Updated/added more lockfree collections
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19c9ae67ee
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@ -36,6 +36,7 @@ import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
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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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@SuppressWarnings("WeakerAccess")
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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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@ -49,8 +50,9 @@ class LockFreeBiMap<K, V> {
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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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private volatile HashMap<K, V> forwardHashMap;
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private volatile HashMap<V, K> reverseHashMap;
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private final LockFreeBiMap<V, K> inverse;
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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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@ -58,6 +60,16 @@ class LockFreeBiMap<K, V> {
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public
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LockFreeBiMap() {
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forwardHashMap = new HashMap<K, V>();
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reverseHashMap = new HashMap<V, K>();
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this.inverse = new LockFreeBiMap<V, K>(reverseHashMap, forwardHashMap, this);
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}
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private
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LockFreeBiMap(final HashMap<K, V> forwardHashMap, final HashMap<V, K> reverseHashMap, final LockFreeBiMap<V, K> inverse) {
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this.forwardHashMap = forwardHashMap;
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this.reverseHashMap = reverseHashMap;
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this.inverse = inverse;
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}
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/**
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@ -70,6 +82,14 @@ class LockFreeBiMap<K, V> {
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reverseHashMap.clear();
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}
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/**
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* @return the inverse view of this bimap, which maps each of this bimap's values to its associated key.
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*/
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public
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LockFreeBiMap<V, K> inverse() {
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return inverse;
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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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@ -157,7 +177,12 @@ class LockFreeBiMap<K, V> {
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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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if (prevForwardValue != null) {
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this.forwardHashMap.put(key, prevForwardValue);
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}
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else {
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this.forwardHashMap.remove(key);
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}
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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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@ -223,7 +248,7 @@ class LockFreeBiMap<K, V> {
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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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if (this.reverseHashMap.containsKey(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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@ -275,36 +300,6 @@ class LockFreeBiMap<K, V> {
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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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@ -16,11 +16,7 @@
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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.*;
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import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
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/**
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@ -102,20 +98,9 @@ class LockFreeHashMap<K, V> implements Map<K, V>, Cloneable, Serializable {
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this.hashMap = new HashMap<K, V>(initialCapacity, loadFactor);
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}
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public synchronized
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void replaceAll(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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this.hashMap.clear();
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this.hashMap.putAll(hashMap);
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}
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@SuppressWarnings("unchecked")
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public
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Map<K, V> elements() {
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Map<K, V> getMap() {
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// 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.
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return Collections.unmodifiableMap(deviceREF.get(this));
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}
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@ -187,18 +172,18 @@ class LockFreeHashMap<K, V> implements Map<K, V>, Cloneable, Serializable {
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@Override
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public
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Set<K> keySet() {
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return elements().keySet();
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return getMap().keySet();
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}
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@Override
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public
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Collection<V> values() {
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return elements().values();
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return getMap().values();
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}
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@Override
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public
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Set<Entry<K, V>> entrySet() {
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return elements().entrySet();
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return getMap().entrySet();
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}
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}
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440
src/dorkbox/util/collections/LockFreeIntBiMap.java
Normal file
440
src/dorkbox/util/collections/LockFreeIntBiMap.java
Normal file
@ -0,0 +1,440 @@
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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.HashMap;
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import java.util.Iterator;
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import java.util.Map;
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import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
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import dorkbox.util.collections.IntMap.Entries;
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import dorkbox.util.collections.IntMap.Keys;
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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
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class LockFreeIntBiMap<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<LockFreeIntBiMap, IntMap> forwardREF =
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AtomicReferenceFieldUpdater.newUpdater(LockFreeIntBiMap.class,
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IntMap.class,
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"forwardHashMap");
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private static final AtomicReferenceFieldUpdater<LockFreeIntBiMap, ObjectIntMap> reverseREF =
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AtomicReferenceFieldUpdater.newUpdater(LockFreeIntBiMap.class,
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ObjectIntMap.class,
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"reverseHashMap");
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private volatile IntMap<V> forwardHashMap;
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private volatile ObjectIntMap<V> reverseHashMap;
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private final int defaultReturnValue;
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private final LockFreeObjectIntBiMap<V> inverse;
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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 static
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void main(String[] args) {
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LockFreeIntBiMap<String> test = new LockFreeIntBiMap<>();
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String one = "One";
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String four = "Four";
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test.put(1, one);
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test.put(2, "Two");
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test.put(3, "Three");
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test.put(4, four);
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// try {
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// test.put(1, four);
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// } catch (IllegalArgumentException e) {
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// }
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test.putForce(1, four);
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test.put(5, one);
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System.out.println(test.toString());
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System.out.println("Reverse");
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System.out.println(test.inverse().toString());
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}
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/**
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* Creates a new bimap using @{link Integer#MIN_VALUE}.
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*/
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public
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LockFreeIntBiMap() {
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this(Integer.MIN_VALUE);
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}
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/**
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* The default return value is used for various get/put operations on the IntMap/ObjectIntMap.
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*
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* @param defaultReturnValue value used for various get/put operations on the IntMap/ObjectIntMap.
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*/
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public
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LockFreeIntBiMap(int defaultReturnValue) {
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this(new IntMap<V>(), new ObjectIntMap<V>(), defaultReturnValue);
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}
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/**
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* The default return value is used for various get/put operations on the IntMap/ObjectIntMap.
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*
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* @param defaultReturnValue value used for various get/put operations on the IntMap/ObjectIntMap.
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*/
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public
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LockFreeIntBiMap(IntMap<V> forwardHashMap, ObjectIntMap<V> reverseHashMap, int defaultReturnValue) {
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this.forwardHashMap = forwardHashMap;
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this.reverseHashMap = reverseHashMap;
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this.defaultReturnValue = defaultReturnValue;
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this.inverse = new LockFreeObjectIntBiMap<V>(reverseHashMap, forwardHashMap, defaultReturnValue, this);
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}
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LockFreeIntBiMap(final IntMap<V> forwardHashMap,
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final ObjectIntMap<V> reverseHashMap,
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final int defaultReturnValue,
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final LockFreeObjectIntBiMap<V> inverse) {
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this.forwardHashMap = forwardHashMap;
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this.reverseHashMap = reverseHashMap;
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this.defaultReturnValue = defaultReturnValue;
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this.inverse = inverse;
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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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* @return the inverse view of this bimap, which maps each of this bimap's values to its associated key.
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*/
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public
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LockFreeObjectIntBiMap<V> inverse() {
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return inverse;
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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(int, 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(int, Object)} putForce(K, V) instead.
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*/
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public synchronized
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V put(final int 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, defaultReturnValue);
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}
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int prevReverseValue = this.reverseHashMap.get(value, defaultReturnValue);
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this.reverseHashMap.put(value, key);
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if (prevReverseValue != defaultReturnValue) {
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// put the old value back
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if (prevForwardValue != null) {
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this.forwardHashMap.put(key, prevForwardValue);
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}
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else {
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this.forwardHashMap.remove(key);
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}
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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(int, Object)}
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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 int 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, defaultReturnValue);
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}
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int prevReverseValue = this.reverseHashMap.get(value, defaultReturnValue);
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this.reverseHashMap.put(value, key);
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if (prevReverseValue != defaultReturnValue) {
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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)} instead.
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*/
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public synchronized
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void putAll(final Map<Integer, V> hashMap) throws IllegalArgumentException {
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LockFreeIntBiMap<V> biMap = new LockFreeIntBiMap<V>();
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try {
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for (Map.Entry<Integer, V> entry : hashMap.entrySet()) {
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Integer 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.containsKey(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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// there is no putAll() method for ObjectIntMap
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this.reverseHashMap.size = biMap.reverseHashMap.size;
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this.reverseHashMap.keyTable = biMap.reverseHashMap.keyTable;
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this.reverseHashMap.valueTable = biMap.reverseHashMap.valueTable;
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this.reverseHashMap.capacity = biMap.reverseHashMap.capacity;
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this.reverseHashMap.stashSize = biMap.reverseHashMap.stashSize;
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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<Integer, V> hashMap) {
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for (Map.Entry<Integer, V> entry : hashMap.entrySet()) {
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Integer 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>.
|
||||
* (A <tt>null</tt> return can also indicate that the map
|
||||
* previously associated <tt>null</tt> with <tt>key</tt>.)
|
||||
*/
|
||||
public synchronized
|
||||
V remove(final int key) {
|
||||
V value = forwardHashMap.remove(key);
|
||||
reverseHashMap.remove(value, defaultReturnValue);
|
||||
return value;
|
||||
}
|
||||
|
||||
|
||||
/**
|
||||
* Returns the value to which the specified key is mapped,
|
||||
* or {@code null} if this map contains no mapping for the key.
|
||||
* <p>
|
||||
* <p>More formally, if this map contains a mapping from a key
|
||||
* {@code k} to a value {@code v} such that {@code (key==null ? k==null :
|
||||
* key.equals(k))}, then this method returns {@code v}; otherwise
|
||||
* it returns {@code null}. (There can be at most one such mapping.)
|
||||
* <p>
|
||||
* <p>A return value of {@code null} does not <i>necessarily</i>
|
||||
* indicate that the map contains no mapping for the key; it's also
|
||||
* possible that the map explicitly maps the key to {@code null}.
|
||||
* The {@link HashMap#containsKey containsKey} operation may be used to
|
||||
* distinguish these two cases.
|
||||
*
|
||||
* @see #put(int, Object)
|
||||
*/
|
||||
@SuppressWarnings("unchecked")
|
||||
public
|
||||
V get(final int key) {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return (V) forwardREF.get(this).get(key);
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns an iterator for the keys in the map. Remove is supported. Note that the same iterator instance is returned each
|
||||
* time this method is called. Use the {@link Entries} constructor for nested or multithreaded iteration.
|
||||
*/
|
||||
@SuppressWarnings("unchecked")
|
||||
public
|
||||
Keys keys() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return forwardREF.get(this)
|
||||
.keys();
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns an iterator for the values in the map. Remove is supported. Note that the same iterator instance is returned each
|
||||
* time this method is called. Use the {@link Entries} constructor for nested or multithreaded iteration.
|
||||
*/
|
||||
@SuppressWarnings("unchecked")
|
||||
public
|
||||
Iterator<V> values() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return forwardREF.get(this).values();
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns <tt>true</tt> if this bimap contains no key-value mappings.
|
||||
*
|
||||
* @return <tt>true</tt> if this bimap contains no key-value mappings
|
||||
*/
|
||||
public
|
||||
boolean isEmpty() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return forwardREF.get(this)
|
||||
.size == 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns the number of key-value mappings in this map. If the
|
||||
* map contains more than <tt>Integer.MAX_VALUE</tt> elements, returns
|
||||
* <tt>Integer.MAX_VALUE</tt>.
|
||||
*
|
||||
* @return the number of key-value mappings in this map
|
||||
*/
|
||||
public
|
||||
int size() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return forwardREF.get(this)
|
||||
.size;
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
boolean equals(final Object o) {
|
||||
if (this == o) {
|
||||
return true;
|
||||
}
|
||||
if (o == null || getClass() != o.getClass()) {
|
||||
return false;
|
||||
}
|
||||
|
||||
final LockFreeIntBiMap<?> that = (LockFreeIntBiMap<?>) o;
|
||||
|
||||
if (defaultReturnValue != that.defaultReturnValue) {
|
||||
return false;
|
||||
}
|
||||
if (!forwardHashMap.equals(that.forwardHashMap)) {
|
||||
return false;
|
||||
}
|
||||
return reverseHashMap.equals(that.reverseHashMap);
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
int hashCode() {
|
||||
int result = forwardHashMap.hashCode();
|
||||
result = 31 * result + reverseHashMap.hashCode();
|
||||
result = 31 * result + defaultReturnValue;
|
||||
return result;
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
String toString() {
|
||||
StringBuilder builder = new StringBuilder("LockFreeIntBiMap {");
|
||||
|
||||
Keys keys = keys();
|
||||
Iterator<V> values = values();
|
||||
|
||||
while (keys.hasNext) {
|
||||
builder.append(keys.next());
|
||||
builder.append(" (")
|
||||
.append(values.next())
|
||||
.append("), ");
|
||||
}
|
||||
|
||||
int length = builder.length();
|
||||
if (length > 1) {
|
||||
// delete the ', '
|
||||
builder.delete(length - 2, length);
|
||||
}
|
||||
|
||||
builder.append('}');
|
||||
|
||||
return builder.toString();
|
||||
}
|
||||
}
|
177
src/dorkbox/util/collections/LockFreeIntMap.java
Normal file
177
src/dorkbox/util/collections/LockFreeIntMap.java
Normal file
@ -0,0 +1,177 @@
|
||||
/*
|
||||
* Copyright 2018 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.io.Serializable;
|
||||
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
|
||||
|
||||
import dorkbox.util.collections.IntMap.Keys;
|
||||
import dorkbox.util.collections.IntMap.Values;
|
||||
|
||||
/**
|
||||
* 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
|
||||
*
|
||||
* This is an unordered map that uses int keys. This implementation is a cuckoo hash map using 3 hashes, random walking, and a small stash
|
||||
* for problematic keys. Null values are allowed. No allocation is done except when growing the table size. <br>
|
||||
* <br>
|
||||
* This map performs very fast get, containsKey, and remove (typically O(1), worst case O(log(n))). Put may be a bit slower,
|
||||
* depending on hash collisions. Load factors greater than 0.91 greatly increase the chances the map will have to rehash to the
|
||||
* next higher POT size.
