataItem>;
  37   ~ShareableBlobDataItem();
  38
  39   scoped_refptr<BlobDataItem> item_;
  40
  41   base::hash_set<std::string> referencing_blobs_;
  42
  43   DISALLOW_COPY_AND_ASSIGN(ShareableBlobDataItem);
  44 };
  45
  46 }  // namespace storage
  47 #endif  // STORAGE_BROWSER_BLOB_SHAREABLE_BLOB_DATA_ITEM_H_