.TH "ost::MappedFile" 3 "Wed Oct 31 2018" "GNU CommonC++" \" -*- nroff -*-
.ad l
.nh
.SH NAME
ost::MappedFile \- Create and map a disk file into memory\&.  

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

.in +1c
.ti -1c
.RI "\fBMappedFile\fP (const char *fname, \fBAccess\fP mode)"
.br
.RI "Open a file for mapping\&. "
.ti -1c
.RI "\fBMappedFile\fP (const char *fname, \fBAccess\fP mode, size_t size)"
.br
.RI "Create if not exists, and map a file of specified size into memory\&. "
.ti -1c
.RI "\fBMappedFile\fP (const char *fname, \fBpos_t\fP offset, size_t size, \fBAccess\fP mode)"
.br
.RI "Map a portion or all of a specified file in the specified shared memory access mode\&. "
.ti -1c
.RI "virtual \fB~MappedFile\fP ()"
.br
.RI "Release a mapped section of memory associated with a file\&. "
.ti -1c
.RI "void \fBsync\fP (void)"
.br
.RI "Synchronize the contents of the mapped portion of memory with the disk file and wait for completion\&. "
.ti -1c
.RI "void \fBsync\fP (caddr_t address, size_t len)"
.br
.RI "Synchronize a segment of memory mapped from a segment fetch\&. "
.ti -1c
.RI "void \fBupdate\fP (size_t offset=0, size_t len=0)"
.br
.RI "Map a portion of the memory mapped from the file back to the file and do not wait for completion\&. "
.ti -1c
.RI "void \fBupdate\fP (caddr_t address, size_t len)"
.br
.RI "Update a mapped region back to disk as specified by address and length\&. "
.ti -1c
.RI "void \fBrelease\fP (caddr_t address, size_t len)"
.br
.RI "Release (unmap) a memory segment\&. "
.ti -1c
.RI "caddr_t \fBfetch\fP (size_t offset=0)"
.br
.RI "Fetch a pointer to an offset within the memory mapped portion of the disk file\&. "
.ti -1c
.RI "caddr_t \fBfetch\fP (off_t pos, size_t len)"
.br
.RI "Fetch and map a portion of a disk file to a logical memory block\&. "
.ti -1c
.RI "bool \fBlock\fP (void)"
.br
.RI "Lock the currently mapped portion of a file\&. "
.ti -1c
.RI "void \fBunlock\fP (void)"
.br
.RI "Unlock a locked mapped portion of a file\&. "
.ti -1c
.RI "size_t \fBpageAligned\fP (size_t size)"
.br
.RI "Compute map size to aligned page boundry\&. "
.in -1c
.SS "Additional Inherited Members"
.SH "Detailed Description"
.PP 
Create and map a disk file into memory\&. 

This portable class works under both Posix via mmap and under the win32 API\&. A mapped file can be referenced directly by it's memory segment\&. One can map and unmap portions of a file on demand, and update changed memory pages mapped from files immediately through \fBsync()\fP\&.
.PP
\fBAuthor:\fP
.RS 4
David Sugar dyfet@ostel.com Map a named disk file into memory\&. 
.RE
.PP

.SH "Constructor & Destructor Documentation"
.PP 
.SS "ost::MappedFile::MappedFile (const char * fname, \fBAccess\fP mode)"

.PP
Open a file for mapping\&. More than one segment of a file may be mapped into separate regions of memory\&.
.PP
\fBParameters:\fP
.RS 4
\fIfname\fP file name to access for mapping\&. 
.br
\fImode\fP access mode to map file\&. 
.RE
.PP

.SS "ost::MappedFile::MappedFile (const char * fname, \fBAccess\fP mode, size_t size)"

.PP
Create if not exists, and map a file of specified size into memory\&. 
.PP
\fBParameters:\fP
.RS 4
\fIfname\fP file name to access for mapping\&. 
.br
\fImode\fP access mode to map file\&. 
.br
\fIsize\fP of file to map\&. 
.RE
.PP

