+++ /dev/null
-package org.apache.lucene.facet.taxonomy.lucene;
-
-import java.io.IOException;
-
-import org.apache.lucene.index.CorruptIndexException;
-import org.apache.lucene.index.IndexReader;
-import org.apache.lucene.index.Term;
-import org.apache.lucene.index.TermPositions;
-
-import org.apache.lucene.facet.taxonomy.TaxonomyReader;
-
-/**
- * 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.
- */
-
-// getParent() needs to be extremely efficient, to the point that we need
-// to fetch all the data in advance into memory, and answer these calls
-// from memory. Currently we use a large integer array, which is
-// initialized when the taxonomy is opened, and potentially enlarged
-// when it is refresh()ed.
-/**
- * @lucene.experimental
- */
-class ParentArray {
-
- // These arrays are not syncrhonized. Rather, the reference to the array
- // is volatile, and the only writing operation (refreshPrefetchArrays)
- // simply creates a new array and replaces the reference. The volatility
- // of the reference ensures the correct atomic replacement and its
- // visibility properties (the content of the array is visible when the
- // new reference is visible).
- private volatile int prefetchParentOrdinal[] = null;
-
- public int[] getArray() {
- return prefetchParentOrdinal;
- }
-
- /**
- * refreshPrefetch() refreshes the parent array. Initially, it fills the
- * array from the positions of an appropriate posting list. If called during
- * a refresh(), when the arrays already exist, only values for new documents
- * (those beyond the last one in the array) are read from the positions and
- * added to the arrays (that are appropriately enlarged). We assume (and
- * this is indeed a correct assumption in our case) that existing categories
- * are never modified or deleted.
- */
- void refresh(IndexReader indexReader) throws IOException {
- // Note that it is not necessary for us to obtain the read lock.
- // The reason is that we are only called from refresh() (precluding
- // another concurrent writer) or from the constructor (when no method
- // could be running).
- // The write lock is also not held during the following code, meaning
- // that reads *can* happen while this code is running. The "volatile"
- // property of the prefetchParentOrdinal and prefetchDepth array
- // references ensure the correct visibility property of the assignment
- // but other than that, we do *not* guarantee that a reader will not
- // use an old version of one of these arrays (or both) while a refresh
- // is going on. But we find this acceptable - until a refresh has
- // finished, the reader should not expect to see new information
- // (and the old information is the same in the old and new versions).
- int first;
- int num = indexReader.maxDoc();
- if (prefetchParentOrdinal==null) {
- prefetchParentOrdinal = new int[num];
- // Starting Lucene 2.9, following the change LUCENE-1542, we can
- // no longer reliably read the parent "-1" (see comment in
- // LuceneTaxonomyWriter.SinglePositionTokenStream). We have no way
- // to fix this in indexing without breaking backward-compatibility
- // with existing indexes, so what we'll do instead is just
- // hard-code the parent of ordinal 0 to be -1, and assume (as is
- // indeed the case) that no other parent can be -1.
- if (num>0) {
- prefetchParentOrdinal[0] = TaxonomyReader.INVALID_ORDINAL;
- }
- first = 1;
- } else {
- first = prefetchParentOrdinal.length;
- if (first==num) {
- return; // nothing to do - no category was added
- }
- // In Java 6, we could just do Arrays.copyOf()...
- int[] newarray = new int[num];
- System.arraycopy(prefetchParentOrdinal, 0, newarray, 0,
- prefetchParentOrdinal.length);
- prefetchParentOrdinal = newarray;
- }
-
- // Read the new part of the parents array from the positions:
- TermPositions positions = indexReader.termPositions(
- new Term(Consts.FIELD_PAYLOADS, Consts.PAYLOAD_PARENT));
- try {
- if (!positions.skipTo(first) && first < num) {
- throw new CorruptIndexException("Missing parent data for category " + first);
- }
- for (int i=first; i<num; i++) {
- // Note that we know positions.doc() >= i (this is an
- // invariant kept throughout this loop)
- if (positions.doc()==i) {
- if (positions.freq() == 0) { // shouldn't happen
- throw new CorruptIndexException(
- "Missing parent data for category "+i);
- }
-
- // TODO (Facet): keep a local (non-volatile) copy of the prefetchParentOrdinal
- // reference, because access to volatile reference is slower (?).
- // Note: The positions we get here are one less than the position
- // increment we added originally, so we get here the right numbers:
- prefetchParentOrdinal[i] = positions.nextPosition();
-
- if (!positions.next()) {
- if ( i+1 < num ) {
- throw new CorruptIndexException(
- "Missing parent data for category "+(i+1));
- }
- break;
- }
- } else { // this shouldn't happen
- throw new CorruptIndexException(
- "Missing parent data for category "+i);
- }
- }
- } finally {
- positions.close(); // to be on the safe side.
- }
- }
-
- /**
- * add() is used in LuceneTaxonomyWriter, not in LuceneTaxonomyReader.
- * It is only called from a synchronized method, so it is not reentrant,
- * and also doesn't need to worry about reads happening at the same time.
- *
- * NOTE: add() and refresh() CANNOT be used together. If you call add(),
- * this changes the arrays and refresh() can no longer be used.
- */
- void add(int ordinal, int parentOrdinal) throws IOException {
- if (ordinal >= prefetchParentOrdinal.length) {
- // grow the array, if necessary.
- // In Java 6, we could just do Arrays.copyOf()...
- int[] newarray = new int[ordinal*2+1];
- System.arraycopy(prefetchParentOrdinal, 0, newarray, 0,
- prefetchParentOrdinal.length);
- prefetchParentOrdinal = newarray;
- }
- prefetchParentOrdinal[ordinal] = parentOrdinal;
- }
-
-}
fnp / pylucene.git / blobdiff