| // Converted, with some major refactors required. Not as memory-efficient as before, could use additional refactoring. |
| // Perhaps use four different types of HashEntry classes for max efficiency: |
| // normal HashEntry for HARD,HARD |
| // HardRefEntry for HARD,(SOFT|WEAK) |
| // RefHardEntry for (SOFT|WEAK),HARD |
| // RefRefEntry for (SOFT|WEAK),(SOFT|WEAK) |
| /* |
| * Copyright 2002-2004 The Apache Software Foundation |
| * |
| * 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 org.jivesoftware.smack.util.collections; |
| |
| import java.io.IOException; |
| import java.io.ObjectInputStream; |
| import java.io.ObjectOutputStream; |
| import java.lang.ref.Reference; |
| import java.lang.ref.ReferenceQueue; |
| import java.lang.ref.SoftReference; |
| import java.lang.ref.WeakReference; |
| import java.util.*; |
| |
| /** |
| * An abstract implementation of a hash-based map that allows the entries to |
| * be removed by the garbage collector. |
| * <p/> |
| * This class implements all the features necessary for a subclass reference |
| * hash-based map. Key-value entries are stored in instances of the |
| * <code>ReferenceEntry</code> class which can be overridden and replaced. |
| * The iterators can similarly be replaced, without the need to replace the KeySet, |
| * EntrySet and Values view classes. |
| * <p/> |
| * Overridable methods are provided to change the default hashing behaviour, and |
| * to change how entries are added to and removed from the map. Hopefully, all you |
| * need for unusual subclasses is here. |
| * <p/> |
| * When you construct an <code>AbstractReferenceMap</code>, you can specify what |
| * kind of references are used to store the map's keys and values. |
| * If non-hard references are used, then the garbage collector can remove |
| * mappings if a key or value becomes unreachable, or if the JVM's memory is |
| * running low. For information on how the different reference types behave, |
| * see {@link Reference}. |
| * <p/> |
| * Different types of references can be specified for keys and values. |
| * The keys can be configured to be weak but the values hard, |
| * in which case this class will behave like a |
| * <a href="http://java.sun.com/j2se/1.4/docs/api/java/util/WeakHashMap.html"> |
| * <code>WeakHashMap</code></a>. However, you can also specify hard keys and |
| * weak values, or any other combination. The default constructor uses |
| * hard keys and soft values, providing a memory-sensitive cache. |
| * <p/> |
| * This {@link Map} implementation does <i>not</i> allow null elements. |
| * Attempting to add a null key or value to the map will raise a |
| * <code>NullPointerException</code>. |
| * <p/> |
| * All the available iterators can be reset back to the start by casting to |
| * <code>ResettableIterator</code> and calling <code>reset()</code>. |
| * <p/> |
| * This implementation is not synchronized. |
| * You can use {@link java.util.Collections#synchronizedMap} to |
| * provide synchronized access to a <code>ReferenceMap</code>. |
| * |
| * @author Paul Jack |
| * @author Matt Hall, John Watkinson, Stephen Colebourne |
| * @version $Revision: 1.1 $ $Date: 2005/10/11 17:05:32 $ |
| * @see java.lang.ref.Reference |
| * @since Commons Collections 3.1 (extracted from ReferenceMap in 3.0) |
| */ |
| public abstract class AbstractReferenceMap <K,V> extends AbstractHashedMap<K, V> { |
| |
| /** |
| * Constant indicating that hard references should be used |
| */ |
| public static final int HARD = 0; |
| |
| /** |
| * Constant indicating that soft references should be used |
| */ |
| public static final int SOFT = 1; |
| |
| /** |
| * Constant indicating that weak references should be used |
| */ |
| public static final int WEAK = 2; |
| |
| /** |
| * The reference type for keys. Must be HARD, SOFT, WEAK. |
| * |
| * @serial |
| */ |
| protected int keyType; |
| |
| /** |
| * The reference type for values. Must be HARD, SOFT, WEAK. |
| * |
| * @serial |
| */ |
| protected int valueType; |
| |
| /** |
| * Should the value be automatically purged when the associated key has been collected? |
| */ |
| protected boolean purgeValues; |
| |
| /** |
| * ReferenceQueue used to eliminate stale mappings. |
| * See purge. |
| */ |
| private transient ReferenceQueue queue; |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Constructor used during deserialization. |
| */ |
| protected AbstractReferenceMap() { |
| super(); |
| } |
| |
| /** |
| * Constructs a new empty map with the specified reference types, |
| * load factor and initial capacity. |
| * |
| * @param keyType the type of reference to use for keys; |
| * must be {@link #SOFT} or {@link #WEAK} |
| * @param valueType the type of reference to use for values; |
| * must be {@link #SOFT} or {@link #WEAK} |
| * @param capacity the initial capacity for the map |
| * @param loadFactor the load factor for the map |
| * @param purgeValues should the value be automatically purged when the |
| * key is garbage collected |
| */ |
| protected AbstractReferenceMap(int keyType, int valueType, int capacity, float loadFactor, boolean purgeValues) { |
| super(capacity, loadFactor); |
| verify("keyType", keyType); |
| verify("valueType", valueType); |
| this.keyType = keyType; |
| this.valueType = valueType; |
| this.purgeValues = purgeValues; |
| } |
| |
| /** |
| * Initialise this subclass during construction, cloning or deserialization. |
| */ |
| protected void init() { |
| queue = new ReferenceQueue(); |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Checks the type int is a valid value. |
| * |
| * @param name the name for error messages |
| * @param type the type value to check |
| * @throws IllegalArgumentException if the value if invalid |
| */ |
| private static void verify(String name, int type) { |
| if ((type < HARD) || (type > WEAK)) { |
| throw new IllegalArgumentException(name + " must be HARD, SOFT, WEAK."); |
| } |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Gets the size of the map. |
| * |
| * @return the size |
| */ |
| public int size() { |
| purgeBeforeRead(); |
| return super.size(); |
| } |
| |
| /** |
| * Checks whether the map is currently empty. |
| * |
| * @return true if the map is currently size zero |
| */ |
| public boolean isEmpty() { |
| purgeBeforeRead(); |
| return super.isEmpty(); |
| } |
| |
| /** |
| * Checks whether the map contains the specified key. |
| * |
| * @param key the key to search for |
| * @return true if the map contains the key |
| */ |
| public boolean containsKey(Object key) { |
| purgeBeforeRead(); |
| Entry entry = getEntry(key); |
| if (entry == null) { |
| return false; |
| } |
| return (entry.getValue() != null); |
| } |
| |
| /** |
| * Checks whether the map contains the specified value. |
| * |
| * @param value the value to search for |
| * @return true if the map contains the value |
| */ |
| public boolean containsValue(Object value) { |
| purgeBeforeRead(); |
| if (value == null) { |
| return false; |
| } |
| return super.containsValue(value); |
| } |
| |
| /** |
| * Gets the value mapped to the key specified. |
| * |
| * @param key the key |
| * @return the mapped value, null if no match |
| */ |
| public V get(Object key) { |
| purgeBeforeRead(); |
| Entry<K, V> entry = getEntry(key); |
| if (entry == null) { |
| return null; |
| } |
| return entry.getValue(); |
| } |
| |
| |
| /** |
| * Puts a key-value mapping into this map. |
| * Neither the key nor the value may be null. |
| * |
| * @param key the key to add, must not be null |
| * @param value the value to add, must not be null |
| * @return the value previously mapped to this key, null if none |
| * @throws NullPointerException if either the key or value is null |
| */ |
| public V put(K key, V value) { |
| if (key == null) { |
| throw new NullPointerException("null keys not allowed"); |
| } |
| if (value == null) { |
| throw new NullPointerException("null values not allowed"); |
| } |
| |
| purgeBeforeWrite(); |
| return super.put(key, value); |
| } |
| |
| /** |
| * Removes the specified mapping from this map. |
| * |
| * @param key the mapping to remove |
| * @return the value mapped to the removed key, null if key not in map |
| */ |
| public V remove(Object key) { |
| if (key == null) { |
| return null; |
| } |
| purgeBeforeWrite(); |
| return super.remove(key); |
| } |
| |
| /** |
| * Clears this map. |
| */ |
