Coroutines without Flow example

coroutines.kt

class UploadFilesUsecase() : BaseObservable<UploadFilesUsecase.Listener>() {
    interface Listener {
        fun onFilesUploaded()
        fun onFilesUploadFailed()
    }

    private val MAX_RETRIES = 3
    private val mutex = Mutex()
    private val scope = CoroutineScope(SupervisorJob() + Dispatchers.IO)


    fun uploadFiles():Boolean = mutex.tryWithLock {
        scope.launch {
            repeat(MAX_RETRIES) { retryCount ->
                try {
                    val files = listOf(
                            async { processAndMergeFilesOfTypeA() },
                            async { processAndMergeFilesOfTypeB() })
                            .map { it.await() }

                    val archive = compressMergedFiles(files)

                    uploadFileToServer(archive)

                    notifySuccess()
                } catch (t: Throwable) {
                    //log exception
                    if (retryCount == MAX_RETRIES - 1) {
                        notifyFaillure()
                    }
                } finally {
                    deleteTempDir()
                }
            }
        }
    }


    private suspend fun uploadFileToServer(archive: File) = suspendCoroutine<Int> { cont ->
        HttpManager.uploadFiles(archive,
                onDone = { code: Int, body: ByteArray ->
                    if (code / 100 == 2) {
                        cont.resume(code)
                    } else {
                        cont.resumeWithException(Throwable())
                    }

                },
                onFailure = {
                    cont.resumeWithException(Throwable())
                }
        )
    }

    private suspend fun processAndMergeFilesOfTypeA(): File = TODO()

    private suspend fun processAndMergeFilesOfTypeB(): File = TODO()

    private suspend fun compressMergedFiles(files: List<File>): File = TODO()

    private fun deleteTempDir(): Unit = TODO()

    private fun notifySuccess() {
        MainScope().launch { listeners.forEach { it.onFilesUploaded() } }
    }

    private fun notifyFaillure() {
        MainScope().launch { listeners.forEach { it.onFilesUploadFailed() } }
    }

}