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/*
 * Copyright (C) 2007 Google Inc.
 *
 * 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 com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
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.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;
import java.util.RandomAccess;
import java.util.Set;
import java.util.SortedSet;

import javax.annotation.Nullable;

/**
 * Synchronized collection views. The returned synchronized collection views are
 * serializable if the backing collection and the mutex are serializable.
 *
 * 

If a {@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. * *

This class should be used by other collection classes only. * * @author Mike Bostock * @author Jared Levy */ @GwtCompatible final class Synchronized { private Synchronized() {} /** Abstract base class for synchronized views. */ static class SynchronizedObject implements Serializable { private final Object delegate; protected final Object mutex; public SynchronizedObject(Object delegate, @Nullable Object mutex) { this.delegate = checkNotNull(delegate); this.mutex = (mutex == null) ? this : mutex; } protected 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. private void writeObject(ObjectOutputStream stream) throws IOException { synchronized (mutex) { stream.defaultWriteObject(); } } private static final long serialVersionUID = 0; } /** * Returns a synchronized (thread-safe) collection backed by the specified * collection using the specified mutex. In order to guarantee serial access, * it is critical that all access to the backing collection is * accomplished through the returned collection. * *

It is imperative that the user manually synchronize on the specified * mutex when iterating over the returned collection: * *

Collection<E> s = Synchronized.collection(
   *      new HashSet<E>(), mutex);
   *   ...
   * synchronized (mutex) {
   *   Iterator<E> i = s.iterator(); // Must be in synchronized block
   *   while (i.hasNext()) {
   *     foo(i.next());
   *   }
   * }
* * Failure to follow this advice may result in non-deterministic behavior. * * @param collection the collection to be wrapped in a synchronized view * @return a synchronized view of the specified collection */ static Collection collection( Collection collection, @Nullable Object mutex) { return new SynchronizedCollection(collection, mutex); } /** @see Synchronized#collection */ static class SynchronizedCollection extends SynchronizedObject implements Collection { public SynchronizedCollection( Collection delegate, @Nullable Object mutex) { super(delegate, mutex); } @SuppressWarnings("unchecked") @Override protected Collection delegate() { return (Collection) super.delegate(); } public boolean add(E e) { synchronized (mutex) { return delegate().add(e); } } public boolean addAll(Collection c) { synchronized (mutex) { return delegate().addAll(c); } } public void clear() { synchronized (mutex) { delegate().clear(); } } public boolean contains(Object o) { synchronized (mutex) { return delegate().contains(o); } } public boolean containsAll(Collection c) { synchronized (mutex) { return delegate().containsAll(c); } } public boolean isEmpty() { synchronized (mutex) { return delegate().isEmpty(); } } public Iterator iterator() { return delegate().iterator(); // manually synchronized } public boolean remove(Object o) { synchronized (mutex) { return delegate().remove(o); } } public boolean removeAll(Collection c) { synchronized (mutex) { return delegate().removeAll(c); } } public boolean retainAll(Collection c) { synchronized (mutex) { return delegate().retainAll(c); } } public int size() { synchronized (mutex) { return delegate().size(); } } public Object[] toArray() { synchronized (mutex) { return delegate().toArray(); } } public T[] toArray(T[] a) { synchronized (mutex) { return delegate().toArray(a); } } private static final long serialVersionUID = 0; } /** * Returns a synchronized (thread-safe) set backed by the specified set using * the specified mutex. In order to guarantee serial access, it is critical * that all access to the backing set is accomplished through the * returned set. * *

It is imperative that the user manually synchronize on the specified * mutex when iterating over the returned set: * *

