| Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
| SoftCache |
|
| 0.0;0 |
| 1 | /* | |
| 2 | * RCache - A collection of simple reference-based cache implementations. | |
| 3 | * Copyright (C) 2007 Rodrigo Ruiz | |
| 4 | * | |
| 5 | * This library is free software; you can redistribute it and/or | |
| 6 | * modify it under the terms of the GNU Lesser General Public | |
| 7 | * License as published by the Free Software Foundation; either | |
| 8 | * version 2.1 of the License, or (at your option) any later version. | |
| 9 | * | |
| 10 | * This library is distributed in the hope that it will be useful, | |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 | * Lesser General Public License for more details. | |
| 14 | * | |
| 15 | * You should have received a copy of the GNU Lesser General Public | |
| 16 | * License along with this library; if not, write to the Free Software | |
| 17 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
| 18 | * | |
| 19 | * Alternatively, the contents of this file may be used under the terms | |
| 20 | * of the Apache 2.0 license (the "Apache License"), in which case its | |
| 21 | * provisions are applicable instead of those above. If you wish to allow use | |
| 22 | * of your version of this file only* under the terms of the Apache License | |
| 23 | * and not to allow others to use your version of this file under the LGPL, | |
| 24 | * indicate your decision by* deleting the provisions above and replace them | |
| 25 | * with the notice and other provisions required by the Apache License. If | |
| 26 | * you do not delete the provisions above, a recipient may use your version of | |
| 27 | * this file under either the LGPL or the Apache License. | |
| 28 | */ | |
| 29 | package net.sourceforge.rcache; | |
| 30 | ||
| 31 | import java.lang.ref.ReferenceQueue; | |
| 32 | ||
| 33 | /** | |
| 34 | * <p>Memory-Sensitive Cache Based on SoftReferences</p> | |
| 35 | * | |
| 36 | * <p>Entries in a SoftCache can be garbage collected if, and only if, the JVM | |
| 37 | * considers that more memory is needed. This means that all SoftCache instances | |
| 38 | * will be effectively cleared before an OutOfMemory error is thrown.</p> | |
| 39 | * | |
| 40 | * <p>For certain applications, this class may be too much memory-consuming. If | |
| 41 | * the programmer only needs to enforce that a single instance is used for a | |
| 42 | * given key, and it is not important to keep this instance afterwards, | |
| 43 | * {@link WeakCache} may be a better option.</p> | |
| 44 | * | |
| 45 | * @see java.lang.ref.SoftReference | |
| 46 | * | |
| 47 | * @author Rodrigo Ruiz | |
| 48 | * @param <K> the type of keys maintained by this cache | |
| 49 | * @param <V> the type of cached values | |
| 50 | */ | |
| 51 | public class SoftCache<K, V> extends BaseCache<K, V> { | |
| 52 | ||
| 53 | /** | |
| 54 | * <p>Default constructor.</p> | |
| 55 | * | |
| 56 | * <p>Instances created with this constructor will have a small initial | |
| 57 | * capacity and a highly restricted concurrency level.</p> | |
| 58 | * | |
| 59 | * <p>For concurrent maps, resizing is a costly operation. Whenever possible, | |
| 60 | * it is advised to specify the expected maximum size, in order to | |
| 61 | * minimise the number of resizes.</p> | |
| 62 | */ | |
| 63 | public SoftCache() { | |
| 64 | 5 | super(DEFAULT_INITIAL_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL); |
| 65 | 5 | } |
| 66 | ||
| 67 | /** | |
| 68 | * <p>Creates an instance with a custom initial capacity.</p> | |
| 69 | * | |
| 70 | * @param initialCapacity The map initial capacity | |
| 71 | */ | |
| 72 | public SoftCache(int initialCapacity) { | |
| 73 | 1 | super(initialCapacity, DEFAULT_LOAD_FACTOR, DEFAULT_CONCURRENCY_LEVEL); |
| 74 | 1 | } |
| 75 | ||
| 76 | /** | |
| 77 | * <p>Creates an instance with a custom initial capacity and load factor.</p> | |
| 78 | * | |
| 79 | * @param initialCapacity The map initial capacity | |
| 80 | * @param loadFactor The map load factor | |
| 81 | */ | |
| 82 | public SoftCache(int initialCapacity, float loadFactor) { | |
| 83 | 1 | super(initialCapacity, loadFactor, DEFAULT_CONCURRENCY_LEVEL); |
| 84 | 1 | } |
| 85 | ||
| 86 | /** | |
| 87 | * <p>Creates an instance with custom capacity and concurrency level.</p> | |
| 88 | * | |
| 89 | * <p>The concurrency level is used as a hint to select the internal Map | |
| 90 | * implementation:</p> | |
| 91 | * | |
| 92 | * <ul> | |
| 93 | * <li>< 0 : Do not care about concurrency. | |
| 94 | * A {@link java.util.HashMap} will be used.</li> | |
| 95 | * <li>= 0 : No concurrent access allowed. | |
| 96 | * A {@link java.util.Hashtable} will be selected.</li> | |
| 97 | * <li>> 0 : A {@link java.util.concurrent.ConcurrentHashMap} will be | |
| 98 | * created with the specified concurrency level.</li> | |
| 99 | * </ul> | |
| 100 | * | |
| 101 | * @param initialCapacity The map initial capacity | |
| 102 | * @param loadFactor The map load factor | |
| 103 | * @param concurrencyLevel The concurrency level. | |
| 104 | */ | |
| 105 | public SoftCache(int initialCapacity, float loadFactor, int concurrencyLevel) { | |
| 106 | 3 | super(initialCapacity, loadFactor, concurrencyLevel); |
| 107 | 3 | } |
| 108 | ||
| 109 | /** | |
| 110 | * {@inheritDoc} | |
| 111 | */ | |
| 112 | @Override protected final KeyedReference<K, V> createRef(K key, V value, | |
| 113 | ReferenceQueue<V> queue) { | |
| 114 | 14 | return new SoftKeyedReference<K, V>(key, value, queue); |
| 115 | } | |
| 116 | } |