Added some lock-free concurrent collections (set, map, bi-map)
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src/dorkbox/util/collections/LockFreeBiMap.java
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412
src/dorkbox/util/collections/LockFreeBiMap.java
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/*
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* Copyright 2018 dorkbox, llc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package dorkbox.util.collections;
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import java.util.Collection;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
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/**
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* A bimap (or "bidirectional map") is a map that preserves the uniqueness of its values as well as that of its keys. This constraint
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* enables bimaps to support an "inverse view", which is another bimap containing the same entries as this bimap but with reversed keys and values.
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*
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* This class uses the "single-writer-principle" for lock-free publication.
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*
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* Since there are only 2 methods to guarantee that modifications can only be called one-at-a-time (either it is only called by
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* one thread, or only one thread can access it at a time) -- we chose the 2nd option -- and use 'synchronized' to make sure that only
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* one thread can access this modification methods at a time. Getting or checking the presence of values can then happen in a lock-free
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* manner.
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*
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* According to my benchmarks, this is approximately 25% faster than ConcurrentHashMap for (all types of) reads, and a lot slower for
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* contended writes.
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*
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* This data structure is for many-read/few-write scenarios
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*/
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public final
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class LockFreeBiMap<K, V> {
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// Recommended for best performance while adhering to the "single writer principle". Must be static-final
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private static final AtomicReferenceFieldUpdater<LockFreeBiMap, HashMap> forwardREF =
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AtomicReferenceFieldUpdater.newUpdater(LockFreeBiMap.class,
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HashMap.class,
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"forwardHashMap");
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private static final AtomicReferenceFieldUpdater<LockFreeBiMap, HashMap> reverseREF =
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AtomicReferenceFieldUpdater.newUpdater(LockFreeBiMap.class,
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HashMap.class,
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"reverseHashMap");
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private volatile HashMap<K, V> forwardHashMap = new HashMap<K, V>();
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private volatile HashMap<V, K> reverseHashMap = new HashMap<V, K>();
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// synchronized is used here to ensure the "single writer principle", and make sure that ONLY one thread at a time can enter this
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// section. Because of this, we can have unlimited reader threads all going at the same time, without contention (which is our
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// use-case 99% of the time)
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public
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LockFreeBiMap() {
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}
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/**
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* Removes all of the mappings from this bimap.
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* The bimap will be empty after this call returns.
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*/
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public synchronized
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void clear() {
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forwardHashMap.clear();
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reverseHashMap.clear();
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}
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/**
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* Replaces all of the mappings from the specified map to this bimap.
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* These mappings will replace any mappings that this map had for
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* any of the keys currently in the specified map.
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*
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* @param hashMap mappings to be stored in this map
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*
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* @throws NullPointerException if the specified map is null
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*
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* @throws IllegalArgumentException if a given value in the map is already bound to a different key in this bimap. The bimap will remain
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* unmodified in this event. To avoid this exception, call {@link #replaceAllForce(Map)} replaceAllForce(map) instead.
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*/
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public synchronized
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void replaceAll(final Map<K, V> hashMap) throws IllegalArgumentException {
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if (hashMap == null) {
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throw new NullPointerException("hashMap");
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}
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LockFreeBiMap<K, V> biMap = new LockFreeBiMap<K, V>();
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try {
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biMap.putAll(hashMap);
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} catch (IllegalArgumentException e) {
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// do nothing if there is an exception
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throw e;
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}
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// only if there are no problems with the creation of the new bimap.
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this.forwardHashMap.clear();
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this.reverseHashMap.clear();
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this.forwardHashMap.putAll(biMap.forwardHashMap);
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this.reverseHashMap.putAll(biMap.reverseHashMap);
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}
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/**
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* Replaces all of the mappings from the specified map to this bimap.
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* These mappings will replace any mappings that this map had for
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* any of the keys currently in the specified map. This is an alternate
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* form of {@link #replaceAll(Map)} replaceAll(K, V) that will silently
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* ignore duplicates
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*
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* @param hashMap mappings to be stored in this map
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*
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* @throws NullPointerException if the specified map is null
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*/
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public synchronized
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void replaceAllForce(final Map<K, V> hashMap) {
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if (hashMap == null) {
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throw new NullPointerException("hashMap");
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}
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// only if there are no problems with the creation of the new bimap.
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this.forwardHashMap.clear();
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this.reverseHashMap.clear();
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putAllForce(hashMap);
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}
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/**
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* Associates the specified value with the specified key in this bimap.
