/*
* 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.jackrabbit.core.query.lucene;
import org.apache.jackrabbit.core.id.NodeId;
import org.apache.jackrabbit.core.SessionImpl;
import org.apache.jackrabbit.core.query.lucene.hits.AdaptingHits;
import org.apache.jackrabbit.core.query.lucene.hits.Hits;
import org.apache.jackrabbit.core.query.lucene.hits.ScorerHits;
import org.apache.jackrabbit.core.state.ItemStateException;
import org.apache.jackrabbit.core.state.ItemStateManager;
import org.apache.jackrabbit.core.state.NodeState;
import org.apache.jackrabbit.core.state.ChildNodeEntry;
import org.apache.jackrabbit.spi.Name;
import org.apache.jackrabbit.spi.commons.query.LocationStepQueryNode;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.search.Explanation;
import org.apache.lucene.search.HitCollector;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.Scorer;
import org.apache.lucene.search.Searcher;
import org.apache.lucene.search.Similarity;
import org.apache.lucene.search.Weight;
import org.apache.lucene.search.Sort;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.List;
import java.util.Set;
import java.util.HashMap;
import java.util.Map;
import java.util.HashSet;
import java.util.ArrayList;
/**
* Implements a lucene <code>Query</code> which returns the child nodes of the
* nodes selected by another <code>Query</code>.
*/
class ChildAxisQuery extends Query implements JackrabbitQuery {
/**
* The logger instance for this class.
*/
private static final Logger log = LoggerFactory.getLogger(ChildAxisQuery.class);
/**
* Threshold when children calculation is switched to
* {@link HierarchyResolvingChildrenCalculator}.
*/
private static int CONTEXT_SIZE_THRESHOLD = 10;
/**
* The item state manager containing persistent item states.
*/
private final ItemStateManager itemMgr;
/**
* The context query
*/
private Query contextQuery;
/**
* The nameTest to apply on the child axis, or <code>null</code> if all
* child nodes should be selected.
*/
private final Name nameTest;
/**
* The context position for the selected child node, or
* {@link LocationStepQueryNode#NONE} if no position is specified.
*/
private final int position;
/**
* The index format version.
*/
private final IndexFormatVersion version;
/**
* The internal namespace mappings.
*/
private final NamespaceMappings nsMappings;
/**
* The scorer of the context query
*/
private Scorer contextScorer;
/**
* The scorer of the name test query
*/
private Scorer nameTestScorer;
/**
* Creates a new <code>ChildAxisQuery</code> based on a <code>context</code>
* query.
*
* @param itemMgr the item state manager.
* @param context the context for this query.
* @param nameTest a name test or <code>null</code> if any child node is
* selected.
* @param version the index format version.
* @param nsMappings the internal namespace mappings.
*/
ChildAxisQuery(ItemStateManager itemMgr,
Query context,
Name nameTest,
IndexFormatVersion version,
NamespaceMappings nsMappings) {
this(itemMgr, context, nameTest, LocationStepQueryNode.NONE, version, nsMappings);
}
/**
* Creates a new <code>ChildAxisQuery</code> based on a <code>context</code>
* query.
*
* @param itemMgr the item state manager.
* @param context the context for this query.
* @param nameTest a name test or <code>null</code> if any child node is
* selected.
* @param position the context position of the child node to select. If
* <code>position</code> is {@link LocationStepQueryNode#NONE}, the context
* position of the child node is not checked.
* @param version the index format version.
* @param nsMapping the internal namespace mappings.
*/
ChildAxisQuery(ItemStateManager itemMgr,
Query context,
Name nameTest,
int position,
IndexFormatVersion version,
NamespaceMappings nsMapping) {
this.itemMgr = itemMgr;
this.contextQuery = context;
this.nameTest = nameTest;
this.position = position;
this.version = version;
this.nsMappings = nsMapping;
}
/**
* @return the context query of this child axis query.
*/
Query getContextQuery() {
return contextQuery;
}
/**
* @return <code>true</code> if this child axis query matches any child
* node; <code>false</code> otherwise.
*/
boolean matchesAnyChildNode() {
return nameTest == null && position == LocationStepQueryNode.NONE;
}
/**
* @return the name test or <code>null</code> if none was specified.
*/
Name getNameTest() {
return nameTest;
}
/**
* @return the position check or {@link LocationStepQueryNode#NONE} is none
* was specified.
