/*
* 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.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermEnum;
import org.apache.lucene.index.TermPositions;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.search.SortComparatorSource;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.WeakHashMap;
import javax.jcr.PropertyType;
/**
* Implements a variant of the lucene class <code>org.apache.lucene.search.FieldCacheImpl</code>.
* The lucene FieldCache class has some sort of support for custom comparators
* but it only works on the basis of a field name. There is no further control
* over the terms to iterate, that's why we use our own implementation.
*/
public class SharedFieldCache {
/**
* Expert: Stores term text values and document ordering data.
*/
public static class ValueIndex {
/**
* Some heuristic factor that determines whether the array is sparse. Note that if less then
* 1% is set, we already count the array as sparse. This is because it will become memory consuming
* quickly by keeping the (sparse) arrays
*/
private static final int SPARSE_FACTOR = 100;
/**
* Values indexed by document id.
*/
private final Comparable[] values;
/**
* Values (Comparable) map indexed by document id.
*/
public final Map<Integer, Comparable> valuesMap;
/**
* Boolean indicating whether the {@link #valuesMap} impl has to be used
*/
public final boolean sparse;
/**
* Creates one of these objects
*/
public ValueIndex(Comparable[] values, int setValues) {
if (isSparse(values, setValues)) {
this.sparse = true;
this.values = null;
if (setValues == 0) {
this.valuesMap = null;
} else {
this.valuesMap = getValuesMap(values, setValues);
}
} else {
this.sparse = false;
this.values = values;
this.valuesMap = null;
}
}
public Comparable getValue(int i) {
if (sparse) {
return valuesMap == null ? null : valuesMap.get(i);
} else {
return values[i];
}
}
private Map<Integer, Comparable> getValuesMap(Comparable[] values, int setValues) {
Map<Integer, Comparable> map = new HashMap<Integer, Comparable>(setValues);
for (int i = 0; i < values.length && setValues > 0; i++) {
if (values[i] != null) {
map.put(i, values[i]);
setValues--;
}
}
return map;
}
private boolean isSparse(Comparable[] values, int setValues) {
// some really simple test to test whether the array is sparse. Currently, when less then 1% is set, the array is already sparse
// for this typical cache to avoid memory issues
if (setValues * SPARSE_FACTOR < values.length) {
return true;
}
return false;
}
}
/**
* Reference to the single instance of <code>SharedFieldCache</code>.
*/
public static final SharedFieldCache INSTANCE = new SharedFieldCache();
/**
* The internal cache. Maps Entry to array of interpreted term values.
*/
private final Map<IndexReader, Map<Key, ValueIndex>> cache = new WeakHashMap<IndexReader, Map<Key, ValueIndex>>();
/**
* Private constructor.
*/
private SharedFieldCache() {
}
/**
* Creates a <code>ValueIndex</code> for a <code>field</code> and a term
* <code>prefix</code>. The term prefix acts as the property name for the
* shared <code>field</code>.
* <p/>
* This method is an adapted version of: <code>FieldCacheImpl.getStringIndex()</code>
*
* @param reader the <code>IndexReader</code>.
* @param field name of the shared field.
* @param prefix the property name, will be used as term prefix.
* @param comparator the sort comparator instance.
* @return a ValueIndex that contains the field values and order
* information.
* @throws IOException if an error occurs while reading from the index.
