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.meta;
  
  import com.alibaba.wasp.FConstants;
  import com.alibaba.wasp.MasterNotRunningException;
  import com.alibaba.wasp.MetaException;
  import com.alibaba.wasp.ZooKeeperConnectionException;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.HColumnDescriptor;
  import org.apache.hadoop.hbase.HTableDescriptor;
  import org.apache.hadoop.hbase.client.HBaseAdmin;
  
  import java.io.IOException;
  
  /**
   * 
   *
   */
  public class FMetaUtil {
  
    public static final Log LOG = LogFactory.getLog(FMetaUtil.class);
  
    /**
     * Use HBaseAdmin to check the meta table exists. if not exists create it. if
     * exists just return.
     */
    public static void checkAndInit(Configuration conf) throws MetaException {
      try {
        HBaseAdmin admin = new HBaseAdmin(conf);
        String metaTable = conf.get(FConstants.METASTORE_TABLE,
            FConstants.DEFAULT_METASTORE_TABLE);
        if (!admin.tableExists(metaTable)) {
          // if meta table don't exists just create it.
          HTableDescriptor desc = new HTableDescriptor(metaTable);
          HColumnDescriptor family = new HColumnDescriptor(
              FConstants.CATALOG_FAMILY_STR);
          family.setInMemory(true);
          desc.addFamily(family);
          admin.createTable(desc);
        }
        admin.close();
      } catch (ZooKeeperConnectionException zce) {
        throw new MetaException("FMeta could not connect to zookeeper ", zce);
      } catch (MasterNotRunningException mnre) {
        throw new MetaException("FMeta Could not connect to HBase Master ", mnre);
      } catch (IOException e) {
        throw new MetaException(e);
      }
    }
  
    /**
     * Use HBaseAdmin to delete the meta table .
     */
    public static boolean clean(Configuration conf) {
      try {
        HBaseAdmin admin = new HBaseAdmin(conf);
        String metaTable = conf.get(FConstants.METASTORE_TABLE,
            FConstants.DEFAULT_METASTORE_TABLE);
        if (admin.tableExists(metaTable)) {
          admin.disableTable(metaTable);
          admin.deleteTable(metaTable);
        }
        admin.close();
        return true;
      } catch (ZooKeeperConnectionException zce) {
        LOG.error("Could not connect to zookeeper ", zce);
      } catch (MasterNotRunningException mnre) {
        LOG.error("Could not connect to HBase Master ", mnre);
      } catch (IOException e) {
        LOG.error(e);
      }
      return false;
    }
  }