*/
int getPosition() {
return position;
}
/**
* Creates a <code>Weight</code> instance for this query.
*
* @param searcher the <code>Searcher</code> instance to use.
* @return a <code>ChildAxisWeight</code>.
*/
protected Weight createWeight(Searcher searcher) {
return new ChildAxisWeight(searcher);
}
/**
* {@inheritDoc}
*/
public void extractTerms(Set terms) {
contextQuery.extractTerms(terms);
}
/**
* {@inheritDoc}
*/
public Query rewrite(IndexReader reader) throws IOException {
Query cQuery = contextQuery.rewrite(reader);
// only try to compact if no position is specified
if (position == LocationStepQueryNode.NONE) {
if (cQuery instanceof DescendantSelfAxisQuery) {
DescendantSelfAxisQuery dsaq = (DescendantSelfAxisQuery) cQuery;
if (dsaq.subQueryMatchesAll()) {
Query sub;
if (nameTest == null) {
sub = new MatchAllDocsQuery();
} else {
sub = new NameQuery(nameTest, version, nsMappings);
}
return new DescendantSelfAxisQuery(dsaq.getContextQuery(),
sub, dsaq.getMinLevels() + 1).rewrite(reader);
}
}
}
// if we get here we could not compact the query
if (cQuery == contextQuery) {
return this;
} else {
return new ChildAxisQuery(itemMgr, cQuery, nameTest,
position, version, nsMappings);
}
}
/**
* {@inheritDoc}
*/
public String toString(String field) {
StringBuffer sb = new StringBuffer();
sb.append("ChildAxisQuery(");
sb.append(contextQuery);
sb.append(", ");
sb.append(nameTest);
if (position != LocationStepQueryNode.NONE) {
sb.append(", ");
sb.append(position);
}
sb.append(")");
return sb.toString();
}
//-------------------< JackrabbitQuery >------------------------------------
/**
* {@inheritDoc}
*/
public QueryHits execute(JackrabbitIndexSearcher searcher,
SessionImpl session,
Sort sort)
throws IOException {
if (sort.getSort().length == 0 && matchesAnyChildNode()) {
Query context = getContextQuery();
return new ChildNodesQueryHits(searcher.evaluate(context), session);
} else {
return null;
}
}
//-------------------< ChildAxisWeight >------------------------------------
/**
* The <code>Weight</code> implementation for this <code>ChildAxisQuery</code>.
*/
private class ChildAxisWeight implements Weight {
/**
* The searcher in use
*/
private final Searcher searcher;
/**
* Creates a new <code>ChildAxisWeight</code> instance using
* <code>searcher</code>.
*
* @param searcher a <code>Searcher</code> instance.
*/
private ChildAxisWeight(Searcher searcher) {
this.searcher = searcher;
}
/**
* Returns this <code>ChildAxisQuery</code>.
*
* @return this <code>ChildAxisQuery</code>.
*/
public Query getQuery() {
return ChildAxisQuery.this;
}
/**
* {@inheritDoc}
*/
public float getValue() {
return 1.0f;
}
/**
* {@inheritDoc}
*/
public float sumOfSquaredWeights() throws IOException {
return 1.0f;
}
/**
* {@inheritDoc}
*/
public void normalize(float norm) {
}
/**
* Creates a scorer for this <code>ChildAxisQuery</code>.
*
* @param reader a reader for accessing the index.
* @return a <code>ChildAxisScorer</code>.
* @throws IOException if an error occurs while reading from the index.
*/
public Scorer scorer(IndexReader reader) throws IOException {
contextScorer = contextQuery.weight(searcher).scorer(reader);
if (nameTest != null) {
nameTestScorer = new NameQuery(nameTest, version, nsMappings).weight(searcher).scorer(reader);
}
return new ChildAxisScorer(searcher.getSimilarity(),
reader, (HierarchyResolver) reader);
}
/**
* {@inheritDoc}
*/
public Explanation explain(IndexReader reader, int doc) throws IOException {
return new Explanation();
}
}
//----------------------< ChildAxisScorer >---------------------------------
/**
* Implements a <code>Scorer</code> for this <code>ChildAxisQuery</code>.
*/
private class ChildAxisScorer extends Scorer {
/**
* An <code>IndexReader</code> to access the index.
*/
private final IndexReader reader;
/**
* The <code>HierarchyResolver</code> of the index.
