presto-main/src/main/java/io/prestosql/execution/SqlTaskExecution.java/SqlTaskExecution/addLifespanIfAbsent
class SqlTaskExecution:        public void addLifespanIfAbsent(Lifespan lifespan)
        {
            if (completedLifespans.contains(lifespan) || lifespans.containsKey(lifespan)) {
                return;
            }
            checkState(!status.isNoMoreLifespans());
            checkState(!sourceStartOrder.isEmpty());
            lifespans.put(lifespan, new SchedulingLifespan(lifespan, this));
        }