fn drain_pending_barriers(
pending_barriers: &mut VecDeque<BarrierInfo>,
new_upstream_barrier: BarrierInfo,
barrier_num_to_inject: usize,
) -> Vec<BarrierInfo>fn drain_pending_barriers(
pending_barriers: &mut VecDeque<BarrierInfo>,
new_upstream_barrier: BarrierInfo,
barrier_num_to_inject: usize,
) -> Vec<BarrierInfo>