/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.solr.util;
import java.io.Serializable;
/** An "open" BitSet implementation that allows direct access to the array of words
* storing the bits.
* <p/>
* Unlike java.util.bitet, the fact that bits are packed into an array of longs
* is part of the interface. This allows efficient implementation of other algorithms
* by someone other than the author. It also allows one to efficiently implement
* alternate serialization or interchange formats.
* <p/>
* <code>OpenBitSet</code> is faster than <code>java.util.BitSet</code> in most operations
* and *much* faster at calculating cardinality of sets and results of set operations.
* It can also handle sets of larger cardinality (up to 64 * 2**32-1)
* <p/>
* The goals of <code>OpenBitSet</code> are the fastest implementation possible, and
* maximum code reuse. Extra safety and encapsulation
* may always be built on top, but if that's built in, the cost can never be removed (and
* hence people re-implement their own version in order to get better performance).
* If you want a "safe", totally encapsulated (and slower and limited) BitSet
* class, use <code>java.util.BitSet</code>.
* <p/>
* <h3>Performance Results</h3>
*
Test system: Pentium 4, Sun Java 1.5_06 -server -Xbatch -Xmx64M
<br/>BitSet size = 1,000,000
<br/>Results are java.util.BitSet time divided by OpenBitSet time.
<table border="1">
<tr>
<th></th> <th>cardinality</th> <th>intersect_count</th> <th>union</th> <th>nextSetBit</th> <th>get</th> <th>iterator</th>
</tr>
<tr>
<th>50% full</th> <td>3.36</td> <td>3.96</td> <td>1.44</td> <td>1.46</td> <td>1.99</td> <td>1.58</td>
</tr>
<tr>
<th>1% full</th> <td>3.31</td> <td>3.90</td> <td> </td> <td>1.04</td> <td> </td> <td>0.99</td>
</tr>
</table>
<br/>
Test system: AMD Opteron, 64 bit linux, Sun Java 1.5_06 -server -Xbatch -Xmx64M
<br/>BitSet size = 1,000,000
<br/>Results are java.util.BitSet time divided by OpenBitSet time.
<table border="1">
<tr>
<th></th> <th>cardinality</th> <th>intersect_count</th> <th>union</th> <th>nextSetBit</th> <th>get</th> <th>iterator</th>
</tr>
<tr>
<th>50% full</th> <td>2.50</td> <td>3.50</td> <td>1.00</td> <td>1.03</td> <td>1.12</td> <td>1.25</td>
</tr>
<tr>
<th>1% full</th> <td>2.51</td> <td>3.49</td> <td> </td> <td>1.00</td> <td> </td> <td>1.02</td>
</tr>
</table>
@deprecated Use {@link org.apache.lucene.util.OpenBitSet} directly.
* @version $Id$
*/
public class OpenBitSet extends org.apache.lucene.util.OpenBitSet implements Cloneable, Serializable {
/** Constructs an OpenBitSet large enough to hold numBits.
*
* @param numBits
*/
public OpenBitSet(long numBits) {
super(numBits);
}
public OpenBitSet() {
super();
}
/** Constructs an OpenBitSet from an existing long[].
* <br/>
* The first 64 bits are in long[0],
* with bit index 0 at the least significant bit, and bit index 63 at the most significant.
* Given a bit index,
* the word containing it is long[index/64], and it is at bit number index%64 within that word.
* <p>
* numWords are the number of elements in the array that contain
* set bits (non-zero longs).
* numWords should be <= bits.length, and
* any existing words in the array at position >= numWords should be zero.
*
*/
public OpenBitSet(long[] bits, int numWords) {
super();
}
}