| public void clear() { |
| super.clear(); |
| while (queue.poll() != null) { |
| } // drain the queue |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Gets a MapIterator over the reference map. |
| * The iterator only returns valid key/value pairs. |
| * |
| * @return a map iterator |
| */ |
| public MapIterator<K, V> mapIterator() { |
| return new ReferenceMapIterator<K, V>(this); |
| } |
| |
| /** |
| * Returns a set view of this map's entries. |
| * An iterator returned entry is valid until <code>next()</code> is called again. |
| * The <code>setValue()</code> method on the <code>toArray</code> entries has no effect. |
| * |
| * @return a set view of this map's entries |
| */ |
| public Set<Map.Entry<K, V>> entrySet() { |
| if (entrySet == null) { |
| entrySet = new ReferenceEntrySet<K, V>(this); |
| } |
| return entrySet; |
| } |
| |
| /** |
| * Returns a set view of this map's keys. |
| * |
| * @return a set view of this map's keys |
| */ |
| public Set<K> keySet() { |
| if (keySet == null) { |
| keySet = new ReferenceKeySet<K, V>(this); |
| } |
| return keySet; |
| } |
| |
| /** |
| * Returns a collection view of this map's values. |
| * |
| * @return a set view of this map's values |
| */ |
| public Collection<V> values() { |
| if (values == null) { |
| values = new ReferenceValues<K, V>(this); |
| } |
| return values; |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Purges stale mappings from this map before read operations. |
| * <p/> |
| * This implementation calls {@link #purge()} to maintain a consistent state. |
| */ |
| protected void purgeBeforeRead() { |
| purge(); |
| } |
| |
| /** |
| * Purges stale mappings from this map before write operations. |
| * <p/> |
| * This implementation calls {@link #purge()} to maintain a consistent state. |
| */ |
| protected void purgeBeforeWrite() { |
| purge(); |
| } |
| |
| /** |
| * Purges stale mappings from this map. |
| * <p/> |
| * Note that this method is not synchronized! Special |
| * care must be taken if, for instance, you want stale |
| * mappings to be removed on a periodic basis by some |
| * background thread. |
| */ |
| protected void purge() { |
| Reference ref = queue.poll(); |
| while (ref != null) { |
| purge(ref); |
| ref = queue.poll(); |
| } |
| } |
| |
| /** |
| * Purges the specified reference. |
| * |
| * @param ref the reference to purge |
| */ |
| protected void purge(Reference ref) { |
| // The hashCode of the reference is the hashCode of the |
| // mapping key, even if the reference refers to the |
| // mapping value... |
| int hash = ref.hashCode(); |
| int index = hashIndex(hash, data.length); |
| HashEntry<K, V> previous = null; |
| HashEntry<K, V> entry = data[index]; |
| while (entry != null) { |
| if (((ReferenceEntry<K, V>) entry).purge(ref)) { |
| if (previous == null) { |
| data[index] = entry.next; |
| } else { |
| previous.next = entry.next; |
| } |
| this.size--; |
| return; |
| } |
| previous = entry; |
| entry = entry.next; |
| } |
| |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Gets the entry mapped to the key specified. |
| * |
| * @param key the key |
| * @return the entry, null if no match |
| */ |
| protected HashEntry<K, V> getEntry(Object key) { |
| if (key == null) { |
| return null; |
| } else { |
| return super.getEntry(key); |
| } |
| } |
| |
| /** |
| * Gets the hash code for a MapEntry. |
| * Subclasses can override this, for example to use the identityHashCode. |
| * |
| * @param key the key to get a hash code for, may be null |
| * @param value the value to get a hash code for, may be null |
| * @return the hash code, as per the MapEntry specification |
| */ |
| protected int hashEntry(Object key, Object value) { |
| return (key == null ? 0 : key.hashCode()) ^ (value == null ? 0 : value.hashCode()); |
| } |
| |
| /** |
| * Compares two keys, in internal converted form, to see if they are equal. |
| * <p/> |
| * This implementation converts the key from the entry to a real reference |
| * before comparison. |
| * |
| * @param key1 the first key to compare passed in from outside |
| * @param key2 the second key extracted from the entry via <code>entry.key</code> |
| * @return true if equal |
| */ |
