/**
* Licensed to Jasig under one or more contributor license
* agreements. See the NOTICE file distributed with this work
* for additional information regarding copyright ownership.
* Jasig 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:
*
* 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.jasig.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.jasig.portal.portlet.om.IPortletEntityId;
import org.jasig.portal.portlet.om.IPortletWindowDescriptor;
import org.jasig.portal.portlet.om.IPortletWindowId;
import org.jasig.portal.utils.threading.NoopLock;
import com.google.common.base.Function;
/**
* Utility for caching portlet windows and window data in memory. Ensures a consistent view for accessing the data by
* different sets of keys
*
* @author Eric Dalquist
* @version $Revision$
* @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(IPortletWindowId portletWindowId, Function<IPortletWindowId, T> windowCreator) {
//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;
}
final T window = windowCreator.apply(portletWindowId);
this.storeWindow(window);
return window;
}
finally {
writeLock.unlock();
}
}
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();
}
}
public void removeWindow(IPortletWindowId portletWindowId) {
writeLock.lock();
try {
final T window = this.windowsById.remove(portletWindowId);
if (window != null) {
final IPortletEntityId portletEntityId = window.getPortletEntityId();
final Set<T> windowSet = this.getWindowSet(portletEntityId, false);
if (windowSet != null) {
windowSet.remove(window);
}
}
}
finally {
writeLock.unlock();
}
}
protected 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;
}
}