| /******************************************************************************* |
| * Copyright (c) 2010, 2013 Sonatype, Inc. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * Stuart McCulloch (Sonatype, Inc.) - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.sisu.inject; |
| |
| import java.lang.ref.Reference; |
| import java.lang.ref.ReferenceQueue; |
| import java.lang.ref.SoftReference; |
| import java.lang.ref.WeakReference; |
| import java.util.AbstractSet; |
| import java.util.Collection; |
| import java.util.Iterator; |
| import java.util.Map; |
| import java.util.NoSuchElementException; |
| import java.util.Set; |
| |
| /** |
| * NON-thread-safe {@link Map} whose keys are kept alive by soft/weak {@link Reference}s. |
| */ |
| class MildKeys<K, V> |
| implements Map<K, V> |
| { |
| // ---------------------------------------------------------------------- |
| // Implementation fields |
| // ---------------------------------------------------------------------- |
| |
| final ReferenceQueue<K> queue = new ReferenceQueue<K>(); |
| |
| final Map<Reference<K>, V> map; |
| |
| private final boolean soft; |
| |
| // ---------------------------------------------------------------------- |
| // Constructors |
| // ---------------------------------------------------------------------- |
| |
| MildKeys( final Map<Reference<K>, V> map, final boolean soft ) |
| { |
| this.map = map; |
| this.soft = soft; |
| } |
| |
| // ---------------------------------------------------------------------- |
| // Public methods |
| // ---------------------------------------------------------------------- |
| |
| public final boolean containsKey( final Object key ) |
| { |
| // skip compact for performance reasons |
| |
| return map.containsKey( tempKey( key ) ); |
| } |
| |
| public final boolean containsValue( final Object value ) |
| { |
| // skip compact for performance reasons |
| |
| return map.containsValue( value ); |
| } |
| |
| public final V get( final Object key ) |
| { |
| // skip compact for performance reasons |
| |
| return map.get( tempKey( key ) ); |
| } |
| |
| public final V put( final K key, final V value ) |
| { |
| compact(); |
| |
| return map.put( mildKey( key ), value ); |
| } |
| |
| public final void putAll( final Map<? extends K, ? extends V> m ) |
| { |
| compact(); |
| |
| for ( final Entry<? extends K, ? extends V> e : m.entrySet() ) |
| { |
| map.put( mildKey( e.getKey() ), e.getValue() ); |
| } |
| } |
| |
| public final V remove( final Object key ) |
| { |
| compact(); |
| |
| return map.remove( tempKey( key ) ); |
| } |
| |
| public final void clear() |
| { |
| map.clear(); |
| |
| compact(); |
| } |
| |
| public final boolean isEmpty() |
| { |
| compact(); |
| |
| return map.isEmpty(); |
| } |
| |
| public final int size() |
| { |
| compact(); |
| |
| return map.size(); |
| } |
| |
| public final Set<K> keySet() |
| { |
| compact(); |
| |
| return new AbstractSet<K>() |
| { |
| @Override |
| public Iterator<K> iterator() |
| { |
| return new KeyItr(); |
| } |
| |
| @Override |
| public int size() |
| { |
| return map.size(); |
| } |
| }; |
| } |
| |
| public final Collection<V> values() |
| { |
| compact(); |
| |
| return map.values(); |
| } |
| |
| public final Set<Entry<K, V>> entrySet() |
| { |
| compact(); |
| |
| return new AbstractSet<Entry<K, V>>() |
| { |
| @Override |
| public Iterator<Entry<K, V>> iterator() |
| { |
| return new EntryItr(); |
| } |
| |
| @Override |
| public int size() |
| { |
| return map.size(); |
| } |
| }; |
| } |
| |
| // ---------------------------------------------------------------------- |
| // Implementation methods |
| // ---------------------------------------------------------------------- |
| |
| /** |
| * @return Soft or weak {@link Reference} for the given key. |
| */ |
| final Reference<K> mildKey( final K key ) |
| { |
| return soft ? new Soft<K>( key, queue ) : new Weak<K>( key, queue ); |
| } |
| |
| /** |
| * @return Temporary {@link Reference} for the given key; used in queries. |
| */ |
| static final <K> Reference<K> tempKey( final K key ) |
| { |
| return new Weak<K>( key, null ); |
| } |
| |
| /** |
| * Compacts the map by removing cleared keys. |
| */ |
| final void compact() |
| { |
| for ( Reference<? extends K> ref; ( ref = queue.poll() ) != null; ) |
| { |
| map.remove( ref ); |
| } |
| } |
| |
| // ---------------------------------------------------------------------- |
| // Implementation types |
| // ---------------------------------------------------------------------- |
| |
| /** |
| * Soft key that maintains a constant hash and uses referential equality. |
| */ |
| static class Soft<T> |
| extends SoftReference<T> |
| { |
| // ---------------------------------------------------------------------- |
| // Implementation fields |
| // ---------------------------------------------------------------------- |
| |
| private final int hash; |
| |
| // ---------------------------------------------------------------------- |
| // Constructors |
| // ---------------------------------------------------------------------- |
| |
| Soft( final T o, final ReferenceQueue<T> queue ) |
| { |
| super( o, queue ); |
| hash = o.hashCode(); |
| } |
| |
| // ---------------------------------------------------------------------- |
| // Public methods |