| protected boolean isEqualKey(Object key1, Object key2) { |
| //if ((key1 == null) && (key2 != null) || (key1 != null) || (key2 == null)) { |
| // return false; |
| //} |
| // GenericsNote: Conversion from reference handled by getKey() which replaced all .key references |
| //key2 = (keyType > HARD ? ((Reference) key2).get() : key2); |
| return (key1 == key2 || key1.equals(key2)); |
| } |
| |
| /** |
| * Creates a ReferenceEntry instead of a HashEntry. |
| * |
| * @param next the next entry in sequence |
| * @param hashCode the hash code to use |
| * @param key the key to store |
| * @param value the value to store |
| * @return the newly created entry |
| */ |
| public HashEntry<K, V> createEntry(HashEntry<K, V> next, int hashCode, K key, V value) { |
| return new ReferenceEntry<K, V>(this, (ReferenceEntry<K, V>) next, hashCode, key, value); |
| } |
| |
| /** |
| * Creates an entry set iterator. |
| * |
| * @return the entrySet iterator |
| */ |
| protected Iterator<Map.Entry<K, V>> createEntrySetIterator() { |
| return new ReferenceEntrySetIterator<K, V>(this); |
| } |
| |
| /** |
| * Creates an key set iterator. |
| * |
| * @return the keySet iterator |
| */ |
| protected Iterator<K> createKeySetIterator() { |
| return new ReferenceKeySetIterator<K, V>(this); |
| } |
| |
| /** |
| * Creates an values iterator. |
| * |
| * @return the values iterator |
| */ |
| protected Iterator<V> createValuesIterator() { |
| return new ReferenceValuesIterator<K, V>(this); |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * EntrySet implementation. |
| */ |
| static class ReferenceEntrySet <K,V> extends EntrySet<K, V> { |
| |
| protected ReferenceEntrySet(AbstractHashedMap<K, V> parent) { |
| super(parent); |
| } |
| |
| public Object[] toArray() { |
| return toArray(new Object[0]); |
| } |
| |
| public <T> T[] toArray(T[] arr) { |
| // special implementation to handle disappearing entries |
| ArrayList<Map.Entry<K, V>> list = new ArrayList<Map.Entry<K, V>>(); |
| Iterator<Map.Entry<K, V>> iterator = iterator(); |
| while (iterator.hasNext()) { |
| Map.Entry<K, V> e = iterator.next(); |
| list.add(new DefaultMapEntry<K, V>(e.getKey(), e.getValue())); |
| } |
| return list.toArray(arr); |
| } |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * KeySet implementation. |
| */ |
| static class ReferenceKeySet <K,V> extends KeySet<K, V> { |
| |
| protected ReferenceKeySet(AbstractHashedMap<K, V> parent) { |
| super(parent); |
| } |
| |
| public Object[] toArray() { |
| return toArray(new Object[0]); |
| } |
| |
| public <T> T[] toArray(T[] arr) { |
| // special implementation to handle disappearing keys |
| List<K> list = new ArrayList<K>(parent.size()); |
| for (Iterator<K> it = iterator(); it.hasNext();) { |
| list.add(it.next()); |
| } |
| return list.toArray(arr); |
| } |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Values implementation. |
| */ |
| static class ReferenceValues <K,V> extends Values<K, V> { |
| |
| protected ReferenceValues(AbstractHashedMap<K, V> parent) { |
| super(parent); |
| } |
| |
| public Object[] toArray() { |
| return toArray(new Object[0]); |
| } |
| |
| public <T> T[] toArray(T[] arr) { |
| // special implementation to handle disappearing values |
| List<V> list = new ArrayList<V>(parent.size()); |
| for (Iterator<V> it = iterator(); it.hasNext();) { |
| list.add(it.next()); |
| } |
| return list.toArray(arr); |
| } |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * A MapEntry implementation for the map. |
| * <p/> |
| * If getKey() or getValue() returns null, it means |
| * the mapping is stale and should be removed. |
| * |
| * @since Commons Collections 3.1 |
| */ |
| protected static class ReferenceEntry <K,V> extends HashEntry<K, V> { |
| /** |
| * The parent map |
| */ |
| protected final AbstractReferenceMap<K, V> parent; |
| |
| protected Reference<K> refKey; |
| protected Reference<V> refValue; |
| |
| /** |
| * Creates a new entry object for the ReferenceMap. |
| * |
| * @param parent the parent map |
| * @param next the next entry in the hash bucket |
| * @param hashCode the hash code of the key |
| * @param key the key |
| * @param value the value |
| */ |
