Mercurial > dive4elements > gnv-client
comparison geo-backend/src/main/java/de/intevation/gnv/geobackend/util/RedundancyRemover.java @ 1129:ccfa07b88476
merged geo-backend
| author | Thomas Arendsen Hein <thomas@intevation.de> |
|---|---|
| date | Fri, 28 Sep 2012 12:14:01 +0200 |
| parents | ebeb56428409 |
| children |
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| 1119:7c4f81f74c47 | 1129:ccfa07b88476 |
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| 1 /* | |
| 2 * Copyright (c) 2010 by Intevation GmbH | |
| 3 * | |
| 4 * This program is free software under the LGPL (>=v2.1) | |
| 5 * Read the file LGPL.txt coming with the software for details | |
| 6 * or visit http://www.gnu.org/licenses/ if it does not exist. | |
| 7 */ | |
| 8 | |
| 9 package de.intevation.gnv.geobackend.util; | |
| 10 | |
| 11 import java.util.LinkedHashMap; | |
| 12 import java.util.Map; | |
| 13 | |
| 14 /** | |
| 15 * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a> | |
| 16 */ | |
| 17 public final class RedundancyRemover | |
| 18 extends LinkedHashMap | |
| 19 { | |
| 20 /** ceil(1029 * 1.75) = 1801, which is prime | |
| 21 * -> suitable for a hash map slot size. | |
| 22 */ | |
| 23 public static final int DEFAULT_LOOKBACK = | |
| 24 Integer.getInteger( | |
| 25 "de.intevation.gnv.geobackend.util.RedundancyRemover.lookback", | |
| 26 1029); | |
| 27 | |
| 28 private int maxCapacity; | |
| 29 private int removed; | |
| 30 | |
| 31 public RedundancyRemover() { | |
| 32 this(DEFAULT_LOOKBACK); | |
| 33 } | |
| 34 | |
| 35 public RedundancyRemover(int maxCapacity) { | |
| 36 super((int)Math.ceil(maxCapacity * 1.75f)); | |
| 37 this.maxCapacity = maxCapacity; | |
| 38 } | |
| 39 | |
| 40 protected boolean removeEldestEntry(Map.Entry eldest) { | |
| 41 return size() > maxCapacity; | |
| 42 } | |
| 43 | |
| 44 public int numRemoved() { | |
| 45 return removed; | |
| 46 } | |
| 47 | |
| 48 public Object filter(Object object) { | |
| 49 if (object == null) { | |
| 50 return object; | |
| 51 } | |
| 52 Object old = get(object); | |
| 53 | |
| 54 if (old != null) { | |
| 55 if (old != object) { // count only identical | |
| 56 ++removed; | |
| 57 } | |
| 58 return old; | |
| 59 } | |
| 60 put(object, object); | |
| 61 return object; | |
| 62 } | |
| 63 } | |
| 64 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |