#5612

Committed 11 Jul 2026 03:47PM UTC coverage: 71.292% (-28.7%) from 100.0%

Build # #5612

Build Type

push

github

Committed by

ben-manes

Commit Message

Preserve timestamps on a raced same-instance refresh

The automatic refreshIfNeeded path checked for an equal-value reload
before the ABA/ownership check and returned without preserving the
timestamps, so a reload completing after a concurrent put(k,
sameInstance) did a full update — shifting the entry's expiration
forward by the reload's in-flight duration and stomping the write.
Mirror the explicit-refresh fix: check ownership first. An owned
reload installs the value (refreshing metadata even for a same
instance), while a raced reload preserves the write's timestamps and
only notifies REPLACED when the value differs.

Coverage Stats

2957 of 4134 branches covered (71.53%)

3 of 3 new or added lines in 1 file covered. (100.0%)

2408 existing lines in 53 files now uncovered.

5980 of 8388 relevant lines covered (71.29%)

0.71 hits per line

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95.92

/caffeine/src/main/java/com/github/benmanes/caffeine/cache/Interner.java

/*
 * Copyright 2022 Ben Manes. All Rights Reserved.
 *
 * 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.github.benmanes.caffeine.cache;

import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

import com.github.benmanes.caffeine.cache.References.LookupKeyEqualsReference;
import com.github.benmanes.caffeine.cache.References.WeakKeyEqualsReference;

/**
 * Provides similar behavior to {@link String#intern} for any immutable type.
 * <p>
 * Note that {@code String.intern()} has some well-known performance limitations and should
 * generally be avoided. Prefer {@link Interner#newWeakInterner} or another {@code Interner}
 * implementation even for {@code String} interning.
 *
 * @param <E> the type of elements
 * @author ben.manes@gmail.com (Ben Manes)
 */
@NullMarked
@FunctionalInterface
public interface Interner<E> {

  /**
   * Chooses and returns the representative instance for any collection of instances that are
   * equal to each other. If two {@linkplain Object#equals equal} inputs are given to this method,
   * both calls will return the same instance. That is, {@code intern(a).equals(a)} always holds,
   * and {@code intern(a) == intern(b)} if and only if {@code a.equals(b)}. Note that {@code
   * intern(a)} is permitted to return one instance now and a different instance later if the
   * original interned instance was garbage-collected.
   * <p>
   * <b>Warning:</b> Do not use with mutable objects.
   *
   * @param sample the element to add if absent
   * @return the representative instance, possibly the {@code sample} if absent
   * @throws NullPointerException if {@code sample} is null
   */
  E intern(E sample);

  /**
   * Returns a new thread-safe interner that retains a strong reference to each instance it has
   * interned, thus preventing these instances from being garbage-collected.
   *
   * @param <E> the type of elements
   * @return an interner for retrieving the canonical instance
   */
  static <E> Interner<E> newStrongInterner() {
    return new StrongInterner<>();
  }

  /**
   * Returns a new thread-safe interner that retains a weak reference to each instance it has
   * interned, and so does not prevent these instances from being garbage-collected.
   *
   * @param <E> the type of elements
   * @return an interner for retrieving the canonical instance
   */
  static <E> Interner<E> newWeakInterner() {
    return new WeakInterner<>();
  }
}

final class StrongInterner<E> implements Interner<E> {
  final ConcurrentMap<E, E> map;

  StrongInterner() {
    map = new ConcurrentHashMap<>();
  }
  @Override public E intern(E sample) {
    E canonical = map.get(sample);
    if (canonical != null) {
      return canonical;
    }

    @Nullable E value = map.putIfAbsent(sample, sample);
    return (value == null) ? sample : value;
  }
}

final class WeakInterner<E> implements Interner<E> {
  final BoundedLocalCache<E, Boolean> cache;

  WeakInterner() {
    cache = Caffeine.newWeakInterner();
  }
  @Override public E intern(E sample) {
    for (;;) {
      E canonical = cache.getKey(sample);
      if (canonical != null) {
        return canonical;
      }

      var value = cache.putIfAbsent(sample, true);
      if (value == null) {
        return sample;
      }
    }
  }
}

@SuppressWarnings({"BooleanLiteral", "unchecked"})
final class Interned<K, V> extends Node<K, V> implements NodeFactory<K, V> {
  static final NodeFactory<Object, Object> FACTORY = new Interned<>();

  volatile Reference<?> keyReference;