*/
private final HierarchyResolver hResolver;
/**
* The next document id to return
*/
private int nextDoc = -1;
/**
* A <code>Hits</code> instance containing all hits
*/
private Hits hits;
/**
* Creates a new <code>ChildAxisScorer</code>.
*
* @param similarity the <code>Similarity</code> instance to use.
* @param reader for index access.
* @param hResolver the hierarchy resolver of <code>reader</code>.
*/
protected ChildAxisScorer(Similarity similarity,
IndexReader reader,
HierarchyResolver hResolver) {
super(similarity);
this.reader = reader;
this.hResolver = hResolver;
}
/**
* {@inheritDoc}
*/
public boolean next() throws IOException {
calculateChildren();
do {
nextDoc = hits.next();
} while (nextDoc > -1 && !indexIsValid(nextDoc));
return nextDoc > -1;
}
/**
* {@inheritDoc}
*/
public int doc() {
return nextDoc;
}
/**
* {@inheritDoc}
*/
public float score() throws IOException {
return 1.0f;
}
/**
* {@inheritDoc}
*/
public boolean skipTo(int target) throws IOException {
calculateChildren();
nextDoc = hits.skipTo(target);
while (nextDoc > -1 && !indexIsValid(nextDoc)) {
next();
}
return nextDoc > -1;
}
/**
* {@inheritDoc}
*
* @throws UnsupportedOperationException this implementation always
* throws an <code>UnsupportedOperationException</code>.
*/
public Explanation explain(int doc) throws IOException {
throw new UnsupportedOperationException();
}
private void calculateChildren() throws IOException {
if (hits == null) {
final ChildrenCalculator[] calc = new ChildrenCalculator[1];
if (nameTestScorer == null) {
// always use simple in that case
calc[0] = new SimpleChildrenCalculator(reader, hResolver);
contextScorer.score(new HitCollector() {
public void collect(int doc, float score) {
calc[0].collectContextHit(doc);
}
});
} else {
// start simple but switch once threshold is reached
calc[0] = new SimpleChildrenCalculator(reader, hResolver);
contextScorer.score(new HitCollector() {
private List<Integer> docIds = new ArrayList<Integer>();
public void collect(int doc, float score) {
calc[0].collectContextHit(doc);
if (docIds != null) {
docIds.add(doc);
if (docIds.size() > CONTEXT_SIZE_THRESHOLD) {
// switch
calc[0] = new HierarchyResolvingChildrenCalculator(
reader, hResolver);
for (int docId : docIds) {
calc[0].collectContextHit(docId);
}
// indicate that we switched
docIds = null;
}
}
}
});
}
hits = calc[0].getHits();
}
}
private boolean indexIsValid(int i) throws IOException {
if (position != LocationStepQueryNode.NONE) {
Document node = reader.document(i, FieldSelectors.UUID_AND_PARENT);
NodeId parentId = NodeId.valueOf(node.get(FieldNames.PARENT));
NodeId id = NodeId.valueOf(node.get(FieldNames.UUID));
try {
NodeState state = (NodeState) itemMgr.getItemState(parentId);
if (nameTest == null) {
// only select this node if it is the child at
// specified position
List<ChildNodeEntry> childNodes = state.getChildNodeEntries();
if (position == LocationStepQueryNode.LAST) {
// only select last
if (childNodes.size() == 0
|| !(childNodes.get(childNodes.size() - 1)).getId().equals(id)) {
return false;
}
} else {
if (position < 1
|| childNodes.size() < position
|| !(childNodes.get(position - 1)).getId().equals(id)) {
return false;
}
}
} else {
// select the node when its index is equal to
// specified position
if (position == LocationStepQueryNode.LAST) {
// only select last
ChildNodeEntry entry =
state.getChildNodeEntry(id);
if (entry == null) {
// no such child node, probably deleted meanwhile
return false;
} else {
// only use the last one
Name name = entry.getName();
List<ChildNodeEntry> childNodes = state.getChildNodeEntries(name);
if (childNodes.size() == 0
|| !(childNodes.get(childNodes.size() - 1)).getId().equals(id)) {
return false;
}
}
} else {
ChildNodeEntry entry =
state.getChildNodeEntry(id);
if (entry == null) {
// no such child node, probably has been deleted meanwhile
return false;
} else {
if (entry.getIndex() != position) {
return false;
}
}
}
}
} catch (ItemStateException e) {
// ignore this node, probably has been deleted meanwhile
return false;
}
}
return true;
}
}
/**
* Base class to calculate the children for a context query.