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* If the bimap previously contained a mapping for the key, the old
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* value is replaced. If the given value is already bound to a different
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* key in this bimap, the bimap will remain unmodified. To avoid throwing
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* an exception, call {@link #putForce(Object, Object)} putForce(K, V) instead.
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*
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* @param key key with which the specified value is to be associated
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* @param value value to be associated with the specified key
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*
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* @return the previous value associated with <tt>key</tt>, or
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* <tt>null</tt> if there was no mapping for <tt>key</tt>.
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* (A <tt>null</tt> return can also indicate that the map
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* previously associated <tt>null</tt> with <tt>key</tt>.)
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*
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* @throws IllegalArgumentException if the given value is already bound to a different key in this bimap. The bimap will remain
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* unmodified in this event. To avoid this exception, call {@link #putForce(Object, Object)} putForce(K, V) instead.
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*/
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public synchronized
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V put(final K key, final V value) throws IllegalArgumentException {
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V prevForwardValue = this.forwardHashMap.put(key, value);
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if (prevForwardValue != null) {
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reverseHashMap.remove(prevForwardValue);
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}
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K prevReverseValue = this.reverseHashMap.put(value, key);
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if (prevReverseValue != null) {
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// put the old value back
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this.forwardHashMap.remove(key);
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this.reverseHashMap.put(value, prevReverseValue);
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throw new IllegalArgumentException("Value already exists. Keys and values must both be unique!");
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}
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return prevForwardValue;
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}
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/**
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* Associates the specified value with the specified key in this bimap.
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* If the bimap previously contained a mapping for the key, the old
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* value is replaced. This is an alternate form of {@link #put(Object, Object)} put(K, V)
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* that will silently ignore duplicates
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*
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* @param key key with which the specified value is to be associated
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* @param value value to be associated with the specified key
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*
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* @return the previous value associated with <tt>key</tt>, or
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* <tt>null</tt> if there was no mapping for <tt>key</tt>.
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* (A <tt>null</tt> return can also indicate that the map
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* previously associated <tt>null</tt> with <tt>key</tt>.)
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*/
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public synchronized
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V putForce(final K key, final V value) {
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V prevForwardValue = this.forwardHashMap.put(key, value);
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if (prevForwardValue != null) {
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reverseHashMap.remove(prevForwardValue);
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}
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K prevReverseValue = this.reverseHashMap.put(value, key);
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if (prevReverseValue != null) {
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forwardHashMap.remove(prevReverseValue);
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}
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return prevForwardValue;
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}
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/**
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* Copies all of the mappings from the specified map to this map.
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* These mappings will replace any mappings that this map had for
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* any of the keys currently in the specified map.
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*
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* @param hashMap mappings to be stored in this map
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*
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* @throws NullPointerException if the specified map is null
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*
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* @throws IllegalArgumentException if the given value is already bound to a different key in this bimap. The bimap will remain
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* unmodified in this event. To avoid this exception, call {@link #putAllForce(Map)} putAllForce(K, V) instead.
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*/
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public synchronized
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void putAll(final Map<K, V> hashMap) throws IllegalArgumentException {
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LockFreeBiMap<K, V> biMap = new LockFreeBiMap<K, V>();
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try {
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for (Map.Entry<K, V> entry : hashMap.entrySet()) {
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K key = entry.getKey();
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V value = entry.getValue();
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biMap.put(key, value);
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// we have to verify that the keys/values between the bimaps are unique
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if (this.forwardHashMap.containsKey(key)) {
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throw new IllegalArgumentException("Key already exists. Keys and values must both be unique!");
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}
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if (this.reverseHashMap.containsValue(value)) {
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throw new IllegalArgumentException("Value already exists. Keys and values must both be unique!");
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}
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}
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} catch (IllegalArgumentException e) {
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// do nothing if there is an exception
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throw e;
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}
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// only if there are no problems with the creation of the new bimap AND the uniqueness constrain is guaranteed
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this.forwardHashMap.putAll(biMap.forwardHashMap);
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this.reverseHashMap.putAll(biMap.reverseHashMap);
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}
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/**
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* Copies all of the mappings from the specified map to this map.
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* These mappings will replace any mappings that this map had for
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* any of the keys currently in the specified map. This is an alternate
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* form of {@link #putAll(Map)} putAll(K, V) that will silently
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* ignore duplicates
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*
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* @param hashMap mappings to be stored in this map
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*
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* @throws NullPointerException if the specified map is null
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*/
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public synchronized
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void putAllForce(final Map<K, V> hashMap) {
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for (Map.Entry<K, V> entry : hashMap.entrySet()) {
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K key = entry.getKey();
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V value = entry.getValue();
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putForce(key, value);
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}
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}
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/**
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* Removes the mapping for the specified key from this map if present.
