trusty (3) sharedpos.3bobcat.gz

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  the
       available shared memory.

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 are available. The default  constructor  does  not  yet  monitor  the
       offsets for a shared memory segment. 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 FBB::SharedPos object into out.

       The copy and move assignment operators are available.

MEMBER FUNCTIONS

       o      bool atMaxOffset() const:
              Returns  true  if  offset equals the maximum offset that can be used for the current shared memory
              segment.
              The behavior of this member is undefined until setup has been called.

       o      size_t blockIdx() const:
              The index of the shared segment data block in which offset is located is returned.

       o      size_t blockOffset() const:
              The index within the shared segment data block matching offset is returned.

       o      bool eof() const:
              Returns true if offset exceeds the maximum offset of any character  ever  written  to  the  shared
              memory  pointed  at  by  sharedData.  If  eof returns true information may still be written to the
              shared memory: writting is possible until the  maximum  shared  memory  segment  offset  has  been
              reached.
              The behavior of this member is undefined until setup has been called.

       o      std::streamsize eos() const:
              The offset just beyond the maximum offset for the current shared segment data block is returned.
              The behavior of this member is undefined until setup has been called.

       o      std::streamsize maxOffset() const:
              The  maximum possible offset that can be used for the currently monitored shared memory segment is
              returned. Zero is returned until setup has been called.

       o      std::streamsize offset() const:
              The offset within the currently monitored shared memory segment  is  returned.  Zero  is  returned
              until setup has been called.

       o      void setup(SharedSegment *sharedData):
              The  SharedPos  object  is  reset  to  monitor  the offset of a new FBB::SharedSegment object. The
              SharedSegment * must point to a SharedSegment segment (cf. sharedsegment(3bobcat)) that must exist
              until  the  end  of the FBB::SharedPos object’s lifetime or until the next reset call. Immediately
              after calling reset offset has the value 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 shared memory segment before calling this
              member. See also the sharedsegment(3bobcat) man-page.
              The behavior of this member is undefined until setup has been called.

       o      std::ios::pos_type seek(std::ios::off_type offset, std::ios::seekdir way = std::ios::beg):
              The monitored offset is changed to this member’s offset argument, relative to way. Seeking  beyond
              eof  is  OK;  -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

SEE ALSO

       bobcat(7), isharedstream(3bobcat), osharedstream(3bobcat),  sharedblock(3bobcat),  sharedmemory(3bobcat),
       sharedmutex(3bobcat), sharedsegment(3bobcat), sharedstream(3bobcat), sharedstreambuf(3bobcat)

BUGS

       None Reported.

DISTRIBUTION FILES

       o      bobcat_3.19.01-x.dsc: detached signature;

       o      bobcat_3.19.01-x.tar.gz: source archive;

       o      bobcat_3.19.01-x_i386.changes: change log;

       o      libbobcat1_3.19.01-x_*.deb: debian package holding the libraries;

       o      libbobcat1-dev_3.19.01-x_*.deb: debian package holding the libraries, headers and manual pages;

       o      http://sourceforge.net/projects/bobcat: public archive location;

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).