/*
* Licensed 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 com.facebook.presto.hive.authentication;
import org.apache.hadoop.security.UserGroupInformation;
import javax.annotation.concurrent.GuardedBy;
import javax.security.auth.Subject;
import javax.security.auth.kerberos.KerberosTicket;
import static com.facebook.presto.hive.authentication.KerberosTicketUtils.getTicketGrantingTicket;
import static com.google.common.base.Preconditions.checkArgument;
import static java.util.Objects.requireNonNull;
import static org.apache.hadoop.security.UserGroupInformationShim.getSubject;
public class CachingKerberosHadoopAuthentication
implements HadoopAuthentication
{
private final KerberosHadoopAuthentication delegate;
private final Object lock = new Object();
@GuardedBy("lock")
private UserGroupInformation userGroupInformation = null;
@GuardedBy("lock")
private long nextRefreshTime = Long.MIN_VALUE;
public CachingKerberosHadoopAuthentication(KerberosHadoopAuthentication delegate)
{
this.delegate = requireNonNull(delegate, "hadoopAuthentication is null");
}
@Override
public UserGroupInformation getUserGroupInformation()
{
synchronized (lock) {
if (refreshIsNeeded()) {
refreshUgi();
}
}
return userGroupInformation;
}
private void refreshUgi()
{
userGroupInformation = delegate.getUserGroupInformation();
nextRefreshTime = calculateNextRefreshTime(userGroupInformation);
}
private boolean refreshIsNeeded()
{
return nextRefreshTime < System.currentTimeMillis() || userGroupInformation == null;
}
private long calculateNextRefreshTime(UserGroupInformation userGroupInformation)
{
Subject subject = getSubject(userGroupInformation);
checkArgument(subject != null, "subject must be present in kerberos based UGI");
KerberosTicket tgtTicket = getTicketGrantingTicket(subject);
return KerberosTicketUtils.getRefreshTime(tgtTicket);
}
}