presto-main/src/main/java/io/prestosql/operator/WorkProcessorUtils.java/WorkProcessorUtils/process
class WorkProcessorUtils:        @Override
        public ProcessState<T> process()
        {
            if (!lastProcessYielded && yieldSignal.getAsBoolean()) {
                lastProcessYielded = true;
                return ProcessState.yield();
            }
            lastProcessYielded = false;

            return getNextState(processor);
        }