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.kafka.timeline;
  
  import java.util.AbstractCollection;
  import java.util.AbstractSet;
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  
  /**
   * This is a hash map which can be snapshotted.
   * <br>
   * See {@link SnapshottableHashTable} for more details about the implementation.
   * <br>
   * This class requires external synchronization.  Null keys and values are not supported.
   *
   * @param <K>   The key type of the set.
   * @param <V>   The value type of the set.
   */
  public class TimelineHashMap<K, V>
          extends SnapshottableHashTable<TimelineHashMap.TimelineHashMapEntry<K, V>>
          implements Map<K, V> {
      static class TimelineHashMapEntry<K, V>
              implements SnapshottableHashTable.ElementWithStartEpoch, Map.Entry<K, V> {
          private final K key;
          private final V value;
          private long startEpoch;
  
          TimelineHashMapEntry(K key, V value) {
              this.key = key;
              this.value = value;
              this.startEpoch = SnapshottableHashTable.LATEST_EPOCH;
          }
  
          @Override
          public K getKey() {
              return key;
          }
  
          @Override
          public V getValue() {
              return value;
          }
  
          @Override
          public V setValue(V value) {
              // This would be inefficient to support since we'd need a back-reference
              // to the enclosing map in each Entry object.  There would also be
              // complications if this entry object was sourced from a historical iterator;
              // we don't support modifying the past.  Since we don't really need this API,
              // let's just not support it.
              throw new UnsupportedOperationException();
          }
  
          @Override
          public void setStartEpoch(long startEpoch) {
              this.startEpoch = startEpoch;
          }
  
          @Override
          public long startEpoch() {
              return startEpoch;
          }
  
          @SuppressWarnings("unchecked")
          @Override
          public boolean equals(Object o) {
              if (!(o instanceof TimelineHashMapEntry)) return false;
              TimelineHashMapEntry<K, V> other = (TimelineHashMapEntry<K, V>) o;
              return key.equals(other.key);
          }
  
          @Override
          public int hashCode() {
              return key.hashCode();
          }
      }
  
      public TimelineHashMap(SnapshotRegistry snapshotRegistry, int expectedSize) {
          super(snapshotRegistry, expectedSize);
      }
  
      @Override
      public int size() {
          return size(SnapshottableHashTable.LATEST_EPOCH);
      }
  
      public int size(long epoch) {
          return snapshottableSize(epoch);
      }
  
      @Override
      public boolean isEmpty() {
          return isEmpty(SnapshottableHashTable.LATEST_EPOCH);
      }
  
      public boolean isEmpty(long epoch) {
          return snapshottableSize(epoch) == 0;
      }
  
      @Override
      public boolean containsKey(Object key) {
          return containsKey(key, SnapshottableHashTable.LATEST_EPOCH);
      }
  
      public boolean containsKey(Object key, long epoch) {
          return snapshottableGet(new TimelineHashMapEntry<>(key, null), epoch) != null;
      }
  
      @Override
      public boolean containsValue(Object value) {
          for (Entry<K, V> e : entrySet()) {
              if (value.equals(e.getValue())) {
                  return true;
              }
          }
          return false;
      }
  
      @Override
      public V get(Object key) {
          return get(key, SnapshottableHashTable.LATEST_EPOCH);
      }
  
      public V get(Object key, long epoch) {
          Entry<K, V> entry =
              snapshottableGet(new TimelineHashMapEntry<>(key, null), epoch);
          if (entry == null) {
              return null;
          }
          return entry.getValue();
      }
  
      @Override
      public V put(K key, V value) {
          Objects.requireNonNull(key);
          Objects.requireNonNull(value);
          TimelineHashMapEntry<K, V> entry = new TimelineHashMapEntry<>(key, value);
          TimelineHashMapEntry<K, V> prev = snapshottableAddOrReplace(entry);
          if (prev == null) {
              return null;
          }
          return prev.getValue();
      }
  
      @Override
      public V remove(Object key) {
          TimelineHashMapEntry<K, V> result = snapshottableRemove(
              new TimelineHashMapEntry<>(key, null));
          return result == null ? null : result.value;
      }
  
      @Override
      public void putAll(Map<? extends K, ? extends V> map) {
          for (Map.Entry<? extends K, ? extends V> e : map.entrySet()) {
              put(e.getKey(), e.getValue());
          }
      }
  
      @Override
      public void clear() {
          reset();
      }
  
      final class KeySet extends AbstractSet<K> {
          private final long epoch;
  
