Function classify_dispatch

nodedb/src/control/planner/calvin/dispatch.rs:144–169

Classify the dispatch class of a task slice by collecting the unique set of write vShards. 0 or 1 unique write vShards → `SingleShard`. 2+ unique write vShards → `MultiShard` with the full `BTreeSet `.

(tasks: &[PhysicalTask])

/// 0 or 1 unique write vShards → `SingleShard`.
/// 2+ unique write vShards → `MultiShard` with the full `BTreeSet<u32>`.
pub fn classify_dispatch(tasks: &[PhysicalTask]) -> DispatchClass {
    let mut vshards: BTreeSet<u32> = BTreeSet::new();
    let mut last_vshard = None;

    for task in tasks {
        if is_write_plan(&task.plan) {
            let id = task.vshard_id.as_u32();
            vshards.insert(id);
            last_vshard = Some(task.vshard_id);
        }
    }

    match vshards.len() {
        0 => DispatchClass::SingleShard {
            vshard: tasks
                .first()
                .map(|t| t.vshard_id)
                .unwrap_or(VShardId::new(0)),
        },
        1 => DispatchClass::SingleShard {
            vshard: last_vshard
                .expect("invariant: vshards.len() == 1 means last_vshard was set during the loop"),
        },
        _ => DispatchClass::MultiShard { vshards },
    }
}

// ── build_static_tx_class ────────────────────────────────────────────────────