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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 com.google.common.collect.Range;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.db.marshal.ByteBufferAccessor;
import org.apache.cassandra.utils.ByteBufferUtil;
/**
* Common superclass for {@link SetSerializer} and {@link MapSerializer}, considering a set as a map without values.
*/
abstract class AbstractMapSerializer extends CollectionSerializer
{
private final boolean hasValues;
private final String name;
protected AbstractMapSerializer(boolean hasValues)
{
this.hasValues = hasValues;
name = hasValues ? "map" : "set";
}
@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, ByteBufferAccessor.instance);
input.position(input.position() + sizeOfCollectionSize());
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 key = readValue(input, ByteBufferAccessor.instance, 0);
input.position(input.position() + sizeOfValue(key, ByteBufferAccessor.instance));
// If we haven't passed the start already, check if we have now
if (!inSlice)
{
int comparison = comparator.compareForCQL(from, key);
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
skipMapValue(input);
continue;
}
}
// Now check if we're done
int comparison = to == ByteBufferUtil.UNSET_BYTE_BUFFER ? -1 : comparator.compareForCQL(key, 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
skipMapValue(input); // value
++count;
// But if we know it 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());
}
catch (BufferUnderflowException | IndexOutOfBoundsException e)
{
throw new MarshalException("Not enough bytes to read a " + name);
}
}
@Override
public int getIndexFromSerialized(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 i;
if (comparison > 0)
// since the set is in sorted order, we know we've gone too far and the element doesn't exist
return -1;
// comparison < 0
if (hasValues)
offset += skipValue(input, ByteBufferAccessor.instance, offset);
}
return -1;
}
catch (BufferUnderflowException e)
{
throw new MarshalException("Not enough bytes to read a " + name);
}
}
@Override
public Range getIndexesRangeFromSerialized(ByteBuffer collection,
ByteBuffer from,
ByteBuffer to,
AbstractType comparator)
{
if (from == ByteBufferUtil.UNSET_BYTE_BUFFER && to == ByteBufferUtil.UNSET_BYTE_BUFFER)
return Range.closed(0, Integer.MAX_VALUE);
try
{
ByteBuffer input = collection.duplicate();
int n = readCollectionSize(input, ByteBufferAccessor.instance);
input.position(input.position() + sizeOfCollectionSize());
int start = from == ByteBufferUtil.UNSET_BYTE_BUFFER ? 0 : -1;
int end = to == ByteBufferUtil.UNSET_BYTE_BUFFER ? n : -1;
for (int i = 0; i < n; i++)
{
if (start >= 0 && end >= 0)
break;
else if (i > 0)
skipMapValue(input);
ByteBuffer key = readValue(input, ByteBufferAccessor.instance, 0);
input.position(input.position() + sizeOfValue(key, ByteBufferAccessor.instance));
if (start < 0)
{
int comparison = comparator.compareForCQL(from, key);
if (comparison <= 0)
start = i;
else
continue;
}
if (end < 0)
{
int comparison = comparator.compareForCQL(key, to);
if (comparison > 0)
end = i;
}
}
if (start < 0)
return Range.closedOpen(0, 0);
if (end < 0)
return Range.closedOpen(start, n);
return Range.closedOpen(start, end);
}
catch (BufferUnderflowException e)
{
throw new MarshalException("Not enough bytes to read a " + name);
}
}
private void skipMapValue(ByteBuffer input)
{
if (hasValues)
skipValue(input);
}
}