sync/api/attachments/attachment_store.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_STORE_H_
   6 #define SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_
   7
   8 #include "base/callback.h"
   9 #include "base/memory/ref_counted.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "sync/api/attachments/attachment.h"
  12 #include "sync/api/attachments/attachment_id.h"
  13 #include "sync/base/sync_export.h"
  14
  15 namespace base {
  16 class RefCountedMemory;
  17 }  // namespace base
  18
  19 namespace syncer {
  20
  21 class Attachment;
  22 class AttachmentId;
  23
  24 // A place to locally store and access Attachments.
  25 //
  26 // Destroying this object does not necessarily cancel outstanding async
  27 // operations. If you need cancel like semantics, use WeakPtr in the callbacks.
  28 class SYNC_EXPORT AttachmentStore {
  29  public:
  30   AttachmentStore();
  31   virtual ~AttachmentStore();
  32
  33   // TODO(maniscalco): Consider udpating Read and Write methods to support
  34   // resumable transfers (bug 353292).
  35
  36   enum Result {
  37     SUCCESS,            // No error, all completed successfully.
  38     UNSPECIFIED_ERROR,  // An unspecified error occurred for one or more items.
  39   };
  40
  41   typedef base::Callback<void(const Result&,
  42                               scoped_ptr<AttachmentMap>,
  43                               scoped_ptr<AttachmentIdList>)> ReadCallback;
  44   typedef base::Callback<void(const Result&)> WriteCallback;
  45   typedef base::Callback<void(const Result&)> DropCallback;
  46
  47   // Asynchronously reads the attachments identified by |ids|.
  48   //
  49   // |callback| will be invoked when finished. AttachmentStore will attempt to
  50   // read all attachments specified in ids. If any of the attachments do not
  51   // exist or could not be read, |callback|'s Result will be UNSPECIFIED_ERROR.
  52   // Callback's AttachmentMap will contain all attachments that were
  53   // successfully read, AttachmentIdList will contain attachment ids of
  54   // attachments that are unavailable in attachment store, these need to be
  55   // downloaded from server.
  56   //
  57   // Reads on individual attachments are treated atomically; |callback| will not
  58   // read only part of an attachment.
  59   virtual void Read(const AttachmentIdList& ids,
  60                     const ReadCallback& callback) = 0;
  61
  62   // Asynchronously writes |attachments| to the store.
  63   //
  64   // Will not overwrite stored attachments. Attempting to overwrite an
  65   // attachment that already exists is not an error.
  66   //
  67   // |callback| will be invoked when finished. If any of the attachments could
  68   // not be written |callback|'s Result will be UNSPECIFIED_ERROR. When this
  69   // happens, some or none of the attachments may have been written
  70   // successfully.
  71   virtual void Write(const AttachmentList& attachments,
  72                      const WriteCallback& callback) = 0;
  73
  74   // Asynchronously drops |attchments| from this store.
  75   //
  76   // This does not remove attachments from the server.
  77   //
  78   // |callback| will be invoked when finished. Attempting to drop an attachment
  79   // that does not exist is not an error. If any of the existing attachment
  80   // could not be dropped, |callback|'s Result will be UNSPECIFIED_ERROR. When
  81   // this happens, some or none of the attachments may have been dropped
  82   // successfully.
  83   virtual void Drop(const AttachmentIdList& ids,
  84                     const DropCallback& callback) = 0;
  85 };
  86
  87 }  // namespace syncer
  88
  89 #endif  // SYNC_API_ATTACHMENTS_ATTACHMENT_STORE_H_