com.cedarsoft.registry.hierarchy.CachingChildDetector Maven / Gradle / Ivy
/**
* Copyright (C) cedarsoft GmbH.
*
* Licensed under the GNU General Public License version 3 (the "License")
* with Classpath Exception; you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.cedarsoft.org/gpl3ce
* (GPL 3 with Classpath Exception)
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 3 only, as
* published by the Free Software Foundation. cedarsoft GmbH designates this
* particular file as subject to the "Classpath" exception as provided
* by cedarsoft GmbH in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 3 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 3 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact cedarsoft GmbH, 72810 Gomaringen, Germany,
* or visit www.cedarsoft.com if you need additional information or
* have any questions.
*/
package com.cedarsoft.registry.hierarchy;
import com.cedarsoft.registry.cache.Cache;
import com.cedarsoft.registry.cache.HashedCache;
import javax.annotation.Nonnull;
import java.util.List;
import java.util.WeakHashMap;
/**
* Special implementation of a child detector that always returns the same list for a given parent.
*
* @author Johannes Schneider ([email protected])
* @param the type of the children
* @param the type of the parent
*/
public abstract class CachingChildDetector extends AbstractChildDetector {
@Nonnull
private final Cache> childrenCache = new HashedCache>( new WeakHashMap>(), new Cache.Factory>() {
@Override
@Nonnull
public List create( @Nonnull P key ) {
return createChildren( key );
}
} );
/**
* createChildren
*
* @param parent a P object.
* @return a List object.
*/
@Nonnull
protected abstract List createChildren( @Nonnull P parent );
/**
* {@inheritDoc}
*/
@Override
@Nonnull
public final List findChildren( @Nonnull P parent ) {
return childrenCache.get( parent );
}
/**
* handleModified
*
* @param parent a P object.
*/
public void handleModified( @Nonnull P parent ) {
invalidateCache( parent );
}
/**
* invalidateCache
*
* @param parent a P object.
*/
public void invalidateCache( @Nonnull P parent ) {
childrenCache.remove( parent );
notifyChildrenChangedFor( parent );
}
}