sync/api/sync_change_processor.h

   1 // Copyright 2012 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_SYNC_CHANGE_PROCESSOR_H_
   6 #define SYNC_API_SYNC_CHANGE_PROCESSOR_H_
   7
   8 #include <vector>
   9
  10 #include "sync/api/sync_data.h"
  11 #include "sync/api/sync_error.h"
  12 #include "sync/base/sync_export.h"
  13 #include "sync/internal_api/public/base/model_type.h"
  14
  15 namespace tracked_objects {
  16 class Location;
  17 }  // namespace tracked_objects
  18
  19 namespace syncer {
  20
  21 class SyncChange;
  22
  23 typedef std::vector<SyncChange> SyncChangeList;
  24
  25 // An interface for services that handle receiving SyncChanges.
  26 class SYNC_EXPORT SyncChangeProcessor {
  27  public:
  28   // Whether a context change should force a datatype refresh or not.
  29   enum ContextRefreshStatus { NO_REFRESH, REFRESH_NEEDED };
  30   typedef base::Callback<void(const SyncData&)> GetSyncDataCallback;
  31
  32   SyncChangeProcessor();
  33   virtual ~SyncChangeProcessor();
  34
  35   // Process a list of SyncChanges.
  36   // Returns: A default SyncError (IsSet() == false) if no errors were
  37   //          encountered, and a filled SyncError (IsSet() == true)
  38   //          otherwise.
  39   // Inputs:
  40   //   |from_here|: allows tracking of where sync changes originate.
  41   //   |change_list|: is the list of sync changes in need of processing.
  42   virtual SyncError ProcessSyncChanges(
  43       const tracked_objects::Location& from_here,
  44       const SyncChangeList& change_list) = 0;
  45
  46   // Fills a list of SyncData. This should create an up to date representation
  47   // of all the data known to the ChangeProcessor for |datatype|, and
  48   // should match/be a subset of the server's view of that datatype.
  49   //
  50   // WARNING: This can be a potentially slow & memory intensive operation and
  51   // should only be used when absolutely necessary / sparingly.
  52   virtual SyncDataList GetAllSyncData(ModelType type) const = 0;
  53
  54   // Retrieves the SyncData identified by |type| and |sync_tag| and invokes
  55   // |callback| asynchronously. If no such SyncData exists locally, IsValid on
  56   // the SyncData passed to |callback| will return false.
  57   //
  58   // This is an asynchronous local operation that may result in disk IO.
  59   //
  60   // Refer to sync_data.h for a description of |sync_tag|.
  61   //
  62   // TODO:(maniscalco): N.B. this method should really be pure virtual. An
  63   // implentation is provided here just to verify that everything compiles.
  64   // Update this method to be pure virtual (bug 353300).
  65   virtual void GetSyncData(const ModelType& type,
  66                            const std::string& sync_tag,
  67                            const GetSyncDataCallback& callback) const {}
  68
  69   // Updates the context for |type|, triggering an optional context refresh.
  70   // Default implementation does nothing. A type's context is a per-client blob
  71   // that can affect all SyncData sent to/from the server, much like a cookie.
  72   // TODO(zea): consider pulling the refresh logic into a separate method
  73   // unrelated to datatype implementations.
  74   virtual syncer::SyncError UpdateDataTypeContext(
  75       ModelType type,
  76       ContextRefreshStatus refresh_status,
  77       const std::string& context);
  78 };
  79
  80 }  // namespace syncer
  81
  82 #endif  // SYNC_API_SYNC_CHANGE_PROCESSOR_H_