storage/browser/blob/blob_data_item.h

   1 // Copyright (c) 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_BLOB_DATA_ITEM_H_
   6 #define STORAGE_BROWSER_BLOB_BLOB_DATA_ITEM_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "storage/browser/storage_browser_export.h"
  11 #include "storage/common/data_element.h"
  12
  13 namespace disk_cache {
  14 class Entry;
  15 }
  16
  17 namespace storage {
  18 class BlobDataBuilder;
  19 class BlobStorageContext;
  20
  21 // Ref counted blob item. This class owns the backing data of the blob item. The
  22 // backing data is immutable, and cannot change after creation. The purpose of
  23 // this class is to allow the resource to stick around in the snapshot even
  24 // after the resource was swapped in the blob (either to disk or to memory) by
  25 // the BlobStorageContext.
  26 class STORAGE_EXPORT BlobDataItem : public base::RefCounted<BlobDataItem> {
  27  public:
  28   // The DataHandle class is used to persist resources that are needed for
  29   // reading this BlobDataItem. This object will stay around while any reads are
  30   // pending. If all blobs with this item are deleted or the item is swapped for
  31   // a different backend version (mem-to-disk or the reverse), then the item
  32   // will be destructed after all pending reads are complete.
  33   class STORAGE_EXPORT DataHandle : public base::RefCounted<DataHandle> {
  34    protected:
  35     virtual ~DataHandle() = 0;
  36
  37    private:
  38     friend class base::RefCounted<DataHandle>;
  39   };
  40
  41   DataElement::Type type() const { return item_->type(); }
  42   const char* bytes() const { return item_->bytes(); }
  43   const base::FilePath& path() const { return item_->path(); }
  44   const GURL& filesystem_url() const { return item_->filesystem_url(); }
  45   const std::string& blob_uuid() const { return item_->blob_uuid(); }
  46   uint64 offset() const { return item_->offset(); }
  47   uint64 length() const { return item_->length(); }
  48   const base::Time& expected_modification_time() const {
  49     return item_->expected_modification_time();
  50   }
  51   const DataElement& data_element() const { return *item_; }
  52   const DataElement* data_element_ptr() const { return item_.get(); }
  53
  54   disk_cache::Entry* disk_cache_entry() const { return disk_cache_entry_; }
  55   int disk_cache_stream_index() const { return disk_cache_stream_index_; }
  56
  57  private:
  58   friend class BlobDataBuilder;
  59   friend class BlobStorageContext;
  60   friend class base::RefCounted<BlobDataItem>;
  61
  62   BlobDataItem(scoped_ptr<DataElement> item);
  63   BlobDataItem(scoped_ptr<DataElement> item,
  64                const scoped_refptr<DataHandle>& data_handle);
  65   BlobDataItem(scoped_ptr<DataElement> item,
  66                const scoped_refptr<DataHandle>& data_handle,
  67                disk_cache::Entry* entry,
  68                int disk_cache_stream_index_);
  69   virtual ~BlobDataItem();
  70
  71   scoped_ptr<DataElement> item_;
  72   scoped_refptr<DataHandle> data_handle_;
  73
  74   // This naked pointer is safe because the scope is protected by the DataHandle
  75   // instance for disk cache entries during the lifetime of this BlobDataItem.
  76   disk_cache::Entry* disk_cache_entry_;
  77   int disk_cache_stream_index_;  // For TYPE_DISK_CACHE_ENTRY.
  78 };
  79
  80 #if defined(UNIT_TEST)
  81 inline bool operator==(const BlobDataItem& a, const BlobDataItem& b) {
  82   return a.disk_cache_entry() == b.disk_cache_entry() &&
  83          a.disk_cache_stream_index() == b.disk_cache_stream_index() &&
  84          a.data_element() == b.data_element();
  85 }
  86
  87 inline bool operator!=(const BlobDataItem& a, const BlobDataItem& b) {
  88   return !(a == b);
  89 }
  90 #endif  // defined(UNIT_TEST)
  91
  92 }  // namespace storage
  93
  94 #endif  // STORAGE_BROWSER_BLOB_BLOB_DATA_ITEM_H_