*/
public ValueIndex getValueIndex(IndexReader reader,
String field,
String prefix,
SortComparatorSource comparator)
throws IOException {
if (reader instanceof ReadOnlyIndexReader) {
reader = ((ReadOnlyIndexReader) reader).getBase();
}
field = field.intern();
ValueIndex ret = lookup(reader, field, prefix, comparator);
if (ret == null) {
Comparable[] retArray = new Comparable[reader.maxDoc()];
int setValues = 0;
if (retArray.length > 0) {
IndexFormatVersion version = IndexFormatVersion.getVersion(reader);
boolean hasPayloads = version.isAtLeast(IndexFormatVersion.V3);
TermDocs termDocs;
byte[] payload = null;
int type;
if (hasPayloads) {
termDocs = reader.termPositions();
payload = new byte[1];
} else {
termDocs = reader.termDocs();
}
TermEnum termEnum = reader.terms(new Term(field, prefix));
char[] tmp = new char[16];
try {
if (termEnum.term() == null) {
throw new RuntimeException("no terms in field " + field);
}
do {
Term term = termEnum.term();
if (term.field() != field || !term.text().startsWith(prefix)) {
break;
}
// make sure term is compacted
String text = term.text();
int len = text.length() - prefix.length();
if (tmp.length < len) {
// grow tmp
tmp = new char[len];
}
text.getChars(prefix.length(), text.length(), tmp, 0);
String value = new String(tmp, 0, len);
termDocs.seek(termEnum);
while (termDocs.next()) {
type = PropertyType.UNDEFINED;
if (hasPayloads) {
TermPositions termPos = (TermPositions) termDocs;
termPos.nextPosition();
if (termPos.isPayloadAvailable()) {
payload = termPos.getPayload(payload, 0);
type = PropertyMetaData.fromByteArray(payload).getPropertyType();
}
}
setValues++;
retArray[termDocs.doc()] = getValue(value, type);
}
} while (termEnum.next());
} finally {
termDocs.close();
termEnum.close();
}
}
ValueIndex value = new ValueIndex(retArray, setValues);
store(reader, field, prefix, comparator, value);
return value;
}
return ret;
}
/**
* See if a <code>ValueIndex</code> object is in the cache.
*/
ValueIndex lookup(IndexReader reader, String field,
String prefix, SortComparatorSource comparer) {
Key key = new Key(field, prefix, comparer);
synchronized (this) {
Map<Key, ValueIndex> readerCache = cache.get(reader);
if (readerCache == null) {
return null;
}
return readerCache.get(key);
}
}
/**
* Put a <code>ValueIndex</code> <code>value</code> to cache.
*/
ValueIndex store(IndexReader reader, String field, String prefix,
SortComparatorSource comparer, ValueIndex value) {
Key key = new Key(field, prefix, comparer);
synchronized (this) {
Map<Key, ValueIndex> readerCache = cache.get(reader);
if (readerCache == null) {
readerCache = new HashMap<Key, ValueIndex>();
cache.put(reader, readerCache);
}
return readerCache.put(key, value);
}
}
/**
* Returns a comparable for the given <code>value</code> that is read from
* the index.
*
* @param value the value as read from the index.
* @param type the property type.
* @return a comparable for the <code>value</code>.
*/
private Comparable getValue(String value, int type) {
switch (type) {
case PropertyType.BOOLEAN:
return Boolean.valueOf(value);
case PropertyType.DATE:
return DateField.stringToTime(value);
case PropertyType.LONG:
return LongField.stringToLong(value);
case PropertyType.DOUBLE:
return DoubleField.stringToDouble(value);
case PropertyType.DECIMAL:
return DecimalField.stringToDecimal(value);
default:
return value;
}
}
/**
* A compound <code>Key</code> that consist of <code>field</code>
* <code>prefix</code> and <code>comparator</code>.
*/
static class Key {
private final String field;
private final String prefix;
private final SortComparatorSource comparator;
/**
* Creates <code>Key</code> for ValueIndex lookup.
*/
Key(String field, String prefix, SortComparatorSource comparator) {
this.field = field.intern();
this.prefix = prefix.intern();
this.comparator = comparator;
}
/**
* Returns <code>true</code> if <code>o</code> is a <code>Key</code>
* instance and refers to the same field, prefix and comparator object.
*/
public boolean equals(Object o) {
if (o instanceof Key) {
Key other = (Key) o;
return other.field == field
&& other.prefix == prefix
&& other.comparator.equals(comparator);
}
return false;
}
/**
* Composes a hashcode based on the field, prefix and comparator.
*/
public int hashCode() {
return field.hashCode() ^ prefix.hashCode() ^ comparator.hashCode();
}
}
}