/*
* Copyright 2002-2007 the original author or authors.
*
* Licensed 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.springmodules.lucene.index.resource;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* @author Juergen Hoeller
* @author Thierry Templier
*/
public abstract class ResourceBindingManager {
private static final Log logger = LogFactory.getLog(ResourceBindingManager.class);
private static final ThreadLocal resources = new ThreadLocal();
//-------------------------------------------------------------------------
// Management of resource-associated resource handles
//-------------------------------------------------------------------------
/**
* Return all resources that are bound to the current thread.
* <p>Mainly for debugging purposes. Resource managers should always invoke
* hasResource for a specific resource key that they are interested in.
* @return Map with resource keys and resource objects,
* or empty Map if currently none bound
* @see #hasResource
*/
public static Map getResourceMap() {
Map map = (Map) resources.get();
if (map == null) {
map = new HashMap();
}
return Collections.unmodifiableMap(map);
}
/**
* Check if there is a resource for the given key bound to the current thread.
* @param key key to check
* @return if there is a value bound to the current thread
*/
public static boolean hasResource(Object key) {
Map map = (Map) resources.get();
return (map != null && map.containsKey(key));
}
/**
* Retrieve a resource for the given key that is bound to the current thread.
* @param key key to check
* @return a value bound to the current thread, or null if none
*/
public static Object getResource(Object key) {
Map map = (Map) resources.get();
if (map == null) {
return null;
}
Object value = map.get(key);
if (value != null && logger.isDebugEnabled()) {
logger.debug("Retrieved value [" + value + "] for key [" + key + "] bound to thread [" +
Thread.currentThread().getName() + "]");
}
return value;
}
/**
* Bind the given resource for the given key to the current thread.
* @param key key to bind the value to
* @param value value to bind
* @throws IllegalStateException if there is already a value bound to the thread
*/
public static void bindResource(Object key, Object value) throws IllegalStateException {
Map map = (Map) resources.get();
// set ThreadLocal Map if none found
if (map == null) {
map = new HashMap();
resources.set(map);
}
if (map.containsKey(key)) {
throw new IllegalStateException("Already value [" + map.get(key) + "] for key [" + key +
"] bound to thread [" + Thread.currentThread().getName() + "]");
}
map.put(key, value);
if (logger.isDebugEnabled()) {
logger.debug("Bound value [" + value + "] for key [" + key + "] to thread [" +
Thread.currentThread().getName() + "]");
}
}
/**
* Unbind a resource for the given key from the current thread.
* @param key key to check
* @return the previously bound value
* @throws IllegalStateException if there is no value bound to the thread
*/
public static Object unbindResource(Object key) throws IllegalStateException {
Map map = (Map) resources.get();
if (map == null || !map.containsKey(key)) {
throw new IllegalStateException(
"No value for key [" + key + "] bound to thread [" + Thread.currentThread().getName() + "]");
}
Object value = map.remove(key);
// remove entire ThreadLocal if empty
if (map.isEmpty()) {
resources.set(null);
}
if (logger.isDebugEnabled()) {
logger.debug("Removed value [" + value + "] for key [" + key + "] from thread [" +
Thread.currentThread().getName() + "]");
}
return value;
}
}