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 SharedFile:

Collaboration diagram for SharedFile:

Public Types
enum	Error {   errSuccess = 0, errNotOpened, errMapFailed, errInitFailed,   errOpenDenied, errOpenFailed, errOpenInUse, errReadInterrupted,   errReadIncomplete, errReadFailure, errWriteInterrupted, errWriteIncomplete,   errWriteFailure, errLockFailure, errExtended }
typedef enum Error	Error
enum	Access { accessReadOnly = O_RDONLY, accessWriteOnly = O_WRONLY, accessReadWrite = O_RDWR }
typedef enum Access	Access
enum	Open {   openReadOnly = O_RDONLY, openWriteOnly = O_WRONLY, openReadWrite = O_RDWR, openAppend = O_WRONLY | O_APPEND,   openSync = O_RDWR, openTruncate = O_RDWR | O_TRUNC }
typedef enum Open	Open
enum	Attr { attrInvalid = 0, attrPrivate = 0400 | 0200, attrGroup = attrPrivate | 0040 | 0020, attrPublic = attrGroup | 0004 | 0002 }
typedef enum Attr	Attr
enum	Mapping { mappedRead = accessReadOnly, mappedWrite = accessWriteOnly, mappedReadWrite = accessReadWrite }
typedef enum Mapping	Mapping
enum	Complete { completionImmediate, completionDelayed, completionDeferred }
typedef enum Complete	Complete

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

Static Public Member Functions
static const char *	getExtension (const char *path)
static const char *	getFilename (const char *path)
static char *	getFilename (const char *path, char *buffer, size_t size=64)
static char *	getDirname (const char *path, char *buffer, size_t size=256)
static char *	getRealpath (const char *path, char *buffer, size_t size=256)

Protected Types
typedef struct File::_fcb	fcb_t

Protected Member Functions
Error	error (Error errid, char *errstr=NULL)
	Post an error event. More...
Error	error (char *err)
	Post an extended string error message. More...
void	setError (bool enable)
	Used to enable or disable throwing of exceptions on errors. More...
Error	setCompletion (Complete mode)
	Used to set file completion modes. More...
void	setTemporary (bool enable)
	Used to set the temporary attribute for the file. More...
virtual Attr	initialize (void)
	This method is used to initialize a newly created file as indicated by the "initial" flag. More...
void	final (void)
	Close the file. More...
void	nameMutex (const char *name)
	Enable setting of mutex name for deadlock debug. More...
void	enterMutex (void)
	Entering a Mutex locks the mutex for the current thread. More...
void	enter (void)
	Future abi will use enter/leave/test members. More...
void	leave (void)
	Future abi will use enter/leave/test members. More...
bool	test (void)
	Future abi will use enter/leave/test members. More...
bool	tryEnterMutex (void)
	Tries to lock the mutex for the current thread. More...
void	leaveMutex (void)
	Leaving a mutex frees that mutex for use by another thread. More...

Static Protected Member Functions
static void	setDebug (bool mode)
	Enable or disable deadlock debugging. More...

Protected Attributes
int	fd
Access	access
char *	pathname
struct {
unsigned   count: 16
bool   thrown: 1
bool   initial: 1
bool   immediate: 1
bool   temp: 1
}	flags

Private Member Functions
Error	open (const char *path)

Private Attributes
fcb_t	fcb

Related Functions
(Note that these are not member functions.)
bool __EXPORT	isDir (const char *path)
bool __EXPORT	isFile (const char *path)
bool __EXPORT	isDevice (const char *path)
bool __EXPORT	canAccess (const char *path)
bool __EXPORT	canModify (const char *path)
time_t __EXPORT	lastModified (const char *path)
time_t __EXPORT	lastAccessed (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 648 of file file.h.