|
||||
* @author Nathan Sweet
|
||||
*/
|
||||
@SuppressWarnings("unchecked")
|
||||
public final
|
||||
class LockFreeIntMap<V> implements Cloneable, Serializable {
|
||||
// Recommended for best performance while adhering to the "single writer principle". Must be static-final
|
||||
private static final AtomicReferenceFieldUpdater<LockFreeIntMap, IntMap> deviceREF = AtomicReferenceFieldUpdater.newUpdater(
|
||||
LockFreeIntMap.class,
|
||||
IntMap.class,
|
||||
"map");
|
||||
|
||||
private volatile IntMap<V> map;
|
||||
|
||||
// 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>IntMap</tt> with the default initial capacity
|
||||
* (16) and the default load factor (0.75).
|
||||
*/
|
||||
public
|
||||
LockFreeIntMap() {
|
||||
map = new IntMap<V>();
|
||||
}
|
||||
|
||||
/**
|
||||
* Constructs an empty <tt>IntMap</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
|
||||
LockFreeIntMap(int initialCapacity) {
|
||||
map = new IntMap<V>(initialCapacity);
|
||||
}
|
||||
|
||||
/**
|
||||
* Constructs an empty <tt>IntMap</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
|
||||
LockFreeIntMap(int initialCapacity, float loadFactor) {
|
||||
this.map = new IntMap<V>(initialCapacity, loadFactor);
|
||||
}
|
||||
|
||||
|
||||
public
|
||||
int size() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return deviceREF.get(this)
|
||||
.size;
|
||||
}
|
||||
|
||||
public
|
||||
boolean isEmpty() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return deviceREF.get(this)
|
||||
.size == 0;
|
||||
}
|
||||
|
||||
public
|
||||
boolean containsKey(final int key) {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return deviceREF.get(this)
|
||||
.containsKey(key);
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns true if the specified value is in the map. Note this traverses the entire map and compares every value, which may be
|
||||
* an expensive operation.
|
||||
*
|
||||
* @param identity If true, uses == to compare the specified value with values in the map. If false, uses
|
||||
* {@link #equals(Object)}.
|
||||
*/
|
||||
public
|
||||
boolean containsValue(final Object value, boolean identity) {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return deviceREF.get(this)
|
||||
.containsValue(value, identity);
|
||||
}
|
||||
|
||||
public
|
||||
V get(final int key) {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return (V) deviceREF.get(this)
|
||||
.get(key);
|
||||
}
|
||||
|
||||
public synchronized
|
||||
V put(final int key, final V value) {
|
||||
return map.put(key, value);
|
||||
}
|
||||
|
||||
public synchronized
|
||||
V remove(final int key) {
|
||||
return map.remove(key);
|
||||
}
|
||||
|
||||
public synchronized
|
||||
void putAll(final IntMap<V> map) {
|
||||
this.map.putAll(map);
|
||||
}
|
||||
|
||||
public synchronized
|
||||
void clear() {
|
||||
map.clear();
|
||||
}
|
||||
|
||||
/**
|
||||
* DO NOT MODIFY THE MAP VIA THIS! It will result in unknown object visibility!
|
||||
*/
|
||||
public
|
||||
Keys keySet() {
|
||||
return deviceREF.get(this)
|
||||
.keys();
|
||||
}
|
||||
|
||||
/**
|
||||
* DO NOT MODIFY THE MAP VIA THIS! It will result in unknown object visibility!
