| /* |
| * 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.aries.rsa.topologymanager.importer; |
| |
| import java.util.Collections; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.CopyOnWriteArraySet; |
| |
| /** |
| * Minimal implementation of a thread-safe map where each key can have multiple values. |
| * |
| * @param <K> the key type |
| * @param <V> the value type |
| */ |
| public class MultiMap<K, V> { |
| |
| private Map<K, Set<V>> map; |
| |
| public MultiMap() { |
| map = new ConcurrentHashMap<>(); |
| } |
| |
| public void put(K key, V value) { |
| map.compute(key, (k, v) -> { |
| if (v == null) { |
| v = new CopyOnWriteArraySet<>(); |
| } |
| v.add(value); |
| return v; |
| }); |
| } |
| |
| public Set<V> get(K key) { |
| Set<V> values = map.get(key); |
| return values == null ? Collections.emptySet() : Collections.unmodifiableSet(values); |
| } |
| |
| public void remove(K key, V value) { |
| // reminder: returning null from the compute lambda will remove the mapping |
| map.compute(key, (k, v) -> v != null && v.remove(value) && v.isEmpty() ? null : v); |
| } |
| |
| public void remove(V value) { |
| for (K key : map.keySet()) { |
| remove(key, value); |
| } |
| } |
| |
| public Set<K> keySet() { |
| return map.keySet(); |
| } |
| |
| public void clear() { |
| map.clear(); |
| } |
| } |