/**
* Copyright (C) 2011 the original author or authors.
* See the notice.md file distributed with this work for additional
* information regarding copyright ownership.
*
* Licensed 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.iq80.leveldb.impl;
import com.google.common.base.Preconditions;
import org.iq80.leveldb.table.UserComparator;
import org.iq80.leveldb.util.Slice;
import static org.iq80.leveldb.impl.SequenceNumber.MAX_SEQUENCE_NUMBER;
public class InternalUserComparator implements UserComparator
{
private final InternalKeyComparator internalKeyComparator;
public InternalUserComparator(InternalKeyComparator internalKeyComparator)
{
this.internalKeyComparator = internalKeyComparator;
}
@Override
public int compare(Slice left, Slice right)
{
return internalKeyComparator.compare(new InternalKey(left), new InternalKey(right));
}
@Override
public String name() {
return internalKeyComparator.name();
}
@Override
public Slice findShortestSeparator(
Slice start,
Slice limit)
{
// Attempt to shorten the user portion of the key
Slice startUserKey = new InternalKey(start).getUserKey();
Slice limitUserKey = new InternalKey(limit).getUserKey();
Slice shortestSeparator = internalKeyComparator.getUserComparator().findShortestSeparator(startUserKey, limitUserKey);
if (internalKeyComparator.getUserComparator().compare(startUserKey, shortestSeparator) < 0) {
// User key has become larger. Tack on the earliest possible
// number to the shortened user key.
InternalKey newInternalKey = new InternalKey(shortestSeparator, MAX_SEQUENCE_NUMBER, ValueType.VALUE);
Preconditions.checkState(compare(start, newInternalKey.encode()) < 0);// todo
Preconditions.checkState(compare(newInternalKey.encode(), limit) < 0);// todo
return newInternalKey.encode();
}
return start;
}
@Override
public Slice findShortSuccessor(Slice key)
{
Slice userKey = new InternalKey(key).getUserKey();
Slice shortSuccessor = internalKeyComparator.getUserComparator().findShortSuccessor(userKey);
if (internalKeyComparator.getUserComparator().compare(userKey, shortSuccessor) < 0) {
// User key has become larger. Tack on the earliest possible
// number to the shortened user key.
InternalKey newInternalKey = new InternalKey(shortSuccessor, MAX_SEQUENCE_NUMBER, ValueType.VALUE);
Preconditions.checkState(compare(key, newInternalKey.encode()) < 0);// todo
return newInternalKey.encode();
}
return key;
}
}