ost::SharedFile Class Reference

This class defines a database I/O file service that can be shared by multiple processes. More...

#include <file.h>

Inheritance diagram for ost::SharedFile:

Collaboration diagram for ost::SharedFile:

Public Member Functions
Error	append (char *address=NULL, ccxx_size_t length=0)
	Add new data to the end of the file.
Error	clear (ccxx_size_t length=0, off_t pos=-1)
	Clear a lock held from a previous fetch operation without updating.
Error	fetch (char *address=NULL, ccxx_size_t length=0, off_t position=-1)
	Lock and Fetch a portion of the file into physical memory.
off_t	getPosition (void)
	Fetch the current file position marker for this thread.
bool	operator++ (void)
bool	operator-- (void)
Error	restart (void)
	Restart an existing database; close and re-open.
	SharedFile (const char *path)
	Open or create a new database file.
	SharedFile (const SharedFile &file)
	Create a shared file as a duplicate of an existing shared file.
Error	update (char *address=NULL, ccxx_size_t length=0, off_t position=-1)
	Update a portion of a file from physical memory.
virtual	~SharedFile ()
	Close and finish a database file.
Public Member Functions inherited from ost::RandomFile
off_t	getCapacity (void)
	Get current file capacity.
Error	getErrorNumber (void) const
	Return current error id.
char *	getErrorString (void) const
	Return current error string.
bool	initial (void)
	This method should be called right after a RandomFile derived object has been created.
	operator bool () const
bool	operator! (void) const
virtual	~RandomFile ()
	Destroy a random access file or it's derived class.

Additional Inherited Members
Data Fields inherited from ost::RandomFile
Protected Member Functions inherited from ost::RandomFile
Error	error (char *err)
	Post an extended string error message.
Error	error (Error errid, char *errstr=NULL)
	Post an error event.
void	final (void)
	Close the file.
virtual Attr	initialize (void)
	This method is used to initialize a newly created file as indicated by the "initial" flag.
	RandomFile (const char *name=NULL)
	Create an unopened random access file.
	RandomFile (const RandomFile &rf)
	Default copy constructor.
Error	setCompletion (Complete mode)
	Used to set file completion modes.
void	setError (bool enable)
	Used to enable or disable throwing of exceptions on errors.
void	setTemporary (bool enable)
	Used to set the temporary attribute for the file.
Protected Attributes inherited from ost::RandomFile
Access	access
int	fd
struct {
unsigned   count: 16
bool   immediate: 1
bool   initial: 1
bool   temp: 1
bool   thrown: 1
}	flags
char *	pathname
Related Symbols inherited from ost::RandomFile
bool	canAccess (const char *path)
bool	canModify (const char *path)
bool	isDevice (const char *path)
bool	isDir (const char *path)
bool	isFile (const char *path)
time_t	lastAccessed (const char *path)
time_t	lastModified (const char *path)

Detailed Description

This class defines a database I/O file service that can be shared by multiple processes.

Each thread should access a dup of the database object, and mutex locks can be used to preserve transaction integrety if multiple threads are used.

SharedFile is used when a database may be shared between multiple processes. SharedFile automatically applies low level byte-range "file locks", and provides an interface to fetch and release byte-range locked portions of a file.

Author

David Sugar dyfet.nosp@m.@ost.nosp@m.el.co.nosp@m.m

This class defines a database I/O file service that can be shared by multiple processes.

Definition at line 563 of file file.h.

Constructor & Destructor Documentation

SharedFile() [1/2]

ost::SharedFile::SharedFile

(

const char *

path

)

Open or create a new database file.

You should also use Initial.

Parameters

path	pathname of database to open.

SharedFile() [2/2]

ost::SharedFile::SharedFile

(

const SharedFile &

file

)

Create a shared file as a duplicate of an existing shared file.

Parameters

file	original file.

Member Function Documentation

append()

Error ost::SharedFile::append	(	char *	address = NULL,
		ccxx_size_t	length = 0 )

Add new data to the end of the file.

Locks file during append.

Parameters

address	address to use, or NULL if same as last I/O.
length	length to use, or 0 if same as last I/O.

clear()

Error ost::SharedFile::clear	(	ccxx_size_t	length = 0,
		off_t	pos = -1 )

Clear a lock held from a previous fetch operation without updating.

Returns

errSuccess on success.

Parameters

length	length to use, or 0 if same as last I/O.
pos	file position to use or -1 if same as last I/O.

fetch()

Error ost::SharedFile::fetch	(	char *	address = NULL,
		ccxx_size_t	length = 0,
		off_t	position = -1 )

Lock and Fetch a portion of the file into physical memory.

This can use state information to fetch the current record multiple times.

Returns

errSuccess on success.

Parameters

address	address to use, or NULL if same as last I/O.
length	length to use, or 0 if same as last I/O.
position	file position to use -1 if same as last I/O.

getPosition()

off_t ost::SharedFile::getPosition

(

void

)

Fetch the current file position marker for this thread.

Returns

file position offset.

restart()

Error ost::SharedFile::restart ( void )

inlinevirtual

Restart an existing database; close and re-open.

Returns

errSuccess if successful.

Reimplemented from ost::RandomFile.

Definition at line 596 of file file.h.

update()

Error ost::SharedFile::update	(	char *	address = NULL,
		ccxx_size_t	length = 0,
		off_t	position = -1 )

Update a portion of a file from physical memory.

This can use state information to commit the last read record. The current lock is also cleared.

Returns

errSuccess on success.

Parameters

address	address to use, or NULL if same as last I/O.
length	length to use, or 0 if same as last I/O.
position	file position to use or -1 if same as last I/O.

---

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

• /builddir/build/BUILD/commoncpp-7.0.1/inc/commoncpp/file.h