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A module that is everything required to understands Druid Segments
/*
* 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.druid.segment.data;
import com.google.common.base.Supplier;
import org.apache.druid.java.util.common.IAE;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
public class CompressedColumnarDoublesSuppliers
{
public static final byte LZF_VERSION = 0x1;
public static final byte VERSION = 0x2;
private CompressedColumnarDoublesSuppliers()
{
}
public static Supplier fromByteBuffer(
ByteBuffer buffer,
ByteOrder order
)
{
byte versionFromBuffer = buffer.get();
if (versionFromBuffer == LZF_VERSION || versionFromBuffer == VERSION) {
final int totalSize = buffer.getInt();
final int sizePer = buffer.getInt();
CompressionStrategy compression = CompressionStrategy.LZF;
if (versionFromBuffer == VERSION) {
byte compressionId = buffer.get();
compression = CompressionStrategy.forId(compressionId);
}
return CompressionFactory.getDoubleSupplier(
totalSize,
sizePer,
buffer.asReadOnlyBuffer(),
order,
compression
);
}
throw new IAE("Unknown version[%s]", versionFromBuffer);
}
}