hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-nativetask/src/main/java/org/apache/hadoop/mapred/nativetask/Platforms.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.mapred.nativetask;

import java.io.IOException;
import java.util.ServiceLoader;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapred.JobConf;
import org.apache.hadoop.mapred.nativetask.serde.INativeSerializer;
import org.apache.hadoop.mapred.nativetask.serde.NativeSerialization;


/**
 * this class will load in and init all platforms on classpath
 * it is also the facade to check for key type support and other
 * platform methods
 */
@InterfaceAudience.Private
public class Platforms {

  private static final Log LOG = LogFactory.getLog(Platforms.class);
  private static final ServiceLoader<Platform> platforms = ServiceLoader.load(Platform.class);
  
  public static void init(Configuration conf) throws IOException {

    NativeSerialization.getInstance().reset();
    synchronized (platforms) {
      for (Platform platform : platforms) {
        platform.init();
      }
    }
  }

  public static boolean support(String keyClassName,
      INativeSerializer<?> serializer, JobConf job) {
    synchronized (platforms) {
      for (Platform platform : platforms) {
        if (platform.support(keyClassName, serializer, job)) {
          LOG.debug("platform " + platform.name() + " support key class"
            + keyClassName);
          return true;
        }
      }
    }
    return false;
  }

  public static boolean define(Class<?> keyComparator) {
    synchronized (platforms) {
      for (Platform platform : platforms) {
        if (platform.define(keyComparator)) {
          LOG.debug("platform " + platform.name() + " define comparator "
            + keyComparator.getName());
          return true;
        }
      }
    }
    return false;
  }
}