.TH "ost::SharedFile" 3 "Sun Dec 27 2020" "GNU CommonC++" \" -*- nroff -*-
.ad l
.nh
.SH NAME
ost::SharedFile \- This class defines a database I/O file service that can be shared by multiple processes\&.  

.SH SYNOPSIS
.br
.PP
.PP
\fC#include <file\&.h>\fP
.PP
Inherits \fBost::RandomFile\fP\&.
.SS "Public Member Functions"

.in +1c
.ti -1c
.RI "\fBSharedFile\fP (const char *path)"
.br
.RI "Open or create a new database file\&. "
.ti -1c
.RI "\fBSharedFile\fP (const \fBSharedFile\fP &file)"
.br
.RI "Create a shared file as a duplicate of an existing shared file\&. "
.ti -1c
.RI "virtual \fB~SharedFile\fP ()"
.br
.RI "Close and finish a database file\&. "
.ti -1c
.RI "\fBError\fP \fBrestart\fP (void)"
.br
.RI "Restart an existing database; close and re-open\&. "
.ti -1c
.RI "\fBError\fP \fBfetch\fP (caddr_t address=NULL, \fBccxx_size_t\fP length=0, off_t position=\-1)"
.br
.RI "Lock and Fetch a portion of the file into physical memory\&. "
.ti -1c
.RI "\fBError\fP \fBupdate\fP (caddr_t address=NULL, \fBccxx_size_t\fP length=0, off_t position=\-1)"
.br
.RI "Update a portion of a file from physical memory\&. "
.ti -1c
.RI "\fBError\fP \fBclear\fP (\fBccxx_size_t\fP length=0, off_t pos=\-1)"
.br
.RI "Clear a lock held from a previous fetch operation without updating\&. "
.ti -1c
.RI "\fBError\fP \fBappend\fP (caddr_t address=NULL, \fBccxx_size_t\fP length=0)"
.br
.RI "Add new data to the end of the file\&. "
.ti -1c
.RI "off_t \fBgetPosition\fP (void)"
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.RI "Fetch the current file position marker for this thread\&. "
.ti -1c
.RI "bool \fBoperator++\fP (void)"
.br
.ti -1c
.RI "bool \fBoperator\-\-\fP (void)"
.br
.in -1c
.SS "Additional Inherited Members"
.SH "Detailed Description"
.PP 
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\&.
.PP
\fBSharedFile\fP is used when a database may be shared between multiple processes\&. \fBSharedFile\fP automatically applies low level byte-range 'file
locks', and provides an interface to fetch and release byte-range locked portions of a file\&.
.PP
\fBAuthor\fP
.RS 4
David Sugar dyfet@ostel.com
.RE
.PP
This class defines a database I/O file service that can be shared by multiple processes\&. 
.SH "Constructor & Destructor Documentation"
.PP 
.SS "ost::SharedFile::SharedFile (const char * path)"

.PP
Open or create a new database file\&. You should also use Initial\&.
.PP
\fBParameters\fP
.RS 4
\fIpath\fP pathname of database to open\&. 
.RE
.PP

.SS "ost::SharedFile::SharedFile (const \fBSharedFile\fP & file)"

.PP
Create a shared file as a duplicate of an existing shared file\&. 
.PP
\fBParameters\fP
.RS 4
\fIfile\fP original file\&. 
.RE
.PP

.SS "virtual ost::SharedFile::~SharedFile ()\fC [virtual]\fP"

.PP
Close and finish a database file\&. 
.SH "Member Function Documentation"
.PP 
.SS "\fBError\fP ost::SharedFile::append (caddr_t address = \fCNULL\fP, \fBccxx_size_t\fP length = \fC0\fP)"

.PP
Add new data to the end of the file\&. Locks file during append\&.
.PP
\fBParameters\fP
.RS 4
\fIaddress\fP address to use, or NULL if same as last I/O\&. 
.br
\fIlength\fP length to use, or 0 if same as last I/O\&. 
.RE
.PP

.SS "\fBError\fP ost::SharedFile::clear (\fBccxx_size_t\fP length = \fC0\fP, off_t pos = \fC\-1\fP)"

.PP
Clear a lock held from a previous fetch operation without updating\&. 
.PP
\fBReturns\fP
.RS 4
errSuccess on success\&. 
.RE
.PP
\fBParameters\fP
.RS 4
\fIlength\fP length to use, or 0 if same as last I/O\&. 
.br
\fIpos\fP file position to use or -1 if same as last I/O\&. 
.RE
.PP

.SS "\fBError\fP ost::SharedFile::fetch (caddr_t address = \fCNULL\fP, \fBccxx_size_t\fP length = \fC0\fP, off_t position = \fC\-1\fP)"

.PP
Lock and Fetch a portion of the file into physical memory\&. This can use state information to fetch the current record multiple times\&.
.PP
\fBReturns\fP
.RS 4
errSuccess on success\&. 
.RE
.PP
\fBParameters\fP
.RS 4
\fIaddress\fP address to use, or NULL if same as last I/O\&. 
.br
\fIlength\fP length to use, or 0 if same as last I/O\&. 
.br
\fIposition\fP file position to use -1 if same as last I/O\&. 
.RE
.PP

.SS "off_t ost::SharedFile::getPosition (void)"

.PP
Fetch the current file position marker for this thread\&. 
.PP
\fBReturns\fP
.RS 4
file position offset\&. 
.RE
.PP

.SS "bool ost::SharedFile::operator++ (void)"

.SS "bool ost::SharedFile::operator\-\- (void)"

.SS "\fBError\fP ost::SharedFile::restart (void)\fC [inline]\fP, \fC [virtual]\fP"

.PP
Restart an existing database; close and re-open\&. 
.PP
\fBReturns\fP
.RS 4
errSuccess if successful\&. 
.RE
.PP

.PP
Reimplemented from \fBost::RandomFile\fP\&.
.SS "\fBError\fP ost::SharedFile::update (caddr_t address = \fCNULL\fP, \fBccxx_size_t\fP length = \fC0\fP, off_t position = \fC\-1\fP)"

.PP
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\&.
.PP
\fBReturns\fP
.RS 4
errSuccess on success\&. 
.RE
.PP
\fBParameters\fP
.RS 4
\fIaddress\fP address to use, or NULL if same as last I/O\&. 
.br
\fIlength\fP length to use, or 0 if same as last I/O\&. 
.br
\fIposition\fP file position to use or -1 if same as last I/O\&. 
.RE
.PP


.SH "Author"
.PP 
Generated automatically by Doxygen for GNU CommonC++ from the source code\&.