90 lines
2.6 KiB
Java
90 lines
2.6 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package it.cavallium.dbengine.lucene;
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import java.util.Objects;
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import java.util.concurrent.atomic.LongAccumulator;
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/** Maintains the maximum score and its corresponding document id concurrently */
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public final class MaxScoreAccumulator {
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// we use 2^10-1 to check the remainder with a bitwise operation
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static final int DEFAULT_INTERVAL = 0x3ff;
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// scores are always positive
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final LongAccumulator acc = new LongAccumulator(Long::max, Long.MIN_VALUE);
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// non-final and visible for tests
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public long modInterval;
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public MaxScoreAccumulator() {
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this.modInterval = DEFAULT_INTERVAL;
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}
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public void accumulate(int docID, float score) {
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assert docID >= 0 && score >= 0;
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long encode = (((long) Float.floatToIntBits(score)) << 32) | docID;
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acc.accumulate(encode);
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}
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public DocAndScore get() {
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long value = acc.get();
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if (value == Long.MIN_VALUE) {
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return null;
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}
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float score = Float.intBitsToFloat((int) (value >> 32));
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int docID = (int) value;
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return new DocAndScore(docID, score);
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}
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public static class DocAndScore implements Comparable<DocAndScore> {
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public final int docID;
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public final float score;
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public DocAndScore(int docID, float score) {
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this.docID = docID;
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this.score = score;
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}
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@Override
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public int compareTo(DocAndScore o) {
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int cmp = Float.compare(score, o.score);
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if (cmp == 0) {
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return Integer.compare(docID, o.docID);
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}
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return cmp;
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}
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@Override
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public boolean equals(Object o) {
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if (this == o) return true;
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if (o == null || getClass() != o.getClass()) return false;
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DocAndScore result = (DocAndScore) o;
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return docID == result.docID && Float.compare(result.score, score) == 0;
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}
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@Override
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public int hashCode() {
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return Objects.hash(docID, score);
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}
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@Override
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public String toString() {
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return "DocAndScore{" + "docID=" + docID + ", score=" + score + '}';
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}
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}
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} |