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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
/**
******************************************************************************
* @author Oivind H. Danielsen
* @date Creation date: 2000-09-21
* @file
* Class definition for FastOS_Linux_File.
*****************************************************************************/
#pragma once
#include "unix_file.h"
/**
* This is the Linux implementation of @ref FastOS_File. Most
* methods are inherited from @ref FastOS_UNIX_File.
*/
class FastOS_Linux_File : public FastOS_UNIX_File
{
public:
using FastOS_UNIX_File::ReadBuf;
protected:
int64_t _cachedSize;
int64_t _filePointer; // Only maintained/used in directio mode
public:
FastOS_Linux_File (const char *filename = nullptr);
~FastOS_Linux_File () override;
bool GetDirectIORestrictions(size_t &memoryAlignment, size_t &transferGranularity, size_t &transferMaximum) override;
bool DirectIOPadding(int64_t offset, size_t length, size_t &padBefore, size_t &padAfter) override;
void EnableDirectIO() override;
bool SetPosition(int64_t desiredPosition) override;
int64_t getPosition() const override;
bool SetSize(int64_t newSize) override;
void ReadBuf(void *buffer, size_t length, int64_t readOffset) override;
void *AllocateDirectIOBuffer(size_t byteSize, void *&realPtr) override;
[[nodiscard]] ssize_t Read(void *buffer, size_t len) override;
[[nodiscard]] ssize_t Write2(const void *buffer, size_t len) override;
bool Open(unsigned int openFlags, const char *filename) override;
static size_t getMaxDirectIOMemAlign();
static int count_open_files();
private:
ssize_t internalWrite2(const void *buffer, size_t len);
ssize_t readUnalignedEnd(void *buffer, size_t length, int64_t readOffset);
ssize_t writeUnalignedEnd(const void *buffer, size_t length, int64_t readOffset);
ssize_t ReadBufInternal(void *buffer, size_t length, int64_t readOffset);
ssize_t readInternal(int fh, void *buffer, size_t length, int64_t readOffset);
ssize_t readInternal(int fh, void *buffer, size_t length);
static ssize_t writeInternal(int fh, const void *buffer, size_t length, int64_t writeOffset);
static ssize_t writeInternal(int fh, const void *buffer, size_t length);
static const size_t _directIOFileAlign;
static const size_t _directIOMemAlign;
};
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