Scroll to navigation

ost::ThreadFile(3) Library Functions Manual ost::ThreadFile(3)

NAME

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

SYNOPSIS

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

Public Member Functions


ThreadFile (const char *path)
 
Open or create a new database file. virtual ~ThreadFile ()
 
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)
 
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 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 threads.
 
All threads access a global copy of the database object, and mutex locks can be used to preserve transaction integrety. pread/pwrite calls can be used for optimized I/O when supported.
ThreadFile is meant for use by a threaded database server where multiple threads may each perform semi-independent operations on a given database table stored on disk. A special 'fcb' structure is used to hold file 'state', and pread/pwrite is used whenever possible for optimized I/O. On systems that do not offer pwread/pwrite, a Mutex lock is used to protect concurrent lseek and read/write operations. ThreadFile managed databases are assumed to be used only by the local server and through a single file descriptor.
Author:
David Sugar dyfet@ostel.com This class defines a database I/O file service that can be shared by multiple threads.
 

Constructor & Destructor Documentation

ost::ThreadFile::ThreadFile (const char *path)

Open or create a new database file. You should also use Initial.
Parameters:
path pathname of database to open.
 

virtual ost::ThreadFile::~ThreadFile () [virtual]

Close and finish a database file.

Member Function Documentation

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

Add new data to the end of the file. 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::ThreadFile::fetch (caddr_taddress = NULL, ccxx_size_tlength = 0, off_tposition = -1)

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::ThreadFile::getPosition (void)

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

bool ost::ThreadFile::operator++ (void)

bool ost::ThreadFile::operator-- (void)

Error ost::ThreadFile::restart (void) [virtual]

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

Error ost::ThreadFile::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.
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.
 
 

Author

Generated automatically by Doxygen for GNU CommonC++ from the source code.
Sat Jun 23 2012 GNU CommonC++