Ubuntu Manpage: FBB::ISharedStream - std::istream operations on shared memory

Provided by: libbobcat-dev_3.19.01-1ubuntu1_amd64

NAME

       FBB::ISharedStream - std::istream operations on shared memory

SYNOPSIS

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

DESCRIPTION

       This class offers the features of the std::istream class, operating on shared memory.

NAMESPACE

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

INHERITS FROM

       FBB::ISharedStreambuf (private inheritance),
       std::istream,
       FBB::SharedEnum__ (cf. sharedmemory(3bobcat) for a description of this last base class).

CONSTRUCTORS

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

o ISharedStream(size_t maxSize, SizeUnit sizeUnit, std::ios::openmode openMode =
std::ios::in, size_t access = 0600):
This constructor creates an std::istream that interfaces to a shared memory segment
having a capacity of at least maxSize * sizeUnit bytes. By default, the shared
memory segment is opened for reading. Different from the open modes used for file
streams, creating a shared memory stream with open modes ios::in is OK. In this
case the shared memory segment is created and once information has been written to
the shared memory by another process (or object) the information can be read. 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 ISharedStream(int id, std::ios::openmode openMode = std::ios::in):
This constructor creates an std::istream that 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. 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::istream and std::ostream and the enum values kB, MB, and GB, defined
       by FBB::ISharedEnum__ are available.

       o      void clear():
              This member clears the error states of the std::istream base class object.

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

       o      void kill():
              Without locking the shared memory first,  all shared  memory  is  returned  to  the
              operating  system.  The  FBB::ISharedStream object is unusable after returning from
              kill. Other processes that were using the shared memory can continue to do so.

       o      void remove():
              The shared memory is first locked. Next, all  shared  memory  is  returned  to  the
              operating  system.  The  FBB::ISharedStream object is unusable after returning from
              remove. Other processes that were using the shared memory can continue to do so.

       o      void memInfo(std::ostream &out, char const *end = "\n"):
              Information about the ISharedMemory 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. Following the information about
              the shaed memory, end is inserted into out.

       o      void  open(size_t  maxSize,  SizeUnit  sizeUnit,  std::ios::openmode   openMode   =
              std::ios::in, size_t access = 0600):
              This member creates a shared memory segment having a capacity of at least maxSize *
              sizeUnit bytes, and connects the shared memory segment to the FBB::ISharedStream. A
              matching  close  member  does not exist and is not required. By default, the shared
              memory segment is opened for reading. Different from the open modes used  for  file
              streams,  creating  a  shared  memory stream with open modes ios::in is OK. In this
              case the shared memory segment is created and once information has been written  to
              the  shared  memory  by  another process it can be read. 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 opening succeeds the shared memory is  ready  for  use.  If  opening  fails,  an
              FBB::Exception is thrown.

       o      void open(int id, std::ios::openmode openMode = std::ios::in):
              This  member  connects  the  FBB::ISharedStream  object  to a shared memory segment
              having ID id. A matching close member does  not  exist  and  is  not  required.  If
              opening  succeeds  the  shared  memory is ready for use. If opening fails (e.g., no
              shared memory segment having ID id exists), an FBB::Exception is thrown.

EXAMPLE

       See the sharedstream(3bobcat) man page.

FILES

       bobcat/isharedstream - 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).