Fixing bug in interferences

esds/simulator.py

@@ -268,11 +268,21 @@ class Simulator:
             if event_type==0 and com[2] == interface:
                 com_sender=int(com[0])
                 com_receiver=int(com[1])
-                # All cases where interferences occurs:
-                receiver_is_sending=(receiver==com_sender and sender!=receiver) # We check also if we are not dealing with the special communication where sender==receiver
-                receiver_is_receiving=(receiver==com_receiver and sender!=com_sender) # We check also if its not our own communication
-                sender_is_receiving=(sender==com_receiver and com_sender!=com_sender) # We check also if its not our own communication
-                # Apply rules:
+                #### All CASES WHERE INTERFERENCES OCCUR
+                # receiver_is_sending
+                # 1) check if current com receiver already sending
+                # 2) if yes, we check if current com is one that should be marked as interterference (current com is actually involving the receiver) see interferences_bug1 test
+                # 3) ensure not dealing with the special com (where sender is the receiver)
+                receiver_is_sending=(receiver==com_sender and com_receiver==receiver and sender!=receiver)
+                # receiver_is_receiving
+                # 1) check if the current com receiver is already receiving (thus interference)
+                # 2) ensure not dealing with the special com (where sender is the receiver)
+                receiver_is_receiving=(com_receiver==receiver and sender!=com_sender)
+                # sender_is_receiving
+                # 1) check if current com receiver is the one who started sending
+                # 2) ensure not dealing with the special com (where sender is the receiver)
+                sender_is_receiving=(com_receiver==sender and com_sender!=com_sender)
+                ##### Update com return code
                 if receiver_is_sending or receiver_is_receiving or sender_is_receiving:
                     status=True
                     if com_sender != com_receiver:

tests/interferences_bug1/README.md

@@ -0,0 +1,16 @@
+# Bug description
+
+## Story
+- Discovered by a master student (Stian Alexander Solli) during his master thesis
+
+## Scenario
+- Three nodes
+- All node reachable by each other except 0 and 2
+- Senders are node 1 and 2
+- Receiver is node 0
+
+## Bug
+- If both sender (1 and 2) send at the same time, node 0 communications are marked as interference which is undesirable
+
+## Fix
+- Add an additional check in the case where "receiver is sending" to ensure that the communication must be mark as interfering

tests/interferences_bug1/out

@@ -0,0 +1,9 @@
+[t=0.000,src=n1,grp=def] Send 1 bytes on wlan0
+[t=0.000,src=n2,grp=def] Send 1 bytes on wlan0
+[t=1.000,src=n0,grp=def] Receive 1 bytes on wlan0
+[t=1.000,src=n2,grp=def] Receive 1 bytes on wlan0 with errors
+[t=1.000,src=n1,grp=def] Receive 1 bytes on wlan0 with errors
+[t=1.000,src=n0,grp=def] Receiver RCode.SUCCESS
+[t=1.000,src=n1,grp=def] Sender RCode.SUCCESS
+[t=1.000,src=n2,grp=def] Sender RCode.SUCCESS
+[t=1.000,src=esds] Simulation ends

tests/interferences_bug1/platform.yaml

@@ -0,0 +1,15 @@
+nodes:
+  count: 3
+  implementations:
+    - 1,2 sender.py
+    - 0 receiver.py
+
+interfaces:
+  wlan0:
+    type: "wireless"
+    nodes: all
+    links:
+      - all 1Bps 0s all
+      - 0,2 0bps 0s 0,2 # Node 0 and 2 are out of range
+    txperfs:
+      - all 1Bps 0s

tests/interferences_bug1/receiver.py

@@ -0,0 +1,6 @@
+#!/usr/bin/env python
+
+def execute(api):
+    code,data=api.receive("wlan0")
+    api.log("Receiver "+str(code))
+

tests/interferences_bug1/sender.py

@@ -0,0 +1,5 @@
+#!/usr/bin/env python
+
+def execute(api):
+    code=api.send("wlan0","Hello World!",1,1)
+    api.log("Sender "+str(code))