44 Accessing Thread

Hard

Newly created threads in Cangjie can terminate early if the thread that created them terminates. However, you can use the return value of a thread to wait until execution is complete. The return value of a thread is Future<T>. You can think of it as a box that promises this value will be computed; you just need to wait.

Normal function call.

The return value of a thread is of type Future<Int64>.

Here we use one of the functions on Future, get(), which waits for a thread to finish execution and produce a value. This way, the main thread will not finish before the newly created ones.

accesing_thread.cj

func sum(nums: Array<Int64>): Int64 {
    var total = 0
    for (i in nums) {
        total += i
    }
    return total
}

main() {
    var sum_even = sum(Array<Int64>(10, {i => 2 * i}))

    var sum_odd: Future<Int64> = spawn {
        sum(Array<Int64>(10, {i => 2 * i + 1}))
    }

    println(sum_even)

    println(sum_odd.get())
}
// Output:
// 90
// 100