/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed 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 com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Collection;
import java.util.Comparator;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.Queue;
import java.util.RandomAccess;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;

import javax.annotation.Nullable;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.VisibleForTesting;

/**
 * Synchronized collection views. The returned synchronized collection views are
 * serializable if the backing collection and the mutex are serializable.
 *
 * <p>
 * If {@code null} is passed as the {@code mutex} parameter to any of this
 * class's top-level methods or inner class constructors, the created object
 * uses itself as the synchronization mutex.
 *
 * <p>
 * This class should be used by other collection classes only.
 *
 * @author Mike Bostock
 * @author Jared Levy
 */
@GwtCompatible(emulated = true)
final class Synchronized {
	private Synchronized() {
	}

	static class SynchronizedObject implements Serializable {
		final Object delegate;
		final Object mutex;

		SynchronizedObject(Object delegate, @Nullable Object mutex) {
			this.delegate = checkNotNull(delegate);
			this.mutex = (mutex == null) ? this : mutex;
		}

		Object delegate() {
			return delegate;
		}

		// No equals and hashCode; see ForwardingObject for details.

		@Override
		public String toString() {
			synchronized (mutex) {
				return delegate.toString();
			}
		}

		// Serialization invokes writeObject only when it's private.
		// The SynchronizedObject subclasses don't need a writeObject method since
		// they don't contain any non-transient member variables, while the
		// following writeObject() handles the SynchronizedObject members.

		@GwtIncompatible("java.io.ObjectOutputStream")
		private void writeObject(ObjectOutputStream stream) throws IOException {
			synchronized (mutex) {
				stream.defaultWriteObject();
			}
		}

		@GwtIncompatible("not needed in emulated source")
		private static final long serialVersionUID = 0;
	}

	private static <E> Collection<E> collection(Collection<E> collection, @Nullable Object mutex) {
		return new SynchronizedCollection<E>(collection, mutex);
	}

	@VisibleForTesting
	static class SynchronizedCollection<E> extends SynchronizedObject implements Collection<E> {
		private SynchronizedCollection(Collection<E> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@SuppressWarnings("unchecked")
		@Override
		Collection<E> delegate() {
			return (Collection<E>) super.delegate();
		}

		@Override
		public boolean add(E e) {
			synchronized (mutex) {
				return delegate().add(e);
			}
		}

		@Override
		public boolean addAll(Collection<? extends E> c) {
			synchronized (mutex) {
				return delegate().addAll(c);
			}
		}

		@Override
		public void clear() {
			synchronized (mutex) {
				delegate().clear();
			}
		}

		@Override
		public boolean contains(Object o) {
			synchronized (mutex) {
				return delegate().contains(o);
			}
		}

		@Override
		public boolean containsAll(Collection<?> c) {
			synchronized (mutex) {
				return delegate().containsAll(c);
			}
		}

		@Override
		public boolean isEmpty() {
			synchronized (mutex) {
				return delegate().isEmpty();
			}
		}

		@Override
		public Iterator<E> iterator() {
			return delegate().iterator(); // manually synchronized
		}

		@Override
		public boolean remove(Object o) {
			synchronized (mutex) {
				return delegate().remove(o);
			}
		}

		@Override
		public boolean removeAll(Collection<?> c) {
			synchronized (mutex) {
				return delegate().removeAll(c);
			}
		}

		@Override
		public boolean retainAll(Collection<?> c) {
			synchronized (mutex) {
				return delegate().retainAll(c);
			}
		}

		@Override
		public int size() {
			synchronized (mutex) {
				return delegate().size();
			}
		}

		@Override
		public Object[] toArray() {
			synchronized (mutex) {
				return delegate().toArray();
			}
		}

		@Override
		public <T> T[] toArray(T[] a) {
			synchronized (mutex) {
				return delegate().toArray(a);
			}
		}

		private static final long serialVersionUID = 0;
	}

	@VisibleForTesting
	static <E> Set<E> set(Set<E> set, @Nullable Object mutex) {
		return new SynchronizedSet<E>(set, mutex);
	}

	static class SynchronizedSet<E> extends SynchronizedCollection<E> implements Set<E> {

		SynchronizedSet(Set<E> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		Set<E> delegate() {
			return (Set<E>) super.delegate();
		}

		@Override
		public boolean equals(Object o) {
			if (o == this) {
				return true;
			}
			synchronized (mutex) {
				return delegate().equals(o);
			}
		}

		@Override
		public int hashCode() {
			synchronized (mutex) {
				return delegate().hashCode();
			}
		}

		private static final long serialVersionUID = 0;
	}

	private static <E> SortedSet<E> sortedSet(SortedSet<E> set, @Nullable Object mutex) {
		return new SynchronizedSortedSet<E>(set, mutex);
	}

	static class SynchronizedSortedSet<E> extends SynchronizedSet<E> implements SortedSet<E> {
		SynchronizedSortedSet(SortedSet<E> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		SortedSet<E> delegate() {
			return (SortedSet<E>) super.delegate();
		}

		@Override
		public Comparator<? super E> comparator() {
			synchronized (mutex) {
				return delegate().comparator();
			}
		}

		@Override
		public SortedSet<E> subSet(E fromElement, E toElement) {
			synchronized (mutex) {
				return sortedSet(delegate().subSet(fromElement, toElement), mutex);
			}
		}

