Swift actor the most boring data race example

swift_actor_data_race_only.swift

import Foundation

class Class {
    var i = 0

    func decrease() {
        i-=1
    }
    
    func increase() {
        i+=1
    }
    
    func log() {
        decrease()
        increase()
        
        print("class i : \(i)")
    }
}

actor Actor {
    var i = 0

    func decrease() {
        i-=1
    }
    
    func increase() {
        i+=1
    }
    
    @objc nonisolated func log() {
        Task {
            await isolatedLog()
        }
    }
    
    func isolatedLog() {
        decrease()
        increase()
        
        print("actor i : \(i)")
    }
}

let actor = Actor()
let `class` = Class()

DispatchQueue.concurrentPerform(iterations: 1000) { _ in
    actor.log()
}

// actor i : 0
// actor i : 0
// actor i : 0
// actor i : 0
// actor i : 0
// actor i : 0
// actor i : 0
// actor i : 0
// actor i : 0
// ...
// ..

DispatchQueue.concurrentPerform(iterations: 1000) { _ in
    `class`.log()
}

// class i : -3
// class i : -5
// class i : -5
// class i : -2
// class i : -2
// class i : -2
// class i : -5
// class i : 0
// class i : -2
// ...
// ..