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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.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.apache.cassandra.db.TypeSizes;
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.transport.ProtocolVersion;
public class ListSerializer extends CollectionSerializer>
{
// interning instances
private static final ConcurrentMap, ListSerializer> instances = new ConcurrentHashMap, ListSerializer>();
public final TypeSerializer elements;
public static ListSerializer getInstance(TypeSerializer elements)
{
ListSerializer t = instances.get(elements);
if (t == null)
t = instances.computeIfAbsent(elements, k -> new ListSerializer<>(k) );
return t;
}
private ListSerializer(TypeSerializer elements)
{
this.elements = elements;
}
protected List serializeValues(List values)
{
List output = new ArrayList<>(values.size());
for (T value: values)
output.add(elements.serialize(value));
return output;
}
public int getElementCount(List value)
{
return value.size();
}
public void validateForNativeProtocol(V input, ValueAccessor accessor, ProtocolVersion version)
{
try
{
int n = readCollectionSize(input, accessor, version);
int offset = sizeOfCollectionSize(n, version);
for (int i = 0; i < n; i++)
{
V value = readValue(input, accessor, offset, version);
offset += sizeOfValue(value, accessor, version);
elements.validate(value, accessor);
}
if (!accessor.isEmptyFromOffset(input, offset))
throw new MarshalException("Unexpected extraneous bytes after list value");
}
catch (BufferUnderflowException | IndexOutOfBoundsException e)
{
throw new MarshalException("Not enough bytes to read a list");
}
}
public List deserializeForNativeProtocol(V input, ValueAccessor accessor, ProtocolVersion version)
{
try
{
int n = readCollectionSize(input, accessor, version);
int offset = sizeOfCollectionSize(n, version);
if (n < 0)
throw new MarshalException("The data cannot be deserialized as a list");
// If the received bytes are not corresponding to a list, n might be a huge number.
// In such a case we do not want to initialize the list with that size as it can result
// in an OOM (see CASSANDRA-12618). On the other hand we do not want to have to resize the list
// if we can avoid it, so we put a reasonable limit on the initialCapacity.
List l = new ArrayList(Math.min(n, 256));
for (int i = 0; i < n; i++)
{
// We can have nulls in lists that are used for IN values
V databb = readValue(input, accessor, offset, version);
offset += sizeOfValue(databb, accessor, version);
if (databb != null)
{
elements.validate(databb, accessor);
l.add(elements.deserialize(databb, accessor));
}
else
{
l.add(null);
}
}
if (!accessor.isEmptyFromOffset(input, offset))
throw new MarshalException("Unexpected extraneous bytes after list value");
return l;
}
catch (BufferUnderflowException | IndexOutOfBoundsException e)
{
throw new MarshalException("Not enough bytes to read a list");
}
}
/**
* Returns the element at the given index in a list.
* @param input a serialized list
* @param index the index to get
* @return the serialized element at the given index, or null if the index exceeds the list size
*/
public V getElement(V input, ValueAccessor accessor, int index)
{
try
{
int n = readCollectionSize(input, accessor, ProtocolVersion.V3);
int offset = sizeOfCollectionSize(n, ProtocolVersion.V3);
if (n <= index)
return null;
for (int i = 0; i < index; i++)
{
int length = accessor.getInt(input, offset);
offset += TypeSizes.INT_SIZE + length;
}
return readValue(input, accessor, offset, ProtocolVersion.V3);
}
catch (BufferUnderflowException | IndexOutOfBoundsException e)
{
throw new MarshalException("Not enough bytes to read a list");
}
}
public ByteBuffer getElement(ByteBuffer input, int index)
{
return getElement(input, ByteBufferAccessor.instance, index);
}
public String toString(List value)
{
StringBuilder sb = new StringBuilder();
boolean isFirst = true;
sb.append('[');
for (T element : value)
{
if (isFirst)
isFirst = false;
else
sb.append(", ");
sb.append(elements.toString(element));
}
sb.append(']');
return sb.toString();
}
public Class> getType()
{
return (Class) List.class;
}
@Override
public ByteBuffer getSerializedValue(ByteBuffer collection, ByteBuffer key, AbstractType comparator)
{
// We don't allow selecting an element of a list so we don't need this.
throw new UnsupportedOperationException();
}
@Override
public ByteBuffer getSliceFromSerialized(ByteBuffer collection,
ByteBuffer from,
ByteBuffer to,
AbstractType comparator,
boolean frozen)
{
// We don't allow slicing of list so we don't need this.
throw new UnsupportedOperationException();
}
}