| // ---------------------------------------------------------------------- |
| |
| @Override |
| public final int hashCode() |
| { |
| return hash; |
| } |
| |
| @Override |
| public final boolean equals( final Object rhs ) |
| { |
| if ( this == rhs ) |
| { |
| return true; // exact same reference |
| } |
| final T o = get(); |
| if ( null != o && rhs instanceof Reference<?> ) |
| { |
| // different reference, but same referent |
| return o == ( (Reference<?>) rhs ).get(); |
| } |
| return false; |
| } |
| } |
| |
| /** |
| * Weak key that maintains a constant hash and uses referential equality. |
| */ |
| static class Weak<T> |
| extends WeakReference<T> |
| { |
| // ---------------------------------------------------------------------- |
| // Implementation fields |
| // ---------------------------------------------------------------------- |
| |
| private final int hash; |
| |
| // ---------------------------------------------------------------------- |
| // Constructors |
| // ---------------------------------------------------------------------- |
| |
| Weak( final T o, final ReferenceQueue<T> queue ) |
| { |
| super( o, queue ); |
| hash = o.hashCode(); |
| } |
| |
| // ---------------------------------------------------------------------- |
| // Public methods |
| // ---------------------------------------------------------------------- |
| |
| @Override |
| public final int hashCode() |
| { |
| return hash; |
| } |
| |
| @Override |
| public final boolean equals( final Object rhs ) |
| { |
| if ( this == rhs ) |
| { |
| return true; // exact same reference |
| } |
| final T o = get(); |
| if ( null != o && rhs instanceof Reference<?> ) |
| { |
| // different reference, but same referent |
| return o == ( (Reference<?>) rhs ).get(); |
| } |
| return false; |
| } |
| } |
| |
| /** |
| * {@link Iterator} that iterates over reachable keys in the map. |
| */ |
| final class KeyItr |
| implements Iterator<K> |
| { |
| // ---------------------------------------------------------------------- |
| // Implementation fields |
| // ---------------------------------------------------------------------- |
| |
| private final Iterator<Reference<K>> itr = map.keySet().iterator(); |
| |
| private K nextKey; |
| |
| // ---------------------------------------------------------------------- |
| // Public methods |
| // ---------------------------------------------------------------------- |
| |
| public boolean hasNext() |
| { |
| // find next key that is still reachable |
| while ( null == nextKey && itr.hasNext() ) |
| { |
| nextKey = itr.next().get(); |
| } |
| return null != nextKey; |
| } |
| |
| public K next() |
| { |
| if ( hasNext() ) |
| { |
| // populated by hasNext() |
| final K key = nextKey; |
| nextKey = null; |
| return key; |
| } |
| throw new NoSuchElementException(); |
| } |
| |
| public void remove() |
| { |
| itr.remove(); |
| } |
| } |
| |
| /** |
| * {@link Iterator} that iterates over reachable entries in the map. |
| */ |
| final class EntryItr |
| implements Iterator<Entry<K, V>> |
| { |
| // ---------------------------------------------------------------------- |
| // Implementation fields |
| // ---------------------------------------------------------------------- |
| |
| private final Iterator<Entry<Reference<K>, V>> itr = map.entrySet().iterator(); |
| |
| private Entry<Reference<K>, V> nextEntry; |
| |
| private K nextKey; |
| |
| // ---------------------------------------------------------------------- |
| // Public methods |
| // ---------------------------------------------------------------------- |
| |
| public boolean hasNext() |
| { |
| // find next entry that is still reachable |
| while ( null == nextKey && itr.hasNext() ) |
| { |
| nextEntry = itr.next(); |
| nextKey = nextEntry.getKey().get(); |
| } |
| return null != nextKey; |
| } |
| |
| public Entry<K, V> next() |
| { |
| if ( hasNext() ) |
| { |
| // populated by hasNext() |
| final Entry<K, V> entry = new StrongEntry( nextEntry, nextKey ); |
| nextEntry = null; |
| nextKey = null; |
| return entry; |
| } |
| throw new NoSuchElementException(); |
| } |
| |
| public void remove() |
| { |
| itr.remove(); |
| } |
| } |
| |
| /** |
| * {@link Entry} that delegates to the original entry, but maintains a strong reference to the key. |
| */ |
| final class StrongEntry |
| implements Entry<K, V> |
| { |
| // ---------------------------------------------------------------------- |
| // Implementation fields |
| // ---------------------------------------------------------------------- |
| |
| private final Entry<Reference<K>, V> entry; |
| |
| private final K key; |
| |
| // ---------------------------------------------------------------------- |
| // Constructors |
| // ---------------------------------------------------------------------- |
| |
| StrongEntry( final Entry<Reference<K>, V> entry, final K key ) |
| { |
| this.entry = entry; |
| this.key = key; |
| } |
| |
| // ---------------------------------------------------------------------- |
| // Public methods |
| // ---------------------------------------------------------------------- |
| |
| public K getKey() |
| { |
| return key; |
| } |
| |
| public V getValue() |
| { |
| return entry.getValue(); |
| } |
| |
| public V setValue( final V value ) |
| { |
| return entry.setValue( value ); |
| } |
| } |
| } |