Ubuntu Manpage: FBB::SharedStreambuf - streambuf interfacing to shared memory

Provided by: libbobcat-dev_3.19.01-1ubuntu1_amd64

NAME

       FBB::SharedStreambuf - streambuf interfacing to shared memory

SYNOPSIS

       #include <bobcat/sharedstreambuf>
       Linking option: -lpthread -lbobcat

DESCRIPTION

       This  class  implements  a  specialization  of  the  std::streambuf class, allowing stream
       classes   (std::istream,   std::ostream,   FBB::ISharedStream,   FBB::OSharedStream    and
       FBB::SharedStream to perform I/O operations on shared memory. FBB::SharedStreambuf objects
       interface to an FBB::SharedStream objects.

NAMESPACE

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

INHERITS FROM

       std::streambuf,  FBB::SharedEnum__  (cf.  sharedmemory(3bobcat)  for  a description of the
       latter class).

CONSTRUCTORS

o SharedStreambuf():
The default constructor defines a stub SharedStreambuf object that cannot
immediately be used to access shared memory. To use it, its member setMemory must
first be called.

o SharedStreambuf(size_t maxSize, SizeUnit sizeUnit, std::ios::openmode openMode =
std::ios::in | std::ios::out, size_t access = 0600):
This constructor creates a shared memory segment having a capacity of at least
maxSize * sizeUnit bytes. By default, the shared memory segment is opened for
reading and writing. Different from the open modes used for file streams, creating
a shared memory stream with open modes ios::in | ios::out is OK. In this case the
shared memory segment is created and once information has been written to the
shared memory it can also be read again. The shared memory’s access rights are
defined by the access parameter, using the well-known (chmod(1)) way to define the
access rights for the owner, the group and others, using octal digits. If
construction succeeds the shared memory is ready for use. If construction fails, an
FBB::Exception is thrown.

o SharedStreambuf(int id, std::ios::openmode openMode = std::ios::in |
std::ios::out):
This constructor connects to a shared memory segment having ID id. If construction
succeeds the shared memory is ready for use. If construction fails (e.g., no shared
memory segment having ID id exists, an FBB::Exception is thrown. Specifying the
ios::trunc flag or specifying ios::out without also specifying ios::in immediately
clears the contents of the shared memory. ) Copy and move constructors are not
available.

OVERLOADED OPERATORS

              The overloaded move and copy assignment operators are not available.

MEMBER FUNCTIONS

              All members of std::streambuf and the enum  values  kB,  MB,  and  GB,  defined  by
              FBB::SharedEnum__ are available.

       o      void clear():
              The  shared  memory  is first locked. Next, all shared data segment are returned to
              the operating system, after which the shared  memory  segment  is  unlocked  again.
              Returning  from clear the shared memory The FBB::SharedMemory object is effectively
              re-initialized, with offset and nReadable returning 0.

       o      int id() const:
              The ID of the shared memory segment is returned.

       o      void kill():
              Without locking the shared  memory  the  FBB::SharedStreambuf’s  shared  memory  is
              deleted. The FBB::SharedStreambuf object is unusable after returning from kill.

       o      void remove():
              The  shared  memory  is  locked,  and  the  FBB::SharedStreambuf’s shared memory is
              deleted. The FBB::SharedStreambuf object is unusable after returning from remove.

       o      void setMemory(SharedMemory &&tmp):
              The anonymous temporary SharedMemory object that is passed to setMemory defines the
              new  shared  memory segment to which the FBB::SharedStreambuf object interfaces. It
              can also be called to reuse a FBB::SharedStreambuf object again after calling  kill
              or remove.

       o      void memInfo(std::ostream &out):
              Information  about  the  SharedMemory  object  is inserted into the provide ostream
              object. The IDs of the shared segments, their sizes, the maximum number  of  shared
              memory  segments,  the number of bytes that can be read from the shared memory, and
              its actual storage capacity, etc., are displayed. The inserted information  is  not
              terminated by a final newline character.

PROTECTED MEMBER FUNCTION

       o      void setOpenMode(std::ios::openmode flag):
              The streambuf’s openmode is changed to the settings defined by flag. This member is
              used by, e.g., SharedStream::open, to adapt the FBB::SharedStreambuf’s openmode  to
              the flags that are passed to open.

EXAMPLE

       See the sharedstream(3bobcat) man page.

FILES

       bobcat/sharedstreambuf - defines the class interface

BUGS

       Note  that by default exceptions thrown from within a std::stream object are caught by the
       stream object, setting its ios::failbit flag.  To  allow  exceptions  to  leave  a  stream
       object, its exceptions member can be called, e.g., using:

           myStream.exceptions(ios::failbit | ios::badbit | ios::eofbit);

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).