		@Override
		public SortedSet<E> headSet(E toElement) {
			synchronized (mutex) {
				return sortedSet(delegate().headSet(toElement), mutex);
			}
		}

		@Override
		public SortedSet<E> tailSet(E fromElement) {
			synchronized (mutex) {
				return sortedSet(delegate().tailSet(fromElement), mutex);
			}
		}

		@Override
		public E first() {
			synchronized (mutex) {
				return delegate().first();
			}
		}

		@Override
		public E last() {
			synchronized (mutex) {
				return delegate().last();
			}
		}

		private static final long serialVersionUID = 0;
	}

	private static <E> List<E> list(List<E> list, @Nullable Object mutex) {
		return (list instanceof RandomAccess) ? new SynchronizedRandomAccessList<E>(list, mutex)
				: new SynchronizedList<E>(list, mutex);
	}

	private static class SynchronizedList<E> extends SynchronizedCollection<E> implements List<E> {
		SynchronizedList(List<E> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		List<E> delegate() {
			return (List<E>) super.delegate();
		}

		@Override
		public void add(int index, E element) {
			synchronized (mutex) {
				delegate().add(index, element);
			}
		}

		@Override
		public boolean addAll(int index, Collection<? extends E> c) {
			synchronized (mutex) {
				return delegate().addAll(index, c);
			}
		}

		@Override
		public E get(int index) {
			synchronized (mutex) {
				return delegate().get(index);
			}
		}

		@Override
		public int indexOf(Object o) {
			synchronized (mutex) {
				return delegate().indexOf(o);
			}
		}

		@Override
		public int lastIndexOf(Object o) {
			synchronized (mutex) {
				return delegate().lastIndexOf(o);
			}
		}

		@Override
		public ListIterator<E> listIterator() {
			return delegate().listIterator(); // manually synchronized
		}

		@Override
		public ListIterator<E> listIterator(int index) {
			return delegate().listIterator(index); // manually synchronized
		}

		@Override
		public E remove(int index) {
			synchronized (mutex) {
				return delegate().remove(index);
			}
		}

		@Override
		public E set(int index, E element) {
			synchronized (mutex) {
				return delegate().set(index, element);
			}
		}

		@Override
		public List<E> subList(int fromIndex, int toIndex) {
			synchronized (mutex) {
				return list(delegate().subList(fromIndex, toIndex), mutex);
			}
		}

		@Override
		public boolean equals(Object o) {
			if (o == this) {
				return true;
			}
			synchronized (mutex) {
				return delegate().equals(o);
			}
		}

		@Override
		public int hashCode() {
			synchronized (mutex) {
				return delegate().hashCode();
			}
		}

		private static final long serialVersionUID = 0;
	}

	private static class SynchronizedRandomAccessList<E> extends SynchronizedList<E> implements RandomAccess {
		SynchronizedRandomAccessList(List<E> list, @Nullable Object mutex) {
			super(list, mutex);
		}

		private static final long serialVersionUID = 0;
	}

	static <E> Multiset<E> multiset(Multiset<E> multiset, @Nullable Object mutex) {
		if (multiset instanceof SynchronizedMultiset || multiset instanceof ImmutableMultiset) {
			return multiset;
		}
		return new SynchronizedMultiset<E>(multiset, mutex);
	}

	private static class SynchronizedMultiset<E> extends SynchronizedCollection<E> implements Multiset<E> {
		transient Set<E> elementSet;
		transient Set<Entry<E>> entrySet;

		SynchronizedMultiset(Multiset<E> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		Multiset<E> delegate() {
			return (Multiset<E>) super.delegate();
		}

		@Override
		public int count(Object o) {
			synchronized (mutex) {
				return delegate().count(o);
			}
		}

		@Override
		public int add(E e, int n) {
			synchronized (mutex) {
				return delegate().add(e, n);
			}
		}

		@Override
		public int remove(Object o, int n) {
			synchronized (mutex) {
				return delegate().remove(o, n);
			}
		}

		@Override
		public int setCount(E element, int count) {
			synchronized (mutex) {
				return delegate().setCount(element, count);
			}
		}

		@Override
		public boolean setCount(E element, int oldCount, int newCount) {
			synchronized (mutex) {
				return delegate().setCount(element, oldCount, newCount);
			}
		}

		@Override
		public Set<E> elementSet() {
			synchronized (mutex) {
				if (elementSet == null) {
					elementSet = typePreservingSet(delegate().elementSet(), mutex);
				}
				return elementSet;
			}
		}

		@Override
		public Set<Entry<E>> entrySet() {
			synchronized (mutex) {
				if (entrySet == null) {
					entrySet = typePreservingSet(delegate().entrySet(), mutex);
				}
				return entrySet;
			}
		}

		@Override
		public boolean equals(Object o) {
			if (o == this) {
				return true;
			}
			synchronized (mutex) {
				return delegate().equals(o);
			}
		}

