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authorSven Gothel <[email protected]>2019-12-30 23:42:03 +0100
committerSven Gothel <[email protected]>2019-12-30 23:42:03 +0100
commit5979d66fb0c619be32ebcf9fbe644cf6d757345f (patch)
treebe3c1179b28496b81ffb1eb63ba484907e2dcb3b /src/java
parent1390bc236de531646aaa4525a17de1a533b1fa06 (diff)
Add WeakIdentityHashMap implementation (from Apache Avro)
Origin <https://github.com/apache/avro/blob/master/lang/java/avro/src/main/java/org/apache/avro/util/WeakIdentityHashMap.java> from their commit 70260919426f89825ca148f5ee815f3b2cf4764d. Apache License Version 2.0 until. Using our JogAmp 'New BSD 2-Clause License' for changes after this initial commit. Related to Bug 1312, where we like to utilize a WeakIdentityHashMap, allowing to have cached shared GLContext to disappear .. a compromise.
Diffstat (limited to 'src/java')
-rw-r--r--src/java/com/jogamp/common/util/WeakIdentityHashMap.java229
1 files changed, 229 insertions, 0 deletions
diff --git a/src/java/com/jogamp/common/util/WeakIdentityHashMap.java b/src/java/com/jogamp/common/util/WeakIdentityHashMap.java
new file mode 100644
index 0000000..92fbbd4
--- /dev/null
+++ b/src/java/com/jogamp/common/util/WeakIdentityHashMap.java
@@ -0,0 +1,229 @@
+/**
+ * Copyright 2019 JogAmp Community. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification, are
+ * permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this list of
+ * conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice, this list
+ * of conditions and the following disclaimer in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JogAmp Community ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JogAmp Community OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * The views and conclusions contained in the software and documentation are those of the
+ * authors and should not be interpreted as representing official policies, either expressed
+ * or implied, of JogAmp Community.
+ *
+ * Original source code of this class taken from Apache Avro
+ * <https://github.com/apache/avro/blob/master/lang/java/avro/src/main/java/org/apache/avro/util/WeakIdentityHashMap.java>
+ * commit 70260919426f89825ca148f5ee815f3b2cf4764d.
+ * Up until commit 70260919426f89825ca148f5ee815f3b2cf4764d,
+ * this code has been licensed as described below:
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * https://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.jogamp.common.util;
+
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * Implements a combination of WeakHashMap and IdentityHashMap. Useful for
+ * caches that need to key off of a == comparison instead of a .equals.
+ *
+ * <b> This class is not a general-purpose Map implementation! While this class
+ * implements the Map interface, it intentionally violates Map's general
+ * contract, which mandates the use of the equals method when comparing objects.
+ * This class is designed for use only in the rare cases wherein
+ * reference-equality semantics are required.
+ *
+ * Note that this implementation is not synchronized. </b>
+ */
+public class WeakIdentityHashMap<K, V> implements Map<K, V> {
+ private final ReferenceQueue<K> queue = new ReferenceQueue<>();
+ private Map<IdentityWeakReference, V> backingStore = new HashMap<>();
+
+ public WeakIdentityHashMap() {
+ }
+
+ @Override
+ public void clear() {
+ backingStore.clear();
+ reap();
+ }
+
+ @Override
+ public boolean containsKey(Object key) {
+ reap();
+ return backingStore.containsKey(new IdentityWeakReference(key));
+ }
+
+ @Override
+ public boolean containsValue(Object value) {
+ reap();
+ return backingStore.containsValue(value);
+ }
+
+ @Override
+ public Set<Map.Entry<K, V>> entrySet() {
+ reap();
+ Set<Map.Entry<K, V>> ret = new HashSet<>();
+ for (Map.Entry<IdentityWeakReference, V> ref : backingStore.entrySet()) {
+ final K key = ref.getKey().get();
+ final V value = ref.getValue();
+ Map.Entry<K, V> entry = new Map.Entry<K, V>() {
+ @Override
+ public K getKey() {
+ return key;
+ }
+
+ @Override
+ public V getValue() {
+ return value;
+ }
+
+ @Override
+ public V setValue(V value) {
+ throw new UnsupportedOperationException();
+ }
+ };
+ ret.add(entry);
+ }
+ return Collections.unmodifiableSet(ret);
+ }
+
+ @Override
+ public Set<K> keySet() {
+ reap();
+ Set<K> ret = new HashSet<>();
+ for (IdentityWeakReference ref : backingStore.keySet()) {
+ ret.add(ref.get());
+ }
+ return Collections.unmodifiableSet(ret);
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (!(o instanceof WeakIdentityHashMap)) {
+ return false;
+ }
+ return backingStore.equals(((WeakIdentityHashMap) o).backingStore);
+ }
+
+ @Override
+ public V get(Object key) {
+ reap();
+ return backingStore.get(new IdentityWeakReference(key));
+ }
+
+ @Override
+ public V put(K key, V value) {
+ reap();
+ return backingStore.put(new IdentityWeakReference(key), value);
+ }
+
+ @Override
+ public int hashCode() {
+ reap();
+ return backingStore.hashCode();
+ }
+
+ @Override
+ public boolean isEmpty() {
+ reap();
+ return backingStore.isEmpty();
+ }
+
+ @Override
+ public void putAll(Map t) {
+ throw new UnsupportedOperationException();
+ }
+
+ @Override
+ public V remove(Object key) {
+ reap();
+ return backingStore.remove(new IdentityWeakReference(key));
+ }
+
+ @Override
+ public int size() {
+ reap();
+ return backingStore.size();
+ }
+
+ @Override
+ public Collection<V> values() {
+ reap();
+ return backingStore.values();
+ }
+
+ private synchronized void reap() {
+ Object zombie = queue.poll();
+
+ while (zombie != null) {
+ IdentityWeakReference victim = (IdentityWeakReference) zombie;
+ backingStore.remove(victim);
+ zombie = queue.poll();
+ }
+ }
+
+ class IdentityWeakReference extends WeakReference<K> {
+ int hash;
+
+ @SuppressWarnings("unchecked")
+ IdentityWeakReference(Object obj) {
+ super((K) obj, queue);
+ hash = System.identityHashCode(obj);
+ }
+
+ @Override
+ public int hashCode() {
+ return hash;
+ }
+
+ @Override
+ public boolean equals(Object o) {
+ if (this == o) {
+ return true;
+ }
+ if (!(o instanceof WeakIdentityHashMap.IdentityWeakReference)) {
+ return false;
+ }
+ IdentityWeakReference ref = (IdentityWeakReference) o;
+ return this.get() == ref.get();
+ }
+ }
+}