onAbort method

@override void Function() onAbort(void listener())

Registers one notification and returns an idempotent removal function.

Notifications run asynchronously in the registration's zone, including registrations made after cancellation. Removing a queued notification suppresses it. A notification is not confirmation that work has stopped.

Implementation

@override
void Function() onAbort(void Function() listener) {
  final registration = _AbortRegistration(listener, Zone.current);
  (_listeners ??= {}).add(registration);
  try {
    if (_notified || aborted) {
      _notify();
    } else if (!_armed) {
      _armed = true;
      armAbort();
      // An adapter may synchronously observe an abort while arming.
      if (aborted) notifyAbort();
    }
  } catch (_) {
    _remove(registration);
    rethrow;
  }
  // Keeping this function is an ordinary Dart root for the token.
  return () => _remove(registration);
}