在Rxjava2+Retrofit中使用retryWhen重新拉取请求失败

使用Rxjava2+ Retrofit 进行网络请求，在请求失败之后，使用retryWhen实现重新请求（如下面代码）。但发现没有实现预想的功能：

 class TestRetryWhenHeartBeatException : Function<Observable<out Throwable>, ObservableSource<*>> {
    companion object {
        private val DELAY: Long = 6
        private val TAG:String = TestRetryWhenHeartBeatException::class.java.simpleName
    }
    override fun apply(t: Observable<out Throwable>): ObservableSource<*> {
        logd(TAG,"retry when")
        return t.flatMap { Observable.timer(DELAY, TimeUnit.SECONDS) }
    }
}

 mHeartBeatDisposable  =
                Observable.interval(5,TimeUnit.SECONDS)
                .subscribeOn(Schedulers.io())
                .unsubscribeOn(Schedulers.io())
//                .repeatWhen(RepeatWhenHeartBeatCompleted())
                .retryWhen(TestRetryWhenHeartBeatException())
                .flatMap {
                    if (TaskManager.mIdle) {
                        logd(TAG, "heartbeat")
                        mNetWorkApi.heartBeat(UrlManager.HEARTBEAT_URL)
                    } else {
                        Observable.create { emitter ->
                            //emit a HttpResult with no data
                            emitter.onNext(nullHeartBeat)
                        }
                    }
                }
                .subscribe({ data ->
                    RxBus.getDefault().post(LostServerEvent(false))
                    logd(TAG, "post lost server false")
                }, { e ->
                    loge(TAG, e.message)
                    loge(TAG, "lost server")
                    RxBus.getDefault().post(LostServerEvent(true))
                }, {})

https://www.jianshu.com/p/f629196e62ff

http://bbs.csdn.net/topics/392302929