| /* |
| * 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.cassandra.utils; |
| |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.Map; |
| import java.util.Objects; |
| import java.util.Set; |
| import java.util.concurrent.ConcurrentHashMap; |
| |
| /** |
| * |
| * A variant of BiMap that permits concurrent access, and expects uniqueness of values in both domain and range. |
| * We synchronize on _modifications only_, and use ConcurrentHashMap so that readers can lookup safely. This does mean there |
| * could be races to lookup the inverse, but we aren't too worried about that. |
| * |
| * @param <K> |
| * @param <V> |
| */ |
| public class ConcurrentBiMap<K, V> implements Map<K, V> |
| { |
| protected final Map<K, V> forwardMap; |
| protected final Map<V, K> reverseMap; |
| |
| public ConcurrentBiMap() |
| { |
| this(new ConcurrentHashMap<K, V>(16, 0.5f, 1), new ConcurrentHashMap<V, K>(16, 0.5f, 1)); |
| } |
| |
| protected ConcurrentBiMap(Map<K, V> forwardMap, Map<V, K> reverseMap) |
| { |
| this.forwardMap = forwardMap; |
| this.reverseMap = reverseMap; |
| } |
| |
| public Map<V, K> inverse() |
| { |
| return Collections.unmodifiableMap(reverseMap); |
| } |
| |
| public void clear() |
| { |
| forwardMap.clear(); |
| reverseMap.clear(); |
| } |
| |
| public boolean containsKey(Object key) |
| { |
| return forwardMap.containsKey(key); |
| } |
| |
| public boolean containsValue(Object value) |
| { |
| return reverseMap.containsKey(value); |
| } |
| |
| public Set<Entry<K, V>> entrySet() |
| { |
| return forwardMap.entrySet(); |
| } |
| |
| public V get(Object key) |
| { |
| return forwardMap.get(key); |
| } |
| |
| public boolean isEmpty() |
| { |
| return forwardMap.isEmpty(); |
| } |
| |
| public Set<K> keySet() |
| { |
| return forwardMap.keySet(); |
| } |
| |
| public synchronized V put(K key, V value) |
| { |
| K oldKey = reverseMap.get(value); |
| if (oldKey != null && !key.equals(oldKey)) |
| throw new IllegalArgumentException(value + " is already bound in reverseMap to " + oldKey); |
| V oldVal = forwardMap.put(key, value); |
| if (oldVal != null && !Objects.equals(reverseMap.remove(oldVal), key)) |
| throw new IllegalStateException(); // for the prior mapping to be correct, we MUST get back the key from the reverseMap |
| reverseMap.put(value, key); |
| return oldVal; |
| } |
| |
| public synchronized void putAll(Map<? extends K, ? extends V> m) |
| { |
| for (Entry<? extends K, ? extends V> entry : m.entrySet()) |
| put(entry.getKey(), entry.getValue()); |
| } |
| |
| public synchronized V remove(Object key) |
| { |
| V oldVal = forwardMap.remove(key); |
| if (oldVal == null) |
| return null; |
| Object oldKey = reverseMap.remove(oldVal); |
| if (oldKey == null || !oldKey.equals(key)) |
| throw new IllegalStateException(); // for the prior mapping to be correct, we MUST get back the key from the reverseMap |
| return oldVal; |
| } |
| |
| public int size() |
| { |
| return forwardMap.size(); |
| } |
| |
| public Collection<V> values() |
| { |
| return reverseMap.keySet(); |
| } |
| } |