		@Override
		public int hashCode() {
			synchronized (mutex) {
				return delegate().hashCode();
			}
		}

		private static final long serialVersionUID = 0;
	}

	static <K, V> Multimap<K, V> multimap(Multimap<K, V> multimap, @Nullable Object mutex) {
		if (multimap instanceof SynchronizedMultimap || multimap instanceof ImmutableMultimap) {
			return multimap;
		}
		return new SynchronizedMultimap<K, V>(multimap, mutex);
	}

	private static class SynchronizedMultimap<K, V> extends SynchronizedObject implements Multimap<K, V> {
		transient Set<K> keySet;
		transient Collection<V> valuesCollection;
		transient Collection<Map.Entry<K, V>> entries;
		transient Map<K, Collection<V>> asMap;
		transient Multiset<K> keys;

		@SuppressWarnings("unchecked")
		@Override
		Multimap<K, V> delegate() {
			return (Multimap<K, V>) super.delegate();
		}

		SynchronizedMultimap(Multimap<K, V> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		public int size() {
			synchronized (mutex) {
				return delegate().size();
			}
		}

		@Override
		public boolean isEmpty() {
			synchronized (mutex) {
				return delegate().isEmpty();
			}
		}

		@Override
		public boolean containsKey(Object key) {
			synchronized (mutex) {
				return delegate().containsKey(key);
			}
		}

		@Override
		public boolean containsValue(Object value) {
			synchronized (mutex) {
				return delegate().containsValue(value);
			}
		}

		@Override
		public boolean containsEntry(Object key, Object value) {
			synchronized (mutex) {
				return delegate().containsEntry(key, value);
			}
		}

		@Override
		public Collection<V> get(K key) {
			synchronized (mutex) {
				return typePreservingCollection(delegate().get(key), mutex);
			}
		}

		@Override
		public boolean put(K key, V value) {
			synchronized (mutex) {
				return delegate().put(key, value);
			}
		}

		@Override
		public boolean putAll(K key, Iterable<? extends V> values) {
			synchronized (mutex) {
				return delegate().putAll(key, values);
			}
		}

		@Override
		public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
			synchronized (mutex) {
				return delegate().putAll(multimap);
			}
		}

		@Override
		public Collection<V> replaceValues(K key, Iterable<? extends V> values) {
			synchronized (mutex) {
				return delegate().replaceValues(key, values); // copy not synchronized
			}
		}

		@Override
		public boolean remove(Object key, Object value) {
			synchronized (mutex) {
				return delegate().remove(key, value);
			}
		}

		@Override
		public Collection<V> removeAll(Object key) {
			synchronized (mutex) {
				return delegate().removeAll(key); // copy not synchronized
			}
		}

		@Override
		public void clear() {
			synchronized (mutex) {
				delegate().clear();
			}
		}

		@Override
		public Set<K> keySet() {
			synchronized (mutex) {
				if (keySet == null) {
					keySet = typePreservingSet(delegate().keySet(), mutex);
				}
				return keySet;
			}
		}

		@Override
		public Collection<V> values() {
			synchronized (mutex) {
				if (valuesCollection == null) {
					valuesCollection = collection(delegate().values(), mutex);
				}
				return valuesCollection;
			}
		}

		@Override
		public Collection<Map.Entry<K, V>> entries() {
			synchronized (mutex) {
				if (entries == null) {
					entries = typePreservingCollection(delegate().entries(), mutex);
				}
				return entries;
			}
		}

		@Override
		public Map<K, Collection<V>> asMap() {
			synchronized (mutex) {
				if (asMap == null) {
					asMap = new SynchronizedAsMap<K, V>(delegate().asMap(), mutex);
				}
				return asMap;
			}
		}

		@Override
		public Multiset<K> keys() {
			synchronized (mutex) {
				if (keys == null) {
					keys = multiset(delegate().keys(), mutex);
				}
				return keys;
			}
		}

		@Override
		public boolean equals(Object o) {
			if (o == this) {
				return true;
			}
			synchronized (mutex) {
				return delegate().equals(o);
			}
		}

		@Override
		public int hashCode() {
			synchronized (mutex) {
				return delegate().hashCode();
			}
		}

		private static final long serialVersionUID = 0;
	}

	static <K, V> ListMultimap<K, V> listMultimap(ListMultimap<K, V> multimap, @Nullable Object mutex) {
		if (multimap instanceof SynchronizedListMultimap || multimap instanceof ImmutableListMultimap) {
			return multimap;
		}
		return new SynchronizedListMultimap<K, V>(multimap, mutex);
	}

	private static class SynchronizedListMultimap<K, V> extends SynchronizedMultimap<K, V>
			implements ListMultimap<K, V> {
		SynchronizedListMultimap(ListMultimap<K, V> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		ListMultimap<K, V> delegate() {
			return (ListMultimap<K, V>) super.delegate();
		}

		@Override
		public List<V> get(K key) {
			synchronized (mutex) {
				return list(delegate().get(key), mutex);
			}
		}

		@Override
		public List<V> removeAll(Object key) {
			synchronized (mutex) {
				return delegate().removeAll(key); // copy not synchronized
			}
		}

		@Override
		public List<V> replaceValues(K key, Iterable<? extends V> values) {
			synchronized (mutex) {
				return delegate().replaceValues(key, values); // copy not synchronized
			}
		}

		private static final long serialVersionUID = 0;
	}

	static <K, V> SetMultimap<K, V> setMultimap(SetMultimap<K, V> multimap, @Nullable Object mutex) {
		if (multimap instanceof SynchronizedSetMultimap || multimap instanceof ImmutableSetMultimap) {
			return multimap;
		}
		return new SynchronizedSetMultimap<K, V>(multimap, mutex);
	}

	private static class SynchronizedSetMultimap<K, V> extends SynchronizedMultimap<K, V> implements SetMultimap<K, V> {
		transient Set<Map.Entry<K, V>> entrySet;