Set<E> s = Synchronized.set(new HashSet<E>(), mutex);
   *   ...
   * synchronized (mutex) {
   *   Iterator<E> i = s.iterator(); // Must be in synchronized block
   *   while (i.hasNext()) {
   *     foo(i.next());
   *   }
   * }
* * Failure to follow this advice may result in non-deterministic behavior. * * @param set the set to be wrapped in a synchronized view * @return a synchronized view of the specified set */ public static Set set(Set set, @Nullable Object mutex) { return new SynchronizedSet(set, mutex); } /** @see Synchronized#set */ static class SynchronizedSet extends SynchronizedCollection implements Set { public SynchronizedSet(Set delegate, @Nullable Object mutex) { super(delegate, mutex); } @Override protected Set delegate() { return (Set) 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; } /** * Returns a synchronized (thread-safe) sorted set backed by the specified * sorted set using the specified mutex. In order to guarantee serial access, * it is critical that all access to the backing sorted set is * accomplished through the returned sorted set. * *

It is imperative that the user manually synchronize on the specified * mutex when iterating over the returned sorted set: * *

SortedSet<E> s = Synchronized.sortedSet(
   *      new TreeSet<E>(), mutex);
   *   ...
   * synchronized (mutex) {
   *   Iterator<E> i = s.iterator(); // Must be in synchronized block
   *   while (i.hasNext()) {
   *     foo(i.next());
   *   }
   * }
* * Failure to follow this advice may result in non-deterministic behavior. * * @param set the sorted set to be wrapped in a synchronized view * @return a synchronized view of the specified sorted set */ static SortedSet sortedSet(SortedSet set, @Nullable Object mutex) { return new SynchronizedSortedSet(set, mutex); } /** @see Synchronized#sortedSet */ static class SynchronizedSortedSet extends SynchronizedSet implements SortedSet { public SynchronizedSortedSet( SortedSet delegate, @Nullable Object mutex) { super(delegate, mutex); } @Override protected SortedSet delegate() { return (SortedSet) super.delegate(); } public Comparator comparator() { synchronized (mutex) { return delegate().comparator(); } } public SortedSet subSet(E fromElement, E toElement) { synchronized (mutex) { return sortedSet(delegate().subSet(fromElement, toElement), mutex); } } public SortedSet headSet(E toElement) { synchronized (mutex) { return sortedSet(delegate().headSet(toElement), mutex); } } public SortedSet tailSet(E fromElement) { synchronized (mutex) { return sortedSet(delegate().tailSet(fromElement), mutex); } } public E first() { synchronized (mutex) { return delegate().first(); } } public E last() { synchronized (mutex) { return delegate().last(); } } private static final long serialVersionUID = 0; } /** * Returns a synchronized (thread-safe) list backed by the specified list * using the specified mutex. In order to guarantee serial access, it is * critical that all access to the backing list is accomplished * through the returned list. * *

It is imperative that the user manually synchronize on the specified * mutex when iterating over the returned list: * *

List<E> l = Synchronized.list(new ArrayList<E>(), mutex);
   *   ...
   * synchronized (mutex) {
   *   Iterator<E> i = l.iterator(); // Must be in synchronized block
   *   while (i.hasNext()) {
   *     foo(i.next());
   *   }
   * }
* * Failure to follow this advice may result in non-deterministic behavior. * *

