| package org.apache.jcs.access; |
| |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF 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. |
| */ |
| |
| import java.io.IOException; |
| import java.io.Serializable; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.Map; |
| import java.util.Set; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.jcs.access.behavior.ICacheAccess; |
| import org.apache.jcs.access.exception.CacheException; |
| import org.apache.jcs.access.exception.InvalidArgumentException; |
| import org.apache.jcs.access.exception.InvalidHandleException; |
| import org.apache.jcs.access.exception.ObjectExistsException; |
| import org.apache.jcs.engine.CacheElement; |
| import org.apache.jcs.engine.behavior.ICacheElement; |
| import org.apache.jcs.engine.behavior.ICompositeCacheAttributes; |
| import org.apache.jcs.engine.behavior.IElementAttributes; |
| import org.apache.jcs.engine.control.CompositeCache; |
| import org.apache.jcs.engine.control.CompositeCacheManager; |
| import org.apache.jcs.engine.stats.behavior.ICacheStats; |
| |
| /** |
| * This class provides an interface for all types of access to the cache. |
| * <p> |
| * An instance of this class is tied to a specific cache region. Static methods are provided to get |
| * such instances. |
| * <p> |
| * Using this class you can retrieve an item, the item's wrapper, and the element's configuration. You can also put an |
| * item in the cache, remove an item, and clear a region. |
| * <p> |
| * The JCS class is the preferred way to access these methods. |
| */ |
| public class CacheAccess |
| implements ICacheAccess |
| { |
| /** The logger. */ |
| private static final Log log = LogFactory.getLog( CacheAccess.class ); |
| |
| /** Cache manager use by the various forms of defineRegion and getAccess */ |
| private static CompositeCacheManager cacheMgr; |
| |
| /** |
| * The cache that a given instance of this class provides access to. |
| * <p> |
| * @TODO Should this be the interface? |
| */ |
| protected CompositeCache cacheControl; |
| |
| /** |
| * Constructor for the CacheAccess object. |
| * <p> |
| * @param cacheControl The cache which the created instance accesses |
| */ |
| public CacheAccess( CompositeCache cacheControl ) |
| { |
| this.cacheControl = cacheControl; |
| } |
| |
| // ----------------------------- static methods for access to cache regions |
| |
| /** |
| * Define a new cache region with the given name. In the oracle specification, these attributes |
| * are global and not region specific, regional overrides is a value add each region should be |
| * able to house both cache and element attribute sets. It is more efficient to define a cache |
| * in the props file and then strictly use the get access method. Use of the define region |
| * outside of an initialization block should be avoided. |
| * <p> |
| * @param name Name that will identify the region |
| * @return CacheAccess instance for the new region |
| * @exception CacheException |
| */ |
| public static CacheAccess defineRegion( String name ) |
| throws CacheException |
| { |
| ensureCacheManager(); |
| |
| return new CacheAccess( cacheMgr.getCache( name ) ); |
| } |
| |
| /** |
| * Define a new cache region with the specified name and attributes. |
| * <p> |
| * @param name Name that will identify the region |
| * @param cattr CompositeCacheAttributes for the region |
| * @return CacheAccess instance for the new region |
| * @exception CacheException |
| */ |
| public static CacheAccess defineRegion( String name, ICompositeCacheAttributes cattr ) |
| throws CacheException |
| { |
| ensureCacheManager(); |
| |
| return new CacheAccess( cacheMgr.getCache( name, cattr ) ); |
| } |
| |
| /** |
| * Define a new cache region with the specified name and attributes and return a CacheAccess to |
| * it. |
| * <p> |
| * @param name Name that will identify the region |
| * @param cattr CompositeCacheAttributes for the region |
| * @param attr Attributes for the region |
| * @return CacheAccess instance for the new region |
| * @exception CacheException |
| */ |
