NAME

       MemoryREADME - Bobcat’s classes accessing memory segments

DESCRIPTION

       The following classes accessing memory segments are available:

       o      MemoryAccess(3bobcat)

              The  class  MemoryAccess(3bobcat)  defines  an  object interfacing to a shared memory segment (cf.
              shmget(2)). If offers functionality to set and retrieve its id, and write and read bytes from  its
              shared  memory  segment.   MemoryAccess  objects are used by MemoryBridge(3bobcat) objects keeping
              track of which segments actually contain the data bytes.

              MemoryAccess objects are used by MemoryBridge and are normally not directly  constructed  by  user
              programs.

       o      MemoryBridge(3bobcat)

              The  class  MemoryBridge  (cf. figure images/sharedsegment1.jpg) interfaces to shared memory using
              MemoryAccess objects. Its main member function is the static member create, returning a pointer to
              a newly allocated MemoryMemory object.

              The member create receives as its input parameters the number of blocks, the size of the  segments
              allocated  by MemoryBridge, and the segment’s access mode (as used by, e.g., chmod(1)). It returns
              a pointer to the allocated MemoryBridge, and its ID (set using a pointer to an int, passed as  its
              first parameter).

              Although the MemoryBridge class defines an array of a single MemoryAccess(3bobcat) object, in fact
              it  will contain d_nAccesss MemoryAccess objects. The member create first allocates a block of raw
              memory of the required total size. Next it initializes the first part of this raw, shared  memory,
              using  the  MemoryBridge  constructor  and placement new. Next, the remaining amount of raw shared
              memory is initialized with d_nAccesss - 1 MemoryAccess objects, again  using  placement  new  (cf.
              figure images/sharedsegment2.jpg in the source distribution).

              Following  read/write operations the offset is updated accordingly. There’s only one offset, which
              is used by [IO]?MemoryStream objects when requesting or updating offsets.  a  MemoryMemory  object
              offers safeguards against inappropriate use. E.g., if no memory has been allocated yet it may thow
              exceptions. Also, offsets can never exceed the MemoryMemory’s maximum possible offset.

       o      MemoryBuf(3bobcat)

              The  class  MemoryBuf  implements  a  std::streambuf  specialization interfacing to a MemoryMemory
              object. In addition to a default constructor which is an empty stub the class offers  constructors
              which immediately interface to a MemoryBridge object.

       o      MemoryStream(3bobcat)

              The  MemoryStream  class  offers  stream-facilities  operating  on  shared  memory maintained by a
              MemoryBuf object.

       An overview of currently defined shared memory segments is shown by the command  ipcs  -ma.  To  erase  a
       defined  shared  memory  segment  the  command ipcrm -m <id> can be used, where <id> is the shared memory
       segment’s ID.

EXAMPLE

       See the memorystream(3bobcat) man page.

FILES

       Images referred to in this man-page are located in the source distribution in bobcat/documents/images, or
       they can be found in the standard location of documentation files in your distribution  (e.g.,  they  are
       located in /usr/share/doc/libbobcat6/images).

SEE ALSO

       bobcat(7),   ipcs(1),   ipcrm(1),   memoryaccess(3bobcat),   memorybridge(3bobcat),   memorybuf(3bobcat),
       memorystream(3bobcat)

BUGS

       None Reported.

BOBCAT PROJECT FILES

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

       Debian Bobcat project files:

       o      libbobcat6: debian package containing the shared library, changelog and copyright note;

       o      libbobcat-dev: debian package containing the static library, headers, manual pages, and  developer
              info;

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).

libbobcat-dev_6.11.00                               2005-2025                              MemoryREADME(7bobcat)