分布式锁到期后：怎样挡住旧任务的写入

import java.util.*;

public class Main {
  record Receipt(long delta, long result) {}
  static final class Resource {
    private long highest = 0, value = 0;
    private final Map<String, Receipt> applied = new HashMap<>();
    synchronized long apply(long token, String operation, long delta) {
      if (token <= 0 || operation == null || operation.isBlank())
        throw new IllegalArgumentException("request");
      if (token < highest) throw new IllegalStateException("stale token"); // 旧代次先拒绝
      Receipt previous = applied.get(operation);
      if (previous != null) {
        if (previous.delta() != delta) throw new IllegalArgumentException("operation reused");
        highest = token; // 新代次重试相同业务可以推进隔离线，但不重复修改值
        return previous.result();
      }
      long next = Math.addExact(value, delta);
      if (next < 0) throw new IllegalArgumentException("negative value");
      value = next;
      highest = token;
      applied.put(operation, new Receipt(delta, next)); // 三份状态处于同一个原子边界
      return next;
    }
    synchronized long value() { return value; }
    synchronized long highest() { return highest; }
  }
  static void check(boolean ok) { if (!ok) throw new AssertionError(); }
  static void bad(Class<? extends RuntimeException> type, Runnable action) {
    try { action.run(); }
    catch (RuntimeException e) { if (type.isInstance(e)) return; throw e; }
    throw new AssertionError("expected rejection");
  }
  public static void main(String[] args) {
    Resource r = new Resource();
    check(r.apply(11,"A",5)==5);
    check(r.apply(11,"A",5)==5 && r.value()==5); // 相同请求不累计
    check(r.apply(12,"B",3)==8);
    bad(IllegalStateException.class, () -> r.apply(11,"C",2));
    check(r.apply(12,"C",2)==10); // 同一有效代次可承载不同操作
    check(r.apply(13,"A",5)==5 && r.value()==10 && r.highest()==13);
    bad(IllegalStateException.class, () -> r.apply(12,"D",1));
    bad(IllegalArgumentException.class, () -> r.apply(13,"A",6));
    bad(IllegalArgumentException.class, () -> r.apply(14,"E",-11));
    check(r.value()==10 && r.highest()==13); // 无效请求不留下半更新
    System.out.println("10 fencing and idempotency checks passed");
  }
}