src/main/java/org/apache/hadoop/chukwa/extraction/engine/datasource/DsDirectory.java

/*
 * 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 org.apache.hadoop.chukwa.extraction.engine.datasource;


import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.hadoop.chukwa.inputtools.mdl.DataConfig;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;

public class DsDirectory {
  private static Object lock = new Object();
  private static DsDirectory dsDirectory = null;
  private static final String[] emptyArray = new String[0];

  private String rootFolder = null;
  private DataConfig dataConfig = null;

  private static FileSystem fs = null;
  private Configuration conf = null;

  private DsDirectory() {
    dataConfig = new DataConfig();
    conf = new Configuration();
    try {
      fs = FileSystem.get(conf);
    } catch (IOException e) {
      e.printStackTrace();
    }
    rootFolder = dataConfig.get("chukwa.engine.dsDirectory.rootFolder");
    if (!rootFolder.endsWith("/")) {
      rootFolder += "/";
    }
  }

  public static DsDirectory getInstance() {
    synchronized (lock) {
      if (dsDirectory == null) {
        dsDirectory = new DsDirectory();
      }
    }
    return dsDirectory;
  }

  public String[] list(String cluster) throws DataSourceException {
    List<String> datasources = new ArrayList<String>();
    try {
      FileStatus[] fileStat = fs.listStatus(new Path(rootFolder + cluster));

      for (FileStatus fstat : fileStat) {
        if (fstat.isDir()) {
          datasources.add(fstat.getPath().getName());
        }
      }
    } catch (IOException e) {
      e.printStackTrace();
      throw new DataSourceException(e);
    }
    return datasources.toArray(emptyArray);
  }

  public static void main(String[] args) throws DataSourceException {
    DsDirectory dsd = DsDirectory.getInstance();
    String[] dss = dsd.list("unknown");
    for (String d : dss) {
      System.out.println(d);
    }
  }
}