Member Typedef Documentation

typedef enum Access File::Access

inherited

Definition at line 150 of file file.h.

typedef enum Attr File::Attr

inherited

Definition at line 213 of file file.h.

typedef enum Complete File::Complete

inherited

Definition at line 239 of file file.h.

typedef enum Error File::Error

inherited

Definition at line 137 of file file.h.

typedef struct File::_fcb File::fcb_t

protectedinherited

typedef enum Mapping File::Mapping

inherited

Definition at line 240 of file file.h.

typedef enum Open File::Open

inherited

Definition at line 183 of file file.h.

Member Enumeration Documentation

enum File::Access

inherited

Enumerator
accessReadOnly
accessWriteOnly
accessReadWrite

Definition at line 139 of file file.h.

enum File::Attr

inherited

Enumerator
attrInvalid
attrPrivate
attrGroup
attrPublic

Definition at line 199 of file file.h.

enum File::Complete

inherited

Enumerator
completionImmediate
completionDelayed
completionDeferred

Definition at line 233 of file file.h.

enum File::Error

inherited

Enumerator
errSuccess
errNotOpened
errMapFailed
errInitFailed
errOpenDenied
errOpenFailed
errOpenInUse
errReadInterrupted
errReadIncomplete
errReadFailure
errWriteInterrupted
errWriteIncomplete
errWriteFailure
errLockFailure
errExtended

Definition at line 120 of file file.h.

enum File::Mapping

inherited

Enumerator
mappedRead
mappedWrite
mappedReadWrite

Definition at line 228 of file file.h.

enum File::Open

inherited

Enumerator
openReadOnly
openWriteOnly
openReadWrite
openAppend
openSync
openTruncate

Definition at line 171 of file file.h.

Constructor & Destructor Documentation

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::SharedFile

(

const SharedFile &

file

)

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

Parameters

file	original file.

virtual SharedFile::~SharedFile ( )

virtual

Close and finish a database file.

Member Function Documentation

Error 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.

Error 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.

void Mutex::enter ( void  )

inlineinherited

Future abi will use enter/leave/test members.

Definition at line 263 of file thread.h.

void Mutex::enterMutex ( void  )

inherited

Entering a Mutex locks the mutex for the current thread.

This also can be done using the ENTER_CRITICAL macro or by using the ++ operator on a mutex.

See Also

leaveMutex

Error RandomFile::error ( Error  errid, char *  errstr = NULL  )

protectedinherited

Post an error event.

Returns

error code.

Parameters

errid	error code.
errstr	error message string.

Error RandomFile::error ( char *  err )

inlineprotectedinherited

Post an extended string error message.

Returns

errExtended.

Parameters

err	error string.

Definition at line 447 of file file.h.

Error 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.

void RandomFile::final ( void  )

protectedinherited

Close the file.

off_t RandomFile::getCapacity ( void  )

inherited

Get current file capacity.

Returns

total file size.

static char* File::getDirname ( const char *  path, char *  buffer, size_t  size = 256  )

staticinherited

Error RandomFile::getErrorNumber ( void  )

inlineinherited

Return current error id.

Returns

last error identifier set.

Definition at line 532 of file file.h.

char* RandomFile::getErrorString ( void  )

inlineinherited

Return current error string.

Returns

last error string set.

Definition at line 540 of file file.h.

static const char* File::getExtension ( const char *  path )

staticinherited

static const char* File::getFilename ( const char *  path )

staticinherited

static char* File::getFilename ( const char *  path, char *  buffer, size_t  size = 64  )

staticinherited

off_t SharedFile::getPosition

(

void

)

Fetch the current file position marker for this thread.

Returns

file position offset.

static char* File::getRealpath ( const char *  path, char *  buffer, size_t  size = 256  )

staticinherited

bool RandomFile::initial ( void  )

inherited

This method should be called right after a RandomFile derived object has been created.

This method will invoke initialize if the object is newly created, and set file access permissions appropriately.

Returns

true if file had to be initialized.

virtual Attr RandomFile::initialize ( void  )

protectedvirtualinherited

This method is used to initialize a newly created file as indicated by the "initial" flag.

