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 org.apache.hive.service.cli.session;
  
  /**
   * Proxy wrapper on HiveSession to execute operations
   * by impersonating given user
   */
  import java.lang.reflect.InvocationHandler;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.lang.reflect.Proxy;
  import java.lang.reflect.UndeclaredThrowableException;
  import java.security.PrivilegedActionException;
  import java.security.PrivilegedExceptionAction;
  
  import org.apache.hadoop.security.UserGroupInformation;
  import org.apache.hive.service.cli.HiveSQLException;
  
  public class HiveSessionProxy implements InvocationHandler {
    private final HiveSession base;
    private final UserGroupInformation ugi;
  
    public HiveSessionProxy(HiveSession hiveSession, UserGroupInformation ugi) {
      this.base = hiveSession;
      this.ugi = ugi;
    }
  
    public static HiveSession getProxy(HiveSession hiveSession, UserGroupInformation ugi)
        throws IllegalArgumentException, HiveSQLException {
      return (HiveSession)Proxy.newProxyInstance(HiveSession.class.getClassLoader(),
          new Class<?>[] {HiveSession.class},
          new HiveSessionProxy(hiveSession, ugi));
    }
  
    @Override
    public Object invoke(Object arg0, final Method method, final Object[] args)
        throws Throwable {
      try {
        if (method.getDeclaringClass() == HiveSessionBase.class) {
          return invoke(method, args);
        }
        return ugi.doAs(
          new PrivilegedExceptionAction<Object>() {
            @Override
            public Object run() throws HiveSQLException {
              return invoke(method, args);
            }
          });
      } catch (UndeclaredThrowableException e) {
        Throwable innerException = e.getCause();
        if (innerException instanceof PrivilegedActionException) {
          throw innerException.getCause();
        } else {
          throw e.getCause();
        }
      }
    }
  
    private Object invoke(final Method method, final Object[] args) throws HiveSQLException {
      try {
        return method.invoke(base, args);
      } catch (InvocationTargetException e) {
        if (e.getCause() instanceof HiveSQLException) {
          throw (HiveSQLException)e.getCause();
        }
        throw new RuntimeException(e.getCause());
      } catch (IllegalArgumentException e) {
        throw new RuntimeException(e);
      } catch (IllegalAccessException e) {
        throw new RuntimeException(e);
      }
    }
  }
  
  