gistfile1.txt

import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.channels.Channel
import kotlinx.coroutines.channels.ReceiveChannel
import kotlinx.coroutines.channels.SendChannel
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import java.io.File

data class UploadResponse(val code: Int,
                          val message: String,
                          val file: File)

fun CoroutineScope.uploadWorker(files: ReceiveChannel<File>,
                                responses: SendChannel<UploadResponse>) {
    launch {
        for (file in files) {
            println("upload file ${file.name} on thread ${Thread.currentThread().name}")
            // this simulates the http client call
            delay(2000)
            responses.send(UploadResponse(200, "done", file))
        }
    }
}

fun CoroutineScope.uploadResponseHandler(responses: ReceiveChannel<UploadResponse>) {
    launch {
        for (response in responses) {
            println("got response with code ${response.code}")
        }
    }
}

fun CoroutineScope.uploader(files: ReceiveChannel<File>,
                            nrOfWorkers: Int = 3) {
    val responses = Channel<UploadResponse>()
    repeat(nrOfWorkers) { uploadWorker(files, responses) }
    uploadResponseHandler(responses)
}