Provided by: libbobcat-dev_5.02.00-1build1_amd64 
NAME
FBB::SharedBuf - streambuf interfacing to shared memory
SYNOPSIS
#include <bobcat/sharedbuf>
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::SharedBuf objects
interface to a FBB::SharedMemory 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).
SIZEUNIT ENUMERATION
The enum SizeUnit defines the following symbolic constants:
o kB, representing 1024 (2**10) bytes of memory;
o MB, representing 1048576 (2**20) bytes of memory;
o GB, representing 1073741824 (2**30) bytes of memory
CONSTRUCTORS
o SharedBuf():
The default constructor defines a stub SharedBuf object that cannot immediately be
used to access shared memory. Before it can be used by, shared stream classes like
FBB::SharedStream, its member setMemory must first have been called.
o SharedBuf(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, interpreted
as an octal value, using the well-known (chmod(1)) way to define the access rights
for owner, group and others.
If construction fails, an FBB::Exception is thrown.
o SharedBuf(int id, std::ios::openmode openMode = std::ios::in | std::ios::out):
This constructor connects to a shared memory segment having ID id.
Specifying the ios::trunc flag immediately clears the contents of the shared
memory.
An FBB::Exception is thrown if construction fails (e.g., no shared memory segment
having ID id exists),
Copy and move constructors (and 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::SharedBuf’s shared memory is deleted.
The FBB::SharedBuf object is unusable after returning from kill.
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.
o void remove():
The shared memory is locked, and the FBB::SharedBuf’s shared memory is deleted. The
FBB::SharedBuf 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::SharedBuf object interfaces. It can
also be called to reuse a FBB::SharedBuf object again after calling kill or remove.
o FBB::SharedMemory &sharedMemory():
A reference to the FBB::SharedMemory object to which the FBB::SharedBuf object
interfaces is returned.
PROTECTED MEMBER FUNCTIONS
o FBB::SharedCondition attachSharedCondition(std::ios::off_type offset,
std::ios::seekdir origin):
Returns an FBB::SharedCondition(3) object, interfacing to a shared condition
variable located at offset offset (relative to origin) in the SharedMemory object
to which the SharedStreamBuf object interfaces.
An FBB::Exception is thrown if the FBB::SharedCondition object could not be
constructed.
o FBB::SharedCondition createSharedCondition():
Returns an FBB::SharedCondition(3) object, interfacing to a newly created shared
condition variable which is created at the current offset of the SharedMemory
object to which the SharedStream object interfaces (or at the first offset of the
next physical shared memory data block, cf. sharedcondition(3bobcat)).
An FBB::Exception is thrown if the FBB::SharedCondition object could not be
constructed.
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::SharedBuf’s openmode to the
flags that are passed to open.
o FBB::SharedMemory &sharedMemory():
Returns a reference to the FBB::SharedMemory object to which the SharedBuf object
interfaces.
EXAMPLE
See the sharedstream(3bobcat) man page.
FILES
bobcat/sharedbuf - defines the class interface
SEE ALSO
bobcat(7), chmod(1), isharedstream(3bobcat), osharedstream(3bobcat),
sharedblock(3bobcat), sharedcondition(3bobcat), sharedmemory(3bobcat)
sharedmutex(3bobcat), sharedpos(3bobcat), sharedreadme(7bobcat), sharedsegment(3bobcat),
sharedstream(3bobcat)
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_5.02.00-x.dsc: detached signature;
o bobcat_5.02.00-x.tar.gz: source archive;
o bobcat_5.02.00-x_i386.changes: change log;
o libbobcat1_5.02.00-x_*.deb: debian package holding the libraries;
o libbobcat1-dev_5.02.00-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).