sync: Loop committing items without downloading updates (v2)

sync/engine/build_commit_command.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.
 
 #ifndef SYNC_ENGINE_BUILD_COMMIT_COMMAND_H_
 #define SYNC_ENGINE_BUILD_COMMIT_COMMAND_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "sync/engine/syncer_command.h"
 #include "sync/engine/syncproto.h"
 #include "sync/syncable/syncable.h"
 
 namespace browser_sync {
 
+namespace sessions {
+class OrderedCommitSet;
+}
+
+// A class that contains the code used to serialize a set of sync items into a
+// protobuf commit message.  This conversion process references the
+// syncable::Directory, which is why it must be called within the same
+// transaction as the GetCommitIdsCommand that fetched the set of items to be
+// committed.
+//
+// See SyncerCommand documentation for more info.
 class BuildCommitCommand : public SyncerCommand {
  public:
-  BuildCommitCommand();
+  // The batch_commit_set parameter contains a set of references to the items
+  // that should be committed.
+  //
+  // The commit_message parameter is an output parameter which will contain the
+  // fully initialized commit message once ExecuteImpl() has been called.
+  BuildCommitCommand(const sessions::OrderedCommitSet& batch_commit_set,
+                     ClientToServerMessage* commit_message);
   virtual ~BuildCommitCommand();
 
   // SyncerCommand implementation.
   virtual SyncerError ExecuteImpl(sessions::SyncSession* session) OVERRIDE;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(BuildCommitCommandTest, InterpolatePosition);
 
   // Functions returning constants controlling range of values.
   static int64 GetFirstPosition();
   static int64 GetLastPosition();
   static int64 GetGap();
 
   void AddExtensionsActivityToMessage(sessions::SyncSession* session,
                                       CommitMessage* message);
   // Helper for computing position.  Find the numeric position value
   // of the closest already-synced entry.  |direction| must be one of
   // NEXT_ID or PREV_ID; this parameter controls the search direction.
   // For an open range (no predecessor or successor), the return
   // value will be kFirstPosition or kLastPosition.
   int64 FindAnchorPosition(syncable::IdField direction,
                            const syncable::Entry& entry);
   // Given two values of the type returned by FindAnchorPosition,
   // compute a third value in between the two ranges.
   int64 InterpolatePosition(int64 lo, int64 hi);
 
   DISALLOW_COPY_AND_ASSIGN(BuildCommitCommand);
+
+  // Input parameter; see constructor comment.
+  const sessions::OrderedCommitSet& batch_commit_set_;
+
+  // Output parameter; see constructor comment.
+  ClientToServerMessage* commit_message_;
 };
 
 }  // namespace browser_sync
 
 #endif  // SYNC_ENGINE_BUILD_COMMIT_COMMAND_H_