| public static CacheAccess defineRegion( String name, ICompositeCacheAttributes cattr, IElementAttributes attr ) |
| throws CacheException |
| { |
| ensureCacheManager(); |
| |
| return new CacheAccess( cacheMgr.getCache( name, cattr, attr ) ); |
| } |
| |
| /** |
| * Get a CacheAccess instance for the given region. |
| * <p> |
| * @param region Name that identifies the region |
| * @return CacheAccess instance for region |
| * @exception CacheException |
| */ |
| public static CacheAccess getAccess( String region ) |
| throws CacheException |
| { |
| ensureCacheManager(); |
| |
| return new CacheAccess( cacheMgr.getCache( region ) ); |
| } |
| |
| /** |
| * Get a CacheAccess instance for the given region with the given attributes. |
| * <p> |
| * @param region Name that identifies the region |
| * @param icca |
| * @return CacheAccess instance for region |
| * @exception CacheException |
| */ |
| public static CacheAccess getAccess( String region, ICompositeCacheAttributes icca ) |
| throws CacheException |
| { |
| ensureCacheManager(); |
| |
| return new CacheAccess( cacheMgr.getCache( region, icca ) ); |
| } |
| |
| /** |
| * Helper method which checks to make sure the cacheMgr class field is set, and if not requests |
| * an instance from CacheManagerFactory. |
| */ |
| protected static void ensureCacheManager() |
| { |
| synchronized ( CacheAccess.class ) |
| { |
| if ( cacheMgr == null ) |
| { |
| cacheMgr = CompositeCacheManager.getInstance(); |
| } |
| } |
| } |
| |
| // ------------------------------------------------------- instance methods |
| |
| /** |
| * Retrieve an object from the cache region this instance provides access to. |
| * <p> |
| * @param name Key the object is stored as |
| * @return The object if found or null |
| */ |
| public Object get( Object name ) |
| { |
| ICacheElement element = this.cacheControl.get( (Serializable) name ); |
| |
| return ( element != null ) ? element.getVal() : null; |
| } |
| |
| /** |
| * Retrieve matching objects from the cache region this instance provides access to. |
| * <p> |
| * @param pattern - a key pattern for the objects stored |
| * @return A map of key to values. These are stripped from the wrapper. |
| */ |
| public HashMap getMatching( String pattern ) |
| { |
| HashMap unwrappedResults = new HashMap(); |
| |
| Map wrappedResults = this.cacheControl.getMatching( pattern ); |
| if ( wrappedResults != null ) |
| { |
| Set keySet = wrappedResults.keySet(); |
| Iterator it = keySet.iterator(); |
| while ( it.hasNext() ) |
| { |
| Object key = it.next(); |
| ICacheElement element = (ICacheElement)wrappedResults.get( key ); |
| if ( element != null ) |
| { |
| unwrappedResults.put( key, element.getVal() ); |
| } |
| } |
| } |
| return unwrappedResults; |
| } |
| |
| /** |
| * This method returns the ICacheElement wrapper which provides access to element info and other |
| * attributes. |
| * <p> |
| * This returns a reference to the wrapper. Any modifications will be reflected in the cache. No |
| * defensive copy is made. |
| * <p> |
| * This method is most useful if you want to determine things such as the how long the element |
| * has been in the cache. |
| * <p> |
| * The last access time in the ElementAttributes should be current. |
| * <p> |
| * @param name Key the object is stored as |
| * @return The ICacheElement if the object is found or null |
| */ |
| public ICacheElement getCacheElement( Object name ) |
| { |
| return this.cacheControl.get( (Serializable) name ); |
| } |
| |
| /** |
| * Get multiple elements from the cache based on a set of cache keys. |
| * <p> |
| * This method returns the ICacheElement wrapper which provides access to element info and other |
| * attributes. |
| * <p> |
| * This returns a reference to the wrapper. Any modifications will be reflected in the cache. No |
| * defensive copy is made. |
| * <p> |
| * This method is most useful if you want to determine things such as the how long the element |
| * has been in the cache. |
| * <p> |
| * The last access time in the ElementAttributes should be current. |
| * <p> |
| * @param names set of Object cache keys |
| * @return a map of Object key to ICacheElement element, or empty map if none of the keys are present |
| */ |
| public Map getCacheElements( Set names ) |
| { |
| return this.cacheControl.getMultiple( names ); |
| } |
| |
| /** |
| * Get multiple elements from the cache based on a set of cache keys. |
| * <p> |
| * This method returns the ICacheElement wrapper which provides access to element info and other |
| * attributes. |
| * <p> |
| * This returns a reference to the wrapper. Any modifications will be reflected in the cache. No |
| * defensive copy is made. |
| * <p> |
| * This method is most useful if you want to determine things such as the how long the element |
| * has been in the cache. |
| * <p> |
| * The last access time in the ElementAttributes should be current. |
| * <p> |
| * @param pattern key search pattern |
| * @return a map of Object key to ICacheElement element, or empty map if no keys match the pattern |
| */ |
| public Map getMatchingCacheElements( String pattern ) |
| { |
| return this.cacheControl.getMatching( pattern ); |
| } |
| |
| /** |
| * Place a new object in the cache, associated with key name. If there is currently an object |
| * associated with name in the region an ObjectExistsException is thrown. Names are scoped to a |
| * region so they must be unique within the region they are placed. |
| * <p> |
| * @param key Key object will be stored with |
| * @param value Object to store |
| * @exception CacheException and ObjectExistsException is thrown if the item is already in the |
| * cache. |
| */ |
| public void putSafe( Object key, Object value ) |
| throws CacheException |
| { |
| if ( this.cacheControl.get( (Serializable) key ) != null ) |
| { |
| throw new ObjectExistsException( "putSafe failed. Object exists in the cache for key [" + key |
| + "]. Remove first or use a non-safe put to override the value." ); |
| } |
| put( key, value ); |
| } |
| |
| /** |
| * Place a new object in the cache, associated with key name. If there is currently an object |
| * associated with name in the region it is replaced. Names are scoped to a region so they must |
| * be unique within the region they are placed. ObjectExistsException |
| * @param name Key object will be stored with |
| * @param obj Object to store |
| * @exception CacheException |
| */ |
| public void put( Object name, Object obj ) |
| throws CacheException |
| { |
| // Call put with a copy of the contained caches default attributes. |
| // the attributes are copied by the cacheControl |
| put( name, obj, this.cacheControl.getElementAttributes() ); |
| } |
| |
| /** |
| * Constructs a cache element with these attributes, and puts it into the cache. |
| * <p> |
| * If the key or the value is null, and InvalidArgumentException is thrown. |
| * <p> |
| * @see org.apache.jcs.access.behavior.ICacheAccess#put(java.lang.Object, java.lang.Object, |
| * org.apache.jcs.engine.behavior.IElementAttributes) |
| */ |
| public void put( Object key, Object val, IElementAttributes attr ) |
| throws CacheException |
| { |
| if ( key == null ) |
| { |
| throw new InvalidArgumentException( "Key must not be null" ); |
| } |
| else if ( val == null ) |
| { |
| throw new InvalidArgumentException( "Value must not be null" ); |
| } |
| |
| // Create the element and update. This may throw an IOException which |
| // should be wrapped by cache access. |
| try |
| { |
| CacheElement ce = new CacheElement( this.cacheControl.getCacheName(), (Serializable) key, |
| (Serializable) val ); |
| |
| ce.setElementAttributes( attr ); |
| |
| this.cacheControl.update( ce ); |
| } |
| catch ( Exception e ) |
| { |
| throw new CacheException( e ); |
| } |
| } |
| |
| /** |
| * Destroy the region and all objects within it. After calling this method, the Cache object can |
| * no longer be used as it will be closed. |
| * <p> |
| * @exception CacheException |
| * @deprecated |
| */ |
| public void destroy() |
| throws CacheException |
| { |
| try |
| { |
| this.cacheControl.removeAll(); |
| } |
| catch ( IOException e ) |
| { |
| throw new CacheException( e ); |
| } |
