Struct DagTopology 

pub struct DagTopology {
    pub views: Vec<ViewDescriptor>,
    pub edges: Vec<DagEdge>,
    pub topo_order: Vec<ViewId>,
}

The static topology of the IVM DAG.

Built once when the view pipeline is constructed. The topological order is pre-computed and cached for efficient per-epoch propagation.

Invariants

1. The DAG is acyclic (enforced on edge insertion).
2. Topological order includes all views.
3. For every edge (A, B), A appears before B in the topological order.
4. Adding or removing views invalidates the cached topological order.

Fields

views: Vec<ViewDescriptor>

All views in the DAG, indexed by ViewId.

edges: Vec<DagEdge>

All edges in the DAG.

topo_order: Vec<ViewId>

Pre-computed topological order (view indices).

Implementations

impl DagTopology

pub fn new() -> Self

Create an empty DAG.

pub fn add_view( &mut self, label: impl Into<String>, domain: ViewDomain, ) -> ViewId

Add a view to the DAG. Returns its ViewId.

pub fn add_edge(&mut self, from: ViewId, to: ViewId)

Add an edge: from produces deltas consumed by to.

Panics

Panics if this would create a cycle in the DAG.

pub fn compute_topo_order(&mut self)

Compute the topological order via Kahn’s algorithm.

Must be called after all views and edges are added. The result is cached in self.topo_order for efficient per-epoch propagation.

Panics

Panics if the DAG contains a cycle (should be impossible due to add_edge validation, but checked defensively).

pub fn downstream(&self, view_id: ViewId) -> Vec<ViewId>

Get the downstream views that consume deltas from view_id.

pub fn upstream(&self, view_id: ViewId) -> Vec<ViewId>

Get the upstream views that produce deltas for view_id.

pub fn view_count(&self) -> usize

Number of views in the DAG.

pub fn edge_count(&self) -> usize

Number of edges in the DAG.

Trait Implementations

impl Clone for DagTopology

fn clone(&self) -> DagTopology

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DagTopology

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DagTopology

fn default() -> Self

Returns the “default value” for a type.