Spurious cyclic dependency detection for federate in TypeScript

[CloverCho]

For the following LF code, the LF language server finds cyclic dependency, so it is not compiled.
However, there is no causality loop in the code actually.

Here are some explanations for this error.

1. This detection is removed when we changed "federated reactor" to "main reactor",
   so the logic for detecting cycle among federates would have problem.
2. This detection is also removed when we remove a connection between "Broker" federate and "Print" federate.
   (It can be done by removing "b.out -> p.inp" at the end of the federated reactor)
   Considering the fact that there is one-way connection between these two federates, it is certainly wrong.

/**
* Test of replacment for error of federate instance
*/
target TypeScript {
    timeout: 10 sec
};

reactor Count(error_time:number(-1)) {
    input inp:number;
    output out:number;
    state count:number(1);
    logical action a;
    logical action infLoop;
    reaction(inp) -> a {=
        if (inp) {
            count = inp;
            actions.a.schedule(0, null);
        }
    =}
    reaction(a) -> out, a, infLoop {=
        out = count++;
        if (count < error_time){
            actions.a.schedule(TimeValue.sec(1), null);
        } else {
            actions.infLoop.schedule(0, null);
        }
    =}
    reaction(infLoop) -> infLoop {=
        actions.infLoop.schedule(TimeValue.sec(1), null);
    =}
}

reactor Print {
    input inp:number;
    reaction(inp) {=
        if (inp){
            console.log(`Received: ${inp as number}`);
        }
    =}
}

reactor Start {
    output out:number;
    reaction(startup) -> out {=
        out = 1;
    =}
}

reactor Broker(timeout: time(1500 msec)) {
    input inp1:number;
    input inp2:number;
    output out:number;
    state time1:time;
    state time2:time;
    state alive1:boolean(true);
    state alive2:boolean(true);
    logical action a1;
    logical action a2;
    reaction(inp1, inp2) -> out, a1, a2 {=
        console.log(`Alive 1: ${alive1}, Alive 2: ${alive2}`);
        if (alive1) {
            if (inp1){
                out = inp1;
                console.log(`Input 1 Received: ${inp1}`);
                time1 = util.getCurrentPhysicalTime();
                actions.a1.schedule(timeout, null);
            }
        } else if (alive2) {
            if (inp2){
                out = inp2;
                console.log(`Input 2 Received: ${inp2}`);
                time2 = util.getCurrentPhysicalTime();
                actions.a2.schedule(timeout, null);
            }
        }
    =}
    reaction(a1) {=
        if (time1) {
            let elapsedPhysical = util.getCurrentPhysicalTime().subtract(time1);
            if (timeout.isEarlierThan(elapsedPhysical)){
                alive1 = false;
            }
        }
    =}
    reaction(a2) {=
        if (time2) {
            let elapsedPhysical = util.getCurrentPhysicalTime().subtract(time2);
            if (timeout.isEarlierThan(elapsedPhysical)){
                alive2 = false;
            }
        }
    =}
}

// Error: Spurious cyclic dependency detected
// If we changed federated to main, the dection is removed
federated reactor {
    b = new Broker();
    s = new Start();
    p = new Print();
    c1 = new Count(error_time = 5);
    c2 = new Count();
    
    s.out -> c1.inp;
    s.out -> c2.inp;
    c1.out -> b.inp1;
    c2.out -> b.inp2;

    // if comment out this code, the detection is removed
    b.out -> p.inp;    
}

[lhstrh]

Also note that the diagram doesn't report a cycle, but the validator does.

[Soroosh129]

Could you please try and see if #1085 fixes this issue for you?

[lhstrh]

That PR seems stalled and is not passing CI...so that's not really a fix...

[CloverCho]

@Soroosh129
I tried on the PR again but it is not fixed

[Soroosh129]

This looks like a TypeScript-specific problem.
When I switch the target to C, there is no cycle error in the federated-delay-fix branch.

[lhstrh]

There are peculiarities in our code base that lead to cycle detection happening multiple times. At least once in the validator, once in the diagram synthesis, and then once more in the code generator. The message @CloverCho describes must come from the code generator...

[lhstrh]

@CloverCho: what is the literal textual content of the error message you're seeing?

[CloverCho]

@lhstrh This is the error I got when I execute runLfc

lfc: error: Cyclic dependency due to succeeding reaction. Consider reordering reactions within reactor Count to avoid causality loop.

and

lfc: error: Reaction triggers involved in cyclic dependency in reactor Count: inp.

These errors occurred many times.

for about diagram synthesis, I found the following error message in the vscode.

Cyclic dependency due to preceding reaction. Consider reordering reactions within reactor Count to avoid causality loop

I'm attaching pictures of these errors.

1. command line error

2. vscode error