IPC::SharedMem - SysV Shared Memory IPC object class
use IPC::SysV qw(IPC_PRIVATE S_IRUSR S_IWUSR);
use IPC::SharedMem;
$shm = IPC::SharedMem->new(IPC_PRIVATE, 8, S_IRWXU);
$shm->write(pack("S", 4711), 2, 2);
$data = $shm->read(0, 2);
$ds = $shm->stat;
$shm->remove;
A class providing an object based interface to SysV IPC shared
memory.
- new ( KEY , SIZE , FLAGS
)
- Creates a new shared memory segment of
"SIZE" bytes size associated with
"KEY". A new segment is created if
- "KEY" is equal to
"IPC_PRIVATE"
- "KEY" does not already have a shared
memory segment associated with it, and
"FLAGS
& IPC_CREAT" is true.
On creation of a new shared memory segment
"FLAGS" is used to set the permissions. Be
careful not to set any flags that the Sys V IPC implementation does not
allow: in some systems setting execute bits makes the operations fail.
- id
- Returns the shared memory identifier.
- read ( POS, SIZE )
- Read "SIZE" bytes from the shared memory
segment at "POS". Returns the string
read, or "undef" if there was an error.
The return value becomes tainted. See shmread.
- write ( STRING, POS, SIZE
)
- Write "SIZE" bytes to the shared memory
segment at "POS". Returns true if
successful, or false if there is an error. See shmwrite.
- remove
- Remove the shared memory segment from the system or mark it as removed as
long as any processes are still attached to it.
- is_removed
- Returns true if the shared memory segment has been removed or marked for
removal.
- stat
- Returns an object of type
"IPC::SharedMem::stat" which is a
sub-class of "Class::Struct". It
provides the following fields. For a description of these fields see you
system documentation.
uid
gid
cuid
cgid
mode
segsz
lpid
cpid
nattch
atime
dtime
ctime
- attach ( [FLAG] )
- Permanently attach to the shared memory segment. When a
"IPC::SharedMem" object is attached, it
will use memread and memwrite instead of shmread and shmwrite for
accessing the shared memory segment. Returns true if successful, or false
on error. See shmat(2).
- detach
- Detach from the shared memory segment that previously has been attached
to. Returns true if successful, or false on error. See
shmdt(2).
- addr
- Returns the address of the shared memory that has been attached to in a
format suitable for use with
"pack('P')". Returns
"undef" if the shared memory has not
been attached.
Marcus Holland-Moritz <mhx@cpan.org>
Version 2.x, Copyright (C) 2007-2013, Marcus Holland-Moritz.
Version 1.x, Copyright (c) 1997, Graham Barr.
This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.