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*
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* @param key key whose mapping is to be removed from the map
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*
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* @return the previous value associated with <tt>key</tt>, or
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* <tt>null</tt> if there was no mapping for <tt>key</tt>.
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* (A <tt>null</tt> return can also indicate that the map
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* previously associated <tt>null</tt> with <tt>key</tt>.)
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*/
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public synchronized
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V remove(final K key) {
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V value = forwardHashMap.remove(key);
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reverseHashMap.remove(value);
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return value;
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}
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/**
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* Returns <tt>true</tt> if this map maps one or more keys to the
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* specified value.
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*
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* @param key value whose presence in this map is to be tested
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*
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* @return <tt>true</tt> if this map maps one or more keys to the
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* specified value
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*/
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public
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boolean containsValue(final K key) {
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// use the SWP to get a lock-free get of the value
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return forwardREF.get(this).containsValue(key);
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}
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/**
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* Returns <tt>true</tt> if this map maps one or more keys to the
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* specified value.
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*
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* @param value value whose presence in this map is to be tested
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*
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* @return <tt>true</tt> if this map maps one or more keys to the
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* specified value
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*/
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public
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boolean containsReverseValue(final V value) {
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// use the SWP to get a lock-free get of the value
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return reverseREF.get(this).containsValue(value);
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}
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/**
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* Returns the value to which the specified key is mapped,
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* or {@code null} if this map contains no mapping for the key.
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* <p>
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* <p>More formally, if this map contains a mapping from a key
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* {@code k} to a value {@code v} such that {@code (key==null ? k==null :
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* key.equals(k))}, then this method returns {@code v}; otherwise
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* it returns {@code null}. (There can be at most one such mapping.)
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* <p>
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* <p>A return value of {@code null} does not <i>necessarily</i>
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* indicate that the map contains no mapping for the key; it's also
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* possible that the map explicitly maps the key to {@code null}.
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* The {@link HashMap#containsKey containsKey} operation may be used to
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* distinguish these two cases.
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*
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* @see #put(Object, Object)
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*/
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@SuppressWarnings("unchecked")
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public
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V get(final K key) {
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// use the SWP to get a lock-free get of the value
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return (V) forwardREF.get(this).get(key);
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}
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/**
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* Returns the reverse key to which the specified key is mapped,
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* or {@code null} if this map contains no mapping for the key.
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* <p>
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* <p>More formally, if this map contains a mapping from a key
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* {@code k} to a value {@code v} such that {@code (key==null ? k==null :
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* key.equals(k))}, then this method returns {@code v}; otherwise
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* it returns {@code null}. (There can be at most one such mapping.)
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* <p>
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* <p>A return value of {@code null} does not <i>necessarily</i>
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* indicate that the map contains no mapping for the key; it's also
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* possible that the map explicitly maps the key to {@code null}.
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* The {@link HashMap#containsKey containsKey} operation may be used to
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* distinguish these two cases.
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*
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* @see #put(Object, Object)
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*/
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@SuppressWarnings("unchecked")
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public
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K getReverse(final V key) {
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// use the SWP to get a lock-free get of the value
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return (K) reverseREF.get(this).get(key);
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}
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/**
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* Returns a {@link Collection} view of the values contained in this map.
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* The collection is backed by the map, so changes to the map are
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* reflected in the collection, and vice-versa. If the map is
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* modified while an iteration over the collection is in progress
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* (except through the iterator's own <tt>remove</tt> operation),
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* the results of the iteration are undefined. The collection
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* supports element removal, which removes the corresponding
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* mapping from the map, via the <tt>Iterator.remove</tt>,
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* <tt>Collection.remove</tt>, <tt>removeAll</tt>,
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* <tt>retainAll</tt> and <tt>clear</tt> operations. It does not
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* support the <tt>add</tt> or <tt>addAll</tt> operations.
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*
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* @return a view of the values contained in this map
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*/
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@SuppressWarnings("unchecked")
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public
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Collection<V> values() {
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// use the SWP to get a lock-free get of the value
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return forwardREF.get(this).values();
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}
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/**
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* Returns <tt>true</tt> if this bimap contains no key-value mappings.
