/*
    * 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.dataloader;
  
  import java.io.IOException;
  import java.util.concurrent.CompletionService;
  import java.util.concurrent.ExecutorCompletionService;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.fs.FileStatus;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.chukwa.conf.ChukwaConfiguration;
  import org.apache.hadoop.chukwa.util.ExceptionUtil;
  
  public class MetricDataLoaderPool extends DataLoaderFactory {
    private static Log log = LogFactory.getLog(MetricDataLoaderPool.class);
  
    protected MetricDataLoader threads[] = null;
    private static String DATA_LOADER_THREAD_LIMIT = "chukwa.data.loader.threads.limit";
    private int size = 1;
    private static CompletionService completion = null;
    private static ExecutorService executor = null;
    
    public MetricDataLoaderPool() {
    }
    
    public void load(ChukwaConfiguration conf, FileSystem fs, FileStatus[] fileList) throws IOException {
  
      if(executor==null) {
        try {
          this.size = Integer.parseInt(conf.get(DATA_LOADER_THREAD_LIMIT));
        } catch(Exception e) {
          this.size = 1;
        }
        executor = Executors.newFixedThreadPool(size);
      }
      if(completion==null) {
        completion = new ExecutorCompletionService(executor);
      }
      try {
        for(int i=0;i<fileList.length;i++) {
          String filename = fileList[i].getPath().toUri().toString();
          log.info("Processing: "+filename);
          completion.submit(new MetricDataLoader(conf, fs, filename));      
        }
        for(int i=0;i<fileList.length;i++) {
          completion.take().get();
        }
      } catch(Exception e) {
        log.error(ExceptionUtil.getStackTrace(e));
        throw new IOException();
      }
    }
  
    public void shutdown() throws InterruptedException {
      executor.shutdown();
      executor.awaitTermination(30, TimeUnit.SECONDS);
      executor.shutdownNow();
    }
  }