CODEWITHSUNDEEP
node.jsweak-referencespinojs
Loic
Loic

Reputation: 184

How to remove weakRef from set when target is gc, is FinalizationRegistry suitable for it?

I am using pinojs as logger in my nodejs server, and for each module I make a child logger for the module to add some common message There is an annoying problem is when I change base logger's loglevel, it won't effect child logger, and pino doesn't record child loggers of a specific parent logger. So I try to update every child logger's loglevel. I assign onChild function for baseLogger and it will record every child logger when created, To avoid memory leak, as WeakSet/WeakMap cannot to be iterated, I use WeakRef to store childLogger. So the first version is

  const childLoggers = new Set<WeakRef<Logger>>();
  baseLogger.onChild = child => {
    // store ref
    child.onChild = baseLogger.onChild;
    const ref = new WeakRef(child);
    childLoggers.add(ref);
    return child;
  };

I suddenly appear to know that there is a problem, although childLogger will be released correctly, but weakRef it self won't. I do some research and found FinalizationRegistry may solve my problem, then I made second version

  const childLoggers = new Set<WeakRef<Logger>>();
  const registry = new FinalizationRegistry<WeakRef<Logger>>(ref => {
    childLoggers.delete(ref);
  });
  baseLogger.onChild = child => {
    // store ref
    child.onChild = baseLogger.onChild;
    const ref = new WeakRef(child);
    registry.register(ref, ref);
    childLoggers.add(ref);
    return child;
  };

I am new to FinalizationRegistry and I am using weakRef itself as heldValue which in every example I see doesn't do it, is it safe to use? And should I pass Set as part of heldValue?

Upvotes: 0

Views: 16

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