|
||||
*/
|
||||
public
|
||||
Values<V> values() {
|
||||
return deviceREF.get(this)
|
||||
.values();
|
||||
}
|
||||
}
|
417
src/dorkbox/util/collections/LockFreeObjectIntBiMap.java
Normal file
417
src/dorkbox/util/collections/LockFreeObjectIntBiMap.java
Normal file
@ -0,0 +1,417 @@
|
||||
/*
|
||||
* Copyright 2018 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.HashMap;
|
||||
import java.util.Iterator;
|
||||
import java.util.Map;
|
||||
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
|
||||
|
||||
import dorkbox.util.collections.IntMap.Entries;
|
||||
import dorkbox.util.collections.IntMap.Keys;
|
||||
|
||||
/**
|
||||
* A bimap (or "bidirectional map") is a map that preserves the uniqueness of its values as well as that of its keys. This constraint
|
||||
* enables bimaps to support an "inverse view", which is another bimap containing the same entries as this bimap but with reversed keys and values.
|
||||
*
|
||||
* This class uses the "single-writer-principle" for lock-free publication.
|
||||
*
|
||||
* 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.
|
||||
*
|
||||
* According to my benchmarks, this is approximately 25% faster than ConcurrentHashMap for (all types of) reads, and a lot slower for
|
||||
* contended writes.
|
||||
*
|
||||
* This data structure is for many-read/few-write scenarios
|
||||
*/
|
||||
public
|
||||
class LockFreeObjectIntBiMap<V> {
|
||||
// Recommended for best performance while adhering to the "single writer principle". Must be static-final
|
||||
private static final AtomicReferenceFieldUpdater<LockFreeObjectIntBiMap, ObjectIntMap> forwardREF =
|
||||
AtomicReferenceFieldUpdater.newUpdater(LockFreeObjectIntBiMap.class,
|
||||
ObjectIntMap.class,
|
||||
"forwardHashMap");
|
||||
|
||||
private static final AtomicReferenceFieldUpdater<LockFreeObjectIntBiMap, IntMap> reverseREF =
|
||||
AtomicReferenceFieldUpdater.newUpdater(LockFreeObjectIntBiMap.class,
|
||||
IntMap.class,
|
||||
"reverseHashMap");
|
||||
|
||||
private volatile ObjectIntMap<V> forwardHashMap;
|
||||
private volatile IntMap<V> reverseHashMap;
|
||||
|
||||
private final int defaultReturnValue;
|
||||
private final LockFreeIntBiMap<V> inverse;
|
||||
|
||||
// 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)
|
||||
|
||||
/**
|
||||
* Creates a new bimap using @{link Integer#MIN_VALUE}.
|
||||
*/
|
||||
public
|
||||
LockFreeObjectIntBiMap() {
|
||||
this(Integer.MIN_VALUE);
|
||||
}
|
||||
|
||||
/**
|
||||
* The default return value is used for various get/put operations on the IntMap/ObjectIntMap.
|
||||
*
|
||||
* @param defaultReturnValue value used for various get/put operations on the IntMap/ObjectIntMap.
|
||||
*/
|
||||
public
|
||||
LockFreeObjectIntBiMap(int defaultReturnValue) {
|
||||
this(new ObjectIntMap<V>(), new IntMap<V>(), defaultReturnValue);
|
||||
}
|
||||
|
||||
/**
|
||||
* The default return value is used for various get/put operations on the IntMap/ObjectIntMap.
|
||||
*
|
||||
* @param defaultReturnValue value used for various get/put operations on the IntMap/ObjectIntMap.
|
||||
*/
|
||||
LockFreeObjectIntBiMap(ObjectIntMap<V> forwardHashMap, IntMap<V> reverseHashMap, int defaultReturnValue) {
|
||||
this.forwardHashMap = forwardHashMap;
|
||||
this.reverseHashMap = reverseHashMap;
|
||||
this.defaultReturnValue = defaultReturnValue;
|
||||
|
||||
this.inverse = new LockFreeIntBiMap<V>(reverseHashMap, forwardHashMap, defaultReturnValue, this);
|
||||
}
|
||||
|
||||
LockFreeObjectIntBiMap(final ObjectIntMap<V> forwardHashMap,
|
||||
final IntMap<V> reverseHashMap,
|
||||
final int defaultReturnValue,
|
||||
final LockFreeIntBiMap<V> inverse) {
|
||||
|
||||
this.forwardHashMap = forwardHashMap;
|
||||
this.reverseHashMap = reverseHashMap;
|
||||
this.defaultReturnValue = defaultReturnValue;
|
||||
this.inverse = inverse;
|
||||
}
|
||||
|
||||
/**
|
||||
* Removes all of the mappings from this bimap.
