Binary Data File. More...

#include <DataFile.h>

Public Member Functions
DataFile *	reference ()
	Add reference to current DataFile.

size_t	refCount () const
	Get reference count.

bool	isTaggedFile ()
	Does the file follow the 2-1-1 format w/ cookie and tags?

void	release ()
	De-reference a data file (Call instead of delete). More...

bool	is_writable () const
	Returns true if DataFile is writable.

FileOffset	getSize () const
	Get current file size in bytes. More...

void	reopen ()
	Closes and re-opens a DataFile. More...

const stdString &	getFilename ()
	Get full name of data file.

const stdString &	getDirname ()
	Get directory name of data file.

const stdString &	getBasename ()
	Get base name of data file.

class DataHeader *	getHeader (FileOffset offset)
	Read header at given offset. More...

size_t	getHeaderSize (const stdString &name, DbrType dbr_type, DbrCount dbr_count, size_t num_samples)
	Get size of a header with given parameters.

class DataHeader *	addHeader (const stdString &name, DbrType dbr_type, DbrCount dbr_count, double period, size_t num_samples)
	Add a new DataHeader to the file. More...

void	addCtrlInfo (const CtrlInfo &info, FileOffset &offset)
	Add CtrlInfo to the data file. More...

void	write (const CtrlInfo &ctrlInfo, FileOffset offset)
	Write ctrlInfo.

void	read (CtrlInfo &ctrlInfo, FileOffset offset)
	Read ctrlInfo.

Static Public Member Functions
static DataFile *	reference (const stdString &dirname, const stdString &basename, bool for_write)
	Reference a data file. More...

static void	show_all_sizes ()
	Show all size.

static size_t	clear_cache ()
	Close as many data files as possible. More...

static void	close_all ()
	Close all data files. More...

Public Attributes
bool	is_new_file
	Indicates if this file was newly created.

Static Public Attributes
static const uint32_t	cookie = 0x41444631
	== 'ADF1', Archive Data File 1

Friends
class	DataHeader

class	DataWriter

class	RawDataReaderEA3

Detailed Description

Binary Data File.

The DataFile class handles access to the binary data files. One important feature is reference counting and caching. When the ArchiveEngine adds samples, it is very likely to add samples for several channels to the same collection of data files.

When referencing a data file for the first time, the file gets opened.
When releasing it, the data file stays open.
During a write cycle, it is likely that at least some of the channels reference the same files, and voila: The file is already open.
Finally, clear_cache() should be called to close all the data files.

Member Function Documentation

void DataFile::addCtrlInfo	(	const CtrlInfo &	info,
		FileOffset &	offset
	)

Add CtrlInfo to the data file.

Parameters

info	info
offset	is set to offset of the info

Exceptions

GenericException in case of error.

class DataHeader* DataFile::addHeader	(	const stdString &	name,
		DbrType	dbr_type,
		DbrCount	dbr_count,
		double	period,
		size_t	num_samples
	)

Add a new DataHeader to the file.

Returns: Alloc'ed header. The header's data type and buffer size info will be initialized. Links (dir, prev, next) need to be configured and saved.

Exceptions

GenericException in case of error.

static size_t DataFile::clear_cache ( )

static

Close as many data files as possible.

Closes all data files that are fully released. For example, the SpreadsheetReader will invoke this in its destructor. Since there might be other readers still open, only the application can decide when to close all files, which it should do via close_all.

See Also: close_all

Returns: Returns the number of files which are left open because there is still a reference to them.

static void DataFile::close_all ( )

static

Close all data files.

The application should invoke this at times where it assumes that all readers/writers are done to check consistency and prevent files left dangling open.

See Also: clear_cache

Exceptions

GenericException if data files are referenced (because there's still a reader?).

class DataHeader* DataFile::getHeader ( FileOffset offset )

Read header at given offset.

Returns: Alloc'ed DataHeader, to be relased by caller.

Exceptions

GenericException in case of error.

FileOffset DataFile::getSize ( ) const

Get current file size in bytes.

Exceptions

GenericException on file seek error.

static DataFile* DataFile::reference	(	const stdString &	dirname,
		const stdString &	basename,
		bool	for_write
	)

static

Reference a data file.

Either opens a new one, or returns another reference to a file that is in the DataFile cache.

Parameters

dirname,:	Path/directory up to the filename
basename,:	filename inside dirname
for_write,:	open for writing or read-only?

The reference call will normalize the dirname/basename/filename. As an example, it's acceptable to pass a basename that still contains pieces of a pathname, which will then be moved into the dirname.

Returns: The referenced DataFile. Do not delete; use release.

See Also: release

Exceptions

GenericException on error.

void DataFile::release ( )

De-reference a data file (Call instead of delete).

See Also: clear_cache

void DataFile::reopen ( )

Closes and re-opens a DataFile.

For synchr. with a file that's actively written by another prog. is might help to reopen.

Exceptions

GenericException on error.

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

/home/malitsky/projects/epics-archiver/sourceforge/trunk/ea4-cpp/include/classic/storage/DataFile.h

Public Member Functions

Static Public Member Functions

Public Attributes

Static Public Attributes

Friends

Detailed Description

Member Function Documentation