| /* |
| * 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.codecs.bloom; |
| |
| import org.apache.lucene.index.FieldInfo; |
| import org.apache.lucene.index.SegmentWriteState; |
| |
| /** |
| * Class used to create index-time {@link FuzzySet} appropriately configured for each field. Also |
| * called to right-size bitsets for serialization. |
| * |
| * @lucene.experimental |
| */ |
| public abstract class BloomFilterFactory { |
| |
| /** |
| * @param state The content to be indexed |
| * @param info the field requiring a BloomFilter |
| * @return An appropriately sized set or null if no BloomFiltering required |
| */ |
| public abstract FuzzySet getSetForField(SegmentWriteState state, FieldInfo info); |
| |
| /** |
| * Called when downsizing bitsets for serialization |
| * |
| * @param fieldInfo The field with sparse set bits |
| * @param initialSet The bits accumulated |
| * @return null or a hopefully more densely packed, smaller bitset |
| */ |
| public FuzzySet downsize(FieldInfo fieldInfo, FuzzySet initialSet) { |
| // Aim for a bitset size that would have 10% of bits set (so 90% of searches |
| // would fail-fast) |
| float targetMaxSaturation = 0.1f; |
| return initialSet.downsize(targetMaxSaturation); |
| } |
| |
| /** |
| * Used to determine if the given filter has reached saturation and should be retired i.e. not |
| * saved any more |
| * |
| * @param bloomFilter The bloomFilter being tested |
| * @param fieldInfo The field with which this filter is associated |
| * @return true if the set has reached saturation and should be retired |
| */ |
| public abstract boolean isSaturated(FuzzySet bloomFilter, FieldInfo fieldInfo); |
| } |