|
||||
*
|
||||
* The bimap will be empty after this call returns.
|
||||
*/
|
||||
public synchronized
|
||||
void clear() {
|
||||
forwardHashMap.clear();
|
||||
reverseHashMap.clear();
|
||||
}
|
||||
|
||||
/**
|
||||
* @return the inverse view of this bimap, which maps each of this bimap's values to its associated key.
|
||||
*/
|
||||
public
|
||||
LockFreeIntBiMap<V> inverse() {
|
||||
return inverse;
|
||||
}
|
||||
|
||||
/**
|
||||
* Associates the specified value with the specified key in this bimap.
|
||||
* If the bimap previously contained a mapping for the key, the old
|
||||
* value is replaced. If the given value is already bound to a different
|
||||
* key in this bimap, the bimap will remain unmodified. To avoid throwing
|
||||
* an exception, call {@link #putForce(Object, int)} instead.
|
||||
*
|
||||
* @param key key with which the specified value is to be associated
|
||||
* @param value value to be associated with the specified key
|
||||
*
|
||||
* @return the previous value associated with <tt>key</tt>, or
|
||||
* <tt>null</tt> if there was no mapping for <tt>key</tt>.
|
||||
* (A <tt>null</tt> return can also indicate that the map
|
||||
* previously associated <tt>null</tt> with <tt>key</tt>.)
|
||||
*
|
||||
* @throws IllegalArgumentException if the given value is already bound to a different key in this bimap. The bimap will remain
|
||||
* unmodified in this event. To avoid this exception, call {@link #putForce(Object, int)} instead.
|
||||
*/
|
||||
public synchronized
|
||||
int put(final V key, final int value) throws IllegalArgumentException {
|
||||
int prevForwardValue = this.forwardHashMap.get(key, defaultReturnValue);
|
||||
this.forwardHashMap.put(key, value);
|
||||
if (prevForwardValue != defaultReturnValue) {
|
||||
reverseHashMap.remove(prevForwardValue);
|
||||
}
|
||||
|
||||
V prevReverseValue = this.reverseHashMap.put(value, key);
|
||||
if (prevReverseValue != null) {
|
||||
// put the old value back
|
||||
if (prevForwardValue != defaultReturnValue) {
|
||||
this.forwardHashMap.put(key, prevForwardValue);
|
||||
}
|
||||
else {
|
||||
this.forwardHashMap.remove(key, defaultReturnValue);
|
||||
}
|
||||
|
||||
this.reverseHashMap.put(value, prevReverseValue);
|
||||
|
||||
throw new IllegalArgumentException("Value already exists. Keys and values must both be unique!");
|
||||
}
|
||||
|
||||
return prevForwardValue;
|
||||
}
|
||||
|
||||
/**
|
||||
* Associates the specified value with the specified key in this bimap.
|
||||
* If the bimap previously contained a mapping for the key, the old
|
||||
* value is replaced. This is an alternate form of {@link #put(Object, int)}
|
||||
* that will silently ignore duplicates
|
||||
*
|
||||
* @param key key with which the specified value is to be associated
|
||||
* @param value value to be associated with the specified key
|
||||
*
|
||||
* @return the previous value associated with <tt>key</tt>, or
|
||||
* <tt>null</tt> if there was no mapping for <tt>key</tt>.
|
||||
* (A <tt>null</tt> return can also indicate that the map
|
||||
* previously associated <tt>null</tt> with <tt>key</tt>.)
|
||||
*/
|
||||
public synchronized
|
||||
int putForce(final V key, final int value) {
|
||||
int prevForwardValue = this.forwardHashMap.get(key, defaultReturnValue);
|
||||
this.forwardHashMap.put(key, value);
|
||||
if (prevForwardValue != defaultReturnValue) {
|
||||
reverseHashMap.remove(prevForwardValue);
|
||||
}
|
||||
|
||||
|
||||
V prevReverseValue = this.reverseHashMap.get(value);
|
||||
this.reverseHashMap.put(value, key);
|
||||
|
||||
if (prevReverseValue != null) {
|
||||
forwardHashMap.remove(prevReverseValue, defaultReturnValue);
|
||||
}
|
||||
|
||||
return prevForwardValue;
|
||||
}
|
||||
|
||||
/**
|
||||
* Copies all of the mappings from the specified map to this map.