.SS "ost::MappedFile::MappedFile (const char * fname, \fBpos_t\fP offset, size_t size, \fBAccess\fP mode)"

.PP
Map a portion or all of a specified file in the specified shared memory access mode\&. Valid mapping modes include mappedRead, mappedWrite, and mappedReadWrite\&.
.PP
\fBParameters:\fP
.RS 4
\fIfname\fP pathname of file to map into memory\&. 
.br
\fIoffset\fP from start of file to begin mapping in bytes\&. 
.br
\fIsize\fP of mapped area in bytes\&. 
.br
\fImode\fP to map file\&. 
.RE
.PP

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

.PP
Release a mapped section of memory associated with a file\&. The mapped area is updated back to disk\&. 
.SH "Member Function Documentation"
.PP 
.SS "caddr_t ost::MappedFile::fetch (size_t offset = \fC0\fP)\fC [inline]\fP"

.PP
Fetch a pointer to an offset within the memory mapped portion of the disk file\&. This really is used for convience of matching operations between Update and Fetch, as one could simply have accessed the base pointer where the file was mapped directly\&.
.PP
\fBParameters:\fP
.RS 4
\fIoffset\fP from start of mapped memory\&. 
.RE
.PP

.PP
References ost::File::_fcb::address\&.
.SS "caddr_t ost::MappedFile::fetch (off_t pos, size_t len)"

.PP
Fetch and map a portion of a disk file to a logical memory block\&. 
.PP
\fBReturns:\fP
.RS 4
pointer to memory segment\&. 
.RE
.PP
\fBParameters:\fP
.RS 4
\fIpos\fP offset of file segment to map\&. 
.br
\fIlen\fP size of memory segment to map\&. 
.RE
.PP

.SS "bool ost::MappedFile::lock (void)"

.PP
Lock the currently mapped portion of a file\&. 
.PP
\fBReturns:\fP
.RS 4
true if pages are locked\&. 
.RE
.PP

.SS "size_t ost::MappedFile::pageAligned (size_t size)"

.PP
Compute map size to aligned page boundry\&. 
.PP
\fBParameters:\fP
.RS 4
\fIsize\fP request\&. 
.RE
.PP
\fBReturns:\fP
.RS 4
page aligned size\&. 
.RE
.PP

.SS "void ost::MappedFile::release (caddr_t address, size_t len)"

.PP
Release (unmap) a memory segment\&. 
.PP
\fBParameters:\fP
.RS 4
\fIaddress\fP address of memory segment to release\&. 
.br
\fIlen\fP length of memory segment to release\&. 
.RE
.PP

.SS "void ost::MappedFile::sync (void)"

.PP
Synchronize the contents of the mapped portion of memory with the disk file and wait for completion\&. This assures the memory mapped from the file is written back\&. 
.SS "void ost::MappedFile::sync (caddr_t address, size_t len)"

.PP
Synchronize a segment of memory mapped from a segment fetch\&. 
.PP
\fBParameters:\fP
.RS 4
\fIaddress\fP memory address to update\&. 
.br
\fIlen\fP size of segment\&. 
.RE
.PP

.SS "void ost::MappedFile::unlock (void)"

.PP
Unlock a locked mapped portion of a file\&. 
.SS "void ost::MappedFile::update (size_t offset = \fC0\fP, size_t len = \fC0\fP)"

.PP
Map a portion of the memory mapped from the file back to the file and do not wait for completion\&. This is useful when mapping a database file and updating a single record\&.
.PP
\fBParameters:\fP
.RS 4
\fIoffset\fP offset into the mapped region of memory\&. 
.br
\fIlen\fP length of partial region (example, record length)\&. 
.RE
.PP

.SS "void ost::MappedFile::update (caddr_t address, size_t len)"

.PP
Update a mapped region back to disk as specified by address and length\&. 
.PP
\fBParameters:\fP
.RS 4
\fIaddress\fP address of segment\&. 
.br
\fIlen\fP length of segment\&. 
.RE
.PP


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