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.TH "ThreadFile" 3 "19 Jul 2003" "CommonC++" \" -*- nroff -*-
.ad l
.nh
.SH NAME
ThreadFile \- This class defines a database I/O file service that can be shared by multiple threads. This class defines a database I/O file service that can be shared by multiple threads.
.SH SYNOPSIS
.br
.PP
\fC#include <file.h>\fP
.PP
Inherits \fBRandomFile\fP.
.PP
.SS "Public Methods"
.in +1c
.ti -1c
.RI "\fBThreadFile\fP (const char *path)"
.br
.RI "\fIOpen or create a new database file.\fP"
.ti -1c
.RI "virtual \fB~ThreadFile\fP ()"
.br
.RI "\fIClose and finish a database file.\fP"
.ti -1c
.RI "\fBError\fP \fBrestart\fP (void)"
.br
.RI "\fIRestart an existing database; close and re-open.\fP"
.ti -1c
.RI "\fBError\fP \fBfetch\fP (char *address=NULL, \fBccxx_size_t\fP length=0, off_t position=-1)"
.br
.RI "\fIFetch a portion of the file into physical memory.\fP"
.ti -1c
.RI "\fBError\fP \fBupdate\fP (char *address=NULL, \fBccxx_size_t\fP length=0, off_t position=-1)"
.br
.RI "\fIUpdate a portion of a file from physical memory.\fP"
.ti -1c
.RI "\fBError\fP \fBappend\fP (char *address=NULL, \fBccxx_size_t\fP length=0)"
.br
.RI "\fIAdd new data to the end of the file.\fP"
.ti -1c
.RI "off_t \fBgetPosition\fP (void)"
.br
.RI "\fIFetch the current file position marker for this thread.\fP"
.ti -1c
.RI "bool \fBoperator++\fP (void)"
.br
.ti -1c
.RI "bool \fBoperator--\fP (void)"
.br
.in -1c
.SH "DETAILED DESCRIPTION"
.PP
This class defines a database I/O file service that can be shared by multiple threads. This class defines a database I/O file service that can be shared by multiple threads.
.PP
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.
.PP
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 \fBMutex\fP 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.
.PP
\fBAuthor: \fP
.in +1c
David Sugar <dyfet@ostel.com>
.PP
.SH "CONSTRUCTOR & DESTRUCTOR DOCUMENTATION"
.PP
.SS "ThreadFile::ThreadFile (const char * path)"
.PP
Open or create a new database file.
.PP
You should also use Initial.
.PP
\fBParameters: \fP
.in +1c
.TP
\fB\fIpath\fP\fP
pathname of database to open.
.SS "virtual ThreadFile::~ThreadFile ()\fC [virtual]\fP"
.PP
Close and finish a database file.
.PP
.SH "MEMBER FUNCTION DOCUMENTATION"
.PP
.SS "\fBError\fP ThreadFile::append (char * address = NULL, \fBccxx_size_t\fP length = 0)"
.PP
Add new data to the end of the file.
.PP
\fBParameters: \fP
.in +1c
.TP
\fB\fIaddress\fP\fP
address to use, or NULL if same as last I/O.
.TP
\fB\fIlength\fP\fP
length to use, or 0 if same as last I/O.
.SS "\fBError\fP ThreadFile::fetch (char * address = NULL, \fBccxx_size_t\fP length = 0, off_t position = -1)"
.PP
Fetch a portion of the file into physical memory.
.PP
This can use state information to fetch the current record multiple times.
.PP
\fBReturns: \fP
.in +1c
errSuccess on success.
.PP
\fBParameters: \fP
.in +1c
.TP
\fB\fIaddress\fP\fP
address to use, or NULL if same as last I/O.
.TP
\fB\fIlength\fP\fP
length to use, or 0 if same as last I/O.
.TP
\fB\fIposition\fP\fP
file position to use -1 if same as last I/O.
.SS "off_t ThreadFile::getPosition (void)"
.PP
Fetch the current file position marker for this thread.
.PP
\fBReturns: \fP
.in +1c
file position offset.
.SS "bool ThreadFile::operator++ (void)"
.PP
.SS "bool ThreadFile::operator-- (void)"
.PP
.SS "\fBError\fP ThreadFile::restart (void)\fC [inline, virtual]\fP"
.PP
Restart an existing database; close and re-open.
.PP
\fBReturns: \fP
.in +1c
errSuccess if successful.
.PP
Reimplemented from \fBRandomFile\fP.
.SS "\fBError\fP ThreadFile::update (char * address = NULL, \fBccxx_size_t\fP length = 0, off_t position = -1)"
.PP
Update a portion of a file from physical memory.
.PP
This can use state information to commit the last read record.
.PP
\fBReturns: \fP
.in +1c
errSuccess on success.
.PP
\fBParameters: \fP
.in +1c
.TP
\fB\fIaddress\fP\fP
address to use, or NULL if same as last I/O.
.TP
\fB\fIlength\fP\fP
length to use, or 0 if same as last I/O.
.TP
\fB\fIposition\fP\fP
file position to use or -1 if same as last I/O.
.SH "AUTHOR"
.PP
Generated automatically by Doxygen for CommonC++ from the source code.
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