Flowable concatMapSingle 没有预取以忽略点击直到处理完成 [英] Flowable concatMapSingle without prefetch to ignore clicks until processing finishes

问题描述

我希望以这样一种方式处理点击，只要我正在处理发生的某些点击，它们就会被忽略.

I want to handle clicks in such a way that they are ignored as long as I'm doing processing of some click that occurred.

我想我可以通过使用背压来做到这一点，就像这样:

I thought I could do it by utilizing the backpressure, like this:

private val clicks = PublishProcessor.create<Unit>()

// ...

clicks
    .onBackpressureDrop()
    .concatMapSingle(::handleClick, 0)

但是这会引发错误，因为要求 concatMapSingle 需要预取至少一个项目，这使得点击排队并在我完成处理后立即处理它，这不是我想要的是.我只想在当前没有处理的情况下处理点击.

But this throws an error, because there's a requirement that concatMapSingle needs to prefetch at least one item, which makes it queue the click and process it immediately after I'm done processing, which is not what I want. I want to process the click only if there is no processing happening at the moment.

我可以使用其他一些运算符来达到预期的效果吗?

Is there some other operator I could use to achieve the desired effect?

推荐答案

使用 flatMapSingle 而不是 concatMapSingle 可以解决问题，如 akarnokd 在 GitHub 上的建议:

Using flatMapSingle instead of concatMapSingle does the trick, as suggested by akarnokd on GitHub:

flatMap 只会在当前项目实际完成时获取下一个上游项目

flatMap will only fetch the next upstream item if the current one actually completed

最后一个参数是maxConcurrency，指定SingleSources的最大活动订阅数:

The last parameter is maxConcurrency, specifying the maximum number of active subscriptions to the SingleSources:

clicks
    .onBackpressureDrop()
    .flatMapSingle(::handleClick, false, 1)

在这种情况下，flatMapSingle 按顺序订阅那些 Single，因此它不会改变我从 concatMapSingle 获得的语义.

In this instance, flatMapSingle subscribes to those Singles sequentially, so it doesn't change the semantics I got from concatMapSingle.

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