sync/api/attachments/attachment.h

   1 // Copyright 2014 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 SYNC_API_ATTACHMENTS_ATTACHMENT_H_
   6 #define SYNC_API_ATTACHMENTS_ATTACHMENT_H_
   7
   8 #include <map>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "base/memory/ref_counted_memory.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "sync/api/attachments/attachment_id.h"
  16 #include "sync/base/sync_export.h"
  17
  18 namespace syncer {
  19
  20 // A blob of in-memory data attached to a sync item.
  21 //
  22 // While Attachment objects themselves aren't immutable (they are assignable)
  23 // the data they wrap is immutable.
  24 //
  25 // It is cheap to copy Attachments. Feel free to store and return by value.
  26 class SYNC_EXPORT Attachment {
  27  public:
  28   ~Attachment();
  29
  30   // Default copy and assignment are welcome.
  31
  32   // Creates an attachment with a unique id and the supplied data.
  33   //
  34   // Used when creating a brand new attachment.
  35   static Attachment Create(const scoped_refptr<base::RefCountedMemory>& data);
  36
  37   // Creates an attachment with the supplied id, data and crc32c.
  38   //
  39   // Used when you want to recreate a specific attachment. E.g. creating a local
  40   // copy of an attachment that already exists on the sync server.
  41   static Attachment CreateFromParts(
  42       const AttachmentId& id,
  43       const scoped_refptr<base::RefCountedMemory>& data,
  44       uint32_t crc32c);
  45
  46   // Returns this attachment's id.
  47   const AttachmentId& GetId() const;
  48
  49   // Returns this attachment's data.
  50   const scoped_refptr<base::RefCountedMemory>& GetData() const;
  51
  52   // Returns precomputed crc32c hash of data. In ideal case this hash is
  53   // computed when attachment is first created. It is then passed around through
  54   // local attachment store and attachment server. Crc is verified when
  55   // attachment is downloaded from server or loaded from local storage.
  56   uint32_t GetCrc32c() const;
  57
  58  private:
  59   AttachmentId id_;
  60   scoped_refptr<base::RefCountedMemory> data_;
  61   uint32_t crc32c_;
  62
  63   Attachment(const AttachmentId& id,
  64              const scoped_refptr<base::RefCountedMemory>& data,
  65              uint32_t crc32c);
  66 };
  67
  68 typedef std::vector<syncer::Attachment> AttachmentList;
  69 typedef std::map<AttachmentId, Attachment> AttachmentMap;
  70
  71 }  // namespace syncer
  72
  73 #endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_H_