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/*
* 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.lucene.facet.taxonomy;
import static org.apache.lucene.facet.taxonomy.TaxonomyReader.INVALID_ORDINAL;
import static org.apache.lucene.facet.taxonomy.TaxonomyReader.ROOT_ORDINAL;
import java.io.IOException;
import org.apache.lucene.index.DocValues;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.SortedNumericDocValues;
/**
* Utility class to easily retrieve previously indexed facet labels, allowing you to skip also
* adding stored fields for these values, reducing your index size.
*
* @lucene.experimental
*/
public class TaxonomyFacetLabels {
/** {@code TaxonomyReader} provided to the constructor */
private final TaxonomyReader taxoReader;
/** field storing the taxonomy ordinals */
private final String indexFieldName;
/**
* Sole constructor. Do not close the provided {@link TaxonomyReader} while still using this
* instance!
*/
public TaxonomyFacetLabels(TaxonomyReader taxoReader, String indexFieldName) {
this.taxoReader = taxoReader;
this.indexFieldName = indexFieldName;
}
/**
* Create and return an instance of {@link FacetLabelReader} to retrieve facet labels for multiple
* documents and (optionally) for a specific dimension. You must create this per-segment, and then
* step through all hits, in order, for that segment.
*
* NOTE: This class is not thread-safe, so you must use a new instance of this class for
* each thread.
*
* @param readerContext LeafReaderContext used to access the {@code BinaryDocValues} facet field
* @return an instance of {@link FacetLabelReader}
* @throws IOException when a low-level IO issue occurs
*/
public FacetLabelReader getFacetLabelReader(LeafReaderContext readerContext) throws IOException {
SortedNumericDocValues ordinalValues =
DocValues.getSortedNumeric(readerContext.reader(), indexFieldName);
if (ordinalValues == null) {
ordinalValues = DocValues.emptySortedNumeric();
}
return new FacetLabelReader(ordinalValues);
}
/**
* Utility class to retrieve facet labels for multiple documents.
*
* @lucene.experimental
*/
public class FacetLabelReader {
/** By default, we store taxonomy ordinals in SortedNumericDocValues field */
private final SortedNumericDocValues ordinalValues;
private int currentDocId = -1;
private boolean currentDocHasValues;
private int currentPos;
private int currentDocOrdinalCount;
// Lazily set when nextFacetLabel(int docId, String facetDimension) is first called
private ParallelTaxonomyArrays.IntArray parents;
/** Construct from a specified {@link SortedNumericDocValues} field. */
public FacetLabelReader(SortedNumericDocValues ordinalValues) {
this.ordinalValues = ordinalValues;
}
/**
* Retrieves the next {@link FacetLabel} for the specified {@code docId}, or {@code null} if
* there are no more. This method has state: if the provided {@code docId} is the same as the
* previous invocation, it returns the next {@link FacetLabel} for that document. Otherwise, it
* advances to the new {@code docId} and provides the first {@link FacetLabel} for that
* document, or {@code null} if that document has no indexed facets. Each new {@code docId} must
* be in strictly monotonic (increasing) order.
*
*
NOTE: The returned FacetLabels may not be in the same order in which they were
* indexed
*
* @param docId input docId provided in monotonic (non-decreasing) order
* @return the first or next {@link FacetLabel}, or {@code null} if there are no more
* @throws IOException when a low-level IO issue occurs
* @throws IllegalArgumentException if docId provided is less than docId supplied in an earlier
* invocation
*/
public FacetLabel nextFacetLabel(int docId) throws IOException {
if (currentDocId != docId) {
if (docId < currentDocId) {
throw new IllegalArgumentException(
"docs out of order: previous docId=" + currentDocId + " current docId=" + docId);
}
currentDocId = docId;
currentDocHasValues = ordinalValues.advanceExact(docId);
if (currentDocHasValues) {
currentDocOrdinalCount = ordinalValues.docValueCount();
currentPos = 0;
}
}
if (currentDocHasValues == false) {
return null;
}
assert currentPos <= currentDocOrdinalCount;
if (currentPos == currentDocOrdinalCount) {
return null;
}
int ord = (int) ordinalValues.nextValue();
currentPos++;
return taxoReader.getPath(ord);
}
private boolean isDescendant(int ord, int ancestorOrd) {
while (ord != INVALID_ORDINAL && ord != ROOT_ORDINAL) {
if (parents.get(ord) == ancestorOrd) {
return true;
}
ord = parents.get(ord);
}
return false;
}
/**
* Retrieves the next {@link FacetLabel} for the specified {@code docId} under the requested
* {@code facetDimension}, or {@code null} if there are no more. This method has state: if the
* provided {@code docId} is the same as the previous invocation, it returns the next {@link
* FacetLabel} for that document. Otherwise, it advances to the new {@code docId} and provides
* the first {@link FacetLabel} for that document, or {@code null} if that document has no
* indexed facets. Each new {@code docId} must be in strictly monotonic (increasing) order.
*
*
NOTE: This method loads the {@code int[] parents} array from the taxonomy index.
* The returned FacetLabels may not be in the same order in which they were indexed.
*
* @param docId input docId provided in non-decreasing order
* @return the first or next {@link FacetLabel}, or {@code null} if there are no more
* @throws IOException if {@link TaxonomyReader} has problems getting path for an ordinal
* @throws IllegalArgumentException if docId provided is less than docId supplied in an earlier
* invocation
* @throws IllegalArgumentException if facetDimension is null
*/
public FacetLabel nextFacetLabel(int docId, String facetDimension) throws IOException {
if (facetDimension == null) {
throw new IllegalArgumentException("Input facet dimension cannot be null");
}
final int parentOrd = taxoReader.getOrdinal(new FacetLabel(facetDimension));
if (parentOrd == INVALID_ORDINAL) {
throw new IllegalArgumentException(
"Category ordinal not found for facet dimension: " + facetDimension);
}
if (currentDocId != docId) {
if (docId < currentDocId) {
throw new IllegalArgumentException(
"docs out of order: previous docId=" + currentDocId + " current docId=" + docId);
}
currentDocId = docId;
currentDocHasValues = ordinalValues.advanceExact(docId);
if (currentDocHasValues) {
currentDocOrdinalCount = ordinalValues.docValueCount();
currentPos = 0;
}
}
if (currentDocHasValues == false) {
return null;
}
assert currentPos <= currentDocOrdinalCount;
if (currentPos == currentDocOrdinalCount) {
return null;
}
if (parents == null) {
parents = taxoReader.getParallelTaxonomyArrays().parents();
}
do {
int ord = (int) ordinalValues.nextValue();
currentPos++;
if (isDescendant(ord, parentOrd) == true) {
return taxoReader.getPath(ord);
}
} while (currentPos < currentDocOrdinalCount);
return null;
}
}
}