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* Licensed to the Apache Software Foundation (ASF) under one
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* 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,
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package org.apache.drill.exec.ops;
import io.netty.buffer.DrillBuf;
/**
* Manages a list of {@link DrillBuf}s that can be reallocated as needed. Upon
* re-allocation the old buffer will be freed. Managing a list of these buffers
* prevents some parts of the system from needing to define a correct location
* to place the final call to free them.
*
* The current uses of these types of buffers are within the pluggable components of Drill.
* In UDFs, memory management should not be a concern. We provide access to re-allocatable
* DrillBufs to give UDF writers general purpose buffers we can account for. To prevent the need
* for UDFs to contain boilerplate to close all of the buffers they request, this list
* is tracked at a higher level and all of the buffers are freed once we are sure that
* the code depending on them is done executing (currently {@link FragmentContext}
* and {@link QueryContext}.
*/
public interface BufferManager extends AutoCloseable {
/**
* Replace an old buffer with a new version at least of the provided size. Does not copy data.
*
* @param old
* Old Buffer that the user is no longer going to use.
* @param newSize
* Size of new replacement buffer.
* @return
*/
public DrillBuf replace(DrillBuf old, int newSize);
/**
* Get a managed buffer of indeterminate size.
*
* @return A buffer.
*/
public DrillBuf getManagedBuffer();
/**
* Get a managed buffer of at least a certain size.
*
* @param size
* The desired size
* @return A buffer
*/
public DrillBuf getManagedBuffer(int size);
public void close();
}