kotlin_fundamentals_4.kt

suspend fun t4(): String {
    println("Inside t4() on ${Thread.currentThread().name}")
    try {
        // Emulate reading a file
        delay(100)
        return "resultT4"
    } catch (e: Exception) {
        // Ignore exception handling for now
        return ""
    }
}

// A way to make custom dispatcher using Executors
object CustomDispatchers {
    val DB = Executors.newSingleThreadExecutor().asCoroutineDispatcher()
}

// Scope is passed so we can launch our db operation while respecting the scope
suspend fun t5(scope: CoroutineScope, param4: String): String {

    // Since this is a db entry operation we run this block 
    // using the DB dispatcher we made.
    return scope.async(CustomDispatchers.DB) {
        println("Inside t5() on ${Thread.currentThread().name}")
        try {
            // Emulate db entry operation
            delay(100)
            return@async param4.plus("_").plus("resultT5")
        } catch (e: Exception) {
            // Ignore exception handling for now
            return@async ""
        }
    }.await()
}