| /* |
| * 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.document; |
| |
| import java.io.IOException; |
| import java.io.Reader; |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Set; |
| |
| import org.apache.lucene.analysis.Analyzer; |
| import org.apache.lucene.analysis.TokenStream; |
| import org.apache.lucene.index.FieldInfo; |
| import org.apache.lucene.index.IndexReader; |
| import org.apache.lucene.index.IndexableField; |
| import org.apache.lucene.index.IndexableFieldType; |
| import org.apache.lucene.util.BytesRef; |
| |
| /** Defers actually loading a field's value until you ask |
| * for it. You must not use the returned Field instances |
| * after the provided reader has been closed. |
| * @see #getField |
| */ |
| public class LazyDocument { |
| private final IndexReader reader; |
| private final int docID; |
| |
| // null until first field is loaded |
| private Document doc; |
| |
| private Map<Integer,List<LazyField>> fields = new HashMap<>(); |
| private Set<String> fieldNames = new HashSet<>(); |
| |
| public LazyDocument(IndexReader reader, int docID) { |
| this.reader = reader; |
| this.docID = docID; |
| } |
| |
| /** |
| * Creates a StorableField whose value will be lazy loaded if and |
| * when it is used. |
| * <p> |
| * <b>NOTE:</b> This method must be called once for each value of the field |
| * name specified in sequence that the values exist. This method may not be |
| * used to generate multiple, lazy, StorableField instances referring to |
| * the same underlying StorableField instance. |
| * </p> |
| * <p> |
| * The lazy loading of field values from all instances of StorableField |
| * objects returned by this method are all backed by a single StoredDocument |
| * per LazyDocument instance. |
| * </p> |
| */ |
| public IndexableField getField(FieldInfo fieldInfo) { |
| |
| fieldNames.add(fieldInfo.name); |
| List<LazyField> values = fields.get(fieldInfo.number); |
| if (null == values) { |
| values = new ArrayList<>(); |
| fields.put(fieldInfo.number, values); |
| } |
| |
| LazyField value = new LazyField(fieldInfo.name, fieldInfo.number); |
| values.add(value); |
| |
| synchronized (this) { |
| // edge case: if someone asks this LazyDoc for more LazyFields |
| // after other LazyFields from the same LazyDoc have been |
| // actuallized, we need to force the doc to be re-fetched |
| // so the new LazyFields are also populated. |
| doc = null; |
| } |
| return value; |
| } |
| |
| /** |
| * non-private for test only access |
| * @lucene.internal |
| */ |
| synchronized Document getDocument() { |
| if (doc == null) { |
| try { |
| doc = reader.document(docID, fieldNames); |
| } catch (IOException ioe) { |
| throw new IllegalStateException("unable to load document", ioe); |
| } |
| } |
| return doc; |
| } |
| |
| // :TODO: synchronize to prevent redundent copying? (sync per field name?) |
| private void fetchRealValues(String name, int fieldNum) { |
| Document d = getDocument(); |
| |
| List<LazyField> lazyValues = fields.get(fieldNum); |
| IndexableField[] realValues = d.getFields(name); |
| |
| assert realValues.length <= lazyValues.size() |
| : "More lazy values then real values for field: " + name; |
| |
| for (int i = 0; i < lazyValues.size(); i++) { |
| LazyField f = lazyValues.get(i); |
| if (null != f) { |
| f.realValue = realValues[i]; |
| } |
| } |
| } |
| |
| |
| /** |
| * @lucene.internal |
| */ |
| public class LazyField implements IndexableField { |
| private String name; |
| private int fieldNum; |
| volatile IndexableField realValue = null; |
| |
| private LazyField(String name, int fieldNum) { |
| this.name = name; |
| this.fieldNum = fieldNum; |
| } |
| |
| /** |
| * non-private for test only access |
| * @lucene.internal |
| */ |
| public boolean hasBeenLoaded() { |
| return null != realValue; |
| } |
| |
| private IndexableField getRealValue() { |
| if (null == realValue) { |
| fetchRealValues(name, fieldNum); |
| } |
| assert hasBeenLoaded() : "field value was not lazy loaded"; |
| assert realValue.name().equals(name()) : |
| "realvalue name != name: " + realValue.name() + " != " + name(); |
| |
| return realValue; |
| } |
| |
| @Override |
| public String name() { |
| return name; |
| } |
| |
| @Override |
| public BytesRef binaryValue() { |
| return getRealValue().binaryValue(); |
| } |
| |
| @Override |
| public String stringValue() { |
| return getRealValue().stringValue(); |
| } |
| |
| @Override |
| public Reader readerValue() { |
| return getRealValue().readerValue(); |
| } |
| |
| @Override |
| public Number numericValue() { |
| return getRealValue().numericValue(); |
| } |
| |
| @Override |
| public IndexableFieldType fieldType() { |
| return getRealValue().fieldType(); |
| } |
| |
| @Override |
| public TokenStream tokenStream(Analyzer analyzer, TokenStream reuse) { |
| return getRealValue().tokenStream(analyzer, reuse); |
| } |
| } |
| } |