Debugging potential leaks

[dbashford]

I'm debugging some leak issues we have using ember-in-viewport. While I haven't got to the source just yet, I did notice this...

In the in-viewport service, you have a startIntersectionObserver function which instantiates an ObserverAdmin (code).

startIntersectionObserver() {
  this.observerAdmin = new ObserverAdmin();
}

In the in-viewport service's watchElement function (code), you protect the creation of observerAdmin, making sure you don't create if you already have one.

watchElement(element, configOptions = {}, enterCallback, exitCallback) {
  if (get(this, 'viewportUseIntersectionObserver')) {
    if (!get(this, 'observerAdmin')) {
      this.startIntersectionObserver();
    }
    ...

However, in the _setInitialViewport function of the in-viewport mixin (code) you call startIntersectionObserver without such a protection.

  _setInitialViewport(element) {
    const isTearingDown = this.isDestroyed || this.isDestroying;
    if (!element || isTearingDown) {
      return;
    }

    const inViewport = get(this, 'inViewport');

    if (get(this, 'viewportUseIntersectionObserver')) {
      inViewport.startIntersectionObserver();
      ...

I'm not positive that this is the cause of our leaks, but the loss/overwrite of the observer admin reference, which holds the registry that IS our leak, is making it hard to make any sort of fix.

Assuming this is the problem I think it might be, the right solution here might be to protect creation of observerAdmin inside startIntersectionObserver rather than its callers. I've made that locally while I debug things.

Happy to PR that in, but to be honest, I've been debugging a straight line to the leak and I've ignored some of what I've debugged through, so I may be missing a reason for re-creation of the observerAdmin

[snewcomer]

@dbashford 👋 I believe you are right! We may need to remove this line. What do you think? If so, a PR is welcome!

https://github.com/DockYard/ember-in-viewport/blob/master/addon/mixins/in-viewport.js#L125

Also, for future reference, the Mixin will surely be deprecated in the future. The service is the recommended path forward just in case I haven't stated it in the README.