fix: memory leak in composite bar

[SimonSiefke]

Fixes a memory leak in composite bar.

A bit simplified the function looks like this:

private updateCompositeSwitcher(donotTrigger?: boolean): void {
  if (totalComposites === compositesToShow.length && this.compositeOverflowAction) {
	this.compositeOverflowAction.dispose();
	this.compositeOverflowAction = undefined;  // item is still registered in this._store
	this.compositeOverflowActionViewItem.dispose();
	this.compositeOverflowActionViewItem = undefined;
}

if (totalComposites > compositesToShow.length && !this.compositeOverflowAction) {
	this.compositeOverflowAction = this._register(this.instantiationService.createInstance(CompositeOverflowActivityAction, () => {
		this.compositeOverflowActionViewItem?.showMenu();
	}));
	this.compositeOverflowActionViewItem = this._register(this.instantiationService.createInstance(
		CompositeOverflowActivityActionViewItem
	));
  }
}

Since the updateCompositeSwitcher can run many times, it can call this._register many times, registering the compositeOverflowAction and the compositeOverflowActionViewItem disposables to this._store each time.

Change

The change is making sure to remove compositeOverflowAction and compositeOverflowActionViewItem from this._store when disposing it and setting it to undefined.

private updateCompositeSwitcher(donotTrigger?: boolean): void {
  if (totalComposites === compositesToShow.length && this.compositeOverflowAction) {
	this._store.delete(this.compositeOverflowAction); // Ensure to remove disposable from this._store
	this.compositeOverflowAction.dispose();
	this.compositeOverflowAction = undefined;

	if (this.compositeOverflowActionViewItem) {
		this._store.delete(this.compositeOverflowActionViewItem);
		this.compositeOverflowActionViewItem.dispose();
	}
}

Before

When creating and closing a terminal 197 times, the number of functions related to CompositeOverflowActivityItem grows by one each time:

After

No more memory leak related to composite bar is detected:

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@bpasero

Matched files:

• src/vs/workbench/browser/parts/compositeBar.ts

[benibenj]

Thank you very much for looking into this and creating a PR! I think mutable disposables would be very handy in this case. I created a PR against your branch, hope you are fine with that approach. SimonSiefke#60