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HADOOP-10852 Fix thread safety issues in NetgroupCache. (Benoy Antony)

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This commit is contained in:
Benoy Antony 2014-12-15 14:00:25 -08:00
parent e597249d36
commit a095622f36
1 changed files with 33 additions and 28 deletions
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61
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/NetgroupCache.java
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@ -17,11 +17,11 @@
*/
package org.apache.hadoop.security;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.HashSet;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.hadoop.classification.InterfaceAudience;
@ -36,14 +36,9 @@
@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
@InterfaceStability.Unstable
public class NetgroupCache {
private static boolean netgroupToUsersMapUpdated = true;
private static Map<String, Set<String>> netgroupToUsersMap =
private static ConcurrentHashMap<String, Set<String>> userToNetgroupsMap =
new ConcurrentHashMap<String, Set<String>>();
private static Map<String, Set<String>> userToNetgroupsMap =
new ConcurrentHashMap<String, Set<String>>();
/**
* Get netgroups for a given user
*
@ -52,21 +47,11 @@ public class NetgroupCache {
*/
public static void getNetgroups(final String user,
List<String> groups) {
if(netgroupToUsersMapUpdated) {
netgroupToUsersMapUpdated = false; // at the beginning to avoid race
//update userToNetgroupsMap
for(String netgroup : netgroupToUsersMap.keySet()) {
for(String netuser : netgroupToUsersMap.get(netgroup)) {
// add to userToNetgroupsMap
if(!userToNetgroupsMap.containsKey(netuser)) {
userToNetgroupsMap.put(netuser, new HashSet<String>());
}
userToNetgroupsMap.get(netuser).add(netgroup);
}
}
}
if(userToNetgroupsMap.containsKey(user)) {
groups.addAll(userToNetgroupsMap.get(user));
Set<String> userGroups = userToNetgroupsMap.get(user);
//ConcurrentHashMap does not allow null values;
//So null value check can be used to check if the key exists
if (userGroups != null) {
groups.addAll(userGroups);
}
}
@ -76,7 +61,15 @@ public static void getNetgroups(final String user,
* @return list of cached groups
*/
public static List<String> getNetgroupNames() {
return new LinkedList<String>(netgroupToUsersMap.keySet());
return new LinkedList<String>(getGroups());
}
private static Set<String> getGroups() {
Set<String> allGroups = new HashSet<String> ();
for (Set<String> userGroups : userToNetgroupsMap.values()) {
allGroups.addAll(userGroups);
}
return allGroups;
}
/**
@ -86,14 +79,13 @@ public static List<String> getNetgroupNames() {
* @return true if group is cached, false otherwise
*/
public static boolean isCached(String group) {
return netgroupToUsersMap.containsKey(group);
return getGroups().contains(group);
}
/**
* Clear the cache
*/
public static void clear() {
netgroupToUsersMap.clear();
userToNetgroupsMap.clear();
}
@ -104,7 +96,20 @@ public static void clear() {
* @param users list of users for a given group
*/
public static void add(String group, List<String> users) {
netgroupToUsersMap.put(group, new HashSet<String>(users));
netgroupToUsersMapUpdated = true; // at the end to avoid race
for (String user : users) {
Set<String> userGroups = userToNetgroupsMap.get(user);
// ConcurrentHashMap does not allow null values;
// So null value check can be used to check if the key exists
if (userGroups == null) {
//Generate a ConcurrentHashSet (backed by the keyset of the ConcurrentHashMap)
userGroups =
Collections.newSetFromMap(new ConcurrentHashMap<String,Boolean>());
Set<String> currentSet = userToNetgroupsMap.putIfAbsent(user, userGroups);
if (currentSet != null) {
userGroups = currentSet;
}
}
userGroups.add(group);
}
}
}