| } |
| |
| /** |
| * Removes all of the elements from a region. |
| * <p> |
| * @deprecated use clear() |
| * @throws CacheException |
| */ |
| public void remove() |
| throws CacheException |
| { |
| clear(); |
| } |
| |
| /** |
| * Removes all of the elements from a region. |
| * <p> |
| * @throws CacheException |
| */ |
| public void clear() |
| throws CacheException |
| { |
| try |
| { |
| this.cacheControl.removeAll(); |
| } |
| catch ( IOException e ) |
| { |
| throw new CacheException( e ); |
| } |
| } |
| |
| /** |
| * Invalidate all objects associated with key name, removing all references to the objects from |
| * the cache. |
| * <p> |
| * @param name Key that specifies object to invalidate |
| * @exception CacheException |
| * @deprecated use remove |
| */ |
| public void destroy( Object name ) |
| throws CacheException |
| { |
| this.cacheControl.remove( (Serializable) name ); |
| } |
| |
| /** |
| * Removes a single item by name. |
| * <p> |
| * @param name the name of the item to remove. |
| * @throws CacheException |
| */ |
| public void remove( Object name ) |
| throws CacheException |
| { |
| this.cacheControl.remove( (Serializable) name ); |
| } |
| |
| /** |
| * ResetAttributes allows for some of the attributes of a region to be reset in particular |
| * expiration time attributes, time to live, default time to live and idle time, and event |
| * handlers. Changing default settings on groups and regions will not affect existing objects. |
| * Only object loaded after the reset will use the new defaults. If no name argument is |
| * provided, the reset is applied to the region. |
| * <p> |
| * NOTE: this method is does not reset the attributes for items already in the cache. It could |
| * potentially do this for items in memory, and maybe on disk (which would be slow) but not |
| * remote items. Rather than have unpredictable behavior, this method just sets the default |
| * attributes. |
| * <p> |
| * TODO is should be renamed "setDefaultElementAttributes" |
| * <p> |
| * @deprecated As of release 1.3 |
| * @see #setDefaultElementAttributes(IElementAttributes) |
| * @param attr New attributes for this region. |
| * @exception CacheException |
| * @exception InvalidHandleException |
| */ |
| public void resetElementAttributes( IElementAttributes attr ) |
| throws CacheException, InvalidHandleException |
| { |
| this.cacheControl.setElementAttributes( attr ); |
| } |
| |
| /** |
| * This method is does not reset the attributes for items already in the cache. It could |
| * potentially do this for items in memory, and maybe on disk (which would be slow) but not |
| * remote items. Rather than have unpredictable behavior, this method just sets the default |
| * attributes. Items subsequently put into the cache will use these defaults if they do not |
| * specify specific attributes. |
| * <p> |
| * @param attr the default attributes. |
| * @throws CacheException if something goes wrong. |
| */ |
| public void setDefaultElementAttributes( IElementAttributes attr ) |
| throws CacheException |
| { |
| this.cacheControl.setElementAttributes( attr ); |
| } |
| |
| /** |
| * Reset attributes for a particular element in the cache. NOTE: this method is currently not |
| * implemented. |
| * <p> |
| * @param name Key of object to reset attributes for |
| * @param attr New attributes for the object |
| * @exception CacheException |
| * @exception InvalidHandleException if the item does not exist. |
| */ |
| public void resetElementAttributes( Object name, IElementAttributes attr ) |
| throws CacheException, InvalidHandleException |
| { |
| ICacheElement element = this.cacheControl.get( (Serializable) name ); |
| |
| if ( element == null ) |
| { |
| throw new InvalidHandleException( "Object for name [" + name + "] is not in the cache" ); |
| } |
| |
| // Although it will work currently, don't assume pass by reference here, |
| // i.e. don't do this: |
| // element.setElementAttributes( attr ); |
| // Another reason to call put is to force the changes to be distributed. |
| |
| put( element.getKey(), element.getVal(), attr ); |
