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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.cql3.selection;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
import java.util.stream.Collectors;
import org.apache.cassandra.cql3.ColumnSpecification;
import org.apache.cassandra.cql3.Maps;
import org.apache.cassandra.cql3.QueryOptions;
import org.apache.cassandra.cql3.functions.Function;
import org.apache.cassandra.db.filter.ColumnFilter.Builder;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.db.marshal.MapType;
import org.apache.cassandra.exceptions.InvalidRequestException;
import org.apache.cassandra.schema.ColumnMetadata;
import org.apache.cassandra.serializers.CollectionSerializer;
import org.apache.cassandra.transport.ProtocolVersion;
import org.apache.cassandra.utils.Pair;
/**
* Selector for literal map (e.g. {'min' : min(value), 'max' : max(value), 'count' : count(value)}).
*
*/
final class MapSelector extends Selector
{
/**
* The map type.
*/
private final MapType type;
/**
* The map elements
*/
private final List> elements;
public static Factory newFactory(final AbstractType type, final List> factories)
{
return new Factory()
{
protected String getColumnName()
{
return Maps.mapToString(factories, Factory::getColumnName);
}
protected AbstractType getReturnType()
{
return type;
}
protected final void addColumnMapping(SelectionColumnMapping mapping, ColumnSpecification resultsColumn)
{
SelectionColumnMapping tmpMapping = SelectionColumnMapping.newMapping();
for (Pair entry : factories)
{
entry.left.addColumnMapping(tmpMapping, resultsColumn);
entry.right.addColumnMapping(tmpMapping, resultsColumn);
}
if (tmpMapping.getMappings().get(resultsColumn).isEmpty())
// add a null mapping for cases where the collection is empty
mapping.addMapping(resultsColumn, (ColumnMetadata)null);
else
// collate the mapped columns from the child factories & add those
mapping.addMapping(resultsColumn, tmpMapping.getMappings().values());
}
public Selector newInstance(final QueryOptions options)
{
return new MapSelector(type,
factories.stream()
.map(p -> Pair.create(p.left.newInstance(options),
p.right.newInstance(options)))
.collect(Collectors.toList()));
}
@Override
public boolean isAggregateSelectorFactory()
{
for (Pair entry : factories)
{
if (entry.left.isAggregateSelectorFactory() || entry.right.isAggregateSelectorFactory())
return true;
}
return false;
}
@Override
public void addFunctionsTo(List functions)
{
for (Pair entry : factories)
{
entry.left.addFunctionsTo(functions);
entry.right.addFunctionsTo(functions);
}
}
@Override
public boolean isWritetimeSelectorFactory()
{
for (Pair entry : factories)
{
if (entry.left.isWritetimeSelectorFactory() || entry.right.isWritetimeSelectorFactory())
return true;
}
return false;
}
@Override
public boolean isTTLSelectorFactory()
{
for (Pair entry : factories)
{
if (entry.left.isTTLSelectorFactory() || entry.right.isTTLSelectorFactory())
return true;
}
return false;
}
@Override
boolean areAllFetchedColumnsKnown()
{
for (Pair entry : factories)
{
if (!entry.left.areAllFetchedColumnsKnown() || !entry.right.areAllFetchedColumnsKnown())
return false;
}
return true;
}
@Override
void addFetchedColumns(Builder builder)
{
for (Pair entry : factories)
{
entry.left.addFetchedColumns(builder);
entry.right.addFetchedColumns(builder);
}
}
};
}
@Override
public void addFetchedColumns(Builder builder)
{
for (int i = 0, m = elements.size(); i < m; i++)
{
Pair pair = elements.get(i);
pair.left.addFetchedColumns(builder);
pair.right.addFetchedColumns(builder);
}
}
public void addInput(ProtocolVersion protocolVersion, ResultSetBuilder rs) throws InvalidRequestException
{
for (int i = 0, m = elements.size(); i < m; i++)
{
Pair pair = elements.get(i);
pair.left.addInput(protocolVersion, rs);
pair.right.addInput(protocolVersion, rs);
}
}
public ByteBuffer getOutput(ProtocolVersion protocolVersion) throws InvalidRequestException
{
Map map = new TreeMap<>(type.getKeysType());
for (int i = 0, m = elements.size(); i < m; i++)
{
Pair pair = elements.get(i);
map.put(pair.left.getOutput(protocolVersion), pair.right.getOutput(protocolVersion));
}
List buffers = new ArrayList<>(elements.size() * 2);
for (Map.Entry entry : map.entrySet())
{
buffers.add(entry.getKey());
buffers.add(entry.getValue());
}
return CollectionSerializer.pack(buffers, elements.size(), protocolVersion);
}
public void reset()
{
for (int i = 0, m = elements.size(); i < m; i++)
{
Pair pair = elements.get(i);
pair.left.reset();
pair.right.reset();
}
}
public AbstractType getType()
{
return type;
}
@Override
public String toString()
{
return Maps.mapToString(elements);
}
private MapSelector(AbstractType type, List> elements)
{
this.type = (MapType) type;
this.elements = elements;
}
}