无法从rxjs 5.0中取消可观测

我有这个功能:

 uploadFiles(files: FileToUpload[]) {
    return Observable.create(async (observable) => {
      const aborters: Aborter[] = [];

      for (const fileToUpload of files) {
        let uploadResponse: UploadResponse;

        const aborter = Aborter.none;

        aborters.push(aborter);

        try {
          uploadResponse = await this.upload(file)
        } catch (err) {
        }
      }

      return () => {
        console.log('coooo');

        this.files$.next([]);

        for (const aborter of aborters) {
          if (!aborter.aborted) {
            aborter.abort();
          }
        }
      };
    });
  }

然后我就这样订阅:

this.uploadSubscription = this.uploadService.uploadFiles(this.control.value).subscribe(
      () => console.log('progress'),
      (e) => {
        console.log(`errored with ${e}`);
        this.uploadSubscription.unsubscribe();
      },
      () => {
        console.log('completed');
        this.uploadSubscription.unsubscribe();
      }
    );

ngOnDestroy 这样地:

ngOnDestroy() {
    if (this.uploadSubscription) {
      this.uploadSubscription.unsubscribe();
    }
  }

但是,即使调用了unsubscribe方法,从 Observable.create