sync/internal_api/public/base/invalidation_interface.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_INTERNAL_API_PUBLIC_BASE_INVALIDATION_INTERFACE_H_
   6 #define SYNC_INTERNAL_API_PUBLIC_BASE_INVALIDATION_INTERFACE_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11 #include "sync/base/sync_export.h"
  12
  13 namespace syncer {
  14
  15 // An interface that wraps sync's interactions with the component that provides
  16 // it with invalidations.
  17 class SYNC_EXPORT InvalidationInterface {
  18  public:
  19   // Orders invalidations based on version number and IsUnknownVersion().
  20   static bool LessThanByVersion(const InvalidationInterface& a,
  21                                 const InvalidationInterface& b);
  22
  23   InvalidationInterface();
  24   virtual ~InvalidationInterface();
  25
  26   // Returns true if this is an 'unknown version' invalidation.
  27   // Such invalidations have no valid payload or version number.
  28   virtual bool IsUnknownVersion() const = 0;
  29
  30   // Returns the payload of this item.
  31   // DCHECKs if this is an unknown version invalidation.
  32   virtual const std::string& GetPayload() const = 0;
  33
  34   // Retursn the version of this item.
  35   // DCHECKs if this is an unknown version invalidation.
  36   //
  37   // It is preferable to use the LessThan() function, which handles unknown
  38   // versions properly, rather than this function.
  39   virtual int64 GetVersion() const = 0;
  40
  41   // This function will be called when the invalidation has been handled
  42   // successfully.
  43   virtual void Acknowledge() = 0;
  44
  45   // This function should be called if a lack of buffer space required that we
  46   // drop this invalidation.
  47   //
  48   // To indicate recovery from a drop event, the receiver of this invalidation
  49   // will call Acknowledge() on the most recently dropped invalidation.
  50   virtual void Drop() = 0;
  51 };
  52
  53 }  // namespace syncer
  54
  55 #endif