content: /*
   * Copyright 2021 4Paradigm
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com._4paradigm.openmldb.taskmanager.zk;
  
  import org.apache.zookeeper.CreateMode;
  import org.apache.zookeeper.KeeperException;
  import org.apache.zookeeper.ZooDefs.Ids;
  import org.apache.zookeeper.ZooKeeper;
  import org.apache.zookeeper.data.ACL;
  import org.apache.zookeeper.data.Stat;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import javax.annotation.Nullable;
  import java.util.ArrayList;
  
  /**
   * Most code is from HBase ZKUtil and ZooKeeperWatcher is replaced with FailoverWatcher.
   */
  public class ZooKeeperUtil {
      private static final Logger LOG = LoggerFactory.getLogger(ZooKeeperUtil.class);
  
      public static boolean watchAndCheckExists(FailoverWatcher failoverWatcher, String znode) throws KeeperException {
          try {
              Stat s = failoverWatcher.getZooKeeper().exists(znode, failoverWatcher);
              boolean exists = s != null;
              if (LOG.isDebugEnabled()) {
                  if (exists) {
                      LOG.debug("Set watcher on existing znode " + znode);
                  } else {
                      LOG.debug(znode + " does not exist. Watcher is set.");
                  }
              }
              return exists;
          } catch (KeeperException e) {
              LOG.warn("Unable to set watcher on znode " + znode, e);
              LOG.warn("Received unexpected KeeperException, re-throwing exception");
              throw e;
          } catch (InterruptedException e) {
              LOG.warn("Unable to set watcher on znode " + znode, e);
              return false;
          }
      }
  
      public static boolean createEphemeralNodeAndWatch(FailoverWatcher failoverWatcher, String znode, byte[] data)
              throws KeeperException {
          try {
              LOG.info("Try to create emphemeral znode " + znode);
              failoverWatcher.getZooKeeper().create(znode, data, Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL);
          } catch (KeeperException.NodeExistsException nee) {
              if (!watchAndCheckExists(failoverWatcher, znode)) {
                  // It did exist but now it doesn't, try again
                  return createEphemeralNodeAndWatch(failoverWatcher, znode, data);
              }
              return false;
          } catch (InterruptedException e) {
              LOG.info("Interrupted", e);
              Thread.currentThread().interrupt();
          }
          return true;
      }
  
      public static void deleteNode(FailoverWatcher failoverWatcher, String node) throws KeeperException {
          deleteNode(failoverWatcher, node, -1);
      }
  
      public static boolean deleteNode(FailoverWatcher failoverWatcher, String node, int version) throws KeeperException {
          try {
              failoverWatcher.getZooKeeper().delete(node, version);
              return true;
          } catch (KeeperException.BadVersionException bve) {
              LOG.debug("Bad version exception when delete node '{}'", node, bve);
              return false;
          } catch (InterruptedException ie) {
              LOG.debug("Received InterruptedException, doing nothing here", ie);
              return false;
          }
      }
  
      public static byte[] getDataAndWatch(FailoverWatcher failoverWatcher, String znode) {
          return getDataInternal(failoverWatcher, znode, null);
      }
  
      @Nullable
      private static byte[] getDataInternal(FailoverWatcher failoverWatcher, String znode, Stat stat) {
          try {
              byte[] data = failoverWatcher.getZooKeeper().getData(znode, failoverWatcher, stat);
              if (LOG.isDebugEnabled()) {
                  LOG.debug("Retrieved " + ((data == null) ? 0 : data.length) + " byte(s) of data from znode " + znode);
              }
              return data;
          } catch (KeeperException.NoNodeException e) {
              if (LOG.isDebugEnabled()) {
                  LOG.debug("Unable to get data of znode " + znode + " " + "because node does not exist (not an error)");
              }
              return null;
          } catch (KeeperException | InterruptedException e) {
              LOG.warn("Unable to get data of znode " + znode, e);
              LOG.warn("Received unexpected KeeperException, re-throwing exception");
              return null;
          }
      }
  
      public static void createAndFailSilent(FailoverWatcher failoverWatcher, String znode)
              throws KeeperException, InterruptedException {
          try {
              LOG.info("Try to create persistent znode " + znode);
              ZooKeeper zk = failoverWatcher.getZooKeeper();
              if (zk.exists(znode, false) == null) {
                  zk.create(znode, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
              }
          } catch (KeeperException.NodeExistsException ignore) {
              // we just ignore result if the node already exist
              LOG.info("Znode " + znode + " already exist");
          } catch (KeeperException.NoAuthException nee) {
              try {
                  if (null == failoverWatcher.getZooKeeper().exists(znode, false)) {
                      // If we failed to create the file and it does not already exist.
                      throw nee;
                  }
              } catch (InterruptedException ie) {
                  LOG.debug("Received InterruptedException, re-throw the exception", ie);
                  throw ie;
              }
          } catch (InterruptedException ie) {
              LOG.debug("Received InterruptedException, re-throw the exception", ie);
              throw ie;
          }
      }
  
  }
  