【Rxjs活用講座】publish().refCount() と share() の微妙な違い

            
            import { Observable } from 'rxjs';
import { of } from 'rxjs';
import { switchMap, share } from 'rxjs/operators';

function hot$() : Observable<any> {
    console.log(`👇Hot stream is getting started.`);
    return of(1).pipe(
            switchMap(_ => of(new Date())
        ),
        share() // HOTストリームで分配 + 支流は即時処理を開始
    );
}

const share$ = hot$();

share$.pipe(
    tap(_ => console.log('Sub stream #1 :'))
).subscribe(
    res => console.log(res),
    err => console.log(err),
    () => console.log('Sub stream #1 is Finished!')
);

share$.pipe(
    tap(_ => console.log('Sub stream #2 :'))
).subscribe(
    res => console.log(res),
    err => console.log(err),
    () => console.log('Sub stream #2 is Finished!')
);
        

            
            $ node dist/index.js
👇Hot stream is getting started.
Sub stream #1 :
2020-07-09T16:54:26.568Z
Sub stream #1 is Finished!
Sub stream #2 :
2020-07-09T16:54:26.575Z
Sub stream #2 is Finished!
        

            
            import { Observable } from 'rxjs';
import { of } from 'rxjs';
import { switchMap, publish, refCount } from 'rxjs/operators';

function hot$() : Observable<any> {
    console.log(`👇Hot Stream is getting started.`);
    return of(1).pipe(
            switchMap(_ => of(new Date())
        ),
        publish(), // HOTストリームとして分配するだけ
        refCount() // 分岐したストリームは任意のタイミングで開始
    );
}

const publishRefCount$ = hot$();
publishRefCount$.pipe(
    tap(_ => console.log('Sub stream #1 :'))
).subscribe(
    res => console.log(res),
    err => console.log(err),
    () => console.log('Sub stream #1 is Finished!')
);
publishRefCount$.pipe(
    tap(_ => console.log('Sub stream #2 :'))
).subscribe(
    res => console.log(res),
    err => console.log(err),
    () => console.log('Sub stream #2 is Finished!')
);
        

            
            $ node dist/index.js
👇Hot stream is getting started.
Sub stream #1 :
2020-07-09T16:54:26.578Z
Sub stream #1 is Finished!
Sub stream #2 is Finished!