content: /*
   *
   * 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.bookkeeper.util.collections;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Optional;
  import java.util.Set;
  import java.util.function.BiPredicate;
  import org.apache.commons.lang3.tuple.Pair;
  /**
   * Simple multimap implementation that only stores key reference once.
   *
   * <p>Implementation is aimed at storing PerChannelBookieClient completions when there
   * are duplicates. If the key is a pooled object, it must not exist once the value
   * has been removed from the map, which can happen with guava multimap implementations.
   *
   * <p>With this map is implemented with pretty heavy locking, but this shouldn't be an
   * issue as the multimap only needs to be used in rare cases, i.e. when a user tries
   * to read or the same entry twice at the same time. This class should *NOT*  be used
   * in critical path code.
   *
   * <p>A unique key-value pair will only be stored once.
   */
  public class SynchronizedHashMultiMap<K, V> {
  
      HashMap<Integer, Set<Pair<K, V>>> map = new HashMap<>();
  
      public synchronized void put(K k, V v) {
          map.computeIfAbsent(k.hashCode(), (ignore) -> new HashSet<>()).add(Pair.of(k, v));
      }
  
      public synchronized Optional<K> getAnyKey() {
          return map.values().stream().findAny().flatMap(pairs -> pairs.stream().findAny().map(p -> p.getLeft()));
      }
  
      public synchronized Optional<V> removeAny(K k) {
          Set<Pair<K, V>> set = map.getOrDefault(k.hashCode(), Collections.emptySet());
          Optional<Pair<K, V>> pair = set.stream().filter(p -> p.getLeft().equals(k)).findAny();
          pair.ifPresent(p -> set.remove(p));
          return pair.map(p -> p.getRight());
      }
  
      public synchronized int removeIf(BiPredicate<K, V> predicate) {
          int removedSum = map.values().stream().mapToInt(
                  pairs -> {
                      int removed = 0;
                      // Can't use removeIf because we need the count
                      Iterator<Pair<K, V>> iter = pairs.iterator();
                      while (iter.hasNext()) {
                          Pair<K, V> kv = iter.next();
                          if (predicate.test(kv.getLeft(), kv.getRight())) {
                              iter.remove();
                              removed++;
                          }
                      }
                      return removed;
                  }).sum();
          map.values().removeIf((s) -> s.isEmpty());
          return removedSum;
      }
  }
  