Java 类org.apache.zookeeper.KeeperException.BadVersionException 实例源码

@Test
public void testMagicVersionNumberAllowsUnconditionalUpdate() throws Exception {
  String nodePath = "/foo";
  ZooKeeperClient zkClient = createZkClient();

  zkClient.get().create(nodePath, "init".getBytes(), ZooDefs.Ids.OPEN_ACL_UNSAFE,
      CreateMode.PERSISTENT);

  Stat initStat = new Stat();
  byte[] initialData = zkClient.get().getData(nodePath, false, initStat);
  assertArrayEquals("init".getBytes(), initialData);

  // bump the version
  Stat rev1Stat = zkClient.get().setData(nodePath, "rev1".getBytes(), initStat.getVersion());

  try {
    zkClient.get().setData(nodePath, "rev2".getBytes(), initStat.getVersion());
    fail("expected correct version to be required");
  } catch (BadVersionException e) {
    // expected
  }

  // expect using the correct version to work
  Stat rev2Stat = zkClient.get().setData(nodePath, "rev2".getBytes(), rev1Stat.getVersion());
  assertNotEquals(ZooKeeperUtils.ANY_VERSION, rev2Stat.getVersion());

  zkClient.get().setData(nodePath, "force-write".getBytes(), ZooKeeperUtils.ANY_VERSION);
  Stat forceWriteStat = new Stat();
  byte[] forceWriteData = zkClient.get().getData(nodePath, false, forceWriteStat);
  assertArrayEquals("force-write".getBytes(), forceWriteData);

  assertTrue(forceWriteStat.getVersion() > rev2Stat.getVersion());
  assertNotEquals(ZooKeeperUtils.ANY_VERSION, forceWriteStat.getVersion());
}

@Override
public Future<Boolean> expunge(final Variable variable)
{
    checkNotNull(variable, "variable is null");
    checkState(!closed.get(), "already closed");
    checkState(variable instanceof ZookeeperVariable, "can not process native variable, use ZookeeperVariable");

    final ZookeeperVariable v = (ZookeeperVariable) variable;
    final String fullName = getFullPath(v.getName());

    return executor.submit(new Callable<Boolean>() {
        @Override
        public Boolean call() throws Exception
        {
            ZookeeperVariable current = load(fullName);

            while (true) {
                if (current == null) {
                    return false;
                }

                if (!current.getUuid().equals(v.getUuid())) {
                    return false;
                }

                checkState(current.getZookeeperVersion() != null, "expunge with unknown zookeeper version (%s)", current.getEntry());

                try {
                    client.delete(fullName, current.getZookeeperVersion());
                    return true;
                }
                catch (BadVersionException | NoNodeException e) {
                    // Version has changed under us or the node has disappeared. Retry (which will probably fail unless it was deleted).
                    LOG.debug("Could not change version %d, retry expunging", current.getZookeeperVersion());
                }

                // Current could be null here if the node was deleted while we were not looking.
                current = load(fullName);
            }
        }
    });
}