使用具有自定义范围的Kotlin协程进行轮询并查看生命周期

我只是从Kotlin协程开始。我正在尝试使用协程轮询服务器，并希望在Activity或Fragment暂停时停止轮询，并相应地恢复轮询。因此，我pollScope的生命周期比所提供的生命周期短ViewModel.viewModelScope。我对目前的实施方式不完全满意，有几个问题：

这是正确的创建方法吗pollScope？我也希望它在取消时viewModelScope也取消，这就是为什么我要指定父级作业。

onResume()如果我取消pollJobs使用，为什么协程不能开始coroutineContext.cancel()？如果我保留一份工作清单并取消它们，它们会很好地启动。

这是整体正确的方法吗？有没有更好的办法？

    import androidx.lifecycle.LifecycleOwner
    import androidx.lifecycle.ViewModel
    import androidx.lifecycle.viewModelScope
    import com.spruce.messenger.utils.FullLifecycleObserverAdapter
    import kotlinx.coroutines.*
    import java.io.IOException
    import java.util.concurrent.CopyOnWriteArrayList
    import kotlin.coroutines.CoroutineContext


    suspend fun poll(initialDelay: LOng= 5000,
                     maxDelay: LOng= 30000,
                     factor: Double = 2.0,
                     block: suspend () -> Unit) {

        var currentDelay = initialDelay
        while (true) {
            try {
                try {
                    block()
                    currentDelay = initialDelay
                } catch (e: IOException) {
                    currentDelay = (currentDelay * factor).toLong().coerceAtMost(maxDelay)
                }
                delay(currentDelay)
                yield()
            } catch (e: CancellationException) {
                break
            }
        }
    }


    class MyDataModel : ViewModel() {
        val pollScope = CloseableCoroutineScope(SupervisorJob(parent = viewModelScope.coroutineContext[Job]) + Dispatchers.Main)

        private val pollJobs = CopyOnWriteArrayList()

        inner class CloseableCoroutineScope(context: CoroutineContext) : FullLifecycleObserverAdapter(), CoroutineScope {
            override val coroutineContext: CoroutineCOntext= context

            override fun onPause(owner: LifecycleOwner) {
                super.onPause(owner)
                // coroutineContext.cancel() // this cancels it but then coroutine doesn't start again in onResume()
                pollJobs.forEach { it.cancel() }
            }

            override fun onResume(owner: LifecycleOwner) {
                super.onResume(owner)
                refresh()
            }
        }

        fun refresh() {
            if (pollJobs.count { it.isActive } == 0) {
                startPoll()
            }
        }

        private fun startPoll() = pollScope.launch {
            try {
                poll {
                    //fetch data from server
                }
            } catch (e: Exception) {
                //ignore
            }
        }.also {
            track(it)
        }

        private fun track(job: Job) {
            pollJobs.add(job)
            job.invokeOnCompletion {
                pollJobs.remove(job)
            }
        }
    }

然后在我的片段中，将pollScope添加为生命周期观察器viewLifecycleOwner.lifecycle.addObserver(viewModel.pollScope)。