content: /**
   *
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.alibaba.wasp.zookeeper;
  
  import com.alibaba.wasp.DeserializationException;
  import com.alibaba.wasp.protobuf.generated.LoadBalancerProtos;
  import com.google.protobuf.InvalidProtocolBufferException;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.Abortable;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.zookeeper.KeeperException;
  
  public class LoadBalancerTracker extends ZooKeeperNodeTracker {
    private static final Log LOG = LogFactory.getLog(LoadBalancerTracker.class);
  
    public LoadBalancerTracker(ZooKeeperWatcher watcher, Abortable abortable) {
      super(watcher, watcher.balancerZNode, abortable);
    }
  
    /**
     * Return true if the balance switch is on, false otherwise
     */
    public boolean isBalancerOn() {
      byte[] upData = super.getData(false);
      try {
        // if data in ZK is null, use default of on.
        return upData == null || parseFrom(upData).getBalancerOn();
      } catch (DeserializationException dex) {
        LOG.error("ZK state for LoadBalancer could not be parsed "
            + Bytes.toStringBinary(upData));
        // return false to be safe.
        return false;
      }
    }
  
    /**
     * Set the balancer on/off
     * 
     * @param balancerOn
     * @throws org.apache.zookeeper.KeeperException
     */
    public void setBalancerOn(boolean balancerOn) throws KeeperException {
      byte[] upData = toByteArray(balancerOn);
      try {
        ZKUtil.createAndWatch(watcher, watcher.balancerZNode, upData);
      } catch (KeeperException.NodeExistsException nee) {
        ZKUtil.setData(watcher, watcher.balancerZNode, upData);
      }
      super.nodeDataChanged(watcher.balancerZNode);
    }
  
    private byte[] toByteArray(boolean isBalancerOn) {
      LoadBalancerProtos.LoadBalancerState.Builder builder = LoadBalancerProtos.LoadBalancerState
          .newBuilder();
      builder.setBalancerOn(isBalancerOn);
      return builder.build().toByteArray();
    }
  
    private LoadBalancerProtos.LoadBalancerState parseFrom(byte[] pbBytes)
        throws DeserializationException {
      LoadBalancerProtos.LoadBalancerState.Builder builder = LoadBalancerProtos.LoadBalancerState
          .newBuilder();
      try {
        builder.mergeFrom(pbBytes, 0, pbBytes.length);
      } catch (InvalidProtocolBufferException e) {
        throw new DeserializationException(e);
      }
      return builder.build();
    }
  }
  