Replace removed ngraph.lib.graph with local SimpleGraph

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Andrey Golovanov

.gitignore

@@ -13,6 +13,7 @@ __pycache__/
 .Python
 bin/
 env/
+venv/
 build/
 develop-eggs/
 dist/

netsim/applications/packet_network/base.py

@@ -6,7 +6,7 @@
 import logging
 from typing import Callable, Dict, List, Optional, Set, Type, Union, Generator, Any
 
-from ngraph.lib.graph import StrictMultiDiGraph
+from netsim.applications.packet_network.graph import SimpleGraph
 from schema import Schema
 
 from netsim.applications.packet_network.common import (
@@ -111,16 +111,16 @@ def __init__(self, starttime: SimTime = 0) -> None:
             starttime: The simulation start time (default 0).
         """
         super().__init__(starttime=starttime)
-        self.topology: Dict[str, StrictMultiDiGraph] = {}
+        self.topology: Dict[str, SimpleGraph] = {}
         self.state_db: Dict[NetSimObjectName, Any] = {}
 
-    def add_topology(self, name: str, graph: StrictMultiDiGraph) -> None:
+    def add_topology(self, name: str, graph: SimpleGraph) -> None:
         """
         Register a topology graph object in the context.
 
         Args:
             name: A unique name for the topology.
-            graph: The StrictMultiDiGraph object representing the topology.
+            graph: The SimpleGraph object representing the topology.
         """
         self.topology[name] = graph
 

netsim/applications/packet_network/graph.py

@@ -0,0 +1,70 @@
+"""Lightweight graph used by the packet-network simulation layer.
+
+This replaces the former dependency on ``ngraph.lib.graph.StrictMultiDiGraph``
+with a minimal, self-contained implementation that exposes only the API surface
+that NetSim actually needs.
+"""
+
+from __future__ import annotations
+
+from typing import Any, Dict, Tuple
+
+
+class SimpleGraph:
+    """A directed multi-graph that stores nodes and edges with attributes.
+
+    Nodes are identified by arbitrary hashable *node_id* values.
+    Edges are stored under integer keys that can be supplied explicitly or
+    auto-assigned.
+    """
+
+    def __init__(self) -> None:
+        self._nodes: dict = {}
+        self._edges: dict = {}
+        self._next_edge_id: int = 0
+
+    # -- node operations --------------------------------------------------- #
+
+    def add_node(self, node_id: Any, **attrs: Any) -> None:
+        """Add (or update) a node with optional keyword attributes."""
+        self._nodes[node_id] = attrs
+
+    def get_nodes(self) -> Dict[Any, Dict[str, Any]]:
+        """Return ``{node_id: {attr_name: attr_value, ...}, ...}``."""
+        return self._nodes
+
+    # -- edge operations --------------------------------------------------- #
+
+    def add_edge(
+        self, src: Any, dst: Any, key: Any = None, **attrs: Any
+    ) -> Any:
+        """Add an edge from *src* to *dst*.
+
+        Parameters
+        ----------
+        src, dst:
+            Source and destination node ids.
+        key:
+            Optional edge key.  When *None* the next available integer id is
+            used automatically.
+        **attrs:
+            Arbitrary edge attributes.
+
+        Returns
+        -------
+        The key under which the edge was stored.
+        """
+        if key is None:
+            key = self._next_edge_id
+            self._next_edge_id += 1
+        else:
+            # Keep the auto-id ahead of any explicitly supplied integer keys
+            # so that future auto-assigned keys never collide.
+            if isinstance(key, int) and key >= self._next_edge_id:
+                self._next_edge_id = key + 1
+        self._edges[key] = (src, dst, key, attrs)
+        return key
+
+    def get_edges(self) -> Dict[Any, Tuple[Any, Any, Any, Dict[str, Any]]]:
+        """Return ``{edge_id: (src, dst, edge_id, {attrs}), ...}``."""
+        return self._edges

netsim/applications/packet_network/simulator.py

@@ -4,7 +4,7 @@
 from copy import deepcopy
 from typing import Any, Dict, Iterator, Optional, Type, Union
 
