public Result search(Query query) {
        timer.sampleSearch(nextIndex(), context.getDetailedDiagnostics());

        // Transfer state between query and execution as the execution constructors does not do that completely
        query.getModel().setExecution(this);
        trace().setTraceLevel(query.getTrace().getLevel());

        return (Result)super.process(query);
    }
Calls search on the next searcher in this chain. If there is no next, an empty result is returned.
container-search/src/main/java/com/yahoo/search/searchchain/Execution.java