First-time sync: asymptotic running time improvement

chrome/browser/sync/engine/process_commit_response_command.cc

 // Copyright (c) 2010 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.
 
 #include "chrome/browser/sync/engine/process_commit_response_command.h"
 
 #include <set>
 #include <string>
 #include <vector>
 
@@ skipping 117 matching lines @@
   // critical error, we trap it and don't LOG(ERROR). To enable this we keep
   // a map of conflicting new folders.
   int transient_error_commits = 0;
   int conflicting_commits = 0;
   int error_commits = 0;
   int successes = 0;
   set<syncable::Id> conflicting_new_folder_ids;
   set<syncable::Id> deleted_folders;
   ConflictProgress* conflict_progress = status->mutable_conflict_progress();
   OrderedCommitSet::Projection proj = status->commit_id_projection();
-  { // Scope for WriteTransaction.
+  if (!proj.empty()) { // Scope for WriteTransaction.
     WriteTransaction trans(dir, SYNCER, __FILE__, __LINE__);
     for (size_t i = 0; i < proj.size(); i++) {
       CommitResponse::ResponseType response_type =
           ProcessSingleCommitResponse(&trans, cr.entryresponse(proj[i]),
                                       commit_message.entries(proj[i]),
                                       status->GetCommitIdAt(proj[i]),
                                       &conflicting_new_folder_ids,
                                       &deleted_folders);
       switch (response_type) {
         case CommitResponse::INVALID_MESSAGE:
@@ skipping 279 matching lines @@
 
   // The server has the final say on positioning, so apply the absolute
   // position that it returns.
   if (entry_response.has_position_in_parent()) {
     // The SERVER_ field should already have been written.
     DCHECK_EQ(entry_response.position_in_parent(),
         local_entry->Get(SERVER_POSITION_IN_PARENT));
 
     // We just committed successfully, so we assume that the position
     // value we got applies to the PARENT_ID we submitted.
-    syncable::Id new_prev = SyncerUtil::ComputePrevIdFromServerPosition(
-        local_entry->write_transaction(), local_entry,
+    syncable::Id new_prev = local_entry->ComputePrevIdFromServerPosition(
         local_entry->Get(PARENT_ID));
     if (!local_entry->PutPredecessor(new_prev))
       LOG(WARNING) << "PutPredecessor failed after successful commit";
   }
 }
 
 void ProcessCommitResponseCommand::ProcessSuccessfulCommitResponse(
     const sync_pb::SyncEntity& committed_entry,
     const CommitResponse_EntryResponse& entry_response,
     const syncable::Id& pre_commit_id, syncable::MutableEntry* local_entry,
@@ skipping 32 matching lines @@
   // been recursively deleted.
   // TODO(nick): Here, commit_message.deleted() would be more correct than
   // local_entry->Get(IS_DEL).  For example, an item could be renamed, and then
   // deleted during the commit of the rename.  Unit test & fix.
   if (local_entry->Get(IS_DIR) && local_entry->Get(IS_DEL)) {
     deleted_folders->insert(local_entry->Get(ID));
   }
 }
 
 }  // namespace browser_sync