		SynchronizedSetMultimap(SetMultimap<K, V> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		SetMultimap<K, V> delegate() {
			return (SetMultimap<K, V>) super.delegate();
		}

		@Override
		public Set<V> get(K key) {
			synchronized (mutex) {
				return set(delegate().get(key), mutex);
			}
		}

		@Override
		public Set<V> removeAll(Object key) {
			synchronized (mutex) {
				return delegate().removeAll(key); // copy not synchronized
			}
		}

		@Override
		public Set<V> replaceValues(K key, Iterable<? extends V> values) {
			synchronized (mutex) {
				return delegate().replaceValues(key, values); // copy not synchronized
			}
		}

		@Override
		public Set<Map.Entry<K, V>> entries() {
			synchronized (mutex) {
				if (entrySet == null) {
					entrySet = set(delegate().entries(), mutex);
				}
				return entrySet;
			}
		}

		private static final long serialVersionUID = 0;
	}

	static <K, V> SortedSetMultimap<K, V> sortedSetMultimap(SortedSetMultimap<K, V> multimap, @Nullable Object mutex) {
		if (multimap instanceof SynchronizedSortedSetMultimap) {
			return multimap;
		}
		return new SynchronizedSortedSetMultimap<K, V>(multimap, mutex);
	}

	private static class SynchronizedSortedSetMultimap<K, V> extends SynchronizedSetMultimap<K, V>
			implements SortedSetMultimap<K, V> {
		SynchronizedSortedSetMultimap(SortedSetMultimap<K, V> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		SortedSetMultimap<K, V> delegate() {
			return (SortedSetMultimap<K, V>) super.delegate();
		}

		@Override
		public SortedSet<V> get(K key) {
			synchronized (mutex) {
				return sortedSet(delegate().get(key), mutex);
			}
		}

		@Override
		public SortedSet<V> removeAll(Object key) {
			synchronized (mutex) {
				return delegate().removeAll(key); // copy not synchronized
			}
		}

		@Override
		public SortedSet<V> replaceValues(K key, Iterable<? extends V> values) {
			synchronized (mutex) {
				return delegate().replaceValues(key, values); // copy not synchronized
			}
		}

		@Override
		public Comparator<? super V> valueComparator() {
			synchronized (mutex) {
				return delegate().valueComparator();
			}
		}

		private static final long serialVersionUID = 0;
	}

	private static <E> Collection<E> typePreservingCollection(Collection<E> collection, @Nullable Object mutex) {
		if (collection instanceof SortedSet) {
			return sortedSet((SortedSet<E>) collection, mutex);
		}
		if (collection instanceof Set) {
			return set((Set<E>) collection, mutex);
		}
		if (collection instanceof List) {
			return list((List<E>) collection, mutex);
		}
		return collection(collection, mutex);
	}

	private static <E> Set<E> typePreservingSet(Set<E> set, @Nullable Object mutex) {
		if (set instanceof SortedSet) {
			return sortedSet((SortedSet<E>) set, mutex);
		} else {
			return set(set, mutex);
		}
	}

	private static class SynchronizedAsMapEntries<K, V> extends SynchronizedSet<Map.Entry<K, Collection<V>>> {
		SynchronizedAsMapEntries(Set<Map.Entry<K, Collection<V>>> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		public Iterator<Map.Entry<K, Collection<V>>> iterator() {
			// Must be manually synchronized.
			final Iterator<Map.Entry<K, Collection<V>>> iterator = super.iterator();
			return new ForwardingIterator<Map.Entry<K, Collection<V>>>() {
				@Override
				protected Iterator<Map.Entry<K, Collection<V>>> delegate() {
					return iterator;
				}

				@Override
				public Map.Entry<K, Collection<V>> next() {
					final Map.Entry<K, Collection<V>> entry = super.next();
					return new ForwardingMapEntry<K, Collection<V>>() {
						@Override
						protected Map.Entry<K, Collection<V>> delegate() {
							return entry;
						}

						@Override
						public Collection<V> getValue() {
							return typePreservingCollection(entry.getValue(), mutex);
						}
					};
				}
			};
		}

		// See Collections.CheckedMap.CheckedEntrySet for details on attacks.

		@Override
		public Object[] toArray() {
			synchronized (mutex) {
				return ObjectArrays.toArrayImpl(delegate());
			}
		}

		@Override
		public <T> T[] toArray(T[] array) {
			synchronized (mutex) {
				return ObjectArrays.toArrayImpl(delegate(), array);
			}
		}

		@Override
		public boolean contains(Object o) {
			synchronized (mutex) {
				return Maps.containsEntryImpl(delegate(), o);
			}
		}

		@Override
		public boolean containsAll(Collection<?> c) {
			synchronized (mutex) {
				return Collections2.containsAllImpl(delegate(), c);
			}
		}

		@Override
		public boolean equals(Object o) {
			if (o == this) {
				return true;
			}
			synchronized (mutex) {
				return Sets.equalsImpl(delegate(), o);
			}
		}

