Demonstrate cancellation in coroutine

CoroutineCancellation.kt

import kotlinx.coroutines.*
import java.net.URL

fun main() {
    cancelWhenFetchingDataOverNetwork()
    // cancelWhenTakeANap()
    // cancelWhenDoingHeavyComputation()
}

fun cancelWhenDoingHeavyComputation() = runBlocking {
    val parentScope = CoroutineScope(SupervisorJob())
    parentScope.launch {
        println("#1")
        launch {
            println("#3")
            fibonacci(1_000)
            println("#4")
        }
        println("#2")
    }
    delay(1_000)
    parentScope.cancel()
    println("Bye")
}

fun cancelWhenTakeANap() = runBlocking {
    val parentScope = CoroutineScope(SupervisorJob())
    parentScope.launch {
        println("#1")
        launch {
            println("#3")
            takeANap()
            println("#4")
        }
        println("#2")
    }
    delay(300)
    parentScope.cancel()
    delay(300)
    println("Bye")
}

fun cancelWhenFetchingDataOverNetwork() = runBlocking {
    val parentScope = CoroutineScope(SupervisorJob())
    parentScope.launch {
        println("#1")
        launch {
            println("#3")
            fetchDataOverNetwork()
            println("#4")
        }
        println("#2")
    }
    delay(1_000)
    parentScope.cancel()
    delay(1_000)
    println("Bye")
}

suspend fun fetchDataOverNetwork() {
    val tenSecondInMillis = 10000
    val result = URL("https://httpstat.us/200?sleep=$tenSecondInMillis").readText()
    println("$result")
}

suspend fun takeANap() {
    Thread.sleep(1_000)
}

suspend fun fibonacci(n: Int): Int {
    return if (n <= 1) {
        n
    } else {
        fibonacci(n - 1) + fibonacci(n - 2)
    }
}