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*
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* @return <tt>true</tt> if this bimap contains no key-value mappings
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*/
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public
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boolean isEmpty() {
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// use the SWP to get a lock-free get of the value
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return forwardREF.get(this)
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.isEmpty();
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}
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/**
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* Returns a {@link Collection} view of the values contained in this map.
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* The collection is backed by the map, so changes to the map are
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* reflected in the collection, and vice-versa. If the map is
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* modified while an iteration over the collection is in progress
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* (except through the iterator's own <tt>remove</tt> operation),
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* the results of the iteration are undefined. The collection
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* supports element removal, which removes the corresponding
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* mapping from the map, via the <tt>Iterator.remove</tt>,
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* <tt>Collection.remove</tt>, <tt>removeAll</tt>,
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* <tt>retainAll</tt> and <tt>clear</tt> operations. It does not
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* support the <tt>add</tt> or <tt>addAll</tt> operations.
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*
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* @return a view of the values contained in this map
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*/
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@SuppressWarnings("unchecked")
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public
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Collection<K> reverseValues() {
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// use the SWP to get a lock-free get of the value
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return reverseREF.get(this).values();
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}
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}
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204
src/dorkbox/util/collections/LockFreeHashMap.java
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204
src/dorkbox/util/collections/LockFreeHashMap.java
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/*
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* Copyright 2015 dorkbox, llc
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package dorkbox.util.collections;
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import java.io.Serializable;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.HashMap;
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import java.util.Map;
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import java.util.Set;
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import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
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/**
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* This class uses the "single-writer-principle" for lock-free publication.
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* <p>
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* Since there are only 2 methods to guarantee that modifications can only be called one-at-a-time (either it is only called by
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* one thread, or only one thread can access it at a time) -- we chose the 2nd option -- and use 'synchronized' to make sure that only
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* one thread can access this modification methods at a time. Getting or checking the presence of values can then happen in a lock-free
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* manner.
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* <p>
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* According to my benchmarks, this is approximately 25% faster than ConcurrentHashMap for (all types of) reads, and a lot slower for
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* contended writes.
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||||
* <p>
|
||||
* This data structure is for many-read/few-write scenarios
|
||||
*/
|
||||
public final
|
||||
class LockFreeHashMap<K, V> implements Map<K, V>, Cloneable, Serializable {
|
||||
// Recommended for best performance while adhering to the "single writer principle". Must be static-final
|
||||
private static final AtomicReferenceFieldUpdater<LockFreeHashMap, HashMap> deviceREF = AtomicReferenceFieldUpdater.newUpdater(
|
||||
LockFreeHashMap.class,
|
||||
HashMap.class,
|
||||
"hashMap");
|
||||
|
||||
private volatile HashMap<K, V> hashMap;
|
||||
|
||||
// synchronized is used here to ensure the "single writer principle", and make sure that ONLY one thread at a time can enter this
|
||||
// section. Because of this, we can have unlimited reader threads all going at the same time, without contention (which is our
|
||||
// use-case 99% of the time)
|
||||
|
||||
/**
|
||||
* Constructs an empty <tt>HashMap</tt> with the default initial capacity
|
||||
* (16) and the default load factor (0.75).
|
||||
*/
|
||||
public
|
||||
LockFreeHashMap() {
|
||||
hashMap = new HashMap<K, V>();
|
||||
}
|
||||
|
||||
/**
|
||||
* Constructs an empty <tt>HashMap</tt> with the specified initial
|
||||
* capacity and the default load factor (0.75).
|
||||
*
|
||||
* @param initialCapacity the initial capacity.
|
||||
*
|
||||
* @throws IllegalArgumentException if the initial capacity is negative.
|
||||
*/
|
||||
public
|
||||
LockFreeHashMap(int initialCapacity) {
|
||||
hashMap = new HashMap<K, V>(initialCapacity);
|
||||
}
|
||||
|
||||
/**
|
||||
* Constructs a new <tt>HashMap</tt> with the same mappings as the
|
||||
* specified <tt>Map</tt>. The <tt>HashMap</tt> is created with
|
||||
* default load factor (0.75) and an initial capacity sufficient to
|
||||
* hold the mappings in the specified <tt>Map</tt>.
|
||||
*
|
||||
* @param map the map whose mappings are to be placed in this map
|
||||
*
|
||||
* @throws NullPointerException if the specified map is null
|
||||
*/
|
||||
public
|
||||
LockFreeHashMap(Map<K, V> map) {
|
||||
this.hashMap = new HashMap<K, V>(map);
|
||||
}
|
||||
|
||||
/**
|
||||
* Constructs an empty <tt>HashMap</tt> with the specified initial
|
||||
* capacity and load factor.
