| /** |
| * 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.hdfs.server.namenode; |
| |
| import java.util.*; |
| |
| /** Manage name-to-serial-number maps for users and groups. */ |
| class SerialNumberManager { |
| /** This is the only instance of {@link SerialNumberManager}.*/ |
| static final SerialNumberManager INSTANCE = new SerialNumberManager(); |
| |
| private SerialNumberMap<String> usermap = new SerialNumberMap<String>(); |
| private SerialNumberMap<String> groupmap = new SerialNumberMap<String>(); |
| |
| private SerialNumberManager() {} |
| |
| int getUserSerialNumber(String u) {return usermap.get(u);} |
| int getGroupSerialNumber(String g) {return groupmap.get(g);} |
| String getUser(int n) {return usermap.get(n);} |
| String getGroup(int n) {return groupmap.get(n);} |
| |
| { |
| getUserSerialNumber(null); |
| getGroupSerialNumber(null); |
| } |
| |
| private static class SerialNumberMap<T> { |
| private int max = 0; |
| private int nextSerialNumber() {return max++;} |
| |
| private Map<T, Integer> t2i = new HashMap<T, Integer>(); |
| private Map<Integer, T> i2t = new HashMap<Integer, T>(); |
| |
| synchronized int get(T t) { |
| Integer sn = t2i.get(t); |
| if (sn == null) { |
| sn = nextSerialNumber(); |
| t2i.put(t, sn); |
| i2t.put(sn, t); |
| } |
| return sn; |
| } |
| |
| synchronized T get(int i) { |
| if (!i2t.containsKey(i)) { |
| throw new IllegalStateException("!i2t.containsKey(" + i |
| + "), this=" + this); |
| } |
| return i2t.get(i); |
| } |
| |
| /** {@inheritDoc} */ |
| public String toString() { |
| return "max=" + max + ",\n t2i=" + t2i + ",\n i2t=" + i2t; |
| } |
| } |
| } |