          KeySet(long epoch) {
              this.epoch = epoch;
          }
  
          public int size() {
              return TimelineHashMap.this.size(epoch);
          }
  
          public void clear() {
              if (epoch != SnapshottableHashTable.LATEST_EPOCH) {
                  throw new RuntimeException("can't modify snapshot");
              }
              TimelineHashMap.this.clear();
          }
  
          public Iterator<K> iterator() {
              return new KeyIterator(epoch);
          }
  
          public boolean contains(Object o) {
              return TimelineHashMap.this.containsKey(o, epoch);
          }
  
          public boolean remove(Object o) {
              if (epoch != SnapshottableHashTable.LATEST_EPOCH) {
                  throw new RuntimeException("can't modify snapshot");
              }
              return TimelineHashMap.this.remove(o) != null;
          }
      }
  
      final class KeyIterator implements Iterator<K> {
          private final Iterator<TimelineHashMapEntry<K, V>> iter;
  
          KeyIterator(long epoch) {
              this.iter = snapshottableIterator(epoch);
          }
  
          @Override
          public boolean hasNext() {
              return iter.hasNext();
          }
  
          @Override
          public K next() {
              TimelineHashMapEntry<K, V> next = iter.next();
              return next.getKey();
          }
  
          @Override
          public void remove() {
              iter.remove();
          }
      }
  
      @Override
      public Set<K> keySet() {
          return keySet(SnapshottableHashTable.LATEST_EPOCH);
      }
  
      public Set<K> keySet(long epoch) {
          return new KeySet(epoch);
      }
  
      final class Values extends AbstractCollection<V> {
          private final long epoch;
  
          Values(long epoch) {
              this.epoch = epoch;
          }
  
          public int size() {
              return TimelineHashMap.this.size(epoch);
          }
  
          public void clear() {
              if (epoch != SnapshottableHashTable.LATEST_EPOCH) {
                  throw new RuntimeException("can't modify snapshot");
              }
              TimelineHashMap.this.clear();
          }
  
          public Iterator<V> iterator() {
              return new ValueIterator(epoch);
          }
  
          public boolean contains(Object o) {
              return TimelineHashMap.this.containsKey(o, epoch);
          }
      }
  
      final class ValueIterator implements Iterator<V> {
          private final Iterator<TimelineHashMapEntry<K, V>> iter;
  
          ValueIterator(long epoch) {
              this.iter = snapshottableIterator(epoch);
          }
  
          @Override
          public boolean hasNext() {
              return iter.hasNext();
          }
  
          @Override
          public V next() {
              TimelineHashMapEntry<K, V> next = iter.next();
              return next.getValue();
          }
  
          @Override
          public void remove() {
              iter.remove();
          }
      }
  
      @Override
      public Collection<V> values() {
          return values(SnapshottableHashTable.LATEST_EPOCH);
      }
  
      public Collection<V> values(long epoch) {
          return new Values(epoch);
      }
  
      final class EntrySet extends AbstractSet<Map.Entry<K, V>> {
          private final long epoch;
  
          EntrySet(long epoch) {
              this.epoch = epoch;
          }
  
          public int size() {
              return TimelineHashMap.this.size(epoch);
          }
  
          public void clear() {
              if (epoch != SnapshottableHashTable.LATEST_EPOCH) {
                  throw new RuntimeException("can't modify snapshot");
              }
              TimelineHashMap.this.clear();
          }
  
          public Iterator<Map.Entry<K, V>> iterator() {
              return new EntryIterator(epoch);
          }
  
          public boolean contains(Object o) {
              return snapshottableGet(o, epoch) != null;
          }
  
          public boolean remove(Object o) {
              if (epoch != SnapshottableHashTable.LATEST_EPOCH) {
                  throw new RuntimeException("can't modify snapshot");
              }
              return snapshottableRemove(new TimelineHashMapEntry<>(o, null)) != null;
          }
      }
  
      final class EntryIterator implements Iterator<Map.Entry<K, V>> {
          private final Iterator<TimelineHashMapEntry<K, V>> iter;
  
          EntryIterator(long epoch) {
              this.iter = snapshottableIterator(epoch);
          }
  
          @Override
          public boolean hasNext() {
              return iter.hasNext();
          }
  
          @Override
          public Map.Entry<K, V> next() {
              return iter.next();
          }
  
          @Override
          public void remove() {
              iter.remove();
          }
      }
  
      @Override
      public Set<Entry<K, V>> entrySet() {
          return entrySet(SnapshottableHashTable.LATEST_EPOCH);
      }
  
      public Set<Entry<K, V>> entrySet(long epoch) {
          return new EntrySet(epoch);
      }
  
      @Override
      public int hashCode() {
          int hash = 0;
          for (Entry<K, V> kvEntry : entrySet()) {
              hash += kvEntry.hashCode();
          }
          return hash;
      }
  
      @Override
      public boolean equals(Object o) {
          if (o == this)
              return true;
          if (!(o instanceof Map<?, ?> m))
              return false;
          if (m.size() != size())
              return false;
          try {
              for (Entry<K, V> entry : entrySet()) {
                  if (!m.get(entry.getKey()).equals(entry.getValue())) {
                      return false;
                  }
              }
          } catch (ClassCastException unused) {
              return false;
          }
          return true;
  
      }
  }
  