是否有一个操作员，我可以使用“处置”在管道中分配的资源？

发布于 2025-02-01 10:41:33 字数 739 浏览 3 评论 0原文

假设我有一个可观察的：

declare function allocateLeakyThing(input: string): { dispose: () => void; };

const somethingLeaky$ = input$.pipe(
  map(allocateLeakyThing)
);

AllocateLeakyThing（）返回必须通过调用其Dispose（）方法来手动处理的资源，以防止内存泄漏。如果输入$排放新值，则我应该处置先前分配的资源；如果可观察到的可观察到的订阅，则如果分配给它，它也应该处理资源。

出于第一个目的，我可以写：

const somethingLeaky$ = input$.pipe(
  withLatestFrom(somethingLeaky$.pipe(startsWith(undefined))),
  tap(([input, somethingLeaky]) => somethingLeaky?.dispose()),
  map(([input])=>allocateLeakyThing(input))
);

第二个目的呢？有没有办法与可观察到的可观察到这一点（例如不涉及使用另一个主题）？

原文

Say I have an observable:

declare function allocateLeakyThing(input: string): { dispose: () => void; };

const somethingLeaky$ = input$.pipe(
  map(allocateLeakyThing)
);

where allocateLeakyThing() returns a resource that has to be manually disposed by calling its dispose() method in order to prevent memory leak. If input$ emits a new value, I should dispose the previously allocated resource; if this observable is unsubscribed, it should dispose the resource too, if it's ever allocated.

For the first purpose I can write:

const somethingLeaky$ = input$.pipe(
  withLatestFrom(somethingLeaky$.pipe(startsWith(undefined))),
  tap(([input, somethingLeaky]) => somethingLeaky?.dispose()),
  map(([input])=>allocateLeakyThing(input))
);

What about the second purpose? Is there a way to do this inline with this observable (e.g. does not involve using another subject)?

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何以畏孤独 2025-02-08 10:41:33

您可以使用 finalize（）运算符，该操作员被处置时称为（未订阅）。

由于RXJS 7.3。您还可以使用tap（{finalize：（）=＆gt; {}}）。

也许在您的情况下，您还可以包裹使用可观察创建ressurce的逻辑（基本上与有没有办法为rxjs可观测值制造驱动器？）：

new Observable(observer => {
  // create resource
  // ...

  // Return teardown function that will be called when the Observable is unsubscribed.
  return () => resource.close();
});

You can use finalize() operator that is called when a chain is being disposed (unsubscribed).

Since RxJS 7.3. you can also use tap({ finalize: () => {} }).

Maybe in your situation you could also wrap the logic that creates the ressurce with Observable (basically the same thing as in Is there a way to make a destructor for RXJS Observables?):

new Observable(observer => {
  // create resource
  // ...

  // Return teardown function that will be called when the Observable is unsubscribed.
  return () => resource.close();
});

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