时滞递推可观测方法

this.connectToServerSafely().pipe(delay(5000)) 将 不停地 函数无法调用自身。这个 delay 接线员会 延迟 发射值 .

我的方法是:

let isConnecting = true;
let isConnected = false;

timer(2000)
  .subscribe(() => (isConnecting = false, isConnected = true));

function connSafely ()/* : Observable<any> */ {
  console.warn('calling `connSafely`');

  if (isConnecting) {
    return timer(500).pipe(concatMap(() => connSafely()))
  }

  if (isConnected) {
    return of(true);
  }

  return connectToServer();
}

function connectToServer () {
  isConnecting = true;

  return of('connecting');
}

connSafely().subscribe();

console.warn("calling 'connSafely'") 初始函数调用 一个4,因为2000/500=4)。

:您必须使用 higher-order mapping operators switchMap , concatMap , mergeMap / flatMap exhaustMap )以确保所有后续函数调用都自动订阅/取消订阅。

尝试使用 tap(() => connSafely())

StackBlitz . ( )

看来你准备好了 this.isConnecting 和 this.isConnected

public connectToServerSafely(): Observable<boolean> {
  if (this.isConnecting) {
    // here function will be called until this.isConnecting change to false
    return this.connectToServerSafely().pipe(delay(5000));
  } else if (this.isConnected) {
    return of(true);
  } else {
    return this.connectToServer();
  }
}

这个解决方案适合我:

public connectToServerSafely(): Observable<boolean> {
  if (this.isConnecting) {
    return new Observable((observer) => {
        setTimeout(() => {
          this.connectToServerSafely().subscribe(result => {
            observer.next(result);
            observer.complete();
          });
        }, 500);
      });
  } else if (this.isConnected) {
    return of(true);
  } else {
    return this.connectToServer();
  }
}