/hudson-core/src/main/java/hudson/util/CopyOnWriteMap.java
http://github.com/hudson/hudson · Java · 231 lines · 143 code · 38 blank · 50 comment · 0 complexity · 500e219558f9afec47782a9fd3588429 MD5 · raw file
- /*
- * The MIT License
- *
- * Copyright (c) 2004-2010, Sun Microsystems, Inc., Kohsuke Kawaguchi
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
- package hudson.util;
- import com.thoughtworks.xstream.converters.MarshallingContext;
- import com.thoughtworks.xstream.converters.UnmarshallingContext;
- import com.thoughtworks.xstream.converters.collections.MapConverter;
- import com.thoughtworks.xstream.converters.collections.TreeMapConverter;
- import com.thoughtworks.xstream.io.HierarchicalStreamReader;
- import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
- import com.thoughtworks.xstream.mapper.Mapper;
- import java.util.Collection;
- import java.util.Collections;
- import java.util.Comparator;
- import java.util.HashMap;
- import java.util.LinkedHashMap;
- import java.util.Map;
- import java.util.Set;
- import java.util.TreeMap;
- /**
- * {@link Map} that has copy-on-write semantics.
- *
- * <p>
- * This class is suitable where highly concurrent access is needed, yet
- * the write operation is relatively uncommon.
- *
- * @author Kohsuke Kawaguchi
- */
- public abstract class CopyOnWriteMap<K,V> implements Map<K,V> {
- protected volatile Map<K,V> core;
- /**
- * Read-only view of {@link #core}.
- */
- private volatile Map<K,V> view;
- protected CopyOnWriteMap(Map<K,V> core) {
- update(core);
- }
- protected CopyOnWriteMap() {
- update(Collections.<K,V>emptyMap());
- }
- protected void update(Map<K,V> m) {
- core = m;
- view = Collections.unmodifiableMap(core);
- }
- public int size() {
- return core.size();
- }
- public boolean isEmpty() {
- return core.isEmpty();
- }
- public boolean containsKey(Object key) {
- return core.containsKey(key);
- }
- public boolean containsValue(Object value) {
- return core.containsValue(value);
- }
- public V get(Object key) {
- return core.get(key);
- }
- public synchronized V put(K key, V value) {
- Map<K,V> m = copy();
- V r = m.put(key,value);
- update(m);
- return r;
- }
- public synchronized V remove(Object key) {
- Map<K,V> m = copy();
- V r = m.remove(key);
- update(m);
- return r;
- }
- public synchronized void putAll(Map<? extends K, ? extends V> t) {
- Map<K,V> m = copy();
- m.putAll(t);
- update(m);
- }
- protected abstract Map<K,V> copy();
- public synchronized void clear() {
- update(Collections.<K,V>emptyMap());
- }
- /**
- * This method will return a read-only {@link Set}.
- */
- public Set<K> keySet() {
- return view.keySet();
- }
- /**
- * This method will return a read-only {@link Collection}.
- */
- public Collection<V> values() {
- return view.values();
- }
- /**
- * This method will return a read-only {@link Set}.
- */
- public Set<Entry<K,V>> entrySet() {
- return view.entrySet();
- }
- /**
- * {@link CopyOnWriteMap} backed by {@link HashMap}.
- */
- public static final class Hash<K,V> extends CopyOnWriteMap<K,V> {
- public Hash(Map<K,V> core) {
- super(new LinkedHashMap<K,V>(core));
- }
- public Hash() {
- }
- protected Map<K,V> copy() {
- return new LinkedHashMap<K,V>(core);
- }
- public static class ConverterImpl extends MapConverter {
- public ConverterImpl(Mapper mapper) {
- super(mapper);
- }
- @Override
- public boolean canConvert(Class type) {
- return type==Hash.class;
- }
- @Override
- public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
- return new Hash((Map) super.unmarshal(reader,context));
- }
- @Override
- public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {
- super.marshal(((Hash)source).core,writer,context);
- }
- }
- }
- /**
- * {@link CopyOnWriteMap} backed by {@link TreeMap}.
- */
- public static final class Tree<K,V> extends CopyOnWriteMap<K,V> {
- private final Comparator<K> comparator;
- public Tree(Map<K,V> core, Comparator<K> comparator) {
- this(comparator);
- putAll(core);
- }
- public Tree(Comparator<K> comparator) {
- super(new TreeMap<K,V>(comparator));
- this.comparator = comparator;
- }
- public Tree() {
- this(null);
- }
- protected Map<K,V> copy() {
- TreeMap<K,V> m = new TreeMap<K,V>(comparator);
- m.putAll(core);
- return m;
- }
- @Override
- public synchronized void clear() {
- update(new TreeMap<K,V>(comparator));
- }
- public static class ConverterImpl extends TreeMapConverter {
- public ConverterImpl(Mapper mapper) {
- super(mapper);
- }
- @Override
- public boolean canConvert(Class type) {
- return type==Tree.class;
- }
- @Override
- public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
- TreeMap tm = (TreeMap) super.unmarshal(reader,context);
- return new Tree(tm,tm.comparator());
- }
- @Override
- public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {
- super.marshal(((Tree)source).core,writer,context);
- }
- }
- }
- }