The returned list implements {@link RandomAccess} if the specified list * implements {@code RandomAccess}. * * @param list the list to be wrapped in a synchronized view * @return a synchronized view of the specified list */ static List list(List list, @Nullable Object mutex) { return (list instanceof RandomAccess) ? new SynchronizedRandomAccessList(list, mutex) : new SynchronizedList(list, mutex); } /** @see Synchronized#list */ static class SynchronizedList extends SynchronizedCollection implements List { public SynchronizedList(List delegate, @Nullable Object mutex) { super(delegate, mutex); } @Override protected List delegate() { return (List) super.delegate(); } public void add(int index, E element) { synchronized (mutex) { delegate().add(index, element); } } public boolean addAll(int index, Collection c) { synchronized (mutex) { return delegate().addAll(index, c); } } public E get(int index) { synchronized (mutex) { return delegate().get(index); } } public int indexOf(Object o) { synchronized (mutex) { return delegate().indexOf(o); } } public int lastIndexOf(Object o) { synchronized (mutex) { return delegate().lastIndexOf(o); } } public ListIterator listIterator() { return delegate().listIterator(); // manually synchronized } public ListIterator listIterator(int index) { return delegate().listIterator(index); // manually synchronized } public E remove(int index) { synchronized (mutex) { return delegate().remove(index); } } public E set(int index, E element) { synchronized (mutex) { return delegate().set(index, element); } } @GwtIncompatible("List.subList") public List subList(int fromIndex, int toIndex) { synchronized (mutex) { return list(Platform.subList(delegate(), 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; } /** @see Synchronized#list */ static class SynchronizedRandomAccessList extends SynchronizedList implements RandomAccess { public SynchronizedRandomAccessList(List list, @Nullable Object mutex) { super(list, mutex); } private static final long serialVersionUID = 0; } /** * Returns a synchronized (thread-safe) multiset backed by the specified * multiset using the specified mutex. In order to guarantee serial access, it * is critical that all access to the backing multiset is accomplished * through the returned multiset. * *

It is imperative that the user manually synchronize on the specified * mutex when iterating over the returned multiset: * *

Multiset<E> s = Synchronized.multiset(
   *      HashMultiset.<E>create(), mutex);
   *   ...
   * synchronized (mutex) {
   *   Iterator<E> i = s.iterator(); // Must be in synchronized block
   *   while (i.hasNext()) {
   *     foo(i.next());
   *   }
   * }
* * Failure to follow this advice may result in non-deterministic behavior. * * @param multiset the multiset to be wrapped * @return a synchronized view of the specified multiset */ private static Multiset multiset( Multiset multiset, @Nullable Object mutex) { return new SynchronizedMultiset(multiset, mutex); } /** @see Synchronized#multiset */ static class SynchronizedMultiset extends SynchronizedCollection implements Multiset { private transient Set elementSet; private transient Set> entrySet; public SynchronizedMultiset(Multiset delegate, @Nullable Object mutex) { super(delegate, mutex); } @Override protected Multiset delegate() { return (Multiset) super.delegate(); } public int count(Object o) { synchronized (mutex) { return delegate().count(o); } } public int add(E e, int n) { synchronized (mutex) { return delegate().add(e, n); } } public int remove(Object o, int n) { synchronized (mutex) { return delegate().remove(o, n); } } public int setCount(E element, int count) { synchronized (mutex) { return delegate().setCount(element, count); } } public boolean setCount(E element, int oldCount, int newCount) { synchronized (mutex) { return delegate().setCount(element, oldCount, newCount); } } public Set elementSet() { synchronized (mutex) { if (elementSet == null) { elementSet = typePreservingSet(delegate().elementSet(), mutex); } return elementSet; } } public Set> 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; } /** * Returns a synchronized (thread-safe) multimap backed by the specified * multimap using the specified mutex. In order to guarantee serial access, it * is critical that all access to the backing multimap is accomplished * through the returned multimap. * *

It is imperative that the user manually synchronize on the specified * mutex when accessing any of the return multimap's collection views: * *

