Implement features needed for local ack handling in InvalidationStateTracker.

sync/notifier/invalidation_state_tracker.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
-// An InvalidationVersionTracker is an interface that handles getting
-// and setting (persisting) max invalidation versions.
+// An InvalidationStateTracker is an interface that handles persisting state
+// needed for invalidations. Currently, it is responsible for managing the
+// following information:
+// - Max version seen from the invalidation server to help dedupe invalidations.
+// - Bootstrap data for the invalidation client.
+// - Payloads and locally generated ack handles, to support local acking.
 
 #ifndef SYNC_NOTIFIER_INVALIDATION_STATE_TRACKER_H_
 #define SYNC_NOTIFIER_INVALIDATION_STATE_TRACKER_H_
 
 #include <map>
+#include <string>
 
 #include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/memory/ref_counted.h"
 #include "google/cacheinvalidation/include/types.h"
+#include "sync/internal_api/public/base/invalidation.h"
 #include "sync/notifier/invalidation_util.h"
 
+namespace base {
+class TaskRunner;
+}  // namespace base
+
 namespace syncer {
 
 struct InvalidationState {
+  InvalidationState();
+  ~InvalidationState();
+
   int64 version;
+  std::string payload;
+  AckHandle expected;
+  AckHandle current;
 };
 
 // TODO(dcheng): Remove this in favor of adding an Equals() method.
 bool operator==(const InvalidationState& lhs, const InvalidationState& rhs);
 
 typedef std::map<invalidation::ObjectId, InvalidationState, ObjectIdLessThan>
     InvalidationStateMap;
+typedef std::map<invalidation::ObjectId, AckHandle, ObjectIdLessThan>
+    AckHandleMap;
 
 class InvalidationStateTracker {
  public:
   InvalidationStateTracker() {}
 
   virtual InvalidationStateMap GetAllInvalidationStates() const = 0;
 
   // |max_version| should be strictly greater than any existing max
   // version for |model_type|.
-  virtual void SetMaxVersion(const invalidation::ObjectId& id,
-                             int64 max_version) = 0;
+  virtual void SetMaxVersionAndPayload(const invalidation::ObjectId& id,
+                                       int64 max_version,
+                                       const std::string& payload) = 0;
   // Removes all state tracked for |ids|.
   virtual void Forget(const ObjectIdSet& ids) = 0;
 
   // Used by invalidation::InvalidationClient for persistence. |data| is an
   // opaque blob that an invalidation client can use after a restart to
   // bootstrap itself. |data| is binary data (not valid UTF8, embedded nulls,
   // etc).
   virtual void SetBootstrapData(const std::string& data) = 0;
   virtual std::string GetBootstrapData() const = 0;
 
+  // Used for generating our own local ack handles. Generates a new ack handle
+  // for each object id in |ids|. The result is returned via |callback| posted
+  // to |task_runner|.
+  virtual void GenerateAckHandles(
+      const ObjectIdSet& ids,
+      const scoped_refptr<base::TaskRunner>& task_runner,
+      base::Callback<void(const AckHandleMap&)> callback) = 0;
+
+  // Records an acknowledgement for |id|. Note that no attempt at ordering is
+  // made. Acknowledge() only records the last ack_handle it received, even if
+  // the last ack_handle it received was generated before the value currently
+  // recorded.
+  virtual void Acknowledge(const invalidation::ObjectId& id,
+                           const AckHandle& ack_handle) = 0;
+
  protected:
   virtual ~InvalidationStateTracker() {}
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_NOTIFIER_INVALIDATION_STATE_TRACKER_H_