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=((void *) 0), 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=((void *) 0), 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 (char *path)
	Open or create a new database file.
	SharedFile (SharedFile &file)
	Create a shared file as a duplicate of an existing shared file.
Error	update (char *address=((void *) 0), 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)
	Return current error id.
char *	getErrorString (void)
	Return current error string.
bool	initial (void)
	This method should be called right after a RandomFile derived object has been created.
bool	operator! (void)
virtual	~RandomFile ()
	Destroy a random access file or it's derived class.

Additional Inherited Members
Public Types inherited from ost::File
enum	Access { accessReadOnly = 00, accessWriteOnly = 01, accessReadWrite = 02 }
typedef enum Access	Access
enum	Attr { attrInvalid = 0, attrPrivate = 0400 | 0200, attrGroup = attrPrivate | ( 0400 >> 3) | ( 0200 >> 3), attrPublic = attrGroup | ( ( 0400 >> 3) >> 3) | ( ( 0200 >> 3) >> 3) }
typedef enum Attr	Attr
enum	Complete { completionImmediate, completionDelayed, completionDeferred }
typedef enum Complete	Complete
enum	Error {   errSuccess = 0, errNotOpened, errMapFailed, errInitFailed,   errOpenDenied, errOpenFailed, errOpenInUse, errReadInterrupted,   errReadIncomplete, errReadFailure, errWriteInterrupted, errWriteIncomplete,   errWriteFailure, errLockFailure, errExtended }
typedef enum Error	Error
enum	Mapping { mappedRead = accessReadOnly, mappedWrite = accessWriteOnly, mappedReadWrite = accessReadWrite }
typedef enum Mapping	Mapping
enum	Open {   openReadOnly = 00, openWriteOnly = 01, openReadWrite = 02, openAppend = 01 | 02000,   openSync = 02 | 04010000, openTruncate = 02 | 01000 }
typedef enum Open	Open
Static Public Member Functions inherited from ost::File
static char *	getDirname (char *path, char *buffer, size_t size=4096)
static char *	getExtension (char *path)
static char *	getFilename (char *path)
static char *	getFilename (char *path, char *buffer, size_t size=255)
static char *	getRealpath (char *path, char *buffer, size_t size=4096)
Protected Types inherited from ost::File
typedef struct ost::File::_fcb	fcb_t
Protected Member Functions inherited from ost::RandomFile
Error	error (Error errid, char *errstr=((void *) 0))
	Post an error event.
Error	error (char *err)
	Post an extended string error message.
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 (char *name=((void *) 0))
	Create an unopened random access file.
	RandomFile (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 Functions inherited from ost::RandomFile
bool	canAccess (char *path)
bool	canModify (char *path)
bool	isDevice (char *path)
bool	isDir (char *path)
bool	isFile (char *path)
time_t	lastAccessed (char *path)
time_t	lastModified (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 541 of file file.h.

Constructor & Destructor Documentation

ost::SharedFile::SharedFile

(

char *

path

)

Open or create a new database file.

You should also use Initial.

Parameters

path	pathname of database to open.

ost::SharedFile::SharedFile

(

SharedFile &

file

)

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

Parameters

file	original file.

Member Function Documentation

Error ost::SharedFile::append	(	char *	address = ((void *) 0),
		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.

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.

Error ost::SharedFile::fetch	(	char *	address = ((void *) 0),
		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.

off_t ost::SharedFile::getPosition

(

void

)

Fetch the current file position marker for this thread.

Returns

file position offset.

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 574 of file file.h.

Error ost::SharedFile::update	(	char *	address = ((void *) 0),
		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.

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

• commoncpp/file.h