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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.cassandra.io.sstable;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import org.apache.cassandra.db.composites.CellNameType;
import org.apache.cassandra.db.composites.Composite;
import org.apache.cassandra.db.marshal.AbstractType;
import static org.apache.cassandra.utils.ByteBufferUtil.minimalBufferFor;
public class ColumnNameHelper
{
private static List maybeGrow(List l, int size)
{
if (l.size() >= size)
return l;
List nl = new ArrayList<>(size);
nl.addAll(l);
for (int i = l.size(); i < size; i++)
nl.add(null);
return nl;
}
private static List getComponents(Composite prefix, int size)
{
List l = new ArrayList<>(size);
for (int i = 0; i < size; i++)
l.add(prefix.get(i));
return l;
}
/**
* finds the max cell name component(s)
*
* Note that this method *can modify maxSeen*.
*
* @param maxSeen the max columns seen so far
* @param candidate the candidate column(s)
* @param comparator the comparator to use
* @return a list with the max column(s)
*/
public static List maxComponents(List maxSeen, Composite candidate, CellNameType comparator)
{
// For a cell name, no reason to look more than the clustering prefix
// (and comparing the collection element would actually crash)
int size = Math.min(candidate.size(), comparator.clusteringPrefixSize());
if (maxSeen.isEmpty())
return getComponents(candidate, size);
// In most case maxSeen is big enough to hold the result so update it in place in those cases
maxSeen = maybeGrow(maxSeen, size);
for (int i = 0; i < size; i++)
maxSeen.set(i, max(maxSeen.get(i), candidate.get(i), comparator.subtype(i)));
return maxSeen;
}
/**
* finds the min cell name component(s)
*
* Note that this method *can modify maxSeen*.
*
* @param minSeen the max columns seen so far
* @param candidate the candidate column(s)
* @param comparator the comparator to use
* @return a list with the min column(s)
*/
public static List minComponents(List minSeen, Composite candidate, CellNameType comparator)
{
// For a cell name, no reason to look more than the clustering prefix
// (and comparing the collection element would actually crash)
int size = Math.min(candidate.size(), comparator.clusteringPrefixSize());
if (minSeen.isEmpty())
return getComponents(candidate, size);
// In most case maxSeen is big enough to hold the result so update it in place in those cases
minSeen = maybeGrow(minSeen, size);
for (int i = 0; i < size; i++)
minSeen.set(i, min(minSeen.get(i), candidate.get(i), comparator.subtype(i)));
return minSeen;
}
/**
* return the min column
*
* note that comparator should not be of CompositeType!
*
* @param b1 lhs
* @param b2 rhs
* @param comparator the comparator to use
* @return the smallest column according to comparator
*/
private static ByteBuffer min(ByteBuffer b1, ByteBuffer b2, AbstractType comparator)
{
if (b1 == null)
return b2;
if (b2 == null)
return b1;
if (comparator.compare(b1, b2) >= 0)
return b2;
return b1;
}
/**
* return the max column
*
* note that comparator should not be of CompositeType!
*
* @param b1 lhs
* @param b2 rhs
* @param comparator the comparator to use
* @return the biggest column according to comparator
*/
private static ByteBuffer max(ByteBuffer b1, ByteBuffer b2, AbstractType comparator)
{
if (b1 == null)
return b2;
if (b2 == null)
return b1;
if (comparator.compare(b1, b2) >= 0)
return b1;
return b2;
}
/**
* Merge 2 lists of min cell name components.
*
* @param minColumnNames lhs
* @param candidates rhs
* @param comparator comparator to use
* @return a list with smallest column names according to (sub)comparator
*/
public static List mergeMin(List minColumnNames, List candidates, CellNameType comparator)
{
if (minColumnNames.isEmpty())
return minimalBuffersFor(candidates);
if (candidates.isEmpty())
return minColumnNames;
List biggest = minColumnNames.size() > candidates.size() ? minColumnNames : candidates;
List smallest = minColumnNames.size() > candidates.size() ? candidates : minColumnNames;
// We want to always copy the smallest list, and maybeGrow does it only if it's actually smaller
List retList = smallest.size() == biggest.size()
? new ArrayList<>(smallest)
: maybeGrow(smallest, biggest.size());
for (int i = 0; i < biggest.size(); i++)
retList.set(i, minimalBufferFor(min(retList.get(i), biggest.get(i), comparator.subtype(i))));
return retList;
}
private static List minimalBuffersFor(List candidates)
{
List minimalBuffers = new ArrayList(candidates.size());
for (ByteBuffer byteBuffer : candidates)
minimalBuffers.add(minimalBufferFor(byteBuffer));
return minimalBuffers;
}
/**
* Merge 2 lists of max cell name components.
*
* @param maxColumnNames lhs
* @param candidates rhs
* @param comparator comparator to use
* @return a list with biggest column names according to (sub)comparator
*/
public static List mergeMax(List maxColumnNames, List candidates, CellNameType comparator)
{
if (maxColumnNames.isEmpty())
return minimalBuffersFor(candidates);
if (candidates.isEmpty())
return maxColumnNames;
List biggest = maxColumnNames.size() > candidates.size() ? maxColumnNames : candidates;
List smallest = maxColumnNames.size() > candidates.size() ? candidates : maxColumnNames;
// We want to always copy the smallest list, and maybeGrow does it only if it's actually smaller
List retList = smallest.size() == biggest.size()
? new ArrayList<>(smallest)
: maybeGrow(smallest, biggest.size());
for (int i = 0; i < biggest.size(); i++)
retList.set(i, minimalBufferFor(max(retList.get(i), biggest.get(i), comparator.subtype(i))));
return retList;
}
/**
* Checks if the given min/max column names could overlap (i.e they could share some column names based on the max/min column names in the sstables)
*/
public static boolean overlaps(List minColumnNames1, List maxColumnNames1, List minColumnNames2, List maxColumnNames2, CellNameType comparator)
{
if (minColumnNames1.isEmpty() || maxColumnNames1.isEmpty() || minColumnNames2.isEmpty() || maxColumnNames2.isEmpty())
return true;
return !(compare(maxColumnNames1, minColumnNames2, comparator) < 0 || compare(minColumnNames1, maxColumnNames2, comparator) > 0);
}
private static int compare(List columnNames1, List columnNames2, CellNameType comparator)
{
for (int i = 0; i < Math.min(columnNames1.size(), columnNames2.size()); i++)
{
int cmp = comparator.subtype(i).compare(columnNames1.get(i), columnNames2.get(i));
if (cmp != 0)
return cmp;
}
return 0;
}
}