Auto-retry API calls for Network exception

[shahzadansari]

• Use Flow's catch { } to catch exceptions instead of try { } catch { } block.
• Retry failed API calls if they get a Network exception.
• Emits Loading state immediately when Flow starts emitting value.
• Flows on Dispatchers.IO by default.

Uses Flow's retryWhen { } to retry API call 3 times if it had gotten a Network exception.

fun <T> Flow<DataState<T>>.safeDataStateFlow(coroutineContext: CoroutineContext = Dispatchers.IO, autoRetry: Boolean = true): Flow<DataState<T>> =
    retryWhen { cause, attempt -> autoRetry && canRetry(cause, attempt) }
        .catch { (it as? Exception)?.toApiException()?.let { exception -> emit(DataState.Error(exception)) } }
        .flowOn(coroutineContext)
        .onStart { emit(DataState.Loading()) }

Current implementation retries 3 times and only if it was a Network exception.

private suspend fun canRetry(cause: Throwable, attempt: Long, retries: Int = 3, delayBetweenRetries: Long = 500): Boolean {
    val isNetworkException = (cause as? Exception)?.toApiException() == ApiException.Network
    val canRetry = isNetworkException && attempt < retries
    return if (canRetry) {
        delay(delayBetweenRetries)
        true
    } else {
        false
    }
}