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Apache Solr (module: core)
/*
* 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.search;
import java.util.Collection;
import java.util.Collections;
import org.apache.lucene.search.TotalHits;
import org.apache.lucene.util.Accountable;
import org.apache.lucene.util.RamUsageEstimator;
/**
* DocSlice
implements DocList as an array of docids and optional scores.
*
* @since solr 0.9
*/
public class DocSlice implements DocList, Accountable {
private static final long BASE_RAM_BYTES_USED =
RamUsageEstimator.shallowSizeOfInstance(DocSlice.class)
+ RamUsageEstimator.NUM_BYTES_ARRAY_HEADER;
final int offset; // starting position of the docs (zero based)
final int len; // number of positions used in arrays
final int[] docs; // a slice of documents (docs 0-100 of the query)
final float[] scores; // optional score list
final long matches;
final TotalHits.Relation matchesRelation;
final float maxScore;
final long ramBytesUsed; // cached value
/**
* Primary constructor for a DocSlice instance.
*
* @param offset starting offset for this range of docs
* @param len length of results
* @param docs array of docids starting at position 0
* @param scores array of scores that corresponds to docs, may be null
* @param matches total number of matches for the query
* @param matchesRelation Indicates if {@code matches} is exact or an approximation
*/
public DocSlice(
int offset,
int len,
int[] docs,
float[] scores,
long matches,
float maxScore,
TotalHits.Relation matchesRelation) {
this.offset = offset;
this.len = len;
this.docs = docs;
this.scores = scores;
this.matches = matches;
this.maxScore = maxScore;
this.ramBytesUsed =
BASE_RAM_BYTES_USED
+ (docs == null ? 0 : ((long) docs.length << 2))
+ (scores == null
? 0
: ((long) scores.length << 2) + RamUsageEstimator.NUM_BYTES_ARRAY_HEADER);
this.matchesRelation = matchesRelation;
}
@Override
public DocList subset(int offset, int len) {
if (this.offset == offset && this.len == len) return this;
// if we didn't store enough (and there was more to store)
// then we can't take a subset.
int requestedEnd = offset + len;
if (requestedEnd > docs.length && this.matches > docs.length) return null;
int realEndDoc = Math.min(requestedEnd, docs.length);
int realLen = Math.max(realEndDoc - offset, 0);
if (this.offset == offset && this.len == realLen) return this;
return new DocSlice(offset, realLen, docs, scores, matches, maxScore, matchesRelation);
}
@Override
public boolean hasScores() {
return scores != null;
}
@Override
public float maxScore() {
return maxScore;
}
@Override
public int offset() {
return offset;
}
@Override
public int size() {
return len;
}
@Override
public long matches() {
return matches;
}
// Hmmm, maybe I could have reused the scorer interface here...
// except that it carries Similarity baggage...
@Override
public DocIterator iterator() {
return new DocIterator() {
int pos = offset;
final int end = offset + len;
@Override
public boolean hasNext() {
return pos < end;
}
@Override
public Integer next() {
return nextDoc();
}
/** The remove operation is not supported by this Iterator. */
@Override
public void remove() {
throw new UnsupportedOperationException(
"The remove operation is not supported by this Iterator.");
}
@Override
public int nextDoc() {
return docs[pos++];
}
@Override
public float score() {
return scores[pos - 1];
}
};
}
/**
* WARNING: this can over-estimate real memory use since backing arrays are shared with other
* DocSlice instances
*/
@Override
public long ramBytesUsed() {
return ramBytesUsed;
}
@Override
public Collection getChildResources() {
return Collections.emptyList();
}
@Override
public TotalHits.Relation hitCountRelation() {
return matchesRelation;
}
}