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// Wrapper around a PressureObserver that:
// 1. Receives and stores multiple updates.
// 2. Allows callers to synchronously wait for an update.
//
// Usage:
// const syncObserver = new SyncPressureObserver(t);
// await syncObserver.observer().observe('cpu');
// await update_virtual_pressure_source(..);
// await syncObserver.waitForUpdate();
// const changes = syncObserver.changes();
// assert_equals(changes[0][0].state, 'nominal');
class SyncPressureObserver {
#observer = null;
#changes = [];
#promisesWithResolver = [Promise.withResolvers()];
#currentPromisePosition = 0;
#currentResolvePosition = 0;
constructor(t) {
this.#observer = new PressureObserver(changes => {
this.#changes.push(changes);
if (this.#currentResolvePosition === this.#promisesWithResolver.length) {
this.#promisesWithResolver.push(Promise.withResolvers());
}
this.#promisesWithResolver[this.#currentResolvePosition++].resolve();
});
t.add_cleanup(() => {this.#observer.disconnect()});
}
changes() {
return this.#changes;
}
observer() {
return this.#observer;
}
async waitForUpdate() {
if (this.#currentPromisePosition === this.#promisesWithResolver.length) {
this.#promisesWithResolver.push(Promise.withResolvers());
}
await this.#promisesWithResolver[this.#currentPromisePosition++].promise;
}
};
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