sclass ExpiringMap2<A, B> extends AbstractMap<A, B> {
  Map<A, Pair<Long, B>> byKey;
  new PriorityBlockingQueue<PairComparedByA<Long, A>> queue;
  long standardExpiryTime; // ms
  
  *() {}
  *(long *standardExpiryTime) {}
  
  void clean() {
    Pair<Long, A> p;
    while ((p = queue.peek()) != null && sysTime() >= p.a) {
      p = queue.poll();
      Pair<Long, B> v = byKey.get(p.a);
      if (v != null && v.a == p.a) byKey.remove(p.a);
    }
  }
  
  public B put(A a, B b) {
    clean();
    timeout = sysTime()+standardExpiryTime;
    Pair<Long, B> p = byKey.get(a);
    if (p != null) queue.remove(PairComparedByA(p.a, a));
    byKey.put(a, pair(timeout, b));
    queue.add(PairComparedByA(timeout, a));
  }
  
  public B remove(O a) {
    clean();
    Pair<Long, B> p = byKey.get(a);
    if (p == null) null;
    queue.remove(PairComparedByA(p.a, a));
    byKey.remove(a);
    ret p.b;
  }
  
  public B get(O a) {
    clean();
    ret pairB(byKey.get(a));
  }
  
  public Set<Map.Entry<A,B>> entrySet() {
    clean();
    ret mapValues(f pairB, byKey);
  }
}