Mercurial > dive4elements > gnv-client
diff geo-backend/src/main/java/de/intevation/gnv/geobackend/util/RedundancyRemover.java @ 662:755dd2fa4a0a 0.5
merged geo-backend/0.5
author | Thomas Arendsen Hein <thomas@intevation.de> |
---|---|
date | Fri, 28 Sep 2012 12:13:53 +0200 |
parents | 825781a39c70 |
children | 1c3efbd2fc5a |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/geo-backend/src/main/java/de/intevation/gnv/geobackend/util/RedundancyRemover.java Fri Sep 28 12:13:53 2012 +0200 @@ -0,0 +1,56 @@ +package de.intevation.gnv.geobackend.util; + +import java.util.LinkedHashMap; +import java.util.Map; + +/** + * @author Sascha L. Teichmann (sascha.teichmann@intevation.de) + */ +public final class RedundancyRemover +extends LinkedHashMap +{ + /** ceil(1029 * 1.75) = 1801, which is prime + * -> suitable for a hash map slot size. + */ + public static final int DEFAULT_LOOKBACK = + Integer.getInteger( + "de.intevation.gnv.geobackend.util.RedundancyRemover.lookback", + 1029); + + private int maxCapacity; + private int removed; + + public RedundancyRemover() { + this(DEFAULT_LOOKBACK); + } + + public RedundancyRemover(int maxCapacity) { + super((int)Math.ceil(maxCapacity * 1.75f)); + this.maxCapacity = maxCapacity; + } + + protected boolean removeEldestEntry(Map.Entry eldest) { + return size() > maxCapacity; + } + + public int numRemoved() { + return removed; + } + + public Object filter(Object object) { + if (object == null) { + return object; + } + Object old = get(object); + + if (old != null) { + if (old != object) { // count only identical + ++removed; + } + return old; + } + put(object, object); + return object; + } +} +// vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :