001    /**
002    * Licensed to the Apache Software Foundation (ASF) under one
003    * or more contributor license agreements.  See the NOTICE file
004    * distributed with this work for additional information
005    * regarding copyright ownership.  The ASF licenses this file
006    * to you under the Apache License, Version 2.0 (the
007    * "License"); you may not use this file except in compliance
008    * with the License.  You may obtain a copy of the License at
009    *
010    *     http://www.apache.org/licenses/LICENSE-2.0
011    *
012    * Unless required by applicable law or agreed to in writing, software
013    * distributed under the License is distributed on an "AS IS" BASIS,
014    * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015    * See the License for the specific language governing permissions and
016    * limitations under the License.
017    */
018    
019    package org.apache.hadoop.yarn.security.client;
020    
021    import java.util.Collection;
022    
023    import org.apache.commons.logging.Log;
024    import org.apache.commons.logging.LogFactory;
025    import org.apache.hadoop.classification.InterfaceAudience.Public;
026    import org.apache.hadoop.classification.InterfaceStability.Stable;
027    import org.apache.hadoop.io.Text;
028    import org.apache.hadoop.security.token.Token;
029    import org.apache.hadoop.security.token.TokenIdentifier;
030    import org.apache.hadoop.security.token.TokenSelector;
031    
032    @Public
033    @Stable
034    public class RMDelegationTokenSelector implements
035        TokenSelector<RMDelegationTokenIdentifier> {
036    
037      private static final Log LOG = LogFactory
038          .getLog(RMDelegationTokenSelector.class);
039    
040      @SuppressWarnings("unchecked")
041      public Token<RMDelegationTokenIdentifier> selectToken(Text service,
042          Collection<Token<? extends TokenIdentifier>> tokens) {
043        if (service == null) {
044          return null;
045        }
046        LOG.debug("Looking for a token with service " + service.toString());
047        for (Token<? extends TokenIdentifier> token : tokens) {
048          LOG.debug("Token kind is " + token.getKind().toString()
049              + " and the token's service name is " + token.getService());
050          if (RMDelegationTokenIdentifier.KIND_NAME.equals(token.getKind())
051              && service.equals(token.getService())) {
052            return (Token<RMDelegationTokenIdentifier>) token;
053          }
054        }
055        return null;
056      }
057    
058    }