Fix virtRoot race condition in nativeMode server nodes

When the initiating node (Alice/Bob) finishes setup and immediately
calls a remote method on a peer, that peer may not have finished
connecting to its virtual node yet, leaving virtRoot as None.

Add a deferLater polling loop (matching the pattern already used in
extendGHZ/bobTest.py) to each remote handler that uses virtRoot,
so it waits until setup_local has set the connection before proceeding.

Affected: corrRNG/bobTest, teleport/bobTest, extendGHZ/charlieTest,
graphState/bobTest, graphState/charlieTest, graphState/davidTest.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Stephanie Wehner

examples/nativeMode/corrRNG/bobTest.py

@@ -33,7 +33,9 @@
 from simulaqron.local.setup import setup_local
 from simulaqron.general.host_config import SocketsConfig
 from simulaqron.settings import network_config
+from twisted.internet import reactor
 from twisted.internet.defer import inlineCallbacks
+from twisted.internet.task import deferLater
 from twisted.spread import pb
 
 from qutip import Qobj
@@ -98,6 +100,11 @@ def remote_process_qubit(self, virtualNum):
         virtualNum    number of the virtual qubit corresponding to the EPR pair received
         """
 
+        # Wait until our virtual node connection is ready — Alice may call us
+        # before setup_local has finished connecting to the virtual node.
+        while self.virtRoot is None:
+            yield deferLater(reactor, 0.05, lambda: None)
+
         qB = yield self.virtRoot.callRemote("get_virtual_ref", virtualNum)
 
         # Measure

examples/nativeMode/extendGHZ/charlieTest.py

@@ -32,7 +32,9 @@
 from simulaqron.local.setup import setup_local
 from simulaqron.general.host_config import SocketsConfig
 from simulaqron.settings import network_config
+from twisted.internet import reactor
 from twisted.internet.defer import inlineCallbacks
+from twisted.internet.task import deferLater
 from twisted.spread import pb
 
 
@@ -97,6 +99,11 @@ def remote_receive_ghz(self, virtualNum):
 
         logging.debug("LOCAL %s: Getting reference to qubit number %d.", self.node.name, virtualNum)
 
+        # Wait until our virtual node connection is ready — Bob may call us
+        # before setup_local has finished connecting to the virtual node.
+        while self.virtRoot is None:
+            yield deferLater(reactor, 0.05, lambda: None)
+
         q = yield self.virtRoot.callRemote("get_virtual_ref", virtualNum)
 
         # Measure it

examples/nativeMode/graphState/bobTest.py

@@ -33,7 +33,9 @@
 from simulaqron.local.setup import setup_local
 from simulaqron.general.host_config import SocketsConfig
 from simulaqron.settings import network_config
+from twisted.internet import reactor
 from twisted.internet.defer import inlineCallbacks
+from twisted.internet.task import deferLater
 from twisted.spread import pb
 
 
@@ -94,6 +96,11 @@ def remote_receive_qubit(self, virtualNum):
 
         logging.debug("LOCAL %s: Getting reference to qubit number %d.", self.node.name, virtualNum)
 
+        # Wait until our virtual node connection is ready — Alice may call us
+        # before setup_local has finished connecting to the virtual node.
+        while self.virtRoot is None:
+            yield deferLater(reactor, 0.05, lambda: None)
+
         # Get ref of qubit
         qB = yield self.virtRoot.callRemote("get_virtual_ref", virtualNum)
 

examples/nativeMode/graphState/charlieTest.py

@@ -33,7 +33,9 @@
 from simulaqron.local.setup import setup_local
 from simulaqron.general.host_config import SocketsConfig
 from simulaqron.settings import network_config
+from twisted.internet import reactor
 from twisted.internet.defer import inlineCallbacks
+from twisted.internet.task import deferLater
 from twisted.spread import pb
 
 
@@ -97,6 +99,11 @@ def remote_receive_qubit(self, virtualNum, sender):
 
             logging.debug("LOCAL %s: Getting reference to qubit number %d.", self.node.name, virtualNum)
 
+            # Wait until our virtual node connection is ready — Bob may call us
+            # before setup_local has finished connecting to the virtual node.
+            while self.virtRoot is None:
+                yield deferLater(reactor, 0.05, lambda: None)
+
             # Get ref of qubit
             self.qC = yield self.virtRoot.callRemote("get_virtual_ref", virtualNum)
             qC = self.qC

examples/nativeMode/graphState/davidTest.py

@@ -33,7 +33,9 @@
 from simulaqron.local.setup import setup_local
 from simulaqron.general.host_config import SocketsConfig
 from simulaqron.settings import network_config
+from twisted.internet import reactor
 from twisted.internet.defer import inlineCallbacks
+from twisted.internet.task import deferLater
 from twisted.spread import pb
 
 
@@ -94,6 +96,11 @@ def remote_receive_qubit(self, virtualNum):
 
         logging.debug("LOCAL %s: Getting reference to qubit number %d.", self.node.name, virtualNum)
 
+        # Wait until our virtual node connection is ready — Charlie may call us
+        # before setup_local has finished connecting to the virtual node.
+        while self.virtRoot is None:
+            yield deferLater(reactor, 0.05, lambda: None)
+
         # Get ref of qubit
         qD = yield self.virtRoot.callRemote("get_virtual_ref", virtualNum)
 

examples/nativeMode/teleport/bobTest.py

@@ -36,7 +36,9 @@
 from simulaqron.general.host_config import SocketsConfig
 from simulaqron.settings import simulaqron_settings, network_config, LOCAL_SIMULAQRON_SETTINGS, LOCAL_NETWORK_SETTINGS
 from simulaqron.toolbox.stabilizer_states import StabilizerState
+from twisted.internet import reactor
 from twisted.internet.defer import inlineCallbacks
+from twisted.internet.task import deferLater
 from twisted.spread import pb
 
 
@@ -102,6 +104,11 @@ def remote_recover_teleport(self, a, b, virtualNum):
 
         logging.debug("LOCAL %s: Getting reference to qubit number %d.", self.node.name, virtualNum)
 
+        # Wait until our virtual node connection is ready — Alice may call us
+        # before setup_local has finished connecting to the virtual node.
+        while self.virtRoot is None:
+            yield deferLater(reactor, 0.05, lambda: None)
+
         eprB = yield self.virtRoot.callRemote("get_virtual_ref", virtualNum)
 
         # Apply the desired correction info