Add idle mode for not "in component" used services. (performance optimization)

[betula]

Interested idea to add counter of subscribed components, and when count of subscribed react component stay 0, don't recalculate data in this store.
Think about It.

[betula]

sleep - return action, when count of components use call useProvide or useSubscribe equal 0. Service is idle.
idle - return boolean, true when count of subscribed (through useProvide or useSubscribe) component is 0
awake - return action, when count of components who use call useProvide or useSubscribe more then 0

class Counters {
  todo = provide(Todo);
  store = {
    active: 0,
    completed: 0
  }
  constructor() {
    subscribe(this.todo, this.calculate, this);
    subscribe(TodoItemChanged, this.calculate, this);
    subscribe(awake(this), this.calculate, this);
    subscribe(sleep(this), this.sleep, this);
    this.calculate();
  }
  calculate() {
    if (idle(this)) return;
    const items = this.todo.store;
    const completed = items.filter(item => item.store.completed).length;
    const active = items.length - completed;
    this.store = { completed, active };
  }
  sleep() {
    console.log('sleep');
  }
}