是否有操作员取消以前的执行？

Question

我知道标题很奇怪，但是就到了。

我订阅了一个可观察的filteredBooks$，它由可观察的this._bookFilter$发出的值触发。但是，该转换有些昂贵，因此，如果从switchMap发出新值，我想取消this._bookFilter$的所有正在进行的执行。

我该如何实现？

  filteredBooks$: Observable<Book[]> = this._bookFilter$.pipe(
    debounceTime(50),
    distinctUntilChanged((f1, f2) => this.filtersAreDistinct(f1, f2)),
    // IF A NEW MESSAGE (bookFilter emission) COMES I WANT TO INTERRUPT THE EXPENSIVE EXECUTION BELOW  
    switchMap(
      bookFilter => findBooksByCategories$(bookFilter.categories),
      scan<Book[], Book[]>((filteredAndSortedResult, chunkOfBooksInCategories) => {
          const filteredAndScoredChunk = [];
          chunkOfBooksInCategory.forEach(bookToScore => {
            const score = bookToScore.getSearchScore().calculateBookScoreByFilter(bookFilter);
            if (score !== 0) {
              filteredAndScoredChunk.push(bookToScore);
            }
          });
          return filteredAndSortedResult.concat(filteredAndScoredChunk).sort(this.bookSortCompare);
        } , []));
      }
    ),
    shareReplay(1)
  );