NAME

POSIX::RT::Signal - POSIX Real-time signal handling functions

VERSION

version 0.015

SYNOPSIS

 use POSIX::RT::Signal qw/sigqueue sigwaitinfo/;
 use Signal::Mask;
 
 $Signal::Mask{USR1}++;
 sigqueue($$, 'USR1');
 my $info = sigwaitinfo('USR1');

DESCRIPTION

This module exposes several advanced features and interfaces of POSIX real-time signals.

FUNCTIONS

sigqueue($pid, $sig, $value = 0)

Queue a signal $sig to process $pid, optionally with the additional argument $value. On error an exception is thrown. $sig must be either a signal number(14) or a signal name ('ALRM'). If the signal queue is full, it returns undef and sets $! to EAGAIN.

sigwaitinfo($signals, $timeout = undef)

Wait for a signal in $signals to arrive and return information on it. The signal handler (if any) will not be called. Unlike signal handlers it is not affected by signal masks, in fact you are expected to mask signals you're waiting for. $signals must either be a POSIX::SigSet object, a signal number or a signal name. If $timeout is specified, it indicates the maximal time the thread is suspended in fractional seconds; if no signal is received it returns an empty list, or in void context an exception. If $timeout is not defined it may wait indefinitely until a signal arrives. On success it returns a hash with the following entries:

• signo

  The signal number

• code

  The signal code, a signal-specific code that gives the reason why the signal was generated

• errno

  If non-zero, an errno value associated with this signal

• pid

  Sending process ID

• uid

  Real user ID of sending process

• addr

  The address of faulting instruction

• status

  Exit value or signal

• band

  Band event for SIGPOLL

• value

  Signal integer value as passed to sigqueue

• ptr

  The pointer integer as passed to sigqueue

Note that not all of these will have meaningful values for all or even most signals

sigtimedwait

This is an alias for sigwaitinfo.

sigwait($signals)

Wait for a signal in $signals to arrive and return it. The signal handler (if any) will not be called. Unlike signal handlers it is not affected by signal masks, in fact you are expected to mask signals you're waiting for. $signals must either be a POSIX::SigSet object, a signal number or a signal name.

allocate_signal($priority)

Pick a signal from the set of signals available to the user. The signal will not be given to any other caller of this function until it has been deallocated. If supported, these will be real-time signals. By default it will choose the lowest priority signal available, but if $priority is true it will pick the highest priority one. If real-time signals are not supported this will return SIGUSR1 and SIGUSR2

deallocate_signal($signal)

Deallocate the signal to be reused for allocate_signal.

SEE ALSO

• Signal::Mask

• IPC::Signal

• POSIX::RT::Timer

• POSIX

• Linux::FD::Signal

AUTHOR

Leon Timmermans <fawaka@gmail.com>

COPYRIGHT AND LICENSE

This software is copyright (c) 2011 by Leon Timmermans.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.