NAME¶

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

SYNOPSIS¶

#include <file.h> Inherits ost::RandomFile.

Public Member Functions¶

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. virtual ~SharedFile () Close and finish a database file. Error restart (void) Restart an existing database; close and re-open. Error fetch (caddr_t address=NULL, ccxx_size_t length=0, off_t position=-1) Lock and Fetch a portion of the file into physical memory. Error update (caddr_t address=NULL, ccxx_size_t length=0, off_t position=-1) Update a portion of a file from physical memory. Error clear ( ccxx_size_t length=0, off_t pos=-1) Clear a lock held from a previous fetch operation without updating. Error append (caddr_t address=NULL, ccxx_size_t length=0) Add new data to the end of the file. off_t getPosition (void) Fetch the current file position marker for this thread. bool operator++ (void) bool operator-- (void)

Additional Inherited Members¶

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:

Constructor & Destructor Documentation¶

ost::SharedFile::SharedFile (const char *path)¶

Open or create a new database file. You should also use Initial. Parameters:

ost::SharedFile::SharedFile (const SharedFile &file)¶

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

virtual ost::SharedFile::~SharedFile () [virtual]¶

Close and finish a database file.

Member Function Documentation¶

Error ost::SharedFile::append (caddr_taddress = NULL, ccxx_size_tlength = 0)¶

Add new data to the end of the file. Locks file during append. Parameters:

Error ost::SharedFile::clear ( ccxx_size_tlength = 0, off_tpos = -1)¶

Clear a lock held from a previous fetch operation without updating. Returns: Parameters:

Error ost::SharedFile::fetch (caddr_taddress = NULL, ccxx_size_tlength = 0, off_tposition = -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: Parameters:

off_t ost::SharedFile::getPosition (void)¶

Fetch the current file position marker for this thread. Returns:

bool ost::SharedFile::operator++ (void)¶

bool ost::SharedFile::operator-- (void)¶

Error ost::SharedFile::restart (void) [inline], [virtual]¶

Restart an existing database; close and re-open. Returns: Reimplemented from ost::RandomFile.

Error ost::SharedFile::update (caddr_taddress = NULL, ccxx_size_tlength = 0, off_tposition = -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: Parameters:

Author¶

Generated automatically by Doxygen for GNU CommonC++ from the source code.