| public ReferenceEntry(AbstractReferenceMap<K, V> parent, ReferenceEntry<K, V> next, int hashCode, K key, V value) { |
| super(next, hashCode, null, null); |
| this.parent = parent; |
| if (parent.keyType != HARD) { |
| refKey = toReference(parent.keyType, key, hashCode); |
| } else { |
| this.setKey(key); |
| } |
| if (parent.valueType != HARD) { |
| refValue = toReference(parent.valueType, value, hashCode); // the key hashCode is passed in deliberately |
| } else { |
| this.setValue(value); |
| } |
| } |
| |
| /** |
| * Gets the key from the entry. |
| * This method dereferences weak and soft keys and thus may return null. |
| * |
| * @return the key, which may be null if it was garbage collected |
| */ |
| public K getKey() { |
| return (parent.keyType > HARD) ? refKey.get() : super.getKey(); |
| } |
| |
| /** |
| * Gets the value from the entry. |
| * This method dereferences weak and soft value and thus may return null. |
| * |
| * @return the value, which may be null if it was garbage collected |
| */ |
| public V getValue() { |
| return (parent.valueType > HARD) ? refValue.get() : super.getValue(); |
| } |
| |
| /** |
| * Sets the value of the entry. |
| * |
| * @param obj the object to store |
| * @return the previous value |
| */ |
| public V setValue(V obj) { |
| V old = getValue(); |
| if (parent.valueType > HARD) { |
| refValue.clear(); |
| refValue = toReference(parent.valueType, obj, hashCode); |
| } else { |
| super.setValue(obj); |
| } |
| return old; |
| } |
| |
| /** |
| * Compares this map entry to another. |
| * <p/> |
| * This implementation uses <code>isEqualKey</code> and |
| * <code>isEqualValue</code> on the main map for comparison. |
| * |
| * @param obj the other map entry to compare to |
| * @return true if equal, false if not |
| */ |
| public boolean equals(Object obj) { |
| if (obj == this) { |
| return true; |
| } |
| if (obj instanceof Map.Entry == false) { |
| return false; |
| } |
| |
| Map.Entry entry = (Map.Entry) obj; |
| Object entryKey = entry.getKey(); // convert to hard reference |
| Object entryValue = entry.getValue(); // convert to hard reference |
| if ((entryKey == null) || (entryValue == null)) { |
| return false; |
| } |
| // compare using map methods, aiding identity subclass |
| // note that key is direct access and value is via method |
| return parent.isEqualKey(entryKey, getKey()) && parent.isEqualValue(entryValue, getValue()); |
| } |
| |
| /** |
| * Gets the hashcode of the entry using temporary hard references. |
| * <p/> |
| * This implementation uses <code>hashEntry</code> on the main map. |
| * |
| * @return the hashcode of the entry |
| */ |
| public int hashCode() { |
| return parent.hashEntry(getKey(), getValue()); |
| } |
| |
| /** |
| * Constructs a reference of the given type to the given referent. |
| * The reference is registered with the queue for later purging. |
| * |
| * @param type HARD, SOFT or WEAK |
| * @param referent the object to refer to |
| * @param hash the hash code of the <i>key</i> of the mapping; |
| * this number might be different from referent.hashCode() if |
| * the referent represents a value and not a key |
| */ |
| protected <T> Reference<T> toReference(int type, T referent, int hash) { |
| switch (type) { |
| case SOFT: |
| return new SoftRef<T>(hash, referent, parent.queue); |
| case WEAK: |
| return new WeakRef<T>(hash, referent, parent.queue); |
| default: |
| throw new Error("Attempt to create hard reference in ReferenceMap!"); |
| } |
| } |
| |
| /** |
| * Purges the specified reference |
| * |
| * @param ref the reference to purge |
| * @return true or false |
| */ |
| boolean purge(Reference ref) { |
| boolean r = (parent.keyType > HARD) && (refKey == ref); |
| r = r || ((parent.valueType > HARD) && (refValue == ref)); |
| if (r) { |
| if (parent.keyType > HARD) { |
| refKey.clear(); |
| } |
| if (parent.valueType > HARD) { |
| refValue.clear(); |
| } else if (parent.purgeValues) { |
| setValue(null); |
| } |
| } |
| return r; |
| } |
| |
| /** |
| * Gets the next entry in the bucket. |
| * |
| * @return the next entry in the bucket |
| */ |
| protected ReferenceEntry<K, V> next() { |
| return (ReferenceEntry<K, V>) next; |
