presto-main/src/main/java/io/prestosql/execution/SqlTaskExecution.java/SqlTaskExecution/getNoMoreSplits
class SqlTaskExecution:    public synchronized Set<PlanNodeId> getNoMoreSplits()
    {
        ImmutableSet.Builder<PlanNodeId> noMoreSplits = ImmutableSet.builder();
        for (Entry<PlanNodeId, DriverSplitRunnerFactory> entry : driverRunnerFactoriesWithSplitLifeCycle.entrySet()) {
            if (entry.getValue().isNoMoreDriverRunner()) {
                noMoreSplits.add(entry.getKey());
            }
        }
        for (TaskSource taskSource : unpartitionedSources.values()) {
            if (taskSource.isNoMoreSplits()) {
                noMoreSplits.add(taskSource.getPlanNodeId());
            }
        }
        return noMoreSplits.build();
    }