hadoop-mapreduce/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/factory/providers/RecordFactoryProvider.java

package org.apache.hadoop.yarn.factory.providers;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.yarn.YarnException;
import org.apache.hadoop.yarn.factories.RecordFactory;
import org.apache.hadoop.yarn.factories.impl.pb.RecordFactoryPBImpl;

public class RecordFactoryProvider {

  public static final String RPC_SERIALIZER_KEY = "org.apache.yarn.ipc.rpc.serializer.property";
  public static final String RPC_SERIALIZER_DEFAULT = "protocolbuffers";
  
  public static final String RECORD_FACTORY_CLASS_KEY = "org.apache.yarn.ipc.record.factory.class";
  
  private static Configuration defaultConf;
  
  static {
    defaultConf = new Configuration();
  }
  
  private RecordFactoryProvider() {
  }
  
  public static RecordFactory getRecordFactory(Configuration conf) {
    if (conf == null) {
      //Assuming the default configuration has the correct factories set.
      //Users can specify a particular factory by providing a configuration.
      conf = defaultConf;
    }
    String recordFactoryClassName = conf.get(RECORD_FACTORY_CLASS_KEY);
    if (recordFactoryClassName == null) {
      String serializer = conf.get(RPC_SERIALIZER_KEY, RPC_SERIALIZER_DEFAULT);
      if (serializer.equals(RPC_SERIALIZER_DEFAULT)) {
        return RecordFactoryPBImpl.get();
      } else {
        throw new YarnException("Unknown serializer: [" + conf.get(RPC_SERIALIZER_KEY) + "]. Use keys: [" + RECORD_FACTORY_CLASS_KEY + "] to specify Record factory");
      }
    } else {
      return (RecordFactory) getFactoryClassInstance(recordFactoryClassName);
    }
  }
  
  private static Object getFactoryClassInstance(String factoryClassName) {
    try {
      Class clazz = Class.forName(factoryClassName);
      Method method = clazz.getMethod("get", null);
      method.setAccessible(true);
      return method.invoke(null, null);
    } catch (ClassNotFoundException e) {
      throw new YarnException(e);
    } catch (NoSuchMethodException e) {
      throw new YarnException(e);
    } catch (InvocationTargetException e) {
      throw new YarnException(e);
    } catch (IllegalAccessException e) {
      throw new YarnException(e);
    }
  }
}