/**
* 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.utils.threading;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.WeakHashMap;
import org.apereo.portal.portlet.rendering.worker.TrackingThreadLocalPortletExecutionInterceptor;
/**
* A ThreadLocal subclass that keeps track of all created instances. Using this ThreadLocal subclass
* in uPortal allows any portlet execution thread wrapped by {@link
* TrackingThreadLocalPortletExecutionInterceptor} to have the values copied into the appropriate
* ThreadLocals in the child thread when the thread is run. This avoids having to write explicit
* code for each ThreadLocal that needs to be copied.<br>
* <br>
* The references kept the the ThreadLocal instances is done using a weak set so this tracking
* subclass will not cause leaks by holding on to thread local instances that are no longer
* referenced.
*
*/
public class TrackingThreadLocal<T> extends ThreadLocal<T> {
@SuppressWarnings("unchecked")
private static Map<TrackingThreadLocal<Object>, Class<TrackingThreadLocal>> INSTANCES =
new WeakHashMap<TrackingThreadLocal<Object>, Class<TrackingThreadLocal>>();
private static Set<TrackingThreadLocal<Object>> KEY_SET =
Collections.unmodifiableSet(INSTANCES.keySet());
@SuppressWarnings("unchecked")
public TrackingThreadLocal() {
synchronized (INSTANCES) {
INSTANCES.put((TrackingThreadLocal<Object>) this, TrackingThreadLocal.class);
}
}
/**
* Gets an umodifiable version of the Set of TrackingThreadLocal's that have been created and
* are still referenced strongly somewhere in the JVM.
*
* @return An unmodifiable set of TrackingThreadLocals
*/
public static Set<TrackingThreadLocal<Object>> getInstances() {
return KEY_SET;
}
public static Map<TrackingThreadLocal<Object>, Object> getCurrentData() {
final Map<TrackingThreadLocal<Object>, Object> localCopies =
new HashMap<TrackingThreadLocal<Object>, Object>();
synchronized (INSTANCES) {
for (final TrackingThreadLocal<Object> local : KEY_SET) {
final Object obj = local.get();
localCopies.put(local, obj);
}
}
return localCopies;
}
public static void setCurrentData(Map<TrackingThreadLocal<Object>, Object> localCopies) {
for (final Map.Entry<TrackingThreadLocal<Object>, Object> localCopyEntry :
localCopies.entrySet()) {
final TrackingThreadLocal<Object> local = localCopyEntry.getKey();
final Object obj = localCopyEntry.getValue();
local.set(obj);
}
}
public static void clearCurrentData() {
synchronized (INSTANCES) {
clearCurrentData(KEY_SET);
}
}
public static void clearCurrentData(Set<TrackingThreadLocal<Object>> locals) {
for (final TrackingThreadLocal<Object> local : locals) {
local.remove();
}
}
}