| /* |
| * 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.search.suggest.document; |
| |
| import java.io.IOException; |
| import java.util.PriorityQueue; |
| |
| import org.apache.lucene.analysis.miscellaneous.ConcatenateGraphFilter; |
| import org.apache.lucene.store.DataOutput; |
| import org.apache.lucene.store.IndexInput; |
| import org.apache.lucene.util.BytesRef; |
| import org.apache.lucene.util.BytesRefBuilder; |
| import org.apache.lucene.util.IntsRefBuilder; |
| import org.apache.lucene.util.fst.Builder; |
| import org.apache.lucene.util.fst.ByteSequenceOutputs; |
| import org.apache.lucene.util.fst.FST; |
| import org.apache.lucene.util.fst.PairOutputs; |
| import org.apache.lucene.util.fst.PositiveIntOutputs; |
| import org.apache.lucene.util.fst.Util; |
| |
| import static org.apache.lucene.search.suggest.document.NRTSuggester.encode; |
| |
| /** |
| * Builder for {@link NRTSuggester} |
| * |
| */ |
| final class NRTSuggesterBuilder { |
| |
| /** |
| * Label used to separate surface form and docID |
| * in the output |
| */ |
| public static final int PAYLOAD_SEP = ConcatenateGraphFilter.SEP_LABEL; |
| |
| /** |
| * Marks end of the analyzed input and start of dedup |
| * byte. |
| */ |
| public static final int END_BYTE = 0x0; |
| |
| private final PairOutputs<Long, BytesRef> outputs; |
| private final Builder<PairOutputs.Pair<Long, BytesRef>> builder; |
| private final IntsRefBuilder scratchInts = new IntsRefBuilder(); |
| private final BytesRefBuilder analyzed = new BytesRefBuilder(); |
| private final PriorityQueue<Entry> entries; |
| private final int payloadSep; |
| private final int endByte; |
| |
| private int maxAnalyzedPathsPerOutput = 0; |
| |
| /** |
| * Create a builder for {@link NRTSuggester} |
| */ |
| public NRTSuggesterBuilder() { |
| this.payloadSep = PAYLOAD_SEP; |
| this.endByte = END_BYTE; |
| this.outputs = new PairOutputs<>(PositiveIntOutputs.getSingleton(), ByteSequenceOutputs.getSingleton()); |
| this.entries = new PriorityQueue<>(); |
| this.builder = new Builder<>(FST.INPUT_TYPE.BYTE1, outputs); |
| } |
| |
| /** |
| * Initializes an FST input term to add entries against |
| */ |
| public void startTerm(BytesRef analyzed) { |
| this.analyzed.copyBytes(analyzed); |
| this.analyzed.append((byte) endByte); |
| } |
| |
| /** |
| * Adds an entry for the latest input term, should be called after |
| * {@link #startTerm(org.apache.lucene.util.BytesRef)} on the desired input |
| */ |
| public void addEntry(int docID, BytesRef surfaceForm, long weight) throws IOException { |
| BytesRef payloadRef = NRTSuggester.PayLoadProcessor.make(surfaceForm, docID, payloadSep); |
| entries.add(new Entry(payloadRef, encode(weight))); |
| } |
| |
| /** |
| * Writes all the entries for the FST input term |
| */ |
| public void finishTerm() throws IOException { |
| int numArcs = 0; |
| int numDedupBytes = 1; |
| analyzed.grow(analyzed.length() + 1); |
| analyzed.setLength(analyzed.length() + 1); |
| for (Entry entry : entries) { |
| if (numArcs == maxNumArcsForDedupByte(numDedupBytes)) { |
| analyzed.setByteAt(analyzed.length() - 1, (byte) (numArcs)); |
| analyzed.grow(analyzed.length() + 1); |
| analyzed.setLength(analyzed.length() + 1); |
| numArcs = 0; |
| numDedupBytes++; |
| } |
| analyzed.setByteAt(analyzed.length() - 1, (byte) numArcs++); |
| Util.toIntsRef(analyzed.get(), scratchInts); |
| builder.add(scratchInts.get(), outputs.newPair(entry.weight, entry.payload)); |
| } |
| maxAnalyzedPathsPerOutput = Math.max(maxAnalyzedPathsPerOutput, entries.size()); |
| entries.clear(); |
| } |
| |
| /** |
| * Builds and stores a FST that can be loaded with |
| * {@link NRTSuggester#load(IndexInput, CompletionPostingsFormat.FSTLoadMode)})} |
| */ |
| public boolean store(DataOutput output) throws IOException { |
| final FST<PairOutputs.Pair<Long, BytesRef>> build = builder.finish(); |
| if (build == null) { |
| return false; |
| } |
| build.save(output, output); |
| |
| /* write some more meta-info */ |
| assert maxAnalyzedPathsPerOutput > 0; |
| output.writeVInt(maxAnalyzedPathsPerOutput); |
| output.writeVInt(END_BYTE); |
| output.writeVInt(PAYLOAD_SEP); |
| return true; |
| } |
| |
| /** |
| * Num arcs for nth dedup byte: |
| * if n <= 5: 1 + (2 * n) |
| * else: (1 + (2 * n)) * n |
| * <p> |
| * TODO: is there a better way to make the fst built to be |
| * more TopNSearcher friendly? |
| */ |
| private static int maxNumArcsForDedupByte(int currentNumDedupBytes) { |
| int maxArcs = 1 + (2 * currentNumDedupBytes); |
| if (currentNumDedupBytes > 5) { |
| maxArcs *= currentNumDedupBytes; |
| } |
| return Math.min(maxArcs, 255); |
| } |
| |
| private final static class Entry implements Comparable<Entry> { |
| final BytesRef payload; |
| final long weight; |
| |
| public Entry(BytesRef payload, long weight) { |
| this.payload = payload; |
| this.weight = weight; |
| } |
| |
| @Override |
| public int compareTo(Entry o) { |
| return Long.compare(weight, o.weight); |
| } |
| } |
| } |