Multimap<K,V> m = Synchronized.multimap(
   *      HashMultimap.create(), mutex);
   *   ...
   *  Set<K> s = m.keySet();  // Needn't be in synchronized block
   *   ...
   *  synchronized (mutex) {
   *    Iterator<K> i = s.iterator(); // Must be in synchronized block
   *    while (i.hasNext()) {
   *      foo(i.next());
   *    }
   *  }
* * Failure to follow this advice may result in non-deterministic behavior. * * @param multimap the multimap to be wrapped in a synchronized view * @return a synchronized view of the specified multimap */ public static Multimap multimap( Multimap multimap, @Nullable Object mutex) { return new SynchronizedMultimap(multimap, mutex); } /** @see Synchronized#multimap */ private static class SynchronizedMultimap extends SynchronizedObject implements Multimap { transient Set keySet; transient Collection valuesCollection; transient Collection> entries; transient Map> asMap; transient Multiset keys; @SuppressWarnings("unchecked") @Override protected Multimap delegate() { return (Multimap) super.delegate(); } SynchronizedMultimap(Multimap delegate, @Nullable Object mutex) { super(delegate, mutex); } public int size() { synchronized (mutex) { return delegate().size(); } } public boolean isEmpty() { synchronized (mutex) { return delegate().isEmpty(); } } public boolean containsKey(Object key) { synchronized (mutex) { return delegate().containsKey(key); } } public boolean containsValue(Object value) { synchronized (mutex) { return delegate().containsValue(value); } } public boolean containsEntry(Object key, Object value) { synchronized (mutex) { return delegate().containsEntry(key, value); } } public Collection get(K key) { synchronized (mutex) { return typePreservingCollection(delegate().get(key), mutex); } } public boolean put(K key, V value) { synchronized (mutex) { return delegate().put(key, value); } } public boolean putAll(K key, Iterable values) { synchronized (mutex) { return delegate().putAll(key, values); } } public boolean putAll(Multimap multimap) { synchronized (mutex) { return delegate().putAll(multimap); } } public Collection replaceValues(K key, Iterable values) { synchronized (mutex) { return delegate().replaceValues(key, values); // copy not synchronized } } public boolean remove(Object key, Object value) { synchronized (mutex) { return delegate().remove(key, value); } } public Collection removeAll(Object key) { synchronized (mutex) { return delegate().removeAll(key); // copy not synchronized } } public void clear() { synchronized (mutex) { delegate().clear(); } } public Set keySet() { synchronized (mutex) { if (keySet == null) { keySet = typePreservingSet(delegate().keySet(), mutex); } return keySet; } } public Collection values() { synchronized (mutex) { if (valuesCollection == null) { valuesCollection = collection(delegate().values(), mutex); } return valuesCollection; } } public Collection> entries() { synchronized (mutex) { if (entries == null) { entries = typePreservingCollection(delegate().entries(), mutex); } return entries; } } public Map> asMap() { synchronized (mutex) { if (asMap == null) { asMap = new SynchronizedAsMap(delegate().asMap(), mutex); } return asMap; } } public Multiset 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; } /** * Returns a synchronized (thread-safe) list multimap backed by the specified * multimap using the specified mutex. * *

You must follow the warnings described for {@link #multimap}. * * @param multimap the multimap to be wrapped in a synchronized view * @return a synchronized view of the specified multimap */ public static ListMultimap listMultimap( ListMultimap multimap, @Nullable Object mutex) { return new SynchronizedListMultimap(multimap, mutex); } /** @see Synchronized#listMultimap */ private static class SynchronizedListMultimap extends SynchronizedMultimap implements ListMultimap { SynchronizedListMultimap( ListMultimap delegate, @Nullable Object mutex) { super(delegate, mutex); } @Override protected ListMultimap delegate() { return (ListMultimap) super.delegate(); } @Override public List get(K key) { synchronized (mutex) { return list(delegate().get(key), mutex); } } @Override public List removeAll(Object key) { synchronized (mutex) { return delegate().removeAll(key); // copy not synchronized } } @Override public List replaceValues( K key, Iterable values) { synchronized (mutex) { return delegate().replaceValues(key, values); // copy not synchronized } } private static final long serialVersionUID = 0; } /** * Returns a synchronized (thread-safe) set multimap backed by the specified * multimap using the specified mutex. * *

