Type Alias EmitCounter 

pub type EmitCounter = Rc<Cell<u64>>;

A shared per-source counter of rows a source emitted into the pipeline. One cell per wrapped source node (so the count is already keyed per NodeId); a child-driven join that re-fetches the same leaf under many constraints accumulates across those fetches into the same cell. Rc<Cell<..>> (not atomic) — a Graph is !Send, single-threaded by construction.

Aliased Type

pub struct EmitCounter { /* private fields */ }