01: /*
02: * <copyright>
03: *
04: * Copyright 2004 BBNT Solutions, LLC
05: * under sponsorship of the Defense Advanced Research Projects
06: * Agency (DARPA).
07: *
08: * You can redistribute this software and/or modify it under the
09: * terms of the Cougaar Open Source License as published on the
10: * Cougaar Open Source Website (www.cougaar.org).
11: *
12: * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
13: * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
14: * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
15: * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
16: * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
17: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
18: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
19: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
20: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
21: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
22: * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
23: *
24: * </copyright>
25: */
26:
27: package org.cougaar.util;
28:
29: import java.util.LinkedHashMap;
30: import java.util.Map;
31:
32: /**
33: * LRUCache is a simple extension of the standard LinkedHashMap
34: * to implement a fixed-size, access-ordered LRU Cache.
35: * <p>
36: * This implementation does no system-time-based removes as
37: * LRUExpireMap does.
38: */
39: public class LRUCache extends LinkedHashMap {
40: private final int CAPACITY;
41:
42: public LRUCache(int capacity) {
43: super (capacity, 0.75f, true);
44: this .CAPACITY = capacity;
45: }
46:
47: /**
48: * Called by the LinkedHashMap when an entry is added,
49: * this allows the cache to remove the LRU "eldest" entry.
50: */
51: protected boolean removeEldestEntry(Map.Entry eldest) {
52: return (size() > CAPACITY);
53: }
54: }
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