1 /*
2 * Copyright (C) 2011 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5 * in compliance with the License. You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software distributed under the License
10 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11 * or implied. See the License for the specific language governing permissions and limitations under
12 * the License.
13 */
14
15 package com.google.common.cache;
16
17 import com.google.common.annotations.GwtIncompatible;
18 import com.google.common.base.Preconditions;
19 import com.google.common.collect.ForwardingObject;
20 import com.google.common.collect.ImmutableMap;
21 import java.util.Map;
22 import java.util.concurrent.Callable;
23 import java.util.concurrent.ConcurrentMap;
24 import java.util.concurrent.ExecutionException;
25 import org.checkerframework.checker.nullness.qual.Nullable;
26
27 /**
28 * A cache which forwards all its method calls to another cache. Subclasses should override one or
29 * more methods to modify the behavior of the backing cache as desired per the <a
30 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
31 *
32 * @author Charles Fry
33 * @since 10.0
34 */
35 @GwtIncompatible
36 public abstract class ForwardingCache<K, V> extends ForwardingObject implements Cache<K, V> {
37
38 /** Constructor for use by subclasses. */
39 protected ForwardingCache() {}
40
41 @Override
42 protected abstract Cache<K, V> delegate();
43
44 /** @since 11.0 */
45 @Override
46 public @Nullable V getIfPresent(Object key) {
47 return delegate().getIfPresent(key);
48 }
49
50 /** @since 11.0 */
51 @Override
52 public V get(K key, Callable<? extends V> valueLoader) throws ExecutionException {
53 return delegate().get(key, valueLoader);
54 }
55
56 /** @since 11.0 */
57 @Override
58 public ImmutableMap<K, V> getAllPresent(Iterable<?> keys) {
59 return delegate().getAllPresent(keys);
60 }
61
62 /** @since 11.0 */
63 @Override
64 public void put(K key, V value) {
65 delegate().put(key, value);
66 }
67
68 /** @since 12.0 */
69 @Override
70 public void putAll(Map<? extends K, ? extends V> m) {
71 delegate().putAll(m);
72 }
73
74 @Override
75 public void invalidate(Object key) {
76 delegate().invalidate(key);
77 }
78
79 /** @since 11.0 */
80 @Override
81 public void invalidateAll(Iterable<?> keys) {
82 delegate().invalidateAll(keys);
83 }
84
85 @Override
86 public void invalidateAll() {
87 delegate().invalidateAll();
88 }
89
90 @Override
91 public long size() {
92 return delegate().size();
93 }
94
95 @Override
96 public CacheStats stats() {
97 return delegate().stats();
98 }
99
100 @Override
101 public ConcurrentMap<K, V> asMap() {
102 return delegate().asMap();
103 }
104
105 @Override
106 public void cleanUp() {
107 delegate().cleanUp();
108 }
109
110 /**
111 * A simplified version of {@link ForwardingCache} where subclasses can pass in an already
112 * constructed {@link Cache} as the delegate.
113 *
114 * @since 10.0
115 */
116 public abstract static class SimpleForwardingCache<K, V> extends ForwardingCache<K, V> {
117 private final Cache<K, V> delegate;
118
119 protected SimpleForwardingCache(Cache<K, V> delegate) {
120 this.delegate = Preconditions.checkNotNull(delegate);
121 }
122
123 @Override
124 protected final Cache<K, V> delegate() {
125 return delegate;
126 }
127 }
128 }