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Diffstat (limited to 'subsonic-android/src/github/daneren2005/subphonic/util/LRUCache.java')
-rw-r--r-- | subsonic-android/src/github/daneren2005/subphonic/util/LRUCache.java | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/subsonic-android/src/github/daneren2005/subphonic/util/LRUCache.java b/subsonic-android/src/github/daneren2005/subphonic/util/LRUCache.java new file mode 100644 index 00000000..3e008da4 --- /dev/null +++ b/subsonic-android/src/github/daneren2005/subphonic/util/LRUCache.java @@ -0,0 +1,102 @@ +/* + This file is part of Subsonic. + + Subsonic is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + Subsonic is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with Subsonic. If not, see <http://www.gnu.org/licenses/>. + + Copyright 2009 (C) Sindre Mehus + */ +package github.daneren2005.subphonic.util; + +import java.lang.ref.SoftReference; +import java.util.HashMap; +import java.util.Map; + +/** + * @author Sindre Mehus + */ +public class LRUCache<K,V>{ + + private final int capacity; + private final Map<K, TimestampedValue> map; + + public LRUCache(int capacity) { + map = new HashMap<K, TimestampedValue>(capacity); + this.capacity = capacity; + } + + public synchronized V get(K key) { + TimestampedValue value = map.get(key); + + V result = null; + if (value != null) { + value.updateTimestamp(); + result = value.getValue(); + } + + return result; + } + + public synchronized void put(K key, V value) { + if (map.size() >= capacity) { + removeOldest(); + } + map.put(key, new TimestampedValue(value)); + } + + public void clear() { + map.clear(); + } + + private void removeOldest() { + K oldestKey = null; + long oldestTimestamp = Long.MAX_VALUE; + + for (Map.Entry<K, TimestampedValue> entry : map.entrySet()) { + K key = entry.getKey(); + TimestampedValue value = entry.getValue(); + if (value.getTimestamp() < oldestTimestamp) { + oldestTimestamp = value.getTimestamp(); + oldestKey = key; + } + } + + if (oldestKey != null) { + map.remove(oldestKey); + } + } + + private final class TimestampedValue { + + private final SoftReference<V> value; + private long timestamp; + + public TimestampedValue(V value) { + this.value = new SoftReference<V>(value); + updateTimestamp(); + } + + public V getValue() { + return value.get(); + } + + public long getTimestamp() { + return timestamp; + } + + public void updateTimestamp() { + timestamp = System.currentTimeMillis(); + } + } + +}
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