webhcat/svr/src/main/java/org/apache/hcatalog/templeton/UgiFactory.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.hcatalog.templeton;

import java.io.IOException;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.hadoop.security.UserGroupInformation;

public class UgiFactory {
    private static ConcurrentHashMap<String, UserGroupInformation> userUgiMap =
            new ConcurrentHashMap<String, UserGroupInformation>();
    
    static UserGroupInformation getUgi(String user) throws IOException{
        UserGroupInformation ugi = userUgiMap.get(user);
        if(ugi == null){
            //create new ugi and add to map
            final UserGroupInformation newUgi = 
                    UserGroupInformation.createProxyUser(user,
                            UserGroupInformation.getLoginUser());

            //if another thread adds an entry before the check in this one
            // the one created here will not be added.
            userUgiMap.putIfAbsent(user, newUgi);

            //use the UGI object that got added
            return userUgiMap.get(user);
            
        }
        return ugi;
    }
    
    
}