You must follow the warnings described for {@link #multimap}. * * @param multimap the multimap to be wrapped in a synchronized view * @return a synchronized view of the specified multimap */ public static SetMultimap setMultimap( SetMultimap multimap, @Nullable Object mutex) { return new SynchronizedSetMultimap(multimap, mutex); } /** @see Synchronized#setMultimap */ private static class SynchronizedSetMultimap extends SynchronizedMultimap implements SetMultimap { transient Set> entrySet; SynchronizedSetMultimap( SetMultimap delegate, @Nullable Object mutex) { super(delegate, mutex); } @Override protected SetMultimap delegate() { return (SetMultimap) super.delegate(); } @Override public Set get(K key) { synchronized (mutex) { return set(delegate().get(key), mutex); } } @Override public Set removeAll(Object key) { synchronized (mutex) { return delegate().removeAll(key); // copy not synchronized } } @Override public Set replaceValues( K key, Iterable values) { synchronized (mutex) { return delegate().replaceValues(key, values); // copy not synchronized } } @Override public Set> entries() { synchronized (mutex) { if (entrySet == null) { entrySet = set(delegate().entries(), mutex); } return entrySet; } } private static final long serialVersionUID = 0; } /** * Returns a synchronized (thread-safe) sorted set multimap backed by the * specified multimap using the specified mutex. * *

You must follow the warnings described for {@link #multimap}. * * @param multimap the multimap to be wrapped in a synchronized view * @return a synchronized view of the specified multimap */ public static SortedSetMultimap sortedSetMultimap( SortedSetMultimap multimap, @Nullable Object mutex) { return new SynchronizedSortedSetMultimap(multimap, mutex); } /** @see Synchronized#sortedSetMultimap */ private static class SynchronizedSortedSetMultimap extends SynchronizedSetMultimap implements SortedSetMultimap { SynchronizedSortedSetMultimap( SortedSetMultimap delegate, @Nullable Object mutex) { super(delegate, mutex); } @Override protected SortedSetMultimap delegate() { return (SortedSetMultimap) super.delegate(); } @Override public SortedSet get(K key) { synchronized (mutex) { return sortedSet(delegate().get(key), mutex); } } @Override public SortedSet removeAll(Object key) { synchronized (mutex) { return delegate().removeAll(key); // copy not synchronized } } @Override public SortedSet replaceValues( K key, Iterable values) { synchronized (mutex) { return delegate().replaceValues(key, values); // copy not synchronized } } public Comparator valueComparator() { synchronized (mutex) { return delegate().valueComparator(); } } private static final long serialVersionUID = 0; } /** * Returns a synchronized (thread-safe) collection backed by the specified * collection using the specified mutex. In order to guarantee serial access, * it is critical that all access to the backing collection is * accomplished through the returned collection. * *

It is imperative that the user manually synchronize on the specified * mutex when iterating over the returned collection: * *

Collection<E> s = Synchronized.typePreservingCollection(
   *      new HashSet<E>(), mutex);
   *   ...
   * synchronized (mutex) {
   *   Iterator<E> i = s.iterator(); // Must be in synchronized block
   *   while (i.hasNext()) {
   *     foo(i.next());
   *   }
   * }
* * Failure to follow this advice may result in non-deterministic behavior. * *

If the specified collection is a {@code SortedSet}, {@code Set} or * {@code List}, this method will behave identically to {@link #sortedSet}, * {@link #set} or {@link #list} respectively, in that order of specificity. * * @param collection the collection to be wrapped in a synchronized view * @return a synchronized view of the specified collection */ private static Collection typePreservingCollection( Collection collection, @Nullable Object mutex) { if (collection instanceof SortedSet) { return sortedSet((SortedSet) collection, mutex); } else if (collection instanceof Set) { return set((Set) collection, mutex); } else if (collection instanceof List) { return list((List) collection, mutex); } else { return collection(collection, mutex); } } /** * Returns a synchronized (thread-safe) set backed by the specified set using * the specified mutex. In order to guarantee serial access, it is critical * that all access to the backing collection is accomplished through * the returned collection. * *

It is imperative that the user manually synchronize on the specified * mutex when iterating over the returned collection: * *