| } |
| |
| /** |
| * GetElementAttributes will return an attribute object describing the current attributes |
| * associated with the object name. |
| * <p> |
| * This was confusing, so I created a new method with a clear name. |
| * <p> |
| * @deprecated As of release 1.3 |
| * @see #getDefaultElementAttributes |
| * @return Attributes for this region |
| * @exception CacheException |
| */ |
| public IElementAttributes getElementAttributes() |
| throws CacheException |
| { |
| return this.cacheControl.getElementAttributes(); |
| } |
| |
| /** |
| * Retrieves A COPY OF the default element attributes used by this region. This does not provide |
| * a reference to the element attributes. |
| * <p> |
| * Each time an element is added to the cache without element attributes, the default element |
| * attributes are cloned. |
| * <p> |
| * @return the deafualt element attributes used by this region. |
| * @throws CacheException |
| */ |
| public IElementAttributes getDefaultElementAttributes() |
| throws CacheException |
| { |
| return this.cacheControl.getElementAttributes(); |
| } |
| |
| /** |
| * GetElementAttributes will return an attribute object describing the current attributes |
| * associated with the object name. The name object must override the Object.equals and |
| * Object.hashCode methods. |
| * <p> |
| * @param name Key of object to get attributes for |
| * @return Attributes for the object, null if object not in cache |
| * @exception CacheException |
| */ |
| public IElementAttributes getElementAttributes( Object name ) |
| throws CacheException |
| { |
| IElementAttributes attr = null; |
| |
| try |
| { |
| attr = this.cacheControl.getElementAttributes( (Serializable) name ); |
| } |
| catch ( IOException ioe ) |
| { |
| log.error( "Failure getting element attributes", ioe ); |
| } |
| |
| return attr; |
| } |
| |
| /** |
| * This returns the ICacheStats object with information on this region and its auxiliaries. |
| * <p> |
| * This data can be formatted as needed. |
| * <p> |
| * @return ICacheStats |
| */ |
| public ICacheStats getStatistics() |
| { |
| return this.cacheControl.getStatistics(); |
| } |
| |
| /** |
| * @return A String version of the stats. |
| */ |
| public String getStats() |
| { |
| return this.cacheControl.getStats(); |
| } |
| |
| /** |
| * Dispose this region. Flushes objects to and closes auxiliary caches. This is a shutdown |
| * command! |
| * <p> |
| * To simply remove all elements from the region use clear(). |
| */ |
| public void dispose() |
| { |
| this.cacheControl.dispose(); |
| } |
| |
| /** |
| * Gets the ICompositeCacheAttributes of the cache region. |
| * <p> |
| * @return ICompositeCacheAttributes, the controllers config info, defined in the top section of |
| * a region definition. |
| */ |
| public ICompositeCacheAttributes getCacheAttributes() |
| { |
| return this.cacheControl.getCacheAttributes(); |
| } |
| |
| /** |
| * Sets the ICompositeCacheAttributes of the cache region. |
| * <p> |
| * @param cattr The new ICompositeCacheAttribute value |
| */ |
| public void setCacheAttributes( ICompositeCacheAttributes cattr ) |
| { |
| this.cacheControl.setCacheAttributes( cattr ); |
| } |
| |
| /** |
| * This instructs the memory cache to remove the <i>numberToFree</i> according to its eviction |
| * policy. For example, the LRUMemoryCache will remove the <i>numberToFree</i> least recently |
| * used items. These will be spooled to disk if a disk auxiliary is available. |
| * <p> |
| * @param numberToFree |
| * @return the number that were removed. if you ask to free 5, but there are only 3, you will |
| * get 3. |
| * @throws CacheException |
| */ |
| public int freeMemoryElements( int numberToFree ) |
| throws CacheException |
| { |
| int numFreed = -1; |
| try |
| { |
| numFreed = this.cacheControl.getMemoryCache().freeElements( numberToFree ); |
| } |
| catch ( IOException ioe ) |
| { |
| String message = "Failure freeing memory elements. "; |
| log.error( message, ioe ); |
| throw new CacheException( message + ioe.getMessage() ); |
| } |
| return numFreed; |
| } |
| } |
