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DeadlockAgent.tla
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DeadlockAgent.tla
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------------------------------- MODULE DeadlockAgent -------------------------------
EXTENDS Integers, Naturals, TLC
(* --fair algorithm algo {
variables
\* Represent the 3 tasks we have in the application
ApplicationTask = "Application";
MQTTAgentTask = "MQTTAgent";
NetworkTask = "Network"; \* We model the network as a process as it acts concurrently
QMax = 5;
packetCount = 0;
agentQueue = 0;
applicationQueue = 0;
fair process (App = ApplicationTask)
{
a1: await agentQueue < QMax;
agentQueue := agentQueue + 1;
a2: if ( applicationQueue > 0) applicationQueue := applicationQueue - 1;
a3: goto a1
}; \* end process
fair process (Agent = MQTTAgentTask)
{
\* The Agent blocks until there is any message to process, if there is it processes it and continues
A1:
await agentQueue > 0;
agentQueue := agentQueue - 1;
if ( packetCount > 0 )
{
packetCount := packetCount - 1;
A2: await applicationQueue < QMax;
applicationQueue := applicationQueue + 1;
};
A3: skip;
A4: goto A1
}; \* end process
fair process (Network = NetworkTask)
{
\* The network task will wait until there is room in the queue, if there is it receives a packet assuming infinite source
N1:
await agentQueue < QMax;
agentQueue := agentQueue + 1;
packetCount := packetCount + 1;
N2: skip;
N3: goto N1
} ; \* end process
}
*)
\* BEGIN TRANSLATION
VARIABLES ApplicationTask, MQTTAgentTask, NetworkTask, QMax, packetCount,
agentQueue, applicationQueue, pc
vars == << ApplicationTask, MQTTAgentTask, NetworkTask, QMax, packetCount,
agentQueue, applicationQueue, pc >>
ProcSet == {ApplicationTask} \cup {MQTTAgentTask} \cup {NetworkTask}
Init == (* Global variables *)
/\ ApplicationTask = "Application"
/\ MQTTAgentTask = "MQTTAgent"
/\ NetworkTask = "Network"
/\ QMax = 5
/\ packetCount = 0
/\ agentQueue = 0
/\ applicationQueue = 0
/\ pc = [self \in ProcSet |-> CASE self = ApplicationTask -> "a1"
[] self = MQTTAgentTask -> "A1"
[] self = NetworkTask -> "N1"]
a1 == /\ pc[ApplicationTask] = "a1"
/\ agentQueue < QMax
/\ agentQueue' = agentQueue + 1
/\ pc' = [pc EXCEPT ![ApplicationTask] = "a2"]
/\ UNCHANGED << ApplicationTask, MQTTAgentTask, NetworkTask, QMax,
packetCount, applicationQueue >>
a2 == /\ pc[ApplicationTask] = "a2"
/\ IF applicationQueue > 0
THEN /\ applicationQueue' = applicationQueue - 1
ELSE /\ TRUE
/\ UNCHANGED applicationQueue
/\ pc' = [pc EXCEPT ![ApplicationTask] = "a3"]
/\ UNCHANGED << ApplicationTask, MQTTAgentTask, NetworkTask, QMax,
packetCount, agentQueue >>
a3 == /\ pc[ApplicationTask] = "a3"
/\ pc' = [pc EXCEPT ![ApplicationTask] = "a1"]
/\ UNCHANGED << ApplicationTask, MQTTAgentTask, NetworkTask, QMax,
packetCount, agentQueue, applicationQueue >>
App == a1 \/ a2 \/ a3
A1 == /\ pc[MQTTAgentTask] = "A1"
/\ agentQueue > 0
/\ agentQueue' = agentQueue - 1
/\ IF packetCount > 0
THEN /\ packetCount' = packetCount - 1
/\ pc' = [pc EXCEPT ![MQTTAgentTask] = "A2"]
ELSE /\ pc' = [pc EXCEPT ![MQTTAgentTask] = "A3"]
/\ UNCHANGED packetCount
/\ UNCHANGED << ApplicationTask, MQTTAgentTask, NetworkTask, QMax,
applicationQueue >>
A2 == /\ pc[MQTTAgentTask] = "A2"
/\ applicationQueue < QMax
/\ applicationQueue' = applicationQueue + 1
/\ pc' = [pc EXCEPT ![MQTTAgentTask] = "A3"]
/\ UNCHANGED << ApplicationTask, MQTTAgentTask, NetworkTask, QMax,
packetCount, agentQueue >>
A3 == /\ pc[MQTTAgentTask] = "A3"
/\ TRUE
/\ pc' = [pc EXCEPT ![MQTTAgentTask] = "A4"]
/\ UNCHANGED << ApplicationTask, MQTTAgentTask, NetworkTask, QMax,
packetCount, agentQueue, applicationQueue >>
A4 == /\ pc[MQTTAgentTask] = "A4"
/\ pc' = [pc EXCEPT ![MQTTAgentTask] = "A1"]
/\ UNCHANGED << ApplicationTask, MQTTAgentTask, NetworkTask, QMax,
packetCount, agentQueue, applicationQueue >>
Agent == A1 \/ A2 \/ A3 \/ A4
N1 == /\ pc[NetworkTask] = "N1"
/\ agentQueue < QMax
/\ agentQueue' = agentQueue + 1
/\ packetCount' = packetCount + 1
/\ pc' = [pc EXCEPT ![NetworkTask] = "N2"]
/\ UNCHANGED << ApplicationTask, MQTTAgentTask, NetworkTask, QMax,
applicationQueue >>
N2 == /\ pc[NetworkTask] = "N2"
/\ TRUE
/\ pc' = [pc EXCEPT ![NetworkTask] = "N3"]
/\ UNCHANGED << ApplicationTask, MQTTAgentTask, NetworkTask, QMax,
packetCount, agentQueue, applicationQueue >>
N3 == /\ pc[NetworkTask] = "N3"
/\ pc' = [pc EXCEPT ![NetworkTask] = "N1"]
/\ UNCHANGED << ApplicationTask, MQTTAgentTask, NetworkTask, QMax,
packetCount, agentQueue, applicationQueue >>
Network == N1 \/ N2 \/ N3
(* Allow infinite stuttering to prevent deadlock on termination. *)
Terminating == /\ \A self \in ProcSet: pc[self] = "Done"
/\ UNCHANGED vars
Next == App \/ Agent \/ Network
\/ Terminating
Spec == /\ Init /\ [][Next]_vars
/\ WF_vars(Next)
/\ WF_vars(App)
/\ WF_vars(Agent)
/\ WF_vars(Network)
Termination == <>(\A self \in ProcSet: pc[self] = "Done")
\* END TRANSLATION
=============================================================================