//$Id: EhCache.java 10716 2006-11-03 19:05:11Z [email protected] $
/**
* Copyright 2003-2006 Greg Luck, Jboss Inc
*
* 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.hibernate.cache;
import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import net.sf.ehcache.CacheManager;
import net.sf.ehcache.Element;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* EHCache plugin for Hibernate
* <p/>
* EHCache uses a {@link net.sf.ehcache.store.MemoryStore} and a
* {@link net.sf.ehcache.store.DiskStore}.
* The {@link net.sf.ehcache.store.DiskStore} requires that both keys and values be {@link java.io.Serializable}.
* However the MemoryStore does not and in ehcache-1.2 nonSerializable Objects are permitted. They are discarded
* if an attempt it made to overflow them to Disk or to replicate them to remote cache peers.
*
* @author Greg Luck
* @author Emmanuel Bernard
*/
public class EhCache implements Cache {
private static final Log log = LogFactory.getLog( EhCache.class );
private static final int SIXTY_THOUSAND_MS = 60000;
private net.sf.ehcache.Cache cache;
/**
* Creates a new Hibernate pluggable cache based on a cache name.
* <p/>
*
* @param cache The underlying EhCache instance to use.
*/
public EhCache(net.sf.ehcache.Cache cache) {
this.cache = cache;
}
/**
* Gets a value of an element which matches the given key.
*
* @param key the key of the element to return.
* @return The value placed into the cache with an earlier put, or null if not found or expired
* @throws CacheException
*/
public Object get(Object key) throws CacheException {
try {
if ( log.isDebugEnabled() ) {
log.debug( "key: " + key );
}
if ( key == null ) {
return null;
}
else {
Element element = cache.get( key );
if ( element == null ) {
if ( log.isDebugEnabled() ) {
log.debug( "Element for " + key + " is null" );
}
return null;
}
else {
return element.getObjectValue();
}
}
}
catch (net.sf.ehcache.CacheException e) {
throw new CacheException( e );
}
}
public Object read(Object key) throws CacheException {
return get( key );
}
/**
* Puts an object into the cache.
*
* @param key a key
* @param value a value
* @throws CacheException if the {@link CacheManager}
* is shutdown or another {@link Exception} occurs.
*/
public void update(Object key, Object value) throws CacheException {
put( key, value );
}
/**
* Puts an object into the cache.
*
* @param key a key
* @param value a value
* @throws CacheException if the {@link CacheManager}
* is shutdown or another {@link Exception} occurs.
*/
public void put(Object key, Object value) throws CacheException {
try {
Element element = new Element( key, value );
cache.put( element );
}
catch (IllegalArgumentException e) {
throw new CacheException( e );
}
catch (IllegalStateException e) {
throw new CacheException( e );
}
catch (net.sf.ehcache.CacheException e) {
throw new CacheException( e );
}
}
/**
* Removes the element which matches the key.
* <p/>
* If no element matches, nothing is removed and no Exception is thrown.
*
* @param key the key of the element to remove
* @throws CacheException
*/
public void remove(Object key) throws CacheException {
try {
cache.remove( key );
}
catch (ClassCastException e) {
throw new CacheException( e );
}
catch (IllegalStateException e) {
throw new CacheException( e );
}
catch (net.sf.ehcache.CacheException e) {
throw new CacheException( e );
}
}
/**
* Remove all elements in the cache, but leave the cache
* in a useable state.
*
* @throws CacheException
*/
public void clear() throws CacheException {
try {
cache.removeAll();
}
catch (IllegalStateException e) {
throw new CacheException( e );
}
catch (net.sf.ehcache.CacheException e) {
throw new CacheException( e );
}
}
/**
* Remove the cache and make it unuseable.
*
* @throws CacheException
*/
public void destroy() throws CacheException {
try {
cache.getCacheManager().removeCache( cache.getName() );
}
catch (IllegalStateException e) {
throw new CacheException( e );
}
catch (net.sf.ehcache.CacheException e) {
throw new CacheException( e );
}
}
/**
* Calls to this method should perform there own synchronization.
* It is provided for distributed caches. Because EHCache is not distributed
* this method does nothing.
*/
public void lock(Object key) throws CacheException {
}
/**
* Calls to this method should perform there own synchronization.
* It is provided for distributed caches. Because EHCache is not distributed
* this method does nothing.
*/
public void unlock(Object key) throws CacheException {
}
/**
* Gets the next timestamp;
*/
public long nextTimestamp() {
return Timestamper.next();
}
/**
* Returns the lock timeout for this cache.
*/
public int getTimeout() {
// 60 second lock timeout
return Timestamper.ONE_MS * SIXTY_THOUSAND_MS;
}
public String getRegionName() {
return cache.getName();
}
/**
* Warning: This method can be very expensive to run. Allow approximately 1 second
* per 1MB of entries. Running this method could create liveness problems
* because the object lock is held for a long period
* <p/>
*
* @return the approximate size of memory ehcache is using for the MemoryStore for this cache
*/
public long getSizeInMemory() {
try {
return cache.calculateInMemorySize();
}
catch (Throwable t) {
return -1;
}
}
public long getElementCountInMemory() {
try {
return cache.getMemoryStoreSize();
}
catch (net.sf.ehcache.CacheException ce) {
throw new CacheException( ce );
}
}
public long getElementCountOnDisk() {
return cache.getDiskStoreSize();
}
public Map toMap() {
try {
Map result = new HashMap();
Iterator iter = cache.getKeys().iterator();
while ( iter.hasNext() ) {
Object key = iter.next();
result.put( key, cache.get( key ).getObjectValue() );
}
return result;
}
catch (Exception e) {
throw new CacheException( e );
}
}
public String toString() {
return "EHCache(" + getRegionName() + ')';
}
}
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