| package org.apache.commons.jcs3.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.util.HashMap; |
| import java.util.Map; |
| import java.util.Map.Entry; |
| import java.util.Set; |
| import java.util.function.Supplier; |
| import java.util.stream.Collectors; |
| |
| import org.apache.commons.jcs3.access.behavior.ICacheAccess; |
| import org.apache.commons.jcs3.access.exception.CacheException; |
| import org.apache.commons.jcs3.access.exception.InvalidArgumentException; |
| import org.apache.commons.jcs3.access.exception.InvalidHandleException; |
| import org.apache.commons.jcs3.access.exception.ObjectExistsException; |
| import org.apache.commons.jcs3.engine.CacheElement; |
| import org.apache.commons.jcs3.engine.behavior.ICacheElement; |
| import org.apache.commons.jcs3.engine.behavior.IElementAttributes; |
| import org.apache.commons.jcs3.engine.control.CompositeCache; |
| |
| /** |
| * 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<K, V> |
| extends AbstractCacheAccess<K, V> |
| implements ICacheAccess<K, V> |
| { |
| /** |
| * Constructor for the CacheAccess object. |
| * <p> |
| * @param cacheControl The cache which the created instance accesses |
| */ |
| public CacheAccess( final CompositeCache<K, V> cacheControl ) |
| { |
| super(cacheControl); |
| } |
| |
| /** |
| * 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 |
| */ |
| @Override |
| public V get( final K name ) |
| { |
| final ICacheElement<K, V> element = this.getCacheControl().get( name ); |
| |
| return ( element != null ) ? element.getVal() : null; |
| } |
| |
| /** |
| * Retrieve an object from the cache region this instance provides access to. |
| * If the object cannot be found in the cache, it will be retrieved by |
| * calling the supplier and subsequently storing it in the cache. |
| * <p> |
| * @param name |
| * @param supplier supplier to be called if the value is not found |
| * @return Object. |
| */ |
| @Override |
| public V get(final K name, final Supplier<V> supplier) |
| { |
| V value = get(name); |
| |
| if (value == null) |
| { |
| value = supplier.get(); |
| put(name, value); |
| } |
| |
| return value; |
| } |
| |
| /** |
| * 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. |
| */ |
| @Override |
| public Map<K, V> getMatching( final String pattern ) |
| { |
| final Map<K, V> unwrappedResults; |
| |
| final Map<K, ICacheElement<K, V>> wrappedResults = this.getCacheControl().getMatching( pattern ); |
| |
| if ( wrappedResults == null ) |
| { |
| unwrappedResults = new HashMap<>(); |
| } |
| else |
| { |
| unwrappedResults = wrappedResults.entrySet() |
| .stream() |
| .filter(entry -> entry.getValue() != null) |
| .collect(Collectors.toMap( |
| Entry::getKey, |
| entry -> entry.getValue().getVal())); |
| } |
| |
| return unwrappedResults; |
| } |
| |
| /** |
| * This method returns the ICacheElement<K, V> 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 Serializable is stored as |
| * @return The ICacheElement<K, V> if the object is found or null |
| */ |
| @Override |
| public ICacheElement<K, V> getCacheElement( final K name ) |
| { |
| return this.getCacheControl().get( name ); |
| } |
| |
| /** |
| * Get multiple elements from the cache based on a set of cache keys. |
| * <p> |
| * This method returns the ICacheElement<K, V> 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 Serializable cache keys |
| * @return a map of K key to ICacheElement<K, V> element, or empty map if none of the keys are present |
| */ |
| @Override |
| public Map<K, ICacheElement<K, V>> getCacheElements( final Set<K> names ) |
| { |
| return this.getCacheControl().getMultiple( names ); |
| } |
| |
| /** |
| * Get multiple elements from the cache based on a set of cache keys. |
| * <p> |
| * This method returns the ICacheElement<K, V> 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 K key to ICacheElement<K, V> element, or empty map if no keys match the pattern |
| */ |
| @Override |
| public Map<K, ICacheElement<K, V>> getMatchingCacheElements( final String pattern ) |
| { |
| return this.getCacheControl().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 |
| * @throws CacheException and ObjectExistsException is thrown if the item is already in the |
| * cache. |
| */ |
| @Override |
| public void putSafe( final K key, final V value ) |
| { |
| if ( this.getCacheControl().get( 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. |
| * @param name Key object will be stored with |
| * @param obj Object to store |
| */ |
| @Override |
| public void put( final K name, final V obj ) |
| { |
| // Call put with a copy of the contained caches default attributes. |
| // the attributes are copied by the cacheControl |
| put( name, obj, this.getCacheControl().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.commons.jcs3.access.behavior.ICacheAccess#put(Object, Object, IElementAttributes) |
| */ |
| @Override |
| public void put( final K key, final V val, final IElementAttributes attr ) |
| { |
| if ( key == null ) |
| { |
| throw new InvalidArgumentException( "Key must not be null" ); |
| } |
| |
| 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 |
| { |
| final CacheElement<K, V> ce = new CacheElement<>( this.getCacheControl().getCacheName(), key, |
| val ); |
| |
| ce.setElementAttributes( attr ); |
| |
| this.getCacheControl().update( ce ); |
| } |
| catch ( final IOException e ) |
| { |
| throw new CacheException( e ); |
| } |
| } |
| |
| /** |
| * Removes a single item by name. |
| * <p> |
| * @param name the name of the item to remove. |
| */ |
| @Override |
| public void remove( final K name ) |
| { |
| this.getCacheControl().remove( name ); |
| } |
| |
| /** |
| * 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 |
| * @throws InvalidHandleException if the item does not exist. |
| */ |
| @Override |
| public void resetElementAttributes( final K name, final IElementAttributes attr ) |
| { |
| final ICacheElement<K, V> element = this.getCacheControl().get( 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. 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 |
| */ |
| @Override |
| public IElementAttributes getElementAttributes( final K name ) throws CacheException |
| { |
| IElementAttributes attr = null; |
| |
| try |
| { |
| attr = this.getCacheControl().getElementAttributes( name ); |
| } |
| catch ( final IOException ioe ) |
| { |
| throw new CacheException("Failure getting element attributes", ioe); |
| } |
| |
| return attr; |
| } |
| } |