package org.apache.cassandra.db.commitlog;
/*
*
* 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.
*
*/
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Comparator;
import com.google.common.base.Function;
import com.google.common.collect.Iterables;
import com.google.common.collect.Ordering;
import org.apache.cassandra.io.ICompactSerializer2;
import org.apache.cassandra.io.sstable.SSTable;
public class ReplayPosition implements Comparable<ReplayPosition>
{
public static final ReplayPositionSerializer serializer = new ReplayPositionSerializer();
// NONE is used for SSTables that are streamed from other nodes and thus have no relationship
// with our local commitlog. The values satisfy the critera that
// - no real commitlog segment will have the given id
// - it will sort before any real replayposition, so it will be effectively ignored by getReplayPosition
public static final ReplayPosition NONE = new ReplayPosition(-1, 0);
/**
* Convenience method to compute the replay position for a group of SSTables.
* @param sstables
* @return the most recent (highest) replay position
*/
public static ReplayPosition getReplayPosition(Iterable<? extends SSTable> sstables)
{
if (Iterables.isEmpty(sstables))
return NONE;
Function<SSTable, ReplayPosition> f = new Function<SSTable, ReplayPosition>()
{
public ReplayPosition apply(SSTable sstable)
{
return sstable.replayPosition;
}
};
Ordering<ReplayPosition> ordering = Ordering.from(ReplayPosition.comparator);
return ordering.max(Iterables.transform(sstables, f));
}
public final long segment;
public final int position;
public static final Comparator<ReplayPosition> comparator = new Comparator<ReplayPosition>()
{
public int compare(ReplayPosition o1, ReplayPosition o2)
{
if (o1.segment != o2.segment)
return Long.valueOf(o1.segment).compareTo(o2.segment);
return Integer.valueOf(o1.position).compareTo(o2.position);
}
};
public ReplayPosition(long segment, int position)
{
this.segment = segment;
assert position >= 0;
this.position = position;
}
public int compareTo(ReplayPosition other)
{
return comparator.compare(this, other);
}
@Override
public boolean equals(Object o)
{
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
ReplayPosition that = (ReplayPosition) o;
if (position != that.position) return false;
return segment == that.segment;
}
@Override
public int hashCode()
{
int result = (int) (segment ^ (segment >>> 32));
result = 31 * result + position;
return result;
}
@Override
public String toString()
{
return "ReplayPosition(" +
"segmentId=" + segment +
", position=" + position +
')';
}
public static class ReplayPositionSerializer implements ICompactSerializer2<ReplayPosition>
{
public void serialize(ReplayPosition rp, DataOutput dos) throws IOException
{
dos.writeLong(rp.segment);
dos.writeInt(rp.position);
}
public ReplayPosition deserialize(DataInput dis) throws IOException
{
return new ReplayPosition(dis.readLong(), dis.readInt());
}
}
}