Add edge mutation support and MutableSet interface for GraphNode adjacencies

Enable adding/removing edges between graph nodes via AdjacencySet (a
MutableSet proxy on GraphNode.pred/succ), node removal via discard(),
and property setters for bulk edge replacement. Includes comprehensive
mutation and interface tests.

Closes part of #1330 (step 2: edge mutation on GraphDef).

Made-with: Cursor

Author: Andy-Jost

cuda_core/cuda/core/_graph/_graph_def/_adjacency_set.pyx

@@ -28,6 +28,10 @@ class AdjacencySet(MutableSet):
     def __init__(self, node, bint is_fwd):
         self._core = _AdjacencySetCore(node, is_fwd)
 
+    @classmethod
+    def _from_iterable(cls, it):
+        return set(it)
+
     # --- abstract methods required by MutableSet ---
 
     def __contains__(self, x):
@@ -45,6 +49,8 @@ class AdjacencySet(MutableSet):
         if not isinstance(value, GraphNode):
             raise TypeError(
                 f"expected GraphNode, got {type(value).__name__}")
+        if value in self:
+            return
         (<_AdjacencySetCore>self._core).add_edge(<GraphNode>value)
 
     def discard(self, value):

cuda_core/cuda/core/_graph/_graph_def/_graph_def.pyx

@@ -314,7 +314,7 @@ cdef class GraphDef:
         with nogil:
             HANDLE_RETURN(cydriver.cuGraphDebugDotPrint(as_cu(self._h_graph), c_path, flags))
 
-    def nodes(self) -> tuple:
+    def nodes(self) -> set:
         """Return all nodes in the graph.
 
         Returns
@@ -335,9 +335,9 @@ cdef class GraphDef:
         with nogil:
             HANDLE_RETURN(cydriver.cuGraphGetNodes(as_cu(self._h_graph), nodes_vec.data(), &num_nodes))
 
-        return tuple(GraphNode._create(self._h_graph, nodes_vec[i]) for i in range(num_nodes))
+        return set(GraphNode._create(self._h_graph, nodes_vec[i]) for i in range(num_nodes))
 
-    def edges(self) -> tuple:
+    def edges(self) -> set:
         """Return all edges in the graph as (from_node, to_node) pairs.
 
         Returns
@@ -369,7 +369,7 @@ cdef class GraphDef:
                 HANDLE_RETURN(cydriver.cuGraphGetEdges(
                     as_cu(self._h_graph), from_nodes.data(), to_nodes.data(), &num_edges))
 
-        return tuple(
+        return set(
             (GraphNode._create(self._h_graph, from_nodes[i]),
              GraphNode._create(self._h_graph, to_nodes[i]))
             for i in range(num_edges)

cuda_core/cuda/core/_graph/_graph_def/_graph_node.pyx

@@ -123,8 +123,8 @@ cdef class GraphNode:
         """
         return as_py(self._h_node)
 
-    def remove(self):
-        """Remove this node and all its edges from the parent graph."""
+    def discard(self):
+        """Discard this node and remove all its edges from the parent graph."""
         cdef cydriver.CUgraphNode node = as_cu(self._h_node)
         with nogil:
             HANDLE_RETURN(cydriver.cuGraphDestroyNode(node))
@@ -134,11 +134,23 @@ cdef class GraphNode:
         """A mutable set-like view of this node's predecessors."""
         return AdjacencySet(self, False)
 
+    @pred.setter
+    def pred(self, value):
+        p = AdjacencySet(self, False)
+        p.clear()
+        p.update(value)
+
     @property
     def succ(self):
         """A mutable set-like view of this node's successors."""
         return AdjacencySet(self, True)
 
+    @succ.setter
+    def succ(self, value):
+        s = AdjacencySet(self, True)
+        s.clear()
+        s.update(value)
+
     def launch(self, config: LaunchConfig, kernel: Kernel, *args) -> KernelNode:
         """Add a kernel launch node depending on this node.
 

cuda_core/tests/graph/test_graphdef_lifetime.py

@@ -68,7 +68,7 @@ def test_branches_survive_parent_deletion(init_cuda, builder, expected_count):
     gc.collect()
 
     for branch in branches:
-        assert branch.nodes() == ()
+        assert branch.nodes() == set()
 
 
 @pytest.mark.parametrize("builder, expected_count", _COND_BUILDERS)
@@ -108,7 +108,7 @@ def test_reconstructed_body_survives_parent_deletion(init_cuda):
     del g, condition, all_nodes, cond_nodes, branches
     gc.collect()
 
-    assert body.nodes() == ()
+    assert body.nodes() == set()
 
 
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