完成后，RxJS 的共享运算符的行为会有所不同吗?

本文介绍了完成后，RxJS 的共享运算符的行为会有所不同吗?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在为一些我不明白为什么会发生的事情而苦苦挣扎.

I'm struggling with something which I can't understand why it is happening .

看这个例子:

 const source = Rx.Observable.of(1).share();

 source.subscribe(console.log); //1
 source.subscribe(console.log); //1

这会打印两次1".AFAIK share 查看 refCount.但是如果我们看一下 - refcount 在这里应该为零:

This prints "1" twice. AFAIK share looks at refCount. But if we look at it - refcount should be ZERO here :

const source = Rx.Observable.of(1).share();

 source.subscribe(console.log); 
             ^--  1)refCount=1
                  2)value emitted - closing subscription ( complete)
                  3)refCount=0

 source.subscribe(console.log);
            ^-- does refCount is 1 again or  is it Zero ?

演示 1

此外 - 当观察者未完成

const source = Rx.Observable.create((o)=>o.next(1)).share();

 source.subscribe(console.log); //1
 source.subscribe(console.log); //nothing

^这只会产生一个值

Demo2

问题

我的 refCount 观察是否正确?为什么两个示例之间的结果不同?

Is my refCount observation was correct and why there are different results between the two examples ?

推荐答案

您的 refCount 观察是正确的.

Your refCount observation is correct.

在共享 Observable 上，如果(且仅当)refCount 重置为 0，则任何新订阅都将重新创建源 Observable.

On a shared Observable, if (and only if) the refCount resets to 0, then any new subscription would recreate the source Observable.

演示 1:每次订阅后引用计数重置

Demo 1: ref count resets after each subscription

演示 2:引用计数永远不会重置，因为订阅不会完成.

Demo 2: the refcount would never reset since the subscriptions won't complete.

第三个例子:

const source = Rx.Observable.create((o)=>o.next(1)).share();

source.take(1).subscribe(console.log); //1
source.take(1).subscribe(console.log); //1

<script src="https://cdnjs.cloudflare.com/ajax/libs/rxjs/5.5.8/Rx.js"></script>

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Refcount