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/*
* 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.index;
import java.util.List;
import org.apache.lucene.util.Bits;
/**
* Concatenates multiple Bits together, on every lookup.
*
* NOTE: This is very costly, as every lookup must do a binary search to locate the right
* sub-reader.
*
* @lucene.experimental
*/
public final class MultiBits implements Bits {
private final Bits[] subs;
// length is 1+subs.length (the last entry has the maxDoc):
private final int[] starts;
private final boolean defaultValue;
private MultiBits(Bits[] subs, int[] starts, boolean defaultValue) {
assert starts.length == 1 + subs.length;
this.subs = subs;
this.starts = starts;
this.defaultValue = defaultValue;
}
/**
* Returns a single {@link Bits} instance for this reader, merging live Documents on the fly. This
* method will return null if the reader has no deletions.
*
*
NOTE: this is a very slow way to access live docs. For example, each Bits access will
* require a binary search. It's better to get the sub-readers and iterate through them yourself.
*/
public static Bits getLiveDocs(IndexReader reader) {
if (reader.hasDeletions()) {
final List leaves = reader.leaves();
final int size = leaves.size();
assert size > 0 : "A reader with deletions must have at least one leave";
if (size == 1) {
return leaves.get(0).reader().getLiveDocs();
}
final Bits[] liveDocs = new Bits[size];
final int[] starts = new int[size + 1];
for (int i = 0; i < size; i++) {
// record all liveDocs, even if they are null
final LeafReaderContext ctx = leaves.get(i);
liveDocs[i] = ctx.reader().getLiveDocs();
starts[i] = ctx.docBase;
}
starts[size] = reader.maxDoc();
return new MultiBits(liveDocs, starts, true);
} else {
return null;
}
}
private boolean checkLength(int reader, int doc) {
final int length = starts[1 + reader] - starts[reader];
assert doc - starts[reader] < length
: "doc="
+ doc
+ " reader="
+ reader
+ " starts[reader]="
+ starts[reader]
+ " length="
+ length;
return true;
}
@Override
public boolean get(int doc) {
final int reader = ReaderUtil.subIndex(doc, starts);
assert reader != -1;
final Bits bits = subs[reader];
if (bits == null) {
return defaultValue;
} else {
assert checkLength(reader, doc);
return bits.get(doc - starts[reader]);
}
}
@Override
public String toString() {
StringBuilder b = new StringBuilder();
b.append(subs.length).append(" subs: ");
for (int i = 0; i < subs.length; i++) {
if (i != 0) {
b.append("; ");
}
if (subs[i] == null) {
b.append("s=").append(starts[i]).append(" l=null");
} else {
b.append("s=")
.append(starts[i])
.append(" l=")
.append(subs[i].length())
.append(" b=")
.append(subs[i]);
}
}
b.append(" end=").append(starts[subs.length]);
return b.toString();
}
@Override
public int length() {
return starts[starts.length - 1];
}
}