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https://github.com/yacy/yacy_search_server.git
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c8624903c6
terms (words) are not any more retrieved by their word hash string, but by a byte[] containing the word hash. this has strong advantages when RWIs are sorted in the ReferenceContainer Cache and compared with the sun.java TreeMap method, which needed getBytes() and new String() transformations before. Many thousands of such conversions are now omitted every second, which increases the indexing speed by a factor of two. git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@5812 6c8d7289-2bf4-0310-a012-ef5d649a1542
91 lines
3.2 KiB
Java
Executable File
91 lines
3.2 KiB
Java
Executable File
// FlatWordPartitionScheme.java
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// ------------------------------
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// part of YaCy
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// (C) 2009 by Michael Peter Christen; mc@yacy.net
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// first published on http://yacy.net
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// Frankfurt, Germany, 28.01.2009
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//
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// $LastChangedDate: 2009-01-23 16:32:27 +0100 (Fr, 23 Jan 2009) $
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// $LastChangedRevision: 5514 $
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// $LastChangedBy: orbiter $
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package de.anomic.yacy.dht;
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import de.anomic.kelondro.order.Base64Order;
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import de.anomic.yacy.yacySeed;
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public class FlatWordPartitionScheme implements PartitionScheme {
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public static final FlatWordPartitionScheme std = new FlatWordPartitionScheme();
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public FlatWordPartitionScheme() {
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// nothing to initialize
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}
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public int verticalPartitions() {
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return 1;
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}
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public long dhtPosition(byte[] wordHash, String urlHash) {
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// the urlHash has no relevance here
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// normalized to Long.MAX_VALUE
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return Base64Order.enhancedCoder.cardinal(wordHash);
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}
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public final long dhtDistance(final byte[] word, final String urlHash, final yacySeed peer) {
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return dhtDistance(word, urlHash, peer.hash.getBytes());
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}
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private final long dhtDistance(final byte[] from, final String urlHash, final byte[] to) {
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// the dht distance is a positive value between 0 and 1
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// if the distance is small, the word more probably belongs to the peer
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assert to != null;
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assert from != null;
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final long toPos = dhtPosition(to, null);
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final long fromPos = dhtPosition(from, urlHash);
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return dhtDistance(fromPos, toPos);
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}
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public long dhtPosition(byte[] wordHash, int verticalPosition) {
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return dhtPosition(wordHash, null);
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}
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public long[] dhtPositions(byte[] wordHash) {
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long[] l = new long[1];
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l[1] = dhtPosition(wordHash, null);
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return l;
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}
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public int verticalPosition(String urlHash) {
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return 0; // this is not a method stub, this is actually true for all FlatWordPartitionScheme
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}
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public final static long dhtDistance(final long fromPos, final long toPos) {
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return (toPos >= fromPos) ?
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toPos - fromPos :
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(Long.MAX_VALUE - fromPos) + toPos + 1;
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}
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public static byte[] positionToHash(final long l) {
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// transform the position of a peer position into a close peer hash
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String s = new String(Base64Order.enhancedCoder.uncardinal(l));
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while (s.length() < 12) s += "A";
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return s.getBytes();
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}
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}
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