		@Override
		public boolean remove(Object o) {
			synchronized (mutex) {
				return Maps.removeEntryImpl(delegate(), o);
			}
		}

		@Override
		public boolean removeAll(Collection<?> c) {
			synchronized (mutex) {
				return Iterators.removeAll(delegate().iterator(), c);
			}
		}

		@Override
		public boolean retainAll(Collection<?> c) {
			synchronized (mutex) {
				return Iterators.retainAll(delegate().iterator(), c);
			}
		}

		private static final long serialVersionUID = 0;
	}

	@VisibleForTesting
	static <K, V> Map<K, V> map(Map<K, V> map, @Nullable Object mutex) {
		return new SynchronizedMap<K, V>(map, mutex);
	}

	private static class SynchronizedMap<K, V> extends SynchronizedObject implements Map<K, V> {
		transient Set<K> keySet;
		transient Collection<V> values;
		transient Set<Map.Entry<K, V>> entrySet;

		SynchronizedMap(Map<K, V> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@SuppressWarnings("unchecked")
		@Override
		Map<K, V> delegate() {
			return (Map<K, V>) super.delegate();
		}

		@Override
		public void clear() {
			synchronized (mutex) {
				delegate().clear();
			}
		}

		@Override
		public boolean containsKey(Object key) {
			synchronized (mutex) {
				return delegate().containsKey(key);
			}
		}

		@Override
		public boolean containsValue(Object value) {
			synchronized (mutex) {
				return delegate().containsValue(value);
			}
		}

		@Override
		public Set<Map.Entry<K, V>> entrySet() {
			synchronized (mutex) {
				if (entrySet == null) {
					entrySet = set(delegate().entrySet(), mutex);
				}
				return entrySet;
			}
		}

		@Override
		public V get(Object key) {
			synchronized (mutex) {
				return delegate().get(key);
			}
		}

		@Override
		public boolean isEmpty() {
			synchronized (mutex) {
				return delegate().isEmpty();
			}
		}

		@Override
		public Set<K> keySet() {
			synchronized (mutex) {
				if (keySet == null) {
					keySet = set(delegate().keySet(), mutex);
				}
				return keySet;
			}
		}

		@Override
		public V put(K key, V value) {
			synchronized (mutex) {
				return delegate().put(key, value);
			}
		}

		@Override
		public void putAll(Map<? extends K, ? extends V> map) {
			synchronized (mutex) {
				delegate().putAll(map);
			}
		}

		@Override
		public V remove(Object key) {
			synchronized (mutex) {
				return delegate().remove(key);
			}
		}

		@Override
		public int size() {
			synchronized (mutex) {
				return delegate().size();
			}
		}

		@Override
		public Collection<V> values() {
			synchronized (mutex) {
				if (values == null) {
					values = collection(delegate().values(), mutex);
				}
				return values;
			}
		}

		@Override
		public boolean equals(Object o) {
			if (o == this) {
				return true;
			}
			synchronized (mutex) {
				return delegate().equals(o);
			}
		}

		@Override
		public int hashCode() {
			synchronized (mutex) {
				return delegate().hashCode();
			}
		}

		private static final long serialVersionUID = 0;
	}

	static <K, V> SortedMap<K, V> sortedMap(SortedMap<K, V> sortedMap, @Nullable Object mutex) {
		return new SynchronizedSortedMap<K, V>(sortedMap, mutex);
	}

	static class SynchronizedSortedMap<K, V> extends SynchronizedMap<K, V> implements SortedMap<K, V> {

		SynchronizedSortedMap(SortedMap<K, V> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		SortedMap<K, V> delegate() {
			return (SortedMap<K, V>) super.delegate();
		}

		@Override
		public Comparator<? super K> comparator() {
			synchronized (mutex) {
				return delegate().comparator();
			}
		}

		@Override
		public K firstKey() {
			synchronized (mutex) {
				return delegate().firstKey();
			}
		}

		@Override
		public SortedMap<K, V> headMap(K toKey) {
			synchronized (mutex) {
				return sortedMap(delegate().headMap(toKey), mutex);
			}
		}

		@Override
		public K lastKey() {
			synchronized (mutex) {
				return delegate().lastKey();
			}
		}

		@Override
		public SortedMap<K, V> subMap(K fromKey, K toKey) {
			synchronized (mutex) {
				return sortedMap(delegate().subMap(fromKey, toKey), mutex);
			}
		}

		@Override
		public SortedMap<K, V> tailMap(K fromKey) {
			synchronized (mutex) {
				return sortedMap(delegate().tailMap(fromKey), mutex);
			}
		}

		private static final long serialVersionUID = 0;
	}

	static <K, V> BiMap<K, V> biMap(BiMap<K, V> bimap, @Nullable Object mutex) {
		if (bimap instanceof SynchronizedBiMap || bimap instanceof ImmutableBiMap) {
			return bimap;
		}
		return new SynchronizedBiMap<K, V>(bimap, mutex, null);
	}

	@VisibleForTesting
	static class SynchronizedBiMap<K, V> extends SynchronizedMap<K, V> implements BiMap<K, V>, Serializable {
		private transient Set<V> valueSet;
		private transient BiMap<V, K> inverse;

		private SynchronizedBiMap(BiMap<K, V> delegate, @Nullable Object mutex, @Nullable BiMap<V, K> inverse) {
			super(delegate, mutex);
			this.inverse = inverse;
		}

		@Override
		BiMap<K, V> delegate() {
			return (BiMap<K, V>) super.delegate();
		}

		@Override
		public Set<V> values() {
			synchronized (mutex) {
				if (valueSet == null) {
					valueSet = set(delegate().values(), mutex);
				}
				return valueSet;
			}
		}

		@Override
		public V forcePut(K key, V value) {
			synchronized (mutex) {
				return delegate().forcePut(key, value);
			}
		}

		@Override
		public BiMap<V, K> inverse() {
			synchronized (mutex) {
				if (inverse == null) {
					inverse = new SynchronizedBiMap<V, K>(delegate().inverse(), mutex, this);
				}
				return inverse;
			}
		}

		private static final long serialVersionUID = 0;
	}

	private static class SynchronizedAsMap<K, V> extends SynchronizedMap<K, Collection<V>> {
		transient Set<Map.Entry<K, Collection<V>>> asMapEntrySet;
		transient Collection<Collection<V>> asMapValues;

		SynchronizedAsMap(Map<K, Collection<V>> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		public Collection<V> get(Object key) {
			synchronized (mutex) {
				Collection<V> collection = super.get(key);
				return (collection == null) ? null : typePreservingCollection(collection, mutex);
			}
		}

		@Override
		public Set<Map.Entry<K, Collection<V>>> entrySet() {
			synchronized (mutex) {
				if (asMapEntrySet == null) {
					asMapEntrySet = new SynchronizedAsMapEntries<K, V>(delegate().entrySet(), mutex);
				}
				return asMapEntrySet;
			}
		}

		@Override
		public Collection<Collection<V>> values() {
			synchronized (mutex) {
				if (asMapValues == null) {
					asMapValues = new SynchronizedAsMapValues<V>(delegate().values(), mutex);
				}
				return asMapValues;
			}
		}

		@Override
		public boolean containsValue(Object o) {
			// values() and its contains() method are both synchronized.
			return values().contains(o);
		}

		private static final long serialVersionUID = 0;
	}

	private static class SynchronizedAsMapValues<V> extends SynchronizedCollection<Collection<V>> {
		SynchronizedAsMapValues(Collection<Collection<V>> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		public Iterator<Collection<V>> iterator() {
			// Must be manually synchronized.
			final Iterator<Collection<V>> iterator = super.iterator();
			return new ForwardingIterator<Collection<V>>() {
				@Override
				protected Iterator<Collection<V>> delegate() {
					return iterator;
				}

				@Override
				public Collection<V> next() {
					return typePreservingCollection(super.next(), mutex);
				}
			};
		}

		private static final long serialVersionUID = 0;
	}

	@GwtIncompatible("NavigableSet")
	@VisibleForTesting
	static class SynchronizedNavigableSet<E> extends SynchronizedSortedSet<E> implements NavigableSet<E> {
		SynchronizedNavigableSet(NavigableSet<E> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		NavigableSet<E> delegate() {
			return (NavigableSet<E>) super.delegate();
		}

		@Override
		public E ceiling(E e) {
			synchronized (mutex) {
				return delegate().ceiling(e);
			}
		}

		@Override
		public Iterator<E> descendingIterator() {
			return delegate().descendingIterator(); // manually synchronized
		}

		transient NavigableSet<E> descendingSet;

		@Override
		public NavigableSet<E> descendingSet() {
			synchronized (mutex) {
				if (descendingSet == null) {
					NavigableSet<E> dS = Synchronized.navigableSet(delegate().descendingSet(), mutex);
					descendingSet = dS;
					return dS;
				}
				return descendingSet;
			}
		}

		@Override
		public E floor(E e) {
			synchronized (mutex) {
				return delegate().floor(e);
			}
		}

		@Override
		public NavigableSet<E> headSet(E toElement, boolean inclusive) {
			synchronized (mutex) {
				return Synchronized.navigableSet(delegate().headSet(toElement, inclusive), mutex);
			}
		}

		@Override
		public E higher(E e) {
			synchronized (mutex) {
				return delegate().higher(e);
			}
		}

		@Override
		public E lower(E e) {
			synchronized (mutex) {
				return delegate().lower(e);
			}
		}

		@Override
		public E pollFirst() {
			synchronized (mutex) {
				return delegate().pollFirst();
			}
		}

		@Override
		public E pollLast() {
			synchronized (mutex) {
				return delegate().pollLast();
			}
		}

		@Override
		public NavigableSet<E> subSet(E fromElement, boolean fromInclusive, E toElement, boolean toInclusive) {
			synchronized (mutex) {
				return Synchronized.navigableSet(delegate().subSet(fromElement, fromInclusive, toElement, toInclusive),
						mutex);
			}
		}

		@Override
		public NavigableSet<E> tailSet(E fromElement, boolean inclusive) {
			synchronized (mutex) {
				return Synchronized.navigableSet(delegate().tailSet(fromElement, inclusive), mutex);
			}
		}

		@Override
		public SortedSet<E> headSet(E toElement) {
			return headSet(toElement, false);
		}

		@Override
		public SortedSet<E> subSet(E fromElement, E toElement) {
			return subSet(fromElement, true, toElement, false);
		}

		@Override
		public SortedSet<E> tailSet(E fromElement) {
			return tailSet(fromElement, true);
		}

		private static final long serialVersionUID = 0;
	}

	@GwtIncompatible("NavigableSet")
	static <E> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet, @Nullable Object mutex) {
		return new SynchronizedNavigableSet<E>(navigableSet, mutex);
	}

	@GwtIncompatible("NavigableSet")
	static <E> NavigableSet<E> navigableSet(NavigableSet<E> navigableSet) {
		return navigableSet(navigableSet, null);
	}

	@GwtIncompatible("NavigableMap")
	static <K, V> NavigableMap<K, V> navigableMap(NavigableMap<K, V> navigableMap) {
		return navigableMap(navigableMap, null);
	}

	@GwtIncompatible("NavigableMap")
	static <K, V> NavigableMap<K, V> navigableMap(NavigableMap<K, V> navigableMap, @Nullable Object mutex) {
		return new SynchronizedNavigableMap<K, V>(navigableMap, mutex);
	}

	@GwtIncompatible("NavigableMap")
	@VisibleForTesting
	static class SynchronizedNavigableMap<K, V> extends SynchronizedSortedMap<K, V> implements NavigableMap<K, V> {

		SynchronizedNavigableMap(NavigableMap<K, V> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		NavigableMap<K, V> delegate() {
			return (NavigableMap<K, V>) super.delegate();
		}

		@Override
		public Entry<K, V> ceilingEntry(K key) {
			synchronized (mutex) {
				return nullableSynchronizedEntry(delegate().ceilingEntry(key), mutex);
			}
		}

		@Override
		public K ceilingKey(K key) {
			synchronized (mutex) {
				return delegate().ceilingKey(key);
			}
		}

		transient NavigableSet<K> descendingKeySet;

		@Override
		public NavigableSet<K> descendingKeySet() {
			synchronized (mutex) {
				if (descendingKeySet == null) {
					return descendingKeySet = Synchronized.navigableSet(delegate().descendingKeySet(), mutex);
				}
				return descendingKeySet;
			}
		}

		transient NavigableMap<K, V> descendingMap;

		@Override
		public NavigableMap<K, V> descendingMap() {
			synchronized (mutex) {
				if (descendingMap == null) {
					return descendingMap = navigableMap(delegate().descendingMap(), mutex);
				}
				return descendingMap;
			}
		}

		@Override
		public Entry<K, V> firstEntry() {
			synchronized (mutex) {
				return nullableSynchronizedEntry(delegate().firstEntry(), mutex);
			}
		}

		@Override
		public Entry<K, V> floorEntry(K key) {
			synchronized (mutex) {
				return nullableSynchronizedEntry(delegate().floorEntry(key), mutex);
			}
		}

		@Override
		public K floorKey(K key) {
			synchronized (mutex) {
				return delegate().floorKey(key);
			}
		}

		@Override
		public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
			synchronized (mutex) {
				return navigableMap(delegate().headMap(toKey, inclusive), mutex);
			}
		}

		@Override
		public Entry<K, V> higherEntry(K key) {
			synchronized (mutex) {
				return nullableSynchronizedEntry(delegate().higherEntry(key), mutex);
			}
		}

		@Override
		public K higherKey(K key) {
			synchronized (mutex) {
				return delegate().higherKey(key);
			}
		}

		@Override
		public Entry<K, V> lastEntry() {
			synchronized (mutex) {
				return nullableSynchronizedEntry(delegate().lastEntry(), mutex);
			}
		}

		@Override
		public Entry<K, V> lowerEntry(K key) {
			synchronized (mutex) {
				return nullableSynchronizedEntry(delegate().lowerEntry(key), mutex);
			}
		}

		@Override
		public K lowerKey(K key) {
			synchronized (mutex) {
				return delegate().lowerKey(key);
			}
		}

		@Override
		public Set<K> keySet() {
			return navigableKeySet();
		}

		transient NavigableSet<K> navigableKeySet;

		@Override
		public NavigableSet<K> navigableKeySet() {
			synchronized (mutex) {
				if (navigableKeySet == null) {
					return navigableKeySet = Synchronized.navigableSet(delegate().navigableKeySet(), mutex);
				}
				return navigableKeySet;
			}
		}

		@Override
		public Entry<K, V> pollFirstEntry() {
			synchronized (mutex) {
				return nullableSynchronizedEntry(delegate().pollFirstEntry(), mutex);
			}
		}

		@Override
		public Entry<K, V> pollLastEntry() {
			synchronized (mutex) {
				return nullableSynchronizedEntry(delegate().pollLastEntry(), mutex);
			}
		}

		@Override
		public NavigableMap<K, V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
			synchronized (mutex) {
				return navigableMap(delegate().subMap(fromKey, fromInclusive, toKey, toInclusive), mutex);
			}
		}

		@Override
		public NavigableMap<K, V> tailMap(K fromKey, boolean inclusive) {
			synchronized (mutex) {
				return navigableMap(delegate().tailMap(fromKey, inclusive), mutex);
			}
		}

		@Override
		public SortedMap<K, V> headMap(K toKey) {
			return headMap(toKey, false);
		}

		@Override
		public SortedMap<K, V> subMap(K fromKey, K toKey) {
			return subMap(fromKey, true, toKey, false);
		}

