带有延迟功能的 Rxjs 重试

问题描述

我正在尝试使用 retry 和 delay 函数，我希望函数会在 1000 毫秒延迟后调用，但它没有，这里有什么错误?看控制台输出，是同一时间16:22:48.

I am trying to use retry with delay function, I expect function will call after 1000ms delay, but it doesnot, what can be error here?look at console output, it is same time 16:22:48.

我预计 16:22:48、16:22:59 ...

I expect there 16:22:48, 16:22:59 ...

canCreate: boolean;
getSomeFunction(): Observable<boolean> {
        return new Observable<boolean>(
            observer => {
                const canCreate = null; // this is just null for now, will some value later
                if (canCreate == null) {
                    observer.error('error');
                } else {
                    observer.next(true);
                }
                observer.complete();
            }
        )
    }


this.getSomeFunction()
      .do((value) => {
        this.cCreate = value;
      }, (error) => {
         console.log(error + new Date().toTimeString());
      })
      .delay(1000)
      .retry(10)
      .subscribe(
        value => this.cCreate = value,
        error => {
          this.cCreate = false;
        },
        () => {}
      );
  }

和控制台结果是:

推荐答案

delay() 用于在 observable 发出的事件之间引入延迟.但是 observable 永远不会发出任何事件.它只是立即出错.

delay() is used to introduce a delay between events emitted by the observable. But the observable never emits any event. It just errors immediately.

您正在寻找的是retryWhen()，它允许决定在多长时间后重试:

What you're looking for is retryWhen(), which allows deciding after how long to retry:

RxJS 5:

  .retryWhen(errors => errors.delay(1000).take(10))

RxJS 6:

import { retryWhen, delay, take } from 'rxjs/operators'
someFunction().pipe(
  // ...
  retryWhen(errors => errors.pipe(delay(1000), take(10)))
)

这将在 10 次尝试后完成整个 observable.如果你想在 10 次尝试后出错整个 observable，retryWhen 回调返回的 observable 必须抛出:

This will complete the whole observable after 10 attempts. If you want to error the whole observable after 10 attempts, the observable returned by the retryWhen callback must throw:

RxJS 5:

  .retryWhen(errors => errors.delay(1000).take(10).concat(Observable.throw()))

RxJS 6:

import { retryWhen, delay, take, concatMap, throwError } from 'rxjs/operators'
someFunction().pipe(
  // ...
  retryWhen(errors => errors.pipe(delay(1000), take(10), concatMap(throwError)))
)

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