NAME
IPC::SharedMem - SysV Shared Memory IPC object class
SYNOPSIS
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;
DESCRIPTION
A class providing an object based interface to SysV IPC shared memory.
METHODS
- new ( KEY , SIZE , FLAGS )
-
Creates a new shared memory segment of
SIZE
bytes size associated withKEY
. A new segment is created ifKEY
is equal toIPC_PRIVATE
KEY
does not already have a shared memory segment associated with it, andFLAGS & 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 atPOS
. Returns the string read, orundef
if there was an error. The return value becomes tainted. See shmread. - write ( STRING, POS, SIZE )
-
Write
SIZE
bytes to the shared memory segment atPOS
. 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 ofClass::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')
. Returnsundef
if the shared memory has not been attached.
SEE ALSO
AUTHORS
Marcus Holland-Moritz <mhx@cpan.org>
COPYRIGHT
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.