		@Override
		public SortedMap<K, V> tailMap(K fromKey) {
			return tailMap(fromKey, true);
		}

		private static final long serialVersionUID = 0;
	}

	@GwtIncompatible("works but is needed only for NavigableMap")
	private static <K, V> Entry<K, V> nullableSynchronizedEntry(@Nullable Entry<K, V> entry, @Nullable Object mutex) {
		if (entry == null) {
			return null;
		}
		return new SynchronizedEntry<K, V>(entry, mutex);
	}

	@GwtIncompatible("works but is needed only for NavigableMap")
	private static class SynchronizedEntry<K, V> extends SynchronizedObject implements Entry<K, V> {

		SynchronizedEntry(Entry<K, V> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@SuppressWarnings("unchecked") // guaranteed by the constructor
		@Override
		Entry<K, V> delegate() {
			return (Entry<K, V>) super.delegate();
		}

		@Override
		public boolean equals(Object obj) {
			synchronized (mutex) {
				return delegate().equals(obj);
			}
		}

		@Override
		public int hashCode() {
			synchronized (mutex) {
				return delegate().hashCode();
			}
		}

		@Override
		public K getKey() {
			synchronized (mutex) {
				return delegate().getKey();
			}
		}

		@Override
		public V getValue() {
			synchronized (mutex) {
				return delegate().getValue();
			}
		}

		@Override
		public V setValue(V value) {
			synchronized (mutex) {
				return delegate().setValue(value);
			}
		}

		private static final long serialVersionUID = 0;
	}

	static <E> Queue<E> queue(Queue<E> queue, @Nullable Object mutex) {
		return (queue instanceof SynchronizedQueue) ? queue : new SynchronizedQueue<E>(queue, mutex);
	}

	private static class SynchronizedQueue<E> extends SynchronizedCollection<E> implements Queue<E> {

		SynchronizedQueue(Queue<E> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		Queue<E> delegate() {
			return (Queue<E>) super.delegate();
		}

		@Override
		public E element() {
			synchronized (mutex) {
				return delegate().element();
			}
		}

		@Override
		public boolean offer(E e) {
			synchronized (mutex) {
				return delegate().offer(e);
			}
		}

		@Override
		public E peek() {
			synchronized (mutex) {
				return delegate().peek();
			}
		}

		@Override
		public E poll() {
			synchronized (mutex) {
				return delegate().poll();
			}
		}

		@Override
		public E remove() {
			synchronized (mutex) {
				return delegate().remove();
			}
		}

		private static final long serialVersionUID = 0;
	}

	@GwtIncompatible("Deque")
	static <E> Deque<E> deque(Deque<E> deque, @Nullable Object mutex) {
		return new SynchronizedDeque<E>(deque, mutex);
	}

	@GwtIncompatible("Deque")
	private static final class SynchronizedDeque<E> extends SynchronizedQueue<E> implements Deque<E> {

		SynchronizedDeque(Deque<E> delegate, @Nullable Object mutex) {
			super(delegate, mutex);
		}

		@Override
		Deque<E> delegate() {
			return (Deque<E>) super.delegate();
		}

		@Override
		public void addFirst(E e) {
			synchronized (mutex) {
				delegate().addFirst(e);
			}
		}

		@Override
		public void addLast(E e) {
			synchronized (mutex) {
				delegate().addLast(e);
			}
		}

		@Override
		public boolean offerFirst(E e) {
			synchronized (mutex) {
				return delegate().offerFirst(e);
			}
		}

		@Override
		public boolean offerLast(E e) {
			synchronized (mutex) {
				return delegate().offerLast(e);
			}
		}

		@Override
		public E removeFirst() {
			synchronized (mutex) {
				return delegate().removeFirst();
			}
		}

		@Override
		public E removeLast() {
			synchronized (mutex) {
				return delegate().removeLast();
			}
		}

		@Override
		public E pollFirst() {
			synchronized (mutex) {
				return delegate().pollFirst();
			}
		}

		@Override
		public E pollLast() {
			synchronized (mutex) {
				return delegate().pollLast();
			}
		}

		@Override
		public E getFirst() {
			synchronized (mutex) {
				return delegate().getFirst();
			}
		}

		@Override
		public E getLast() {
			synchronized (mutex) {
				return delegate().getLast();
			}
		}

		@Override
		public E peekFirst() {
			synchronized (mutex) {
				return delegate().peekFirst();
			}
		}

		@Override
		public E peekLast() {
			synchronized (mutex) {
				return delegate().peekLast();
			}
		}

		@Override
		public boolean removeFirstOccurrence(Object o) {
			synchronized (mutex) {
				return delegate().removeFirstOccurrence(o);
			}
		}

		@Override
		public boolean removeLastOccurrence(Object o) {
			synchronized (mutex) {
				return delegate().removeLastOccurrence(o);
			}
		}

		@Override
		public void push(E e) {
			synchronized (mutex) {
				delegate().push(e);
			}
		}

		@Override
		public E pop() {
			synchronized (mutex) {
				return delegate().pop();
			}
		}

		@Override
		public Iterator<E> descendingIterator() {
			synchronized (mutex) {
				return delegate().descendingIterator();
			}
		}

		private static final long serialVersionUID = 0;
	}
}