  Interned() {
    this.keyReference = NodeFactory.DEAD_WEAK_KEY;
  }
  Interned(Reference<K> keyReference) {
    this.keyReference = keyReference;
  }
  @Override public @Nullable K getKey() {
    return (K) keyReference.get();
  }
  @Override public Object getKeyReference() {
    return keyReference;
  }
  @Override public Object getKeyReferenceOrNull() {
    return keyReference;
  }
  @Override public V getValue() {
    return (V) Boolean.TRUE;
  }
  @Override public V getValueReference() {
    return (V) Boolean.TRUE;
  }
  @Override public void setValue(V value, @Nullable ReferenceQueue<V> referenceQueue) {}
  @Override public boolean containsValue(Object value) {
    return Objects.equals(value, getValue());
  }
  @Override public Node<K, V> newNode(Object keyReference, V value,
      @Nullable ReferenceQueue<V> valueReferenceQueue, int weight, long now) {
    return new Interned<>((Reference<K>) keyReference);
  }
  @Override public Object newLookupKey(Object key) {
    return new LookupKeyEqualsReference<>(key);
  }
  @Override public Object newReferenceKey(K key, ReferenceQueue<K> referenceQueue) {
    return new WeakKeyEqualsReference<>(key, referenceQueue);
  }
  @Override public boolean isAlive() {
    Object keyRef = keyReference;
    return (keyRef != RETIRED_WEAK_KEY) && (keyRef != DEAD_WEAK_KEY);
  }
  @Override public boolean isRetired() {
    return (keyReference == RETIRED_WEAK_KEY);
  }
  @Override public void retire() {
    var keyRef = keyReference;
    keyReference = RETIRED_WEAK_KEY;
    keyRef.clear();
  }
  @Override public boolean isDead() {
    return (keyReference == DEAD_WEAK_KEY);
  }
  @Override public void die() {
    var keyRef = keyReference;
    keyReference = DEAD_WEAK_KEY;
    keyRef.clear();
  }
}