|
||||
* These mappings will replace any mappings that this map had for
|
||||
* any of the keys currently in the specified map.
|
||||
*
|
||||
* @param hashMap mappings to be stored in this map
|
||||
*
|
||||
* @throws NullPointerException if the specified map is null
|
||||
*
|
||||
* @throws IllegalArgumentException if the given value is already bound to a different key in this bimap. The bimap will remain
|
||||
* unmodified in this event. To avoid this exception, call {@link #putAllForce(Map)} instead.
|
||||
*/
|
||||
public synchronized
|
||||
void putAll(final Map<V, Integer> hashMap) throws IllegalArgumentException {
|
||||
LockFreeObjectIntBiMap<V> biMap = new LockFreeObjectIntBiMap<V>();
|
||||
|
||||
try {
|
||||
for (Map.Entry<V, Integer> entry : hashMap.entrySet()) {
|
||||
V key = entry.getKey();
|
||||
Integer value = entry.getValue();
|
||||
|
||||
biMap.put(key, value);
|
||||
|
||||
// we have to verify that the keys/values between the bimaps are unique
|
||||
if (this.forwardHashMap.containsKey(key)) {
|
||||
throw new IllegalArgumentException("Key already exists. Keys and values must both be unique!");
|
||||
}
|
||||
|
||||
if (this.reverseHashMap.containsKey(value)) {
|
||||
throw new IllegalArgumentException("Value already exists. Keys and values must both be unique!");
|
||||
}
|
||||
}
|
||||
} catch (IllegalArgumentException e) {
|
||||
// do nothing if there is an exception
|
||||
throw e;
|
||||
}
|
||||
|
||||
// there is no putAll() method for ObjectIntMap
|
||||
this.forwardHashMap.size = biMap.forwardHashMap.size;
|
||||
this.forwardHashMap.keyTable = biMap.forwardHashMap.keyTable;
|
||||
this.forwardHashMap.valueTable = biMap.forwardHashMap.valueTable;
|
||||
this.forwardHashMap.capacity = biMap.forwardHashMap.capacity;
|
||||
this.forwardHashMap.stashSize = biMap.forwardHashMap.stashSize;
|
||||
|
||||
// only if there are no problems with the creation of the new bimap AND the uniqueness constrain is guaranteed
|
||||
this.reverseHashMap.putAll(biMap.reverseHashMap);
|
||||
}
|
||||
|
||||
/**
|
||||
* Copies all of the mappings from the specified map to this map.
|
||||
* These mappings will replace any mappings that this map had for
|
||||
* any of the keys currently in the specified map. This is an alternate
|
||||
* form of {@link #putAll(Map)} putAll(K, V) that will silently
|
||||
* ignore duplicates
|
||||
*
|
||||
* @param hashMap mappings to be stored in this map
|
||||
*
|
||||
* @throws NullPointerException if the specified map is null
|
||||
*/
|
||||
public synchronized
|
||||
void putAllForce(final Map<V, Integer> hashMap) {
|
||||
for (Map.Entry<V, Integer> entry : hashMap.entrySet()) {
|
||||
V key = entry.getKey();
|
||||
Integer value = entry.getValue();
|
||||
|
||||
putForce(key, value);
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Removes the mapping for the specified key from this map if present.
|
||||
*
|
||||
* @param key key whose mapping is to be removed from the map
|
||||
*
|
||||
* @return the previous value associated with <tt>key</tt>, or
|
||||
* <tt>defaultReturnValue</tt> if there was no mapping for <tt>key</tt>.
|
||||
* (A <tt>defaultReturnValue</tt> return can also indicate that the map
|
||||
* previously associated <tt>defaultReturnValue</tt> with <tt>key</tt>.)
|
||||
*/
|
||||
public synchronized
|
||||
int remove(final V key) {
|
||||
int value = forwardHashMap.remove(key, defaultReturnValue);
|
||||
reverseHashMap.remove(value);
|
||||
return value;
|
||||
}
|
||||
|
||||
|
||||
/**
|
||||
* Returns the value to which the specified key is mapped,
|
||||
* or {@code defaultReturnValue} if this map contains no mapping for the key.