|
||||
*
|
||||
* @param initialCapacity the initial capacity
|
||||
* @param loadFactor the load factor
|
||||
*
|
||||
* @throws IllegalArgumentException if the initial capacity is negative
|
||||
* or the load factor is nonpositive
|
||||
*/
|
||||
public
|
||||
LockFreeHashMap(int initialCapacity, float loadFactor) {
|
||||
this.hashMap = new HashMap<K, V>(initialCapacity, loadFactor);
|
||||
}
|
||||
|
||||
|
||||
public synchronized
|
||||
void replaceAll(final Map<K, V> hashMap) {
|
||||
if (hashMap == null) {
|
||||
throw new NullPointerException("hashMap");
|
||||
}
|
||||
|
||||
this.hashMap.clear();
|
||||
this.hashMap.putAll(hashMap);
|
||||
}
|
||||
|
||||
@SuppressWarnings("unchecked")
|
||||
public
|
||||
Map<K, V> elements() {
|
||||
// use the SWP to get a lock-free get of the map. It's values are only valid at the moment this method is called.
|
||||
return Collections.unmodifiableMap(deviceREF.get(this));
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
int size() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return deviceREF.get(this)
|
||||
.size();
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
boolean isEmpty() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return deviceREF.get(this)
|
||||
.isEmpty();
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
boolean containsKey(final Object key) {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return deviceREF.get(this)
|
||||
.containsKey(key);
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
boolean containsValue(final Object value) {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return deviceREF.get(this)
|
||||
.containsValue(value);
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
V get(final Object key) {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return (V) deviceREF.get(this)
|
||||
.get(key);
|
||||
}
|
||||
|
||||
@Override
|
||||
public synchronized
|
||||
V put(final K key, final V value) {
|
||||
return hashMap.put(key, value);
|
||||
}
|
||||
|
||||
@Override
|
||||
public synchronized
|
||||
V remove(final Object key) {
|
||||
return hashMap.remove(key);
|
||||
}
|
||||
|
||||
@Override
|
||||
public synchronized
|
||||
void putAll(final Map<? extends K, ? extends V> map) {
|
||||
this.hashMap.putAll(map);
|
||||
}
|
||||
|
||||
@Override
|
||||
public synchronized
|
||||
void clear() {
|
||||
hashMap.clear();
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
Set<K> keySet() {
|
||||
return elements().keySet();
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
Collection<V> values() {
|
||||
return elements().values();
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
Set<Entry<K, V>> entrySet() {
|
||||
return elements().entrySet();
|
||||
}
|
||||
}
|
199
src/dorkbox/util/collections/LockFreeSet.java
Normal file
199
src/dorkbox/util/collections/LockFreeSet.java
Normal file
@ -0,0 +1,199 @@
|
||||
/*
|
||||
* Copyright 2015 dorkbox, llc
|
||||
*
|
||||
* 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 dorkbox.util.collections;
|
||||
|
||||
import java.util.Collection;
|
||||
import java.util.Collections;
|
||||
import java.util.HashSet;
|
||||
import java.util.Iterator;
|
||||
import java.util.Set;
|
||||
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
|
||||
|
||||
/**
|
||||
* This class uses the "single-writer-principle" for lock-free publication.
|
||||
* <p>
|
||||
* Since there are only 2 methods to guarantee that modifications can only be called one-at-a-time (either it is only called by
|
||||
* one thread, or only one thread can access it at a time) -- we chose the 2nd option -- and use 'synchronized' to make sure that only
|
||||
* one thread can access this modification methods at a time. Getting or checking the presence of values can then happen in a lock-free
|
||||
* manner.
|
||||
* <p>
|
||||
* According to my benchmarks, this is approximately 25% faster than ConcurrentHashMap for (all types of) reads, and a lot slower for
|
||||
* contended writes.
|
||||
* <p>
|
||||
* This data structure is for many-read/few-write scenarios
|
||||
*/
|
||||
public final
|
||||
class LockFreeSet<E> implements Set<E>, Cloneable, java.io.Serializable {
|
||||
// Recommended for best performance while adhering to the "single writer principle". Must be static-final
|
||||
private static final AtomicReferenceFieldUpdater<LockFreeSet, Set> setREF = AtomicReferenceFieldUpdater.newUpdater(LockFreeSet.class,
|
||||
Set.class,
|
||||
"hashSet");
|
||||
|
||||
private volatile Set<E> hashSet;
|
||||
|
||||
// synchronized is used here to ensure the "single writer principle", and make sure that ONLY one thread at a time can enter this
|
||||
// section. Because of this, we can have unlimited reader threads all going at the same time, without contention (which is our
|
||||
// use-case 99% of the time)
|
||||
|
||||
/**
|
||||
* Constructs a new, empty set; the backing <tt>HashMap</tt> instance has
|
||||
* default initial capacity (16) and load factor (0.75).
