RX.Net:使用重试,但记录任何异常 [英] RX.Net : Use Retry but log any Exception
问题描述
我是RX的新手,一直在研究错误处理和Retry的使用;我有以下内容(是的,我知道这不是一个真正的"单元测试,但是它给了我一些摆弄的地方!),想知道如何继续重试,但能够记录任何异常?
I am new to RX and have been investigating error handling and the use of Retry; I have the following (yes I know it's not a 'real' unit test but it gives me place to fiddle!!) and was wondering how I go about keeping the Retry but be able to log any Exception?
[Test]
public void Test()
{
var scheduler = new TestScheduler();
var source = scheduler.CreateHotObservable(
new Recorded<Notification<long>>(10000000, Notification.CreateOnNext(0L)),
new Recorded<Notification<long>>(20000000, Notification.CreateOnNext(1L)),
new Recorded<Notification<long>>(30000000, Notification.CreateOnNext(2L)),
new Recorded<Notification<long>>(30000001, Notification.CreateOnError<long>(new Exception("Fail"))),
new Recorded<Notification<long>>(40000000, Notification.CreateOnNext(3L)),
new Recorded<Notification<long>>(40000000, Notification.CreateOnCompleted<long>())
);
source.Retry().Subscribe(
l => Console.WriteLine($"OnNext {l}"),
exception => Console.WriteLine(exception.ToString()), // Would be logging this in production
() => Console.WriteLine("OnCompleted"));
scheduler.Start(
() => source,
0,
TimeSpan.FromSeconds(1).Ticks,
TimeSpan.FromSeconds(5).Ticks);
}
这将导致...
OnNext 0
OnNext 1
OnNext 2
OnNext 3
OnCompleted
...除了我想记录发生在2到3之间的异常之外,这正是我想要发生的事情.
...which is exactly what I want to happen apart from fact I would like to log the Exception which occurs between 2 and 3.
是否有一种方法可以使订阅服务器在OnError中看到异常(并记录该异常),然后重新订阅,使其看到3?
Is there a way to allow the Subscriber to see the Exception in OnError (and log it) and then re-subscribe so it sees 3?
谢谢!
推荐答案
您可以这样实现:
source
.Do(_ => { }, exception => Console.WriteLine(exception.ToString()), () => {})
.Retry()
.Subscribe(
l => Console.WriteLine($"OnNext {l}"),
// exception => Console.WriteLine(exception.ToString()), // Would be logging this in production
() => Console.WriteLine("OnCompleted")
);
只是为了澄清这里发生的事情:OnError
是终止信号.如果错误到达订阅,则将终止流的其余部分. .Retry
终止订阅,吞下OnError
,然后重新订阅,将两个订阅融合在一起.例如看这个:
Just to clarify what's going on here: OnError
is a terminating signal. If the error reached the subscription, that would terminate the rest of the stream. .Retry
terminates the subscription, swallows the OnError
, and then re-subscribes, melding the two subscriptions together. For example look at this:
source
.StartWith(-1)
.Retry()
.Subscribe(
l => Console.WriteLine($"OnNext {l}"),
() => Console.WriteLine("OnCompleted")
);
您的输出应为
OnNext -1
OnNext 0
OnNext 1
OnNext 2
OnNext -1
OnNext 3
OnCompleted
OnNext -1
显示两次,因为每次您订阅时都会显示(Retry
在OnError
之后执行.
The OnNext -1
shows up twice, because it shows up whenever you subscribe (which Retry
does after the OnError
.
坦率地说,您的测试是一个不好的测试.它破坏了"Rx合同",即通知遵循以下模式:
Your test observable is frankly a bad test. It breaks the "Rx Contract" which is that notifications follow the following pattern:
OnNext* (OnCompleted | OnError)?
即0个或更多OnNext
通知,后跟一个可选的OnError
或可选的OnCompleted
. OnError
或OnCompleted
都不能跟随任何类型的通知.
That is, 0 or more OnNext
notifications, followed by an optional OnError
or an optional OnCompleted
. No notifications of any type should follow either an OnError
or an OnCompleted
.
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