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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.marshal.AbstractType;
import org.apache.cassandra.db.marshal.ByteBufferAccessor;
import org.apache.cassandra.db.marshal.ValueComparators;
import org.apache.cassandra.db.marshal.ValueAccessor;
import org.apache.cassandra.transport.ProtocolVersion;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.Pair;
public class MapSerializer extends CollectionSerializer>
{
// interning instances
private static final ConcurrentMap, TypeSerializer>, MapSerializer> instances = new ConcurrentHashMap<>();
public final TypeSerializer keys;
public final TypeSerializer values;
private final ValueComparators comparators;
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)
{
this.keys = keys;
this.values = values;
this.comparators = comparators;
}
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())));
Collections.sort(pairs, (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;
}
public int getElementCount(Map value)
{
return value.size();
}
public void validateForNativeProtocol(T input, ValueAccessor accessor, ProtocolVersion version)
{
try
{
// Empty values are still valid.
if (accessor.isEmpty(input)) return;
int n = readCollectionSize(input, accessor, version);
int offset = sizeOfCollectionSize(n, version);
for (int i = 0; i < n; i++)
{
T key = readNonNullValue(input, accessor, offset, version);
offset += sizeOfValue(key, accessor, version);
keys.validate(key, accessor);
T value = readNonNullValue(input, accessor, offset, version);
offset += sizeOfValue(value, accessor, version);
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");
}
}
public Map deserializeForNativeProtocol(I 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 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, version);
offset += sizeOfValue(key, accessor, version);
keys.validate(key, accessor);
I value = readNonNullValue(input, accessor, offset, version);
offset += sizeOfValue(value, accessor, version);
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, ProtocolVersion.V3);
int offset = sizeOfCollectionSize(n, ProtocolVersion.V3);
for (int i = 0; i < n; i++)
{
ByteBuffer kbb = readValue(input, ByteBufferAccessor.instance, offset, ProtocolVersion.V3);
offset += sizeOfValue(kbb, ByteBufferAccessor.instance, ProtocolVersion.V3);
int comparison = comparator.compareForCQL(kbb, key);
if (comparison == 0)
return readValue(input, ByteBufferAccessor.instance, offset, ProtocolVersion.V3);
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, ProtocolVersion.V3);
}
return null;
}
catch (BufferUnderflowException | IndexOutOfBoundsException e)
{
throw new MarshalException("Not enough bytes to read a map");
}
}
@Override
public ByteBuffer getSliceFromSerialized(ByteBuffer collection,
ByteBuffer from,
ByteBuffer to,
AbstractType comparator,
boolean frozen)
{
if (from == ByteBufferUtil.UNSET_BYTE_BUFFER && to == ByteBufferUtil.UNSET_BYTE_BUFFER)
return collection;
try
{
ByteBuffer input = collection.duplicate();
int n = readCollectionSize(input, ProtocolVersion.V3);
input.position(input.position() + sizeOfCollectionSize(n, ProtocolVersion.V3));
int startPos = input.position();
int count = 0;
boolean inSlice = from == ByteBufferUtil.UNSET_BYTE_BUFFER;
for (int i = 0; i < n; i++)
{
int pos = input.position();
ByteBuffer kbb = readValue(input, ByteBufferAccessor.instance, 0, ProtocolVersion.V3); // key
input.position(input.position() + sizeOfValue(kbb, ByteBufferAccessor.instance, ProtocolVersion.V3));
// If we haven't passed the start already, check if we have now
if (!inSlice)
{
int comparison = comparator.compareForCQL(from, kbb);
if (comparison <= 0)
{
// We're now within the slice
inSlice = true;
startPos = pos;
}
else
{
// We're before the slice so we know we don't care about this element
skipValue(input, ProtocolVersion.V3); // value
continue;
}
}
// Now check if we're done
int comparison = to == ByteBufferUtil.UNSET_BYTE_BUFFER ? -1 : comparator.compareForCQL(kbb, to);
if (comparison > 0)
{
// We're done and shouldn't include the key we just read
input.position(pos);
break;
}
// Otherwise, we'll include that element
skipValue(input, ProtocolVersion.V3); // value
++count;
// But if we know if was the last of the slice, we break early
if (comparison == 0)
break;
}
if (count == 0 && !frozen)
return null;
return copyAsNewCollection(collection, count, startPos, input.position(), ProtocolVersion.V3);
}
catch (BufferUnderflowException | IndexOutOfBoundsException e)
{
throw new MarshalException("Not enough bytes to read a map");
}
}
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();
}
public Class> getType()
{
return (Class)Map.class;
}
}