| } |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * The EntrySet iterator. |
| */ |
| static class ReferenceIteratorBase <K,V> { |
| /** |
| * The parent map |
| */ |
| final AbstractReferenceMap<K, V> parent; |
| |
| // These fields keep track of where we are in the table. |
| int index; |
| ReferenceEntry<K, V> entry; |
| ReferenceEntry<K, V> previous; |
| |
| // These Object fields provide hard references to the |
| // current and next entry; this assures that if hasNext() |
| // returns true, next() will actually return a valid element. |
| K nextKey; |
| V nextValue; |
| K currentKey; |
| V currentValue; |
| |
| int expectedModCount; |
| |
| public ReferenceIteratorBase(AbstractReferenceMap<K, V> parent) { |
| super(); |
| this.parent = parent; |
| index = (parent.size() != 0 ? parent.data.length : 0); |
| // have to do this here! size() invocation above |
| // may have altered the modCount. |
| expectedModCount = parent.modCount; |
| } |
| |
| public boolean hasNext() { |
| checkMod(); |
| while (nextNull()) { |
| ReferenceEntry<K, V> e = entry; |
| int i = index; |
| while ((e == null) && (i > 0)) { |
| i--; |
| e = (ReferenceEntry<K, V>) parent.data[i]; |
| } |
| entry = e; |
| index = i; |
| if (e == null) { |
| currentKey = null; |
| currentValue = null; |
| return false; |
| } |
| nextKey = e.getKey(); |
| nextValue = e.getValue(); |
| if (nextNull()) { |
| entry = entry.next(); |
| } |
| } |
| return true; |
| } |
| |
| private void checkMod() { |
| if (parent.modCount != expectedModCount) { |
| throw new ConcurrentModificationException(); |
| } |
| } |
| |
| private boolean nextNull() { |
| return (nextKey == null) || (nextValue == null); |
| } |
| |
| protected ReferenceEntry<K, V> nextEntry() { |
| checkMod(); |
| if (nextNull() && !hasNext()) { |
| throw new NoSuchElementException(); |
| } |
| previous = entry; |
| entry = entry.next(); |
| currentKey = nextKey; |
| currentValue = nextValue; |
| nextKey = null; |
| nextValue = null; |
| return previous; |
| } |
| |
| protected ReferenceEntry<K, V> currentEntry() { |
| checkMod(); |
| return previous; |
| } |
| |
| public ReferenceEntry<K, V> superNext() { |
| return nextEntry(); |
| } |
| |
| public void remove() { |
| checkMod(); |
| if (previous == null) { |
| throw new IllegalStateException(); |
| } |
| parent.remove(currentKey); |
| previous = null; |
| currentKey = null; |
| currentValue = null; |
| expectedModCount = parent.modCount; |
| } |
| } |
| |
| /** |
| * The EntrySet iterator. |
| */ |
| static class ReferenceEntrySetIterator <K,V> extends ReferenceIteratorBase<K, V> implements Iterator<Map.Entry<K, V>> { |
| |
| public ReferenceEntrySetIterator(AbstractReferenceMap<K, V> abstractReferenceMap) { |
| super(abstractReferenceMap); |
| } |
| |
| public ReferenceEntry<K, V> next() { |
| return superNext(); |
| } |
| |
| } |
| |
| /** |
| * The keySet iterator. |
| */ |
| static class ReferenceKeySetIterator <K,V> extends ReferenceIteratorBase<K, V> implements Iterator<K> { |
| |
| ReferenceKeySetIterator(AbstractReferenceMap<K, V> parent) { |
| super(parent); |
| } |
| |
| public K next() { |
| return nextEntry().getKey(); |
| } |
| } |
| |
| /** |
| * The values iterator. |
| */ |
| static class ReferenceValuesIterator <K,V> extends ReferenceIteratorBase<K, V> implements Iterator<V> { |
| |
| ReferenceValuesIterator(AbstractReferenceMap<K, V> parent) { |
| super(parent); |
| } |
| |
| public V next() { |
| return nextEntry().getValue(); |
| } |
| } |
| |
| /** |
| * The MapIterator implementation. |
| */ |
| static class ReferenceMapIterator <K,V> extends ReferenceIteratorBase<K, V> implements MapIterator<K, V> { |
| |
| protected ReferenceMapIterator(AbstractReferenceMap<K, V> parent) { |
| super(parent); |
| } |
| |
| public K next() { |
| return nextEntry().getKey(); |
| } |
| |
| public K getKey() { |
| HashEntry<K, V> current = currentEntry(); |
| if (current == null) { |
| throw new IllegalStateException(AbstractHashedMap.GETKEY_INVALID); |
| } |
| return current.getKey(); |
| } |
| |
| public V getValue() { |
| HashEntry<K, V> current = currentEntry(); |
| if (current == null) { |
| throw new IllegalStateException(AbstractHashedMap.GETVALUE_INVALID); |
| } |
| return current.getValue(); |
