Ubuntu Manpage: FBB::Sharedpos - Shared Memory offset controller

Provided by: libbobcat-dev_6.04.00-1ubuntu3_amd64

NAME

       FBB::Sharedpos - Shared Memory offset controller

SYNOPSIS

       #include <bobcat/sharedpos>
       Linking option: -lbobcat

DESCRIPTION

       The  class  SharedPos  is  a support class for Bobcat’s shared memory handling classes. It
       controls the shared memory read/write ofset and  ensures  that  shared  memory  operations
       never exceed the shared memory’s maximum offset.

       The  class  SharedPos  has several public members, but they are primarily useful for other
       Shared* classes offered by  Bobcat.  There  is  probably  little  use  for  a  stand-alone
       SharedPos object.

       In the descriptions of the class’s member functions offset refers to the read/write offset
       within  a  FBB::SharedSegment(3bobcat)   object   for   which   SharedPos   performs   the
       offset-administration.

NAMESPACE

       FBB
       All  constructors,  members,  operators  and manipulators, mentioned in this man-page, are
       defined in the namespace FBB.

INHERITS FROM

TYPEDEFS AND ENUMS

CONSTRUCTORS

       Default, copy and move constructors as well as the copy and move assignment operators  are
       available.   The   default   constructor   does   not   yet   monitor  the  offset  of  an
       FBB::SharedSegment object. The member reset is used to start monitoring offsets.

OVERLOADED OPERATORS

       o      void operator++():
              The offset is incremented. If this member is called when the offset is equal to the
              shared memory’s maximum offset an FBB::Exception is thrown.

       o      void operator+=(size_t len):
              The  offset  is  incremented  by  len.  If offset + len exceeds the shared memory’s
              maximum offset then the offset is set to the maximum offset and  an  FBB::Exception
              is thrown.

       o      std::ostream &operator<<(std::ostream &out, SharedPos const &pos):
              Inserts information about the SharedPos object into out.

MEMBER FUNCTIONS

Note: the behavior of member functions returning values which refer to information of an
FBB::SharedSegment is undefined until the member reset has been called.

o bool atMaxOffset() const:
Returns true if offset equals the maximum offset that can be used for the
configured FBB::SharedSegment object.

o size_t blockIdx() const:
The index of the configured FBB::SharedSegment object’s shared segment data block
to which offset refers is returned.

o size_t blockOffset() const:
The offset within the shared segment data block matching the member offset’s return
value is returned.

o bool eof() const:
Returns true if offset exceeds the maximum offset of any character ever written to
the shared memory to which the SharedPos object interfaces. If eof returns true
information may still be written to the shared memory: writing is possible until
the maximum shared memory segment offset has been reached.

o std::streamsize eos() const:
The offset just beyond the maximum offset for the current shared segment data block
is returned. E.g., if blockIdx returns 5, and the size of the shared segment data
blocks equals 2000, then eos returns 12000 (the first offset of segment 6).

o std::streamsize maxOffset() const:
The maximum possible offset that can be used for the currently monitored
FBB::SharedSegment is returned.

o std::streamsize offset() const:
The offset within the currently monitored shared memory segment is returned.

o void reset(SharedSegment *sharedData):
The SharedPos object is reset to monitor the offset of the FBB::SharedSegment
object whose address is passed as argument to reset. The address must point to a
sharedsegment(3bobcat) object that must exist until the end of the SharedPos
object’s lifetime or until its next reset call. Immediately after calling reset
offset is reset to 0.

o std::streamsize showmanyc() const:
The number of characters that can be read from the current shared segment data
block is returned. This member interrogates the number of readable characters in
the shared memory segment. This number may change while this member is being
executed. In order to receive a stable return value, calling functions should have
obtained a lock on the FBB::SharedSegment data before calling this member. See also
the sharedsegment(3bobcat) man-page.

o std::ios::pos_type seek(std::ios::off_type offset, std::ios::seekdir origin =
std::ios::beg):
The monitored offset is changed to this member’s offset argument, relative to
origin. Seeking beyond eof is OK. However, -1 is returned when seeking beyond
maxOffset or seeking before the shared segment’s offset 0.

EXAMPLE

       See the sharedstream(3bobcat) man page.

FILES

       bobcat/sharedpos - defines the class interface

BUGS

       None Reported.

BOBCAT PROJECT FILES

       o      https://fbb-git.gitlab.io/bobcat/: gitlab project page;

       o      bobcat_6.04.00-x.dsc: detached signature;

       o      bobcat_6.04.00-x.tar.gz: source archive;

       o      bobcat_6.04.00-x_i386.changes: change log;

       o      libbobcat1_6.04.00-x_*.deb: debian package containing the libraries;

       o      libbobcat1-dev_6.04.00-x_*.deb:  debian  package  containing the libraries, headers
              and manual pages;

BOBCAT

       Bobcat is an acronym of `Brokken’s Own Base Classes And Templates’.

COPYRIGHT

       This is free software, distributed under the terms  of  the  GNU  General  Public  License
       (GPL).

AUTHOR

       Frank B. Brokken (f.b.brokken@rug.nl).