code_projects_kotlin/STEP1_Basics/8_Threads/main.kt

package org.example

var sum: Int = 0
var lock: Int = -1
var workers: Array<Int> = arrayOf()

class WorkerThread(private val threadI: Int): Thread() {
    public override fun run() {
        for (i in 1..3) {
            // Wait until unlocked
            while (lock != threadI) {
                Thread.sleep(100)
            }
            sum += 1
            println("T$threadI | $sum")
            Thread.sleep(500)
            // Pass execution to the next thread
            // Check if we not last
            if (workers.size > 1) {
                // Check if thread last in array
                if (workers.indexOf(threadI) == (workers.size - 1)) {
                    lock = 0
                }
                else {
                    lock = workers.indexOf(threadI) + 1
                }
            }
        }
    }
}

fun main() {
    val threadNums = 3;

    var threadArray: Array<Thread> = arrayOf()
    var firstThread: Boolean = true
    for (i in 0..<threadNums) {
        if (firstThread) {
            lock = i
            firstThread = false
        }
        threadArray += WorkerThread(i)
        workers += i
    }
    for (i in threadArray) {
        i.start()
    }
}