Test::Without::Shm - simulate shmget() etc not available
# pretend shm not implemented on the system perl -MTest::Without::Shm myprog.pl ... # pretend not enough memory for shm perl -MTest::Without::Shm=-nomem myprog.pl ...
This module overrides the Perl core functions
shmget() shmread() shmwrite() shmctl()
to pretend that their System-V style shared memory is either not implemented or there's not enough memory.
This fakery can be used during testing to check how module code etc might behave on a system without shm or when there's not enough memory. A module might throw an error, use an I/O fallback, etc.
The shm functions are overridden using the
CORE::GLOBAL mechanism (see "OVERRIDING CORE FUNCTIONS" in CORE) so
Test::Without::Shm must be loaded before compiling any code which might call them.
The default import behaviour is to pretend shm is not implemented on the system.
-M can be used on the command line when running a program,
perl -MTest::Without::Shm myprog.pl ...
-nomem option pretends that shm exists but there's not enough memory,
perl -MTest::Without::Shm=-nomem myprog.pl ...
For the usual
ExtUtils::MakeMaker test harness the
-M can be put in the
HARNESS_PERL_SWITCHES environment variable in the usual way,
HARNESS_PERL_SWITCHES="-MTest::Without::Shm" make test
The same effect as the above
-M can be had in a script,
use Test::Without::Shm; # shm not implemented
use Test::Without::Shm '-nomem';
If you want to load the
Test::Without::Shm module but not activate it then give a
() in the usual way to skip its
# setups, but no "without" yet use Test::Without::Shm ();
Don't forget that this must be done before any code using the
shm...() functions, which probably means somewhere early in the mainline script.
The import options are
Make shm "not implemented", as if the system doesn't have the underlying functions. This makes the Perl functions croak with "shmget not implemented", or "shm I/O not implemented", etc.
ENOMEMas if the system says there's not enough memory to make a shm segment. This is arranged even when the system doesn't have shm (ie. when "not implemented" would be the normal state).
$mode = Test::Without::Shm->mode ()
Get or set the shm fakery mode.
$modeis a string
"notimp" "nomem" "normal"
Normal mode means the
shm...()functions are Perl's normal behaviour, whatever that might be. In the current implementation this is done by leaving the
CORE::GLOBALsetups installed but dispatching to the actual
Copyright 2011, 2012, 2013, 2015 Kevin Ryde
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