/**
* Licensed to Apereo under one or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information regarding copyright ownership. Apereo
* licenses this file to you 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 the
* following location:
*
* <p>http://www.apache.org/licenses/LICENSE-2.0
*
* <p>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.apereo.portal.portlet.registry;
import java.io.Serializable;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import org.apereo.portal.portlet.om.IPortletEntityId;
import org.apereo.portal.portlet.om.IPortletWindowDescriptor;
import org.apereo.portal.portlet.om.IPortletWindowId;
import org.apereo.portal.utils.threading.NoopLock;
/**
* Utility for caching portlet windows and window data in memory. Ensures a consistent view for
* accessing the data by different sets of keys
*
* @param <T>
*/
class PortletWindowCache<T extends IPortletWindowDescriptor> implements Serializable {
private static final long serialVersionUID = 1L;
private final Lock writeLock;
private final Lock readLock;
private final Map<IPortletEntityId, Set<T>> windowSetByEntityId =
new HashMap<IPortletEntityId, Set<T>>();
private final Map<IPortletWindowId, T> windowsById = new HashMap<IPortletWindowId, T>();
public PortletWindowCache() {
this(true);
}
/**
* @param threadSafe If set to false no locking is done around read or write operations and this
* class is NOT thread safe
*/
public PortletWindowCache(boolean threadSafe) {
if (threadSafe) {
final ReadWriteLock cacheLock = new ReentrantReadWriteLock(true);
writeLock = cacheLock.writeLock();
readLock = cacheLock.readLock();
} else {
writeLock = NoopLock.INSTANCE;
readLock = NoopLock.INSTANCE;
}
}
public T storeIfAbsentWindow(T window) {
final IPortletWindowId portletWindowId = window.getPortletWindowId();
//Check if the entity already exists (uses a read lock)
T existingWindow = this.getWindow(portletWindowId);
if (existingWindow != null) {
return existingWindow;
}
writeLock.lock();
try {
//Check again inside the write lock
existingWindow = this.windowsById.get(portletWindowId);
if (existingWindow != null) {
return existingWindow;
}
this.storeWindow(window);
} finally {
writeLock.unlock();
}
return window;
}
public void storeWindow(T window) {
writeLock.lock();
try {
final IPortletEntityId portletEntityId = window.getPortletEntityId();
final Set<T> windowSet = this.getWindowSet(portletEntityId, true);
windowSet.add(window);
final IPortletWindowId portletWindowId = window.getPortletWindowId();
this.windowsById.put(portletWindowId, window);
} finally {
writeLock.unlock();
}
}
public boolean containsWindow(IPortletWindowId portletWindowId) {
if (this.windowSetByEntityId.isEmpty()) {
return false;
}
readLock.lock();
try {
return this.windowsById.containsKey(portletWindowId);
} finally {
readLock.unlock();
}
}
public Set<T> getWindows(IPortletEntityId portletEntityId) {
if (this.windowSetByEntityId.isEmpty()) {
return null;
}
readLock.lock();
try {
final Set<T> windowSet = this.getWindowSet(portletEntityId, false);
if (windowSet == null) {
return Collections.emptySet();
}
return Collections.unmodifiableSet(windowSet);
} finally {
readLock.unlock();
}
}
public T getWindow(IPortletWindowId portletWindowId) {
if (this.windowsById.isEmpty()) {
return null;
}
readLock.lock();
try {
return this.windowsById.get(portletWindowId);
} finally {
readLock.unlock();
}
}
private Set<T> getWindowSet(final IPortletEntityId portletEntityId, boolean create) {
Set<T> windowSet = this.windowSetByEntityId.get(portletEntityId);
if (windowSet == null && create) {
windowSet = new LinkedHashSet<T>();
this.windowSetByEntityId.put(portletEntityId, windowSet);
}
return windowSet;
}
}