This method also returns the file access permissions that should be associated with the file. This method should never be called directly, but is instead used to impliment the "Initial" method. Typically one would use this to build an empty database shell when a previously empty database file is created.

Returns

access, or attrInvalid if should be removed.

void Mutex::leave ( void  )

inlineinherited

Future abi will use enter/leave/test members.

Definition at line 269 of file thread.h.

void Mutex::leaveMutex ( void  )

inherited

Leaving a mutex frees that mutex for use by another thread.

If the mutex has been entered (invoked) multiple times (recursivily) by the same thread, then it will need to be exited the same number of instances before it is free for re-use. This operation can also be done using the LEAVE_CRITICAL macro or by the – operator on a mutex.

See Also

enterMutex

void Mutex::nameMutex ( const char *  name )

inlineinherited

Enable setting of mutex name for deadlock debug.

Parameters

name	for mutex.

Definition at line 248 of file thread.h.

Error SharedFile::open ( const char *  path )

private

bool RandomFile::operator! ( void  )

inherited

bool SharedFile::operator++

(

void

)

bool SharedFile::operator--

(

void

)

Error SharedFile::restart ( void  )

inlinevirtual

Restart an existing database; close and re-open.

Returns

errSuccess if successful.

Reimplemented from RandomFile.

Definition at line 681 of file file.h.

Error RandomFile::setCompletion ( Complete  mode )

protectedinherited

Used to set file completion modes.

Returns

errSuccess if okay.

Parameters

mode	completion mode.

Todo:

implement in win32

static void Mutex::setDebug ( bool  mode )

inlinestaticinherited

Enable or disable deadlock debugging.

Parameters

mode	debug mode.

Definition at line 240 of file thread.h.

void RandomFile::setError ( bool  enable )

inlineprotectedinherited

Used to enable or disable throwing of exceptions on errors.

Parameters

enable

true if errors will be thrown.

Definition at line 456 of file file.h.

void RandomFile::setTemporary ( bool  enable )

inlineprotectedinherited

Used to set the temporary attribute for the file.

Temporary files are automatically deleted when closed.

Parameters

enable

true for marking as temporary.

Definition at line 476 of file file.h.

bool Mutex::test ( void  )

inlineinherited

Future abi will use enter/leave/test members.

Returns

true if entered.

Definition at line 277 of file thread.h.

bool Mutex::tryEnterMutex ( void  )

inherited

Tries to lock the mutex for the current thread.

Behaves like enterMutex , except that it doesn't block the calling thread if the mutex is already locked by another thread.

Returns

true if locking the mutex was succesful otherwise false

See Also

enterMutex

leaveMutex

Error 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.

Friends And Related Function Documentation

bool __EXPORT canAccess ( const char *  path )

related

bool __EXPORT canModify ( const char *  path )

related

bool __EXPORT isDevice ( const char *  path )

related

bool __EXPORT isDir ( const char *  path )

related

bool __EXPORT isFile ( const char *  path )

related

time_t __EXPORT lastAccessed ( const char *  path )

related

time_t __EXPORT lastModified ( const char *  path )

related

Field Documentation

Access RandomFile::access

protectedinherited

Definition at line 406 of file file.h.

unsigned RandomFile::count

inherited

Definition at line 413 of file file.h.

fcb_t SharedFile::fcb

private

Definition at line 651 of file file.h.

int RandomFile::fd

protectedinherited

Definition at line 404 of file file.h.

struct { ... } RandomFile::flags

bool RandomFile::immediate

inherited

Definition at line 417 of file file.h.

bool RandomFile::initial

inherited

Definition at line 415 of file file.h.

char* RandomFile::pathname

protectedinherited

Definition at line 410 of file file.h.

bool RandomFile::temp

inherited

Definition at line 419 of file file.h.

bool RandomFile::thrown

inherited

Definition at line 414 of file file.h.

---

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

• file.h