|
||||
* <p>
|
||||
* <p>More formally, if this map contains a mapping from a key
|
||||
* {@code k} to a value {@code v} such that {@code (key==null ? k==null :
|
||||
* key.equals(k))}, then this method returns {@code v}; otherwise
|
||||
* it returns {@code defaultReturnValue}. (There can be at most one such mapping.)
|
||||
* <p>
|
||||
* <p>A return value of {@code defaultReturnValue} does not <i>necessarily</i>
|
||||
* indicate that the map contains no mapping for the key; it's also
|
||||
* possible that the map explicitly maps the key to {@code null}.
|
||||
* The {@link HashMap#containsKey containsKey} operation may be used to
|
||||
* distinguish these two cases.
|
||||
*
|
||||
* @see #put(Object, int)
|
||||
*/
|
||||
@SuppressWarnings("unchecked")
|
||||
public
|
||||
int get(final V key) {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return forwardREF.get(this).get(key, defaultReturnValue);
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns an iterator for the keys in the map. Remove is supported. Note that the same iterator instance is returned each
|
||||
* time this method is called. Use the {@link Entries} constructor for nested or multithreaded iteration.
|
||||
*/
|
||||
@SuppressWarnings("unchecked")
|
||||
public
|
||||
Iterator<V> keys() {
|
||||
// the ObjectIntMap doesn't have iterators, but the IntMap does
|
||||
return inverse.values();
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns an iterator for the values in the map. Remove is supported. Note that the same iterator instance is returned each
|
||||
* time this method is called. Use the {@link Entries} constructor for nested or multithreaded iteration.
|
||||
*/
|
||||
@SuppressWarnings("unchecked")
|
||||
public
|
||||
Keys values() {
|
||||
// the ObjectIntMap doesn't have iterators, but the IntMap does
|
||||
return inverse.keys();
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns <tt>true</tt> if this bimap contains no key-value mappings.
|
||||
*
|
||||
* @return <tt>true</tt> if this bimap contains no key-value mappings
|
||||
*/
|
||||
public
|
||||
boolean isEmpty() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return forwardREF.get(this)
|
||||
.size == 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* Returns the number of key-value mappings in this map. If the
|
||||
* map contains more than <tt>Integer.MAX_VALUE</tt> elements, returns
|
||||
* <tt>Integer.MAX_VALUE</tt>.
|
||||
*
|
||||
* @return the number of key-value mappings in this map
|
||||
*/
|
||||
public
|
||||
int size() {
|
||||
// use the SWP to get a lock-free get of the value
|
||||
return forwardREF.get(this)
|
||||
.size;
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
boolean equals(final Object o) {
|
||||
if (this == o) {
|
||||
return true;
|
||||
}
|
||||
if (o == null || getClass() != o.getClass()) {
|
||||
return false;
|
||||
}
|
||||
|
||||
final LockFreeObjectIntBiMap<?> that = (LockFreeObjectIntBiMap<?>) o;
|
||||
|
||||
if (defaultReturnValue != that.defaultReturnValue) {
|
||||
return false;
|
||||
}
|
||||
if (!forwardHashMap.equals(that.forwardHashMap)) {
|
||||
return false;
|
||||
}
|
||||
return reverseHashMap.equals(that.reverseHashMap);
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
int hashCode() {
|
||||
int result = forwardHashMap.hashCode();
|
||||
result = 31 * result + reverseHashMap.hashCode();
|
||||
result = 31 * result + defaultReturnValue;
|
||||
return result;
|
||||
}
|
||||
|
||||
@Override
|
||||
public
|
||||
String toString() {
|
||||
StringBuilder builder = new StringBuilder("LockFreeObjectIntBiMap {");
|
||||
|
||||
Iterator<V> keys = keys();
|
||||
Keys values = values();
|
||||
|
||||
while (keys.hasNext()) {
|
||||
builder.append(keys.next());
|
||||
builder.append(" (")
|
||||
.append(values.next())
|
||||
.append("), ");
|
||||
}
|
||||
|
||||
int length = builder.length();
|
||||
if (length > 1) {
|
||||
// delete the ', '
|
||||
builder.delete(length - 2, length);
|
||||
}
|
||||
|
||||
builder.append('}');
|
||||
|
||||
return builder.toString();
|
||||
}
|
||||
}
|
Loading…
Reference in New Issue
Block a user