Set<E> s = Synchronized.typePreservingSet(
   *      new HashSet<E>(), mutex);
   *   ...
   * synchronized (mutex) {
   *   Iterator<E> i = s.iterator(); // Must be in synchronized block
   *   while (i.hasNext()) {
   *     foo(i.next());
   *   }
   * }
* * Failure to follow this advice may result in non-deterministic behavior. * *

If the specified collection is a {@code SortedSet} this method will * behave identically to {@link #sortedSet}. * * @param set the set to be wrapped in a synchronized view * @return a synchronized view of the specified set */ public static Set typePreservingSet( Set set, @Nullable Object mutex) { if (set instanceof SortedSet) { return sortedSet((SortedSet) set, mutex); } else { return set(set, mutex); } } /** @see Synchronized#multimap */ static class SynchronizedAsMapEntries extends SynchronizedSet>> { public SynchronizedAsMapEntries( Set>> delegate, @Nullable Object mutex) { super(delegate, mutex); } @Override public Iterator>> iterator() { final Iterator>> iterator = super.iterator(); // The iterator and entry aren't synchronized, but the entry value is. return new ForwardingIterator>>() { @Override protected Iterator>> delegate() { return iterator; } @Override public Map.Entry> next() { final Map.Entry> entry = iterator.next(); return new ForwardingMapEntry>() { @Override protected Map.Entry> delegate() { return entry; } @Override public Collection 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[] 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.containsAll(delegate(), c); } } @Override public boolean equals(Object o) { if (o == this) { return true; } synchronized (mutex) { return Collections2.setEquals(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; } /** * Returns a synchronized (thread-safe) map backed by the specified map using * the specified mutex. In order to guarantee serial access, it is critical * that all access to the backing map is accomplished through the * returned map. * *

It is imperative that the user manually synchronize on the specified * mutex when accessing any of the return map's collection views: * *

Map<K,V> m = Synchronized.map(
   *      new HashMap<K,V>(), mutex);
   *   ...
   *  Set<K> s = m.keySet();  // Needn't be in synchronized block
   *   ...
   *  synchronized (mutex) {
   *    Iterator<K> i = s.iterator(); // Must be in synchronized block
   *    while (i.hasNext()) {
   *      foo(i.next());
   *    }
   *  }
* * Failure to follow this advice may result in non-deterministic behavior. * * @param map the map to be wrapped in a synchronized view * @return a synchronized view of the specified map */ public static Map map(Map map, @Nullable Object mutex) { return new SynchronizedMap(map, mutex); } /** @see Synchronized#map */ static class SynchronizedMap extends SynchronizedObject implements Map { private transient Set keySet; private transient Collection values; private transient Set> entrySet; public SynchronizedMap(Map delegate, @Nullable Object mutex) { super(delegate, mutex); } @SuppressWarnings("unchecked") @Override protected Map delegate() { return (Map) super.delegate(); } public void clear() { synchronized (mutex) { delegate().clear(); } } public boolean containsKey(Object key) { synchronized (mutex) { return delegate().containsKey(key); } } public boolean containsValue(Object value) { synchronized (mutex) { return delegate().containsValue(value); } } public Set> entrySet() { synchronized (mutex) { if (entrySet == null) { entrySet = set(delegate().entrySet(), mutex); } return entrySet; } } public V get(Object key) { synchronized (mutex) { return delegate().get(key); } } public boolean isEmpty() { synchronized (mutex) { return delegate().isEmpty(); } } public Set keySet() { synchronized (mutex) { if (keySet == null) { keySet = set(delegate().keySet(), mutex); } return keySet; } } public V put(K key, V value) { synchronized (mutex) { return delegate().put(key, value); } } public void putAll(Map map) { synchronized (mutex) { delegate().putAll(map); } } public V remove(Object key) { synchronized (mutex) { return delegate().remove(key); } } public int size() { synchronized (mutex) { return delegate().size(); } } public Collection 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; } /** * Returns a synchronized (thread-safe) bimap backed by the specified bimap * using the specified mutex. In order to guarantee serial access, it is * critical that all access to the backing bimap is accomplished * through the returned bimap. * *

