/*
* 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 java.io.IOException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.WeakHashMap;
import javax.jcr.PropertyType;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.index.TermEnum;
import org.apache.lucene.index.TermPositions;
/**
* 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 static 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 static 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;
}
}
static class ComparableArray implements Comparable<ComparableArray> {
private int offset = 0;
private Comparable<?>[] c = new Comparable[0];
public ComparableArray(Comparable<?> item, int index) {
insert(item, index);
}
public int compareTo(ComparableArray o) {
return Util.compare(c, o.c);
}
/**
* testing purpose only.
*
* @return the offset
*/
int getOffset() {
return offset;
}
public ComparableArray insert(Comparable<?> item, int index) {
// optimize for most common scenario
if (c.length == 0) {
offset = index;
c = new Comparable<?>[] { item };
return this;
}
// inside
if (index >= offset && index < offset + c.length) {
c[index - offset] = item;
return this;
}
// before
if (index < offset) {
int relativeOffset = offset - index;
Comparable<?>[] newC = new Comparable[relativeOffset + c.length];
newC[0] = item;
System.arraycopy(c, 0, newC, relativeOffset, c.length);
c = newC;
offset = index;
return this;
}
// after
if (index >= offset + c.length) {
Comparable<?>[] newC = new Comparable[index - offset + 1];
System.arraycopy(c, 0, newC, 0, c.length);
newC[index - offset] = item;
c = newC;
return this;
}
return this;
}
/*
* This is needed by {@link UpperCaseSortComparator} and {@link LowerCaseSortComparator}
*/
@Override
public String toString() {
if (c == null) {
return null;
}
if (c.length == 1) {
return c[0].toString();
}
return Arrays.toString(c);
}
}
/**
* 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.
* @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) throws IOException {
if (reader instanceof ReadOnlyIndexReader) {
reader = ((ReadOnlyIndexReader) reader).getBase();
}
field = field.intern();
ValueIndex ret = lookup(reader, field, prefix);
if (ret == null) {
final int maxDocs = reader.maxDoc();
Comparable<?>[] retArray = new Comparable<?>[maxDocs];
Map<Integer, Integer> positions = new HashMap<Integer, Integer>();
boolean usingSimpleComparable = true;
int setValues = 0;
if (maxDocs > 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));
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;
}
final String value = termValueAsString(term, prefix);
termDocs.seek(term);
while (termDocs.next()) {
int termPosition = 0;
type = PropertyType.UNDEFINED;
if (hasPayloads) {
TermPositions termPos = (TermPositions) termDocs;
termPosition = termPos.nextPosition();
if (termPos.isPayloadAvailable()) {
payload = termPos.getPayload(payload, 0);
type = PropertyMetaData.fromByteArray(payload).getPropertyType();
}
}
setValues++;
Comparable<?> v = getValue(value, type);
int doc = termDocs.doc();
Comparable<?> ca = retArray[doc];
if (ca == null) {
if (usingSimpleComparable) {
// put simple value on the queue
positions.put(doc, termPosition);
retArray[doc] = v;
} else {
retArray[doc] = new ComparableArray(v,
termPosition);
}
} else {
if (ca instanceof ComparableArray) {
((ComparableArray) ca).insert(v,
termPosition);
} else {
// transform all of the existing values from
// Comparable to ComparableArray
for (int pos : positions.keySet()) {
retArray[pos] = new ComparableArray(
retArray[pos],
positions.get(pos));
}
positions = null;
usingSimpleComparable = false;
ComparableArray caNew = (ComparableArray) retArray[doc];
retArray[doc] = caNew.insert(v,
termPosition);
}
}
}
} while (termEnum.next());
} finally {
termDocs.close();
termEnum.close();
}
}
ValueIndex value = new ValueIndex(retArray, setValues);
store(reader, field, prefix, value);
return value;
}
return ret;
}
/**
* Extracts the value from a given Term as a String
*
* @param term
* @param prefix
* @return string value contained in the term
*/
private static String termValueAsString(Term term, String prefix) {
// make sure term is compacted
String text = term.text();
int length = text.length() - prefix.length();
char[] tmp = new char[length];
text.getChars(prefix.length(), text.length(), tmp, 0);
return new String(tmp, 0, length);
}
/**
* See if a <code>ValueIndex</code> object is in the cache.
*/
ValueIndex lookup(IndexReader reader, String field, String prefix) {
synchronized (cache) {
Map<Key, ValueIndex> readerCache = cache.get(reader);
if (readerCache == null) {
return null;
}
return readerCache.get(new Key(field, prefix));
}
}
/**
* Put a <code>ValueIndex</code> <code>value</code> to cache.
*/
void store(IndexReader reader, String field, String prefix, ValueIndex value) {
synchronized (cache) {
Map<Key, ValueIndex> readerCache = cache.get(reader);
if (readerCache == null) {
readerCache = new HashMap<Key, ValueIndex>();
cache.put(reader, readerCache);
}
readerCache.put(new Key(field, prefix), 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>
* and <code>prefix</code>.
*/
static class Key {
private final String field;
private final String prefix;
/**
* Creates <code>Key</code> for ValueIndex lookup.
*/
Key(String field, String prefix) {
this.field = field.intern();
this.prefix = prefix.intern();
}
/**
* Returns <code>true</code> if <code>o</code> is a <code>Key</code>
* instance and refers to the same field and prefix.
*/
public boolean equals(Object o) {
if (o instanceof Key) {
Key other = (Key) o;
return other.field == field
&& other.prefix == prefix;
}
return false;
}
/**
* Composes a hashcode based on the field and prefix.
*/
public int hashCode() {
return field.hashCode() ^ prefix.hashCode();
}
}
}