#include <FileUnbufferedIO.h>

Public Member Functions
	FileUnbufferedIO (const RegularFile &fileName, ByteIO::OpenOption option, Bool useODirect=False)
	The constructor opens or creates a file.

	~FileUnbufferedIO () override
	The destructor closes the file.

	FileUnbufferedIO (const FileUnbufferedIO &)=delete
	Copy constructor and assignment cannot be used.

FileUnbufferedIO &	operator= (const FileUnbufferedIO &)=delete

void	reopenRW () override
	Reopen the file for read/write.

Public Member Functions inherited from casacore::FiledesIO
	FiledesIO ()
	Default constructor.

	FiledesIO (int fd, const String &fileName=String())
	Construct from the given file descriptor.

void	attach (int fd, const String &fileName)
	Attach to the given file descriptor.

void	detach ()
	Detach from the file descriptor.

virtual	~FiledesIO ()
	The destructor detaches, but does not close the file.

virtual void	write (Int64 size, const void *buf)
	Write the number of bytes.

virtual void	pwrite (Int64 size, Int64 offset, const void *buf)
	Write the number of bytes at offset from start of the file.

virtual Int64	read (Int64 size, void *buf, Bool throwException=True)
	Read `size` bytes from the descriptor.

virtual Int64	pread (Int64 size, Int64 offset, void *buf, Bool throwException=True)
	Like read except reads from offset of the start of the file.

virtual Int64	length ()
	Get the length of the byte stream.

virtual Bool	isReadable () const
	Is the IO stream readable?

virtual Bool	isWritable () const
	Is the IO stream writable?

virtual Bool	isSeekable () const
	Is the IO stream seekable?

void	setWritable ()
	Set that the IO stream is writable.

virtual String	fileName () const
	Get the file name of the file attached.

virtual void	fsync ()
	Fsync the file (i.e.

virtual void	truncate (Int64 size)
	Truncate the file to the given size.

Public Member Functions inherited from casacore::ByteIO
	ByteIO ()
	The constructor does nothing.

virtual	~ByteIO ()

Int64	seek (Int offset, ByteIO::SeekOption=ByteIO::Begin)
	This function sets the position on the given offset.

Int64	seek (Int64 offset, ByteIO::SeekOption=ByteIO::Begin)

virtual void	flush ()
	Flush the data to the file.

virtual void	resync ()
	Resync the file (i.e.

Private Attributes
Bool	itsUseODirect

Additional Inherited Members
Public Types inherited from casacore::ByteIO
enum	OpenOption { Old , Update , Append , New , NewNoReplace , Scratch , Delete }
	Define the possible ByteIO open options. More...

enum	SeekOption { Begin , Current , End }
	Define the possible seek options. More...

Static Public Member Functions inherited from casacore::FiledesIO
static int	create (const Char *name, int mode=0666)
	Some static convenience functions for file create/open/close.

static int	open (const Char *name, Bool writable=False, Bool throwExcp=True)

static void	close (int fd)

Protected Member Functions inherited from casacore::FiledesIO
int	fd () const
	Get the file descriptor.

void	fillRWFlags (int fd)
	Determine if the file descriptor is readable and/or writable.

void	fillSeekable ()
	Determine if the file is seekable.

virtual Int64	doSeek (Int64 offset, ByteIO::SeekOption)
	Reset the position pointer to the given value.

Protected Member Functions inherited from casacore::ByteIO
	ByteIO (const ByteIO &byteIO)
	Make copy constructor and assignment protected, so a user cannot use them (but a derived class can).

ByteIO &	operator= (const ByteIO &byteIO)

Detailed Description

Class for unbuffered IO on a file.

Intended use:

Public interface

Review Status

Reviewed By:: Friso Olnon
Date Reviewed:: 1996/11/06
Test programs:: tByteIO

Prerequisite

ByteIO class
file descriptors

Synopsis

This class is a specialization of class FiledesIO to make it easier to open a file. It reads/writes the data directly instead of using a buffer to reduce the number of IO-operations. It is meant for file access using large reads and writes as done by MultiFile.

Optionally the file can be used with O_DIRECT to bypass the system's file cache for more predictable IO behaviour which can be of importance in real-time applications.

Motivation

Make it possible to use the Casacore IO functionality on any file. In this way any device can be hooked to the IO framework.

Definition at line 68 of file FileUnbufferedIO.h.

Constructor & Destructor Documentation

◆ FileUnbufferedIO() [1/2]

casacore::FileUnbufferedIO::FileUnbufferedIO	(	const RegularFile &	fileName,
		ByteIO::OpenOption	option,
		Bool	useODirect = `False`
	)

explicit

The constructor opens or creates a file.

For option NewNoReplace it is checked if the file does not exist yet. If useODirect=True and if supported by the OS, the file will be opened with O_DIRECT which bypasses the kernel's file cache for more predictable I/O behaviour. It requires the size and the alignment of the data read or written to be a multiple of the the disk's logical block size.

◆ ~FileUnbufferedIO()

casacore::FileUnbufferedIO::~FileUnbufferedIO ( )

override

The destructor closes the file.

◆ FileUnbufferedIO() [2/2]

casacore::FileUnbufferedIO::FileUnbufferedIO ( const FileUnbufferedIO & )

delete

Copy constructor and assignment cannot be used.

Member Function Documentation

◆ operator=()

FileUnbufferedIO & casacore::FileUnbufferedIO::operator= ( const FileUnbufferedIO & )

delete

◆ reopenRW()

void casacore::FileUnbufferedIO::reopenRW ( )

overridevirtual

Reopen the file for read/write.

Nothing is done if already opened for read/write. An exception is thrown if the file is readonly.

Reimplemented from casacore::ByteIO.

Member Data Documentation

◆ itsUseODirect

Bool casacore::FileUnbufferedIO::itsUseODirect

private

Definition at line 94 of file FileUnbufferedIO.h.

The documentation for this class was generated from the following file:

casa/IO/FileUnbufferedIO.h

Public Member Functions

Private Attributes

Additional Inherited Members