It is imperative that the user manually synchronize on the specified * mutex when accessing any of the return bimap's collection views: * *

BiMap<K,V> m = Synchronized.biMap(
   *      HashBiMap.<K,V>create(), mutex);
   *   ...
   *  Set<K> s = m.keySet();  // Needn't be in synchronized block
   *   ...
   *  synchronized (mutex) {
   *    Iterator<K> i = s.iterator(); // Must be in synchronized block
   *    while (i.hasNext()) {
   *      foo(i.next());
   *    }
   *  }
* * Failure to follow this advice may result in non-deterministic behavior. * * @param bimap the bimap to be wrapped in a synchronized view * @return a synchronized view of the specified bimap */ public static BiMap biMap( BiMap bimap, @Nullable Object mutex) { return new SynchronizedBiMap(bimap, mutex, null); } /** @see Synchronized#biMap */ static class SynchronizedBiMap extends SynchronizedMap implements BiMap, Serializable { private transient Set valueSet; private transient BiMap inverse; public SynchronizedBiMap( BiMap delegate, @Nullable Object mutex, @Nullable BiMap inverse) { super(delegate, mutex); this.inverse = inverse; } @Override protected BiMap delegate() { return (BiMap) super.delegate(); } @Override public Set values() { synchronized (mutex) { if (valueSet == null) { valueSet = set(delegate().values(), mutex); } return valueSet; } } public V forcePut(K key, V value) { synchronized (mutex) { return delegate().forcePut(key, value); } } public BiMap inverse() { synchronized (mutex) { if (inverse == null) { inverse = new SynchronizedBiMap(delegate().inverse(), mutex, this); } return inverse; } } private static final long serialVersionUID = 0; } /** @see SynchronizedMultimap#asMap */ static class SynchronizedAsMap extends SynchronizedMap> { private transient Set>> asMapEntrySet; private transient Collection> asMapValues; public SynchronizedAsMap( Map> delegate, @Nullable Object mutex) { super(delegate, mutex); } @Override public Collection get(Object key) { synchronized (mutex) { Collection collection = super.get(key); return (collection == null) ? null : typePreservingCollection(collection, mutex); } } @Override public Set>> entrySet() { if (asMapEntrySet == null) { asMapEntrySet = new SynchronizedAsMapEntries( delegate().entrySet(), mutex); } return asMapEntrySet; } @Override public Collection> values() { if (asMapValues == null) { asMapValues = new SynchronizedAsMapValues(delegate().values(), mutex); } return asMapValues; } @Override public boolean containsValue(Object o) { return values().contains(o); } private static final long serialVersionUID = 0; } /** @see SynchronizedMultimap#asMap */ static class SynchronizedAsMapValues extends SynchronizedCollection> { SynchronizedAsMapValues( Collection> delegate, @Nullable Object mutex) { super(delegate, mutex); } @Override public Iterator> iterator() { // The iterator isn't synchronized, but its value is. final Iterator> iterator = super.iterator(); return new ForwardingIterator>() { @Override protected Iterator> delegate() { return iterator; } @Override public Collection next() { return typePreservingCollection(iterator.next(), mutex); } }; } // See Collections.CheckedMap.CheckedEntrySet for details on attacks. @Override public Object[] toArray() { synchronized (mutex) { return ObjectArrays.toArrayImpl(delegate()); } } @Override public T[] toArray(T[] array) { synchronized (mutex) { return ObjectArrays.toArrayImpl(delegate(), array); } } @Override public boolean contains(Object o) { synchronized (mutex) { return Iterators.contains(delegate().iterator(), o); } } @Override public boolean containsAll(Collection c) { synchronized (mutex) { return Collections2.containsAll(delegate(), c); } } @Override public boolean remove(Object o) { synchronized (mutex) { return Iterables.remove(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; } }




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