| 1 | package net.spy.memcached; |
| 2 | |
| 3 | import java.util.Collection; |
| 4 | import java.util.Collections; |
| 5 | import java.util.Map; |
| 6 | import java.util.Set; |
| 7 | |
| 8 | import net.spy.memcached.transcoders.Transcoder; |
| 9 | |
| 10 | /** |
| 11 | * Base class for a Map interface to memcached. |
| 12 | * |
| 13 | * <p> |
| 14 | * This Map interface makes memcached a bit easier to use for some purposes |
| 15 | * by providing a limited Map implementation. |
| 16 | * </p> |
| 17 | * |
| 18 | * <p> |
| 19 | * Do note that nothing that iterates over the map will work (such is |
| 20 | * memcached). All iteration mechanisms will return empty iterators and |
| 21 | * such. |
| 22 | * </p> |
| 23 | * |
| 24 | * @param <V> the type of value taken and returned by this Map's underlying |
| 25 | * transcoder, and thus taken and returned by this Map. |
| 26 | */ |
| 27 | public class BaseCacheMap<V> implements Map<String, V> { |
| 28 | |
| 29 | private final String keyPrefix; |
| 30 | private final Transcoder<V> transcoder; |
| 31 | private final MemcachedClientIF client; |
| 32 | private final int exp; |
| 33 | |
| 34 | /** |
| 35 | * Build a BaseCacheMap. |
| 36 | * |
| 37 | * @param c the underlying client |
| 38 | * @param expiration the expiration for objects set through this Map |
| 39 | * @param prefix a prefix to ensure objects in this map are unique |
| 40 | * @param t the transcoder to serialize and deserialize objects |
| 41 | */ |
| 42 | public BaseCacheMap(MemcachedClientIF c, int expiration, |
| 43 | String prefix, Transcoder<V> t) { |
| 44 | super(); |
| 45 | keyPrefix = prefix; |
| 46 | transcoder = t; |
| 47 | client = c; |
| 48 | exp = expiration; |
| 49 | } |
| 50 | |
| 51 | public void clear() { |
| 52 | // TODO: Support a rolling key generation. |
| 53 | throw new UnsupportedOperationException(); |
| 54 | } |
| 55 | |
| 56 | private String getKey(String k) { |
| 57 | return keyPrefix + k; |
| 58 | } |
| 59 | |
| 60 | public boolean containsKey(Object key) { |
| 61 | return get(key) != null; |
| 62 | } |
| 63 | |
| 64 | /** |
| 65 | * This method always returns false, as truth cannot be determined without |
| 66 | * iteration. |
| 67 | */ |
| 68 | public boolean containsValue(Object value) { |
| 69 | return false; |
| 70 | } |
| 71 | |
| 72 | public Set<Map.Entry<String, V>> entrySet() { |
| 73 | return Collections.emptySet(); |
| 74 | } |
| 75 | |
| 76 | public V get(Object key) { |
| 77 | V rv = null; |
| 78 | try { |
| 79 | rv = client.get(getKey((String)key), transcoder); |
| 80 | } catch(ClassCastException e) { |
| 81 | // Most likely, this is because the key wasn't a String. |
| 82 | // Either way, it's a no. |
| 83 | } |
| 84 | return rv; |
| 85 | } |
| 86 | |
| 87 | public boolean isEmpty() { |
| 88 | return false; |
| 89 | } |
| 90 | |
| 91 | public Set<String> keySet() { |
| 92 | return Collections.emptySet(); |
| 93 | } |
| 94 | |
| 95 | public void putAll(Map<? extends String, ? extends V> t) { |
| 96 | for(Map.Entry<? extends String, ? extends V> me : t.entrySet()) { |
| 97 | client.set(getKey(me.getKey()), exp, me.getValue()); |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | public V remove(Object key) { |
| 102 | V rv = null; |
| 103 | try { |
| 104 | rv = get(key); |
| 105 | client.delete(getKey((String)key)); |
| 106 | } catch(ClassCastException e) { |
| 107 | // Not a string key. Ignore. |
| 108 | } |
| 109 | return rv; |
| 110 | } |
| 111 | |
| 112 | public int size() { |
| 113 | return 0; |
| 114 | } |
| 115 | |
| 116 | public Collection<V> values() { |
| 117 | return Collections.emptySet(); |
| 118 | } |
| 119 | |
| 120 | public V put(String key, V value) { |
| 121 | V rv = get(key); |
| 122 | client.set(getKey(key), exp, value); |
| 123 | return rv; |
| 124 | } |
| 125 | |
| 126 | } |