disposeAll method
Permanently closes the pool, including acquisitions already in flight.
Implementation
Future<void> disposeAll() {
if (_disposeFuture != null) return _disposeFuture!;
_isDisposed = true;
final ids = {..._handles.keys, ..._pending.keys, ..._releasing.keys};
return _disposeFuture = Future.wait(
ids.map(releaseConnection),
).then((_) {});
}