casacore::MFFileIO Class Reference

Class for IO on a virtual file in a MultiFileBase. More...

#include <MFFileIO.h>

Inheritance diagram for casacore::MFFileIO:

Public Member Functions
	MFFileIO (MultiFileBase &, const String &name, ByteIO::OpenOption=ByteIO::Old)
	Open or create a virtual file with the given name.
virtual	~MFFileIO ()
	The destructor flushes and closes the file.
virtual Int64	read (Int64 size, void *buf, Bool throwException=True)
	Read `size` bytes from the byte stream.
virtual void	write (Int64 size, const void *buffer)
	Write a block at the given offset.
virtual void	reopenRW ()
	Reopen the file (and possibly underlying MultiFileBase) for read/write access.
void	remove ()
	Remove the file from the MultiFileBase object.
virtual void	flush ()
	Flush the file by writing all dirty data and all header info.
virtual Int64	length ()
	Get the length of the file.
virtual Bool	isReadable () const
	The file is always readable.
virtual Bool	isWritable () const
	Is the file writable?
virtual Bool	isSeekable () const
	The file is always seekable.
virtual String	fileName () const
	Get the file name of the file attached.
virtual void	fsync ()
	Fsync the file (i.e.
virtual Int64	doSeek (Int64 offset, ByteIO::SeekOption)
	Reset the position pointer to the given value.
Private Attributes
MultiFileBase &	itsFile
Int64	itsPosition
String	itsName
Int	itsId

Detailed Description

Class for IO on a virtual file in a MultiFileBase.

Intended use:

Public interface

Review Status

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

Synopsis

This class is a specialization of class ByteIO . It uses a MultiFileBase as the data store.

Similar to a regular file it is possible to read and write data and to seek in the file. The object keeps track of the current file offset.

Example

 // Create a new MultiFile using a block size of 1 MB.
 MultiFile mfile("file.mf', ByteIO::New, 1048576);
 // Create a virtual file in it.
 MFFileIO mf1(mfile, "mf1", ByteIO::New);
 // Use it (for example) as the sink of AipsIO.
 AipsIO stream (&mf1);
 // Write values.
 stream << (Int)10;
 stream << True;
 // Seek to beginning of file and read data in.
 stream.setpos (0);
 Int vali;
 Bool valb;
 stream >> vali >> valb;

Definition at line 77 of file MFFileIO.h.

Constructor & Destructor Documentation

casacore::MFFileIO::MFFileIO	(	MultiFileBase &	,
		const String &	name,
		ByteIO::OpenOption	= `ByteIO::Old`
	)

Open or create a virtual file with the given name.

Note that only the basename of the file name is actually used. It is created in the given MultiFileBase.

virtual casacore::MFFileIO::~MFFileIO ( ) [virtual]

The destructor flushes and closes the file.

Member Function Documentation

virtual Int64 casacore::MFFileIO::doSeek	(	Int64	offset,
		ByteIO::SeekOption
	)			`[virtual]`

Reset the position pointer to the given value.

It returns the new position.

Implements casacore::ByteIO.

virtual String casacore::MFFileIO::fileName ( ) const [virtual]

Get the file name of the file attached.

Reimplemented from casacore::ByteIO.

virtual void casacore::MFFileIO::flush ( ) [virtual]

Flush the file by writing all dirty data and all header info.

Reimplemented from casacore::ByteIO.

virtual void casacore::MFFileIO::fsync ( ) [virtual]

Fsync the file (i.e.

force the data to be physically written).

Reimplemented from casacore::ByteIO.

virtual Bool casacore::MFFileIO::isReadable ( ) const [virtual]

The file is always readable.

Implements casacore::ByteIO.

virtual Bool casacore::MFFileIO::isSeekable ( ) const [virtual]

The file is always seekable.

Implements casacore::ByteIO.

virtual Bool casacore::MFFileIO::isWritable ( ) const [virtual]

Is the file writable?

Implements casacore::ByteIO.

virtual Int64 casacore::MFFileIO::length ( ) [virtual]

Get the length of the file.

Implements casacore::ByteIO.

virtual Int64 casacore::MFFileIO::read	(	Int64	size,
		void *	buf,
		Bool	throwException = `True`
	)			`[virtual]`

Read size bytes from the byte stream.

Returns the number of bytes actually read, or a negative number if an error occurred. Will also throw an Exception (AipsError) if the requested number of bytes could not be read unless throwException is set to False.

Implements casacore::ByteIO.

void casacore::MFFileIO::remove ( )

Remove the file from the MultiFileBase object.

It makes the object invalid by setting the fileId to -1.

virtual void casacore::MFFileIO::reopenRW ( ) [virtual]

Reopen the file (and possibly underlying MultiFileBase) for read/write access.

Nothing will be done if the stream is writable already. An exception will be thrown if it is not possible to reopen it for read/write access.

Reimplemented from casacore::ByteIO.