/**
* 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.hadoop.mapred.gridmix;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.hadoop.util.LineReader;
import java.io.IOException;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
public class RoundRobinUserResolver implements UserResolver {
public static final Log LOG = LogFactory.getLog(RoundRobinUserResolver.class);
private int uidx = 0;
private List<UserGroupInformation> users = Collections.emptyList();
/**
* Mapping between user names of original cluster and UGIs of proxy users of
* simulated cluster
*/
private final HashMap<String,UserGroupInformation> usercache =
new HashMap<String,UserGroupInformation>();
/**
* Userlist assumes one user per line.
* Each line in users-list-file is of the form <username>[,group]*
* <br> Group names are ignored(they are not parsed at all).
*/
private List<UserGroupInformation> parseUserList(URI userUri,
Configuration conf)
throws IOException {
if (null == userUri) {
return Collections.emptyList();
}
final Path userloc = new Path(userUri.toString());
final Text rawUgi = new Text();
final FileSystem fs = userloc.getFileSystem(conf);
final ArrayList<UserGroupInformation> ugiList =
new ArrayList<UserGroupInformation>();
LineReader in = null;
try {
in = new LineReader(fs.open(userloc));
while (in.readLine(rawUgi) > 0) {//line is of the form username[,group]*
if(rawUgi.toString().trim().equals("")) {
continue; //Continue on empty line
}
// e is end position of user name in this line
int e = rawUgi.find(",");
if (e == 0) {
throw new IOException("Missing username: " + rawUgi);
}
if (e == -1) {
e = rawUgi.getLength();
}
final String username = Text.decode(rawUgi.getBytes(), 0, e).trim();
UserGroupInformation ugi = null;
try {
ugi = UserGroupInformation.createProxyUser(username,
UserGroupInformation.getLoginUser());
} catch (IOException ioe) {
LOG.error("Error while creating a proxy user " ,ioe);
}
if (ugi != null) {
ugiList.add(ugi);
}
// No need to parse groups, even if they exist. Go to next line
}
} finally {
if (in != null) {
in.close();
}
}
return ugiList;
}
@Override
public synchronized boolean setTargetUsers(URI userloc, Configuration conf)
throws IOException {
uidx = 0;
users = parseUserList(userloc, conf);
if (users.size() == 0) {
throw new IOException(buildEmptyUsersErrorMsg(userloc));
}
usercache.clear();
return true;
}
static String buildEmptyUsersErrorMsg(URI userloc) {
return "Empty user list is not allowed for RoundRobinUserResolver. Provided"
+ " user resource URI '" + userloc + "' resulted in an empty user list.";
}
@Override
public synchronized UserGroupInformation getTargetUgi(
UserGroupInformation ugi) {
// UGI of proxy user
UserGroupInformation targetUGI = usercache.get(ugi.getUserName());
if (targetUGI == null) {
targetUGI = users.get(uidx++ % users.size());
usercache.put(ugi.getUserName(), targetUGI);
}
return targetUGI;
}
/**
* {@inheritDoc}
* <p>
* {@link RoundRobinUserResolver} needs to map the users in the
* trace to the provided list of target users. So user list is needed.
*/
public boolean needsTargetUsersList() {
return true;
}
}