protected ShardSkywalkerResponse shardOperation(ShardSkywalkerRequest request) throws ElasticsearchException {
synchronized (mutex) {
IndexService indexService = indicesService.indexServiceSafe(request.index());
InternalIndexShard indexShard = (InternalIndexShard) indexService.shardSafe(request.shardId());
MapperService mapperService = indexService.mapperService();
Engine.Searcher searcher = indexShard.acquireSearcher("skywalker_action");
try {
IndexReader reader = searcher.reader();
Skywalker skywalker = new Skywalker(reader);