-from ngraph.lib.graph import StrictMultiDiGraph
+from netsim.applications.packet_network.graph import SimpleGraph
 
 from netsim.common import SimTime, TimeInterval
 from netsim.core import (
@@ -147,7 +147,7 @@ def enable_packet_trace(self) -> None:
             if getattr(ns_obj.stat, "enable_packet_trace", None):
                 ns_obj.stat.enable_packet_trace(prefix=ns_obj.name)
 
-    def _parse_graph_nodes(self, graph: StrictMultiDiGraph) -> None:
+    def _parse_graph_nodes(self, graph: SimpleGraph) -> None:
         """
         Parse the nodes of the input graph, creating NetSimObjects accordingly.
         """
@@ -165,7 +165,7 @@ def _parse_graph_nodes(self, graph: StrictMultiDiGraph) -> None:
 
             self._ns[node] = ns_node_obj
 
-    def _parse_graph_edges(self, graph: StrictMultiDiGraph) -> None:
+    def _parse_graph_edges(self, graph: SimpleGraph) -> None:
         """
         Parse edges of the input graph, hooking up subscriptions or creating interfaces for PacketSwitch objects.
         """
@@ -196,7 +196,7 @@ def _postprocess_ns_obj(self) -> None:
             if isinstance(ns_node_obj, PacketSwitch):
                 ns_node_obj.create_packet_processor()
 
-    def load_graph(self, graph: StrictMultiDiGraph) -> None:
+    def load_graph(self, graph: SimpleGraph) -> None:
         """
         Load a topology graph into the simulation, creating NetSimObjects and hooking them up.
         """

tests/applications/packet_network/test_netsim_sim.py

@@ -3,7 +3,7 @@
 import math
 from typing import Dict
 
-from ngraph.lib.graph import StrictMultiDiGraph
+from netsim.applications.packet_network.graph import SimpleGraph
 
 from netsim.applications.packet_network.simulator import NetSim
 from netsim.applications.packet_network.base import (
@@ -37,7 +37,7 @@ def _src_profile(size: int = 1000, interval: float = 1.0, count: int = 10) -> Di
 # --------------------------------------------------------------------------- #
 def test_load_graph_creates_objects() -> None:
     sim = NetSim()
-    g = StrictMultiDiGraph()
+    g = SimpleGraph()
     g.add_node("S", ns_type="PacketSource", ns_attr=_src_profile())
     g.add_node("D", ns_type="PacketSink", ns_attr={})
     g.add_edge("S", "D", key=1, ns_attr={})
@@ -58,7 +58,7 @@ def test_load_graph_creates_objects() -> None:
 # --------------------------------------------------------------------------- #
 def test_run_until_time_collects_stats() -> None:
     sim = NetSim(stat_interval=1.0)  # 1 s snapshots
-    g = StrictMultiDiGraph()
+    g = SimpleGraph()
     g.add_node("S", ns_type="PacketSource", ns_attr=_src_profile(count=6))
     g.add_node("D", ns_type="PacketSink", ns_attr={})
     g.add_edge("S", "D", key=1, ns_attr={})
@@ -82,7 +82,7 @@ def test_run_until_time_collects_stats() -> None:
 # --------------------------------------------------------------------------- #
 def test_switch_interfaces_and_forwarding() -> None:
     sim = NetSim()
-    g = StrictMultiDiGraph()
+    g = SimpleGraph()
 
     g.add_node("SRC", ns_type="PacketSource", ns_attr=_src_profile(count=5))
     g.add_node("SW", ns_type="PacketSwitch", ns_attr={})
@@ -131,7 +131,7 @@ def _safe_todict(self):  # type: ignore[override]
     monkeypatch.setattr(_Packet, "todict", _safe_todict, raising=True)
 
     sim = NetSim()
-    g = StrictMultiDiGraph()
+    g = SimpleGraph()
     g.add_node("S", ns_type="PacketSource", ns_attr=_src_profile(count=2))
     g.add_node("D", ns_type="PacketSink", ns_attr={})
     g.add_edge("S", "D", key=1, ns_attr={})