Mercurial > dive4elements > gnv-client
comparison geo-backend/src/main/java/de/intevation/gnv/geobackend/util/RedundancyRemover.java @ 899:3f9fc88aec2b
merged geo-backend/1.0
| author | Thomas Arendsen Hein <thomas@intevation.de> |
|---|---|
| date | Fri, 28 Sep 2012 12:13:57 +0200 |
| parents | b757def3ff55 |
| children | ebeb56428409 |
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| 875:5e9efdda6894 | 899:3f9fc88aec2b |
|---|---|
| 1 package de.intevation.gnv.geobackend.util; | |
| 2 | |
| 3 import java.util.LinkedHashMap; | |
| 4 import java.util.Map; | |
| 5 | |
| 6 /** | |
| 7 * @author <a href="mailto:sascha.teichmann@intevation.de">Sascha L. Teichmann</a> | |
| 8 */ | |
| 9 public final class RedundancyRemover | |
| 10 extends LinkedHashMap | |
| 11 { | |
| 12 /** ceil(1029 * 1.75) = 1801, which is prime | |
| 13 * -> suitable for a hash map slot size. | |
| 14 */ | |
| 15 public static final int DEFAULT_LOOKBACK = | |
| 16 Integer.getInteger( | |
| 17 "de.intevation.gnv.geobackend.util.RedundancyRemover.lookback", | |
| 18 1029); | |
| 19 | |
| 20 private int maxCapacity; | |
| 21 private int removed; | |
| 22 | |
| 23 public RedundancyRemover() { | |
| 24 this(DEFAULT_LOOKBACK); | |
| 25 } | |
| 26 | |
| 27 public RedundancyRemover(int maxCapacity) { | |
| 28 super((int)Math.ceil(maxCapacity * 1.75f)); | |
| 29 this.maxCapacity = maxCapacity; | |
| 30 } | |
| 31 | |
| 32 protected boolean removeEldestEntry(Map.Entry eldest) { | |
| 33 return size() > maxCapacity; | |
| 34 } | |
| 35 | |
| 36 public int numRemoved() { | |
| 37 return removed; | |
| 38 } | |
| 39 | |
| 40 public Object filter(Object object) { | |
| 41 if (object == null) { | |
| 42 return object; | |
| 43 } | |
| 44 Object old = get(object); | |
| 45 | |
| 46 if (old != null) { | |
| 47 if (old != object) { // count only identical | |
| 48 ++removed; | |
| 49 } | |
| 50 return old; | |
| 51 } | |
| 52 put(object, object); | |
| 53 return object; | |
| 54 } | |
| 55 } | |
| 56 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |