没有订阅者时如何暂停 shareReplay

Question

For example:

const s = rxjs.interval(2000).pipe(tap(console.log), shareReplay(1))
const b = s.subscribe(v => {})
// wait, console will begin output 0, 1, 2, 3, ...
b.unsubscribe()
// console will continue output 4, 5, 6, 7, ...

I want my stream paused when there are no subscribers to save CPU usage.

How do I pause the stream when there are no subscribers ?

The goal is to let multiple subscribers share a single stream.

• When the first subscriber comes, the stream will start with an initial value and provide data periodically.
• When a new subscriber comes, it will get the most recently value in the stream.
• When all subscriber gone, the data stream can be closed safely, next one comes will be treated as first one.

Answer 1

You'll need a multicast to share your data via ReplaySubject , with refCount to keep track of subscribers count.

const s = rxjs.interval(2000).pipe(
  tap(console.log), 
  multicast(() => new ReplaySubject(1)),
  refCount()
);

const b = s.subscribe(v => {})

setTimeout(()=>{
  b.unsubscribe()
}, 5000)