| } |
| |
| public V setValue(V value) { |
| HashEntry<K, V> current = currentEntry(); |
| if (current == null) { |
| throw new IllegalStateException(AbstractHashedMap.SETVALUE_INVALID); |
| } |
| return current.setValue(value); |
| } |
| } |
| |
| //----------------------------------------------------------------------- |
| // These two classes store the hashCode of the key of |
| // of the mapping, so that after they're dequeued a quick |
| // lookup of the bucket in the table can occur. |
| |
| /** |
| * A soft reference holder. |
| */ |
| static class SoftRef <T> extends SoftReference<T> { |
| /** |
| * the hashCode of the key (even if the reference points to a value) |
| */ |
| private int hash; |
| |
| public SoftRef(int hash, T r, ReferenceQueue q) { |
| super(r, q); |
| this.hash = hash; |
| } |
| |
| public int hashCode() { |
| return hash; |
| } |
| } |
| |
| /** |
| * A weak reference holder. |
| */ |
| static class WeakRef <T> extends WeakReference<T> { |
| /** |
| * the hashCode of the key (even if the reference points to a value) |
| */ |
| private int hash; |
| |
| public WeakRef(int hash, T r, ReferenceQueue q) { |
| super(r, q); |
| this.hash = hash; |
| } |
| |
| public int hashCode() { |
| return hash; |
| } |
| } |
| |
| //----------------------------------------------------------------------- |
| /** |
| * Replaces the superclass method to store the state of this class. |
| * <p/> |
| * Serialization is not one of the JDK's nicest topics. Normal serialization will |
| * initialise the superclass before the subclass. Sometimes however, this isn't |
| * what you want, as in this case the <code>put()</code> method on read can be |
| * affected by subclass state. |
| * <p/> |
| * The solution adopted here is to serialize the state data of this class in |
| * this protected method. This method must be called by the |
| * <code>writeObject()</code> of the first serializable subclass. |
| * <p/> |
| * Subclasses may override if they have a specific field that must be present |
| * on read before this implementation will work. Generally, the read determines |
| * what must be serialized here, if anything. |
| * |
| * @param out the output stream |
| */ |
| protected void doWriteObject(ObjectOutputStream out) throws IOException { |
| out.writeInt(keyType); |
| out.writeInt(valueType); |
| out.writeBoolean(purgeValues); |
| out.writeFloat(loadFactor); |
| out.writeInt(data.length); |
| for (MapIterator it = mapIterator(); it.hasNext();) { |
| out.writeObject(it.next()); |
| out.writeObject(it.getValue()); |
| } |
| out.writeObject(null); // null terminate map |
| // do not call super.doWriteObject() as code there doesn't work for reference map |
| } |
| |
| /** |
| * Replaces the superclassm method to read the state of this class. |
| * <p/> |
| * Serialization is not one of the JDK's nicest topics. Normal serialization will |
| * initialise the superclass before the subclass. Sometimes however, this isn't |
| * what you want, as in this case the <code>put()</code> method on read can be |
| * affected by subclass state. |
| * <p/> |
| * The solution adopted here is to deserialize the state data of this class in |
| * this protected method. This method must be called by the |
| * <code>readObject()</code> of the first serializable subclass. |
| * <p/> |
| * Subclasses may override if the subclass has a specific field that must be present |
| * before <code>put()</code> or <code>calculateThreshold()</code> will work correctly. |
| * |
| * @param in the input stream |
| */ |
| protected void doReadObject(ObjectInputStream in) throws IOException, ClassNotFoundException { |
| this.keyType = in.readInt(); |
| this.valueType = in.readInt(); |
| this.purgeValues = in.readBoolean(); |
| this.loadFactor = in.readFloat(); |
| int capacity = in.readInt(); |
| init(); |
| data = new HashEntry[capacity]; |
| while (true) { |
| K key = (K) in.readObject(); |
| if (key == null) { |
| break; |
| } |
| V value = (V) in.readObject(); |
| put(key, value); |
| } |
| threshold = calculateThreshold(data.length, loadFactor); |
| // do not call super.doReadObject() as code there doesn't work for reference map |
| } |
| |
| } |
