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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.serializers;
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.function.Consumer;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.db.marshal.ByteBufferAccessor;
import org.apache.cassandra.db.marshal.ValueAccessor;
import org.apache.cassandra.db.marshal.ValueComparators;
import org.apache.cassandra.utils.Pair;
public class MapSerializer extends AbstractMapSerializer>
{
// interning instances
@SuppressWarnings("rawtypes")
private static final ConcurrentMap, TypeSerializer>, MapSerializer> instances = new ConcurrentHashMap<>();
public final TypeSerializer keys;
public final TypeSerializer values;
private final ValueComparators comparators;
@SuppressWarnings("unchecked")
public static MapSerializer getInstance(TypeSerializer keys, TypeSerializer values, ValueComparators comparators)
{
Pair, TypeSerializer> p = Pair.create(keys, values);
MapSerializer t = instances.get(p);
if (t == null)
t = instances.computeIfAbsent(p, k -> new MapSerializer<>(k.left, k.right, comparators));
return t;
}
private MapSerializer(TypeSerializer keys, TypeSerializer values, ValueComparators comparators)
{
super(true);
this.keys = keys;
this.values = values;
this.comparators = comparators;
}
@Override
public List serializeValues(Map map)
{
List> pairs = new ArrayList<>(map.size());
for (Map.Entry entry : map.entrySet())
pairs.add(Pair.create(keys.serialize(entry.getKey()), values.serialize(entry.getValue())));
pairs.sort((l, r) -> comparators.buffer.compare(l.left, r.left));
List buffers = new ArrayList<>(pairs.size() * 2);
for (Pair p : pairs)
{
buffers.add(p.left);
buffers.add(p.right);
}
return buffers;
}
@Override
public int getElementCount(Map value)
{
return value.size();
}
@Override
public void validate(T input, ValueAccessor accessor)
{
if (accessor.isEmpty(input))
throw new MarshalException("Not enough bytes to read a map");
try
{
// Empty values are still valid.
if (accessor.isEmpty(input)) return;
int n = readCollectionSize(input, accessor);
int offset = sizeOfCollectionSize();
for (int i = 0; i < n; i++)
{
T key = readNonNullValue(input, accessor, offset);
offset += sizeOfValue(key, accessor);
keys.validate(key, accessor);
T value = readNonNullValue(input, accessor, offset);
offset += sizeOfValue(value, accessor);
values.validate(value, accessor);
}
if (!accessor.isEmptyFromOffset(input, offset))
throw new MarshalException("Unexpected extraneous bytes after map value");
}
catch (BufferUnderflowException | IndexOutOfBoundsException e)
{
throw new MarshalException("Not enough bytes to read a map");
}
}
@Override
public Map deserialize(I input, ValueAccessor accessor)
{
try
{
int n = readCollectionSize(input, accessor);
int offset = sizeOfCollectionSize();
if (n < 0)
throw new MarshalException("The data cannot be deserialized as a map");
// If the received bytes are not corresponding to a map, n might be a huge number.
// In such a case we do not want to initialize the map with that initialCapacity as it can result
// in an OOM when put is called (see CASSANDRA-12618). On the other hand we do not want to have to resize
// the map if we can avoid it, so we put a reasonable limit on the initialCapacity.
Map m = new LinkedHashMap<>(Math.min(n, 256));
for (int i = 0; i < n; i++)
{
I key = readNonNullValue(input, accessor, offset);
offset += sizeOfValue(key, accessor);
keys.validate(key, accessor);
I value = readNonNullValue(input, accessor, offset);
offset += sizeOfValue(value, accessor);
values.validate(value, accessor);
m.put(keys.deserialize(key, accessor), values.deserialize(value, accessor));
}
if (!accessor.isEmptyFromOffset(input, offset))
throw new MarshalException("Unexpected extraneous bytes after map value");
return m;
}
catch (BufferUnderflowException | IndexOutOfBoundsException e)
{
throw new MarshalException("Not enough bytes to read a map");
}
}
@Override
public ByteBuffer getSerializedValue(ByteBuffer collection, ByteBuffer key, AbstractType comparator)
{
try
{
ByteBuffer input = collection.duplicate();
int n = readCollectionSize(input, ByteBufferAccessor.instance);
int offset = sizeOfCollectionSize();
for (int i = 0; i < n; i++)
{
ByteBuffer kbb = readValue(input, ByteBufferAccessor.instance, offset);
offset += sizeOfValue(kbb, ByteBufferAccessor.instance);
int comparison = comparator.compareForCQL(kbb, key);
if (comparison == 0)
return readValue(input, ByteBufferAccessor.instance, offset);
else if (comparison > 0)
// since the map is in sorted order, we know we've gone too far and the element doesn't exist
return null;
else // comparison < 0
offset += skipValue(input, ByteBufferAccessor.instance, offset);
}
return null;
}
catch (BufferUnderflowException | IndexOutOfBoundsException e)
{
throw new MarshalException("Not enough bytes to read a map");
}
}
@Override
public String toString(Map value)
{
StringBuilder sb = new StringBuilder();
sb.append('{');
boolean isFirst = true;
for (Map.Entry element : value.entrySet())
{
if (isFirst)
isFirst = false;
else
sb.append(", ");
sb.append(keys.toString(element.getKey()));
sb.append(": ");
sb.append(values.toString(element.getValue()));
}
sb.append('}');
return sb.toString();
}
@Override
@SuppressWarnings({ "rawtypes", "unchecked" })
public Class> getType()
{
return (Class) Map.class;
}
@Override
public void forEach(ByteBuffer input, Consumer action)
{
throw new UnsupportedOperationException();
}
}