确保 RxWorker 永远不会失败

Question

我正在实现我的第一个 WorkManager 用于与服务器的每日同步，这可能会返回 HTTP 错误，因此使 createWork() 流失败并调用 onError() 所以 Result.failure() 被“抛出”在流的订阅。

我想确保永远不会调用 Result.failure() 并始终调用 Result.retry()。

这是我的RxWorker

class DailySyncWorker (appContext: Context, workerParams: WorkerParameters): RxWorker(appContext, workerParams) {

    private val disposable: CompositeDisposable = CompositeDisposable()
    private val httpManager = AppFactory.httpManager()
    private val dbManager = AppFactory.dbManager()
    private val prefsManager = AppFactory.sharedManager(appContext)

    companion object {
        const val WORKER_NAME = "com.blabla.blah.DAILY_SYNC_WORKER"
    }

    override fun createWork(): Single<Result> {
        Timber.e("Worker - Executing ${System.currentTimeMillis() - prefsManager.lastMillis}")
        prefsManager.lastMillis = System.currentTimeMillis()

        return dbManager.alarmDAO.getNewAlarms(prefsManager.lastSyncedAlarm)
            .flatMap { alarms -> syncWithServer(alarms)
                .doOnSuccess {
                    if(alarms.size != 0)
                        prefsManager.lastSyncedAlarm = alarms[0].date // The query is in descending order, the first record is the last recorded alarm
                }
            }
    }

    private fun syncWithServer(alarms: MutableList<Alarm>): Single<Result> {
        val syncRequestModel = SyncRequestModel(alarms)

        return if(alarms.size != 0)
            httpManager.service().create(SyncService::class.java).sync(syncRequestModel)
                    .observeOn(Schedulers.io())
                    .flatMap { result ->
                        if(result == "OK") { // TODO - the service has not been created yet
                            Timber.e("Worker - success")
                            Single.just(Result.success())
                        } else {
                            Timber.e("Worker - failure")
                            Single.just(Result.retry())
                        }
                    }
        else {
            Timber.e("Worker - no sync is necessary")
            Single.just(Result.success())
        }
    }
}

我尝试在流的许多不同onError() 中调用Result.retry()，但似乎Result.failure() 正在我无法覆盖的订阅的onError() 中调用。

那么我怎样才能确保我的工人永远不会失败呢？

Answer 1

在syncWithServer() 函数中，您只检查flatMap 部分的结果。但是，在到达flatMap 部分之前可能会发生错误，这意味着Result.retry() 可能永远不会返回。此外，您不需要指定特定线程，因为工作人员默认在后台线程上运行。这是我上面提到的更改的工人：

class DailySyncWorker (appContext: Context, workerParams: WorkerParameters): RxWorker(appContext, workerParams) {

    private val disposable: CompositeDisposable = CompositeDisposable()
    private val httpManager = AppFactory.httpManager()
    private val dbManager = AppFactory.dbManager()
    private val prefsManager = AppFactory.sharedManager(appContext)

    companion object {
        const val WORKER_NAME = "com.blabla.blah.DAILY_SYNC_WORKER"
    }

    override fun createWork(): Single<Result> {
        Timber.e("Worker - Executing ${System.currentTimeMillis() - prefsManager.lastMillis}")
        prefsManager.lastMillis = System.currentTimeMillis()

        return dbManager.alarmDAO.getNewAlarms(prefsManager.lastSyncedAlarm)
            .flatMap { alarms -> syncWithServer(alarms)
                .doOnSuccess {
                    if(alarms.size != 0)
                        prefsManager.lastSyncedAlarm = alarms[0].date // The query is in descending order, the first record is the last recorded alarm
                }
            }
            .onErrorReturnItem(Result.retry()) // Here is error handling
    }

    private fun syncWithServer(alarms: MutableList<Alarm>): Single<Result> {
        val syncRequestModel = SyncRequestModel(alarms)

        return if(alarms.size != 0)
            httpManager.service().create(SyncService::class.java).sync(syncRequestModel)
                    .flatMap { result ->
                        if(result == "OK") { // TODO - the service has not been created yet
                            Timber.e("Worker - success")
                            Single.just(Result.success())
                        } else {
                            Timber.e("Worker - failure")
                            Single.just(Result.retry())
                        }
                    }
        else {
            Timber.e("Worker - no sync is necessary")
            Single.just(Result.success())
        }
    }
}