1	/*
2	* Copyright 2022 Ben Manes. All Rights Reserved.
3	*
4	* Licensed under the Apache License, Version 2.0 (the "License");
5	* you may not use this file except in compliance with the License.
6	* You may obtain a copy of the License at
7	*
8	* http://www.apache.org/licenses/LICENSE-2.0
9	*
10	* Unless required by applicable law or agreed to in writing, software
11	* distributed under the License is distributed on an "AS IS" BASIS,
12	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13	* See the License for the specific language governing permissions and
14	* limitations under the License.
15	*/
16	package com.github.benmanes.caffeine.cache;
17
18	import java.lang.ref.Reference;
19	import java.lang.ref.ReferenceQueue;
20	import java.util.Objects;
21	import java.util.concurrent.ConcurrentHashMap;
22	import java.util.concurrent.ConcurrentMap;
23
24	import org.jspecify.annotations.NullMarked;
25	import org.jspecify.annotations.Nullable;
26
27	import com.github.benmanes.caffeine.cache.References.LookupKeyEqualsReference;
28	import com.github.benmanes.caffeine.cache.References.WeakKeyEqualsReference;
29
30	/**
31	* Provides similar behavior to {@link String#intern} for any immutable type.
32	* <p>
33	* Note that {@code String.intern()} has some well-known performance limitations and should
34	* generally be avoided. Prefer {@link Interner#newWeakInterner} or another {@code Interner}
35	* implementation even for {@code String} interning.
36	*
37	* @param <E> the type of elements
38	* @author ben.manes@gmail.com (Ben Manes)
39	*/
40	@NullMarked
41	@FunctionalInterface
42	public interface Interner<E> {
43
44	/**
45	* Chooses and returns the representative instance for any collection of instances that are
46	* equal to each other. If two {@linkplain Object#equals equal} inputs are given to this method,
47	* both calls will return the same instance. That is, {@code intern(a).equals(a)} always holds,
48	* and {@code intern(a) == intern(b)} if and only if {@code a.equals(b)}. Note that {@code
49	* intern(a)} is permitted to return one instance now and a different instance later if the
50	* original interned instance was garbage-collected.
51	* <p>
52	* <b>Warning:</b> Do not use with mutable objects.
53	*
54	* @param sample the element to add if absent
55	* @return the representative instance, possibly the {@code sample} if absent
56	* @throws NullPointerException if {@code sample} is null
57	*/
58	E intern(E sample);
59
60	/**
61	* Returns a new thread-safe interner that retains a strong reference to each instance it has
62	* interned, thus preventing these instances from being garbage-collected.
63	*
64	* @param <E> the type of elements
65	* @return an interner for retrieving the canonical instance
66	*/
67	static <E> Interner<E> newStrongInterner() {
68	return new StrongInterner<>();	1✔
69	}
70
71	/**
72	* Returns a new thread-safe interner that retains a weak reference to each instance it has
73	* interned, and so does not prevent these instances from being garbage-collected.
74	*
75	* @param <E> the type of elements
76	* @return an interner for retrieving the canonical instance
77	*/
78	static <E> Interner<E> newWeakInterner() {
79	return new WeakInterner<>();	1✔
80	}
81	}
82
83	final class StrongInterner<E> implements Interner<E> {
84	final ConcurrentMap<E, E> map;
85
86	StrongInterner() {	1✔
87	map = new ConcurrentHashMap<>();	1✔
88	}	1✔
89	@Override public E intern(E sample) {
90	E canonical = map.get(sample);	1✔
91	if (canonical != null) {	1!
UNCOV 92	return canonical;	×
93	}
94
95	@Nullable E value = map.putIfAbsent(sample, sample);	1✔
96	return (value == null) ? sample : value;	1!
97	}
98	}
99
100	final class WeakInterner<E> implements Interner<E> {
101	final BoundedLocalCache<E, Boolean> cache;
102
103	WeakInterner() {	1✔
104	cache = Caffeine.newWeakInterner();	1✔
105	}	1✔
106	@Override public E intern(E sample) {
107	for (;;) {
108	E canonical = cache.getKey(sample);	1✔
109	if (canonical != null) {	1✔
110	return canonical;	1✔
111	}
112
113	var value = cache.putIfAbsent(sample, true);	1✔
114	if (value == null) {	1✔
115	return sample;	1✔
116	}
117	}	1✔
118	}
119	}
120
121	@SuppressWarnings({"BooleanLiteral", "unchecked"})
122	final class Interned<K, V> extends Node<K, V> implements NodeFactory<K, V> {
123	static final NodeFactory<Object, Object> FACTORY = new Interned<>();	1✔
124
125	volatile Reference<?> keyReference;
126
127	Interned() {	1✔
128	this.keyReference = NodeFactory.DEAD_WEAK_KEY;	1✔
129	}	1✔
130	Interned(Reference<K> keyReference) {	1✔
131	this.keyReference = keyReference;	1✔
132	}	1✔
133	@Override public @Nullable K getKey() {
134	return (K) keyReference.get();	1✔
135	}
136	@Override public Object getKeyReference() {
137	return keyReference;	1✔
138	}
139	@Override public Object getKeyReferenceOrNull() {
140	return keyReference;	1✔
141	}
142	@Override public V getValue() {
143	return (V) Boolean.TRUE;	1✔
144	}
145	@Override public V getValueReference() {
146	return (V) Boolean.TRUE;	1✔
147	}
UNCOV 148	@Override public void setValue(V value, @Nullable ReferenceQueue<V> referenceQueue) {}	×
149	@Override public boolean containsValue(Object value) {
150	return Objects.equals(value, getValue());	1✔
151	}
152	@Override public Node<K, V> newNode(Object keyReference, V value,
153	@Nullable ReferenceQueue<V> valueReferenceQueue, int weight, long now) {
154	return new Interned<>((Reference<K>) keyReference);	1✔
155	}
156	@Override public Object newLookupKey(Object key) {
157	return new LookupKeyEqualsReference<>(key);	1✔
158	}
159	@Override public Object newReferenceKey(K key, ReferenceQueue<K> referenceQueue) {
160	return new WeakKeyEqualsReference<>(key, referenceQueue);	1✔
161	}
162	@Override public boolean isAlive() {
163	Object keyRef = keyReference;	1✔
164	return (keyRef != RETIRED_WEAK_KEY) && (keyRef != DEAD_WEAK_KEY);	1✔
165	}
166	@Override public boolean isRetired() {
167	return (keyReference == RETIRED_WEAK_KEY);	1✔
168	}
169	@Override public void retire() {
170	var keyRef = keyReference;	1✔
171	keyReference = RETIRED_WEAK_KEY;	1✔
172	keyRef.clear();	1✔
173	}	1✔
174	@Override public boolean isDead() {
175	return (keyReference == DEAD_WEAK_KEY);	1✔
176	}
177	@Override public void die() {
178	var keyRef = keyReference;	1✔
179	keyReference = DEAD_WEAK_KEY;	1✔
180	keyRef.clear();	1✔
181	}	1✔
182	}

ben-manes / caffeine / #5612

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