|
||||
*/
|
||||
public
|
||||
LockFreeSet() {
|
||||
hashSet = new HashSet<E>();
|
||||
}
|
||||
|
||||
/**
|
||||
* Constructs a new, empty set; the backing <tt>HashMap</tt> instance has
|
||||
* the specified initial capacity and the specified load factor.
|
||||
*
|
||||
* @param initialCapacity the initial capacity of the hash map
|
||||
* @param loadFactor the load factor of the hash map
|
||||
*
|
||||
* @throws IllegalArgumentException if the initial capacity is less
|
||||
* than zero, or if the load factor is nonpositive
|
||||
*/
|
||||
public
|
||||
LockFreeSet(int initialCapacity, float loadFactor) {
|
||||
hashSet = new HashSet<E>(initialCapacity, loadFactor);
|
||||
}
|
||||
|
||||
/**
|
||||
* Constructs a new, empty set; the backing <tt>HashMap</tt> instance has
|
||||
* the specified initial capacity and default load factor (0.75).
|
||||
*
|
||||
* @param initialCapacity the initial capacity of the hash table
|
||||
*
|
||||
* @throws IllegalArgumentException if the initial capacity is less
|
||||
* than zero
|
||||
*/
|
||||
public
|
||||
LockFreeSet(int initialCapacity) {
|
||||
hashSet = new HashSet<E>(initialCapacity);
|
||||
}
|
||||
|
||||
/**
|
||||
* Constructs a new set containing the elements in the specified
|
||||
* collection. The <tt>HashMap</tt> is created with default load factor
|
||||
* (0.75) and an initial capacity sufficient to contain the elements in
|
||||
* the specified collection.
|
||||
*
|
||||
* @param collection the collection whose elements are to be placed into this set
|
||||
*
|
||||
* @throws NullPointerException if the specified collection is null
|
||||
*/
|
||||
public
|
||||
LockFreeSet(final Collection<E> collection) {
|
||||
hashSet = new HashSet<E>(collection);
|
||||
}
|
||||
|
||||
|
||||
@SuppressWarnings("unchecked")
|
||||
public
|
||||
Set<E> elements() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return Collections.unmodifiableSet(setREF.get(this));
|
||||
}
|
||||
|
||||
|
||||
@Override
|
||||
public
|
||||
int size() {
|
||||
return setREF.get(this)
|
||||
.size();
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
boolean isEmpty() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return setREF.get(this)
|
||||
.isEmpty();
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
boolean contains(final Object element) {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return setREF.get(this)
|
||||
.contains(element);
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
Iterator<E> iterator() {
|
||||
return elements().iterator();
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
Object[] toArray() {
|
||||
return setREF.get(this)
|
||||
.toArray();
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
<T> T[] toArray(final T[] a) {
|
||||
return (T[]) setREF.get(this)
|
||||
.toArray(a);
|
||||
}
|
||||
|
||||
@Override
|
||||
public synchronized
|
||||
boolean add(final E element) {
|
||||
return hashSet.add(element);
|
||||
}
|
||||
|
||||
@Override
|
||||
public synchronized
|
||||
boolean remove(final Object element) {
|
||||
return hashSet.remove(element);
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
boolean containsAll(final Collection<?> collection) {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return setREF.get(this)
|
||||
.containsAll(collection);
|
||||
}
|
||||
|
||||
@Override
|
||||
public synchronized
|
||||
boolean addAll(final Collection<? extends E> elements) {
|
||||
return hashSet.addAll(elements);
|
||||
}
|
||||
|
||||
@Override
|
||||
public synchronized
|
||||
boolean retainAll(final Collection<?> collection) {
|
||||
return hashSet.retainAll(collection);
|
||||
}
|
||||
|
||||
@Override
|
||||
public synchronized
|
||||
boolean removeAll(final Collection<?> collection) {
|
||||
return hashSet.removeAll(collection);
|
||||
}
|
||||
|
||||
@Override
|
||||
public synchronized
|
||||
void clear() {
|
||||
hashSet.clear();
|
||||
}
|
||||
}
|
Loading…
Reference in New Issue
Block a user