org.apache.jackrabbit.oak.plugins.segment.ListRecord Maven / Gradle / Ivy
/*
* 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.oak.plugins.segment;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkElementIndex;
import static com.google.common.base.Preconditions.checkPositionIndexes;
import static com.google.common.collect.Lists.newArrayListWithCapacity;
import static java.util.Collections.emptyList;
import static java.util.Collections.singletonList;
import java.util.List;
/**
* A record of type "LIST".
*/
class ListRecord extends Record {
static final int LEVEL_SIZE = Segment.SEGMENT_REFERENCE_LIMIT;
private final int size;
private final int bucketSize;
ListRecord(RecordId id, int size) {
super(id);
checkArgument(size >= 0);
this.size = size;
int bs = 1;
while (bs * LEVEL_SIZE < size) {
bs *= LEVEL_SIZE;
}
this.bucketSize = bs;
}
public int size() {
return size;
}
public RecordId getEntry(int index) {
checkElementIndex(index, size);
if (size == 1) {
return getRecordId();
} else {
int bucketIndex = index / bucketSize;
int bucketOffset = index % bucketSize;
Segment segment = getSegment();
RecordId id = segment.readRecordId(getOffset(0, bucketIndex));
ListRecord bucket = new ListRecord(
id, Math.min(bucketSize, size - bucketIndex * bucketSize));
return bucket.getEntry(bucketOffset);
}
}
public List getEntries() {
return getEntries(0, size);
}
public List getEntries(int index, int count) {
if (index + count > size) {
count = size - index;
}
if (count == 0) {
return emptyList();
} else if (count == 1) {
return singletonList(getEntry(index));
} else {
List ids = newArrayListWithCapacity(count);
getEntries(index, count, ids);
return ids;
}
}
private void getEntries(int index, int count, List ids) {
checkPositionIndexes(index, index + count, size);
Segment segment = getSegment();
if (size == 1) {
ids.add(getRecordId());
} else if (bucketSize == 1) {
for (int i = 0; i < count; i++) {
ids.add(segment.readRecordId(getOffset(0, index + i)));
}
} else {
while (count > 0) {
int bucketIndex = index / bucketSize;
int bucketOffset = index % bucketSize;
RecordId id = segment.readRecordId(getOffset(0, bucketIndex));
ListRecord bucket = new ListRecord(
id, Math.min(bucketSize, size - bucketIndex * bucketSize));
int n = Math.min(bucket.size() - bucketOffset, count);
bucket.getEntries(bucketOffset, n, ids);
index += n;
count -= n;
}
}
}
}