disposeNode method

Future<void> disposeNode(AsyncGraphNode node)

Tear down node, dispatching on its own kind.

Idempotent: disposing an already-disposed node is a no-op, so teardown paths compose. Effects additionally await their pending cleanup, which is why this returns a Future; for a slot or a cell the returned future is already complete.

Without this a node is permanent. The graph holds a strong reverse edge to every dependent, so dropping the last user-held reference reclaims nothing and a long-lived source retains every node that ever read it.

Implementation

Future<void> disposeNode(AsyncGraphNode node) async {
  switch (node) {
    case _AsyncEffectHandle():
      await node.disposeAsync();
    case AsyncEffectHandle():
      await node.disposeAsync();
    case AsyncSlotHandle():
      if (node._nodeDisposed) return;
      node._nodeDisposed = true;
      _detachAndDirty(node, node._dependencies);
      node._failInFlight(const _Superseded());
    case AsyncCellHandle():
      if (node._nodeDisposed) return;
      node._nodeDisposed = true;
      // A cell is a pure source: no upstream set to detach.
      _detachAndDirty(node, <Object>{});
  }
}