*/
private abstract class ChildrenCalculator {
/**
* The current index reader.
*/
protected final IndexReader reader;
/**
* The current hierarchy resolver.
*/
protected final HierarchyResolver hResolver;
/**
* Creates a new children calculator with the given index reader and
* hierarchy resolver.
*
* @param reader the current index reader.
* @param hResolver the current hierarchy resolver.
*/
public ChildrenCalculator(IndexReader reader,
HierarchyResolver hResolver) {
this.reader = reader;
this.hResolver = hResolver;
}
/**
* Collects a context hit.
*
* @param doc the lucene document number of the context hit.
*/
protected abstract void collectContextHit(int doc);
/**
* @return the hits that contains the children.
* @throws IOException if an error occurs while reading from the index.
*/
public abstract Hits getHits() throws IOException;
}
/**
* An implementation of a children calculator using the item state manager.
*/
private final class SimpleChildrenCalculator extends ChildrenCalculator {
/**
* The context hits.
*/
private final Hits contextHits = new AdaptingHits();
/**
* Creates a new simple children calculator.
*
* @param reader the current index reader.
* @param hResolver the current hierarchy resolver.
*/
public SimpleChildrenCalculator(IndexReader reader,
HierarchyResolver hResolver) {
super(reader, hResolver);
}
/**
* {@inheritDoc}
*/
protected void collectContextHit(int doc) {
contextHits.set(doc);
}
/**
* {@inheritDoc}
*/
public Hits getHits() throws IOException {
// read the uuids of the context nodes
Map<Integer, String> uuids = new HashMap<Integer, String>();
for (int i = contextHits.next(); i > -1; i = contextHits.next()) {
String uuid = reader.document(i, FieldSelectors.UUID).get(FieldNames.UUID);
uuids.put(i, uuid);
}
// get child node entries for each hit
Hits childrenHits = new AdaptingHits();
for (String uuid : uuids.values()) {
NodeId id = new NodeId(uuid);
try {
long time = System.currentTimeMillis();
NodeState state = (NodeState) itemMgr.getItemState(id);
time = System.currentTimeMillis() - time;
log.debug("got NodeState with id {} in {} ms.", id, time);
List<ChildNodeEntry> entries;
if (nameTest != null) {
entries = state.getChildNodeEntries(nameTest);
} else {
// get all children
entries = state.getChildNodeEntries();
}
for (ChildNodeEntry entry : entries) {
NodeId childId = entry.getId();
Term uuidTerm = TermFactory.createUUIDTerm(childId.toString());
TermDocs docs = reader.termDocs(uuidTerm);
try {
if (docs.next()) {
childrenHits.set(docs.doc());
}
} finally {
docs.close();
}
}
} catch (ItemStateException e) {
// does not exist anymore -> ignore
}
}
return childrenHits;
}
}
/**
* An implementation of a children calculator that uses the hierarchy
* resolver. This implementation requires that
* {@link ChildAxisQuery#nameTestScorer} is non null.
*/
private final class HierarchyResolvingChildrenCalculator
extends ChildrenCalculator {
/**
* The document numbers of the context hits.
*/
private final Set<Integer> docIds = new HashSet<Integer>();
/**
* Creates a new hierarchy resolving children calculator.
*
* @param reader the current index reader.
* @param hResolver the current hierarchy resolver.
*/
public HierarchyResolvingChildrenCalculator(IndexReader reader,
HierarchyResolver hResolver) {
super(reader, hResolver);
}
/**
* {@inheritDoc}
*/
protected void collectContextHit(int doc) {
docIds.add(doc);
}
/**
* {@inheritDoc}
*/
public Hits getHits() throws IOException {
long time = System.currentTimeMillis();
Hits childrenHits = new AdaptingHits();
Hits nameHits = new ScorerHits(nameTestScorer);
int[] docs = new int[1];
for (int h = nameHits.next(); h > -1; h = nameHits.next()) {
docs = hResolver.getParents(h, docs);
if (docs.length == 1) {
// optimize single value
if (docIds.contains(docs[0])) {
childrenHits.set(h);
}
} else {
for (int i = 0; i < docs.length; i++) {
if (docIds.contains(docs[i])) {
childrenHits.set(h);
}
}
}
}
time = System.currentTimeMillis() - time;
log.debug("Filtered hits in {} ms.", time);
return childrenHits;
}
}
}