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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <cstddef>
#include <cstdint>
class FastOS_FileInterface;
namespace search {
class FileAlign
{
private:
size_t _directIOFileAlign;
size_t _preferredFileAlign;
size_t _minDirectIOSize;
size_t _minAlignedSize;
size_t _elemSize;
size_t _directIOMemAlign;
bool _directio;
public:
FileAlign();
~FileAlign();
/**
* Adjust number of bytes for IO (read or write), reducing
* number of bytes if it helps making end of IO matching
* an alignment boundary.
*
* @param offset position of start of IO, measured in bytes
* @param size number of bytes for IO
*
* @return adjusted number of bytes for IO
*/
size_t adjustSize(int64_t offset, size_t size) const;
/**
* Adjust number of elements for IO (read or write), reducing
* number of elements if it helps making end of IO matching
* an alignment boundary.
*
* @param eoffset position of start of IO, measured in elements
* @param esize number of elements for IO
*
* @return adjusted number of elements for IO
*/
size_t adjustElements(int64_t eoffset, size_t esize) const;
/**
* Setup alignment
*
* @param elements suggested number of elements in buffer
* @param elemSize size of each elements
* @param file File interface for IO
* @param preferredFileAlignment prefered alignment for IO
*
* @return adjusted number of elements in buffer
*/
size_t setupAlign(size_t elements, size_t elemSize, FastOS_FileInterface *file, size_t preferredFileAlignment);
bool getDirectIO() const { return _directio; }
size_t getDirectIOFileAlign() const { return _directIOFileAlign; }
size_t getDirectIOMemAlign() const { return _directIOMemAlign; }
size_t getMinDirectIOSize() const { return _minDirectIOSize; }
size_t getMinAlignedSize() const { return _minAlignedSize; }
size_t getPreferredFileAlign() const { return _preferredFileAlign; }
size_t getElemSize() const { return _elemSize; }
};
}
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