Reactive Extensions - polling observable - why won't it skip?

Question

       return Observable
            .Timer(TimeSpan.FromSeconds(2))
            .SelectAsync(delegate { return this.getResponse(request); })
            .Repeat()
            .Timeout(TimeSpan.FromSeconds(10), Observable.Return(new InMemoryDataSetIsGoodResponse(false, "Connection to Mongo timed out after 10 seconds."))
            .SkipWhile(r => r.IsGood)
            .Take(1)
            .StartWith(new InMemoryDataSetIsGoodResponse(true, null)));

I want to poll a database to make sure that a particular record is still in the database. getResponse returns an IsGood response as long as the record is there, then it returns a bad response.

I just want to start with the assumption that it's there and do nothing until it's bad, at which point I just want to publish the bad response once and be done with it.

But an observer sees an IsGood response every two seconds. Can anyone explain that?

Regardless of what everything before `Take(1)` does, an observer should see at most 2 values. Could you post some code how you do the subscription. — Daniel C. Weber, Jan 06 '15 at 14:52

score 2 · Accepted Answer · answered Jan 07 '15 at 13:47

2

To confirm Daniel's comment, the code as published will have at most 2 events - one from the StartWith, and possibly one from the Take(1). Check your assumptions... the output you are seeing is coming from something else other than a subscription to the posted code.

One possibility is that you are inadvertently making a new subscription to the query on each response? Pure guesswork though.

answered Jan 07 '15 at 13:47

James World

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Thank you. I am still trying to find the answer, but your remarks & Daniel's satisfy me that it isn't with my observable, but with subscription. – masonk Jan 07 '15 at 19:07

Reactive Extensions - polling observable - why won't it skip?

1 Answers1