Net::Server::SIG - phpMan

NAME
    Net::Server::SIG - adpf - Safer signal handling

SYNOPSIS
        use Net::Server::SIG qw(register_sig check_sigs);
        use IO::Select ();
        use POSIX qw(WNOHANG);

        my $select = IO::Select->new();

        register_sig(PIPE => 'IGNORE',
                     HUP  => 'DEFAULT',
                     USR1 => sub { print "I got a SIG $_[0]\n"; },
                     USR2 => sub { print "I got a SIG $_[0]\n"; },
                     CHLD => sub { 1 while waitpid(-1, WNOHANG) > 0; },
                     );

        # add some handles to the select
        $select->add(\*STDIN);

        # loop forever trying to stay alive
        while (1) {

            # do a timeout to see if any signals got passed us
            # while we were processing another signal
            my @fh = $select->can_read(10);

            my $key;
            my $val;

            # this is the handler for safe (fine under unsafe also)
            if (check_sigs()) {
              # or my @sigs = check_sigs();
              next unless @fh;
            }

            my $handle = $fh[@fh];

            # do something with the handle

        }

DESCRIPTION
    Signals prior in Perl prior to 5.7 were unsafe. Since then signals have
    been implemented in a more safe algorithm. Net::Server::SIG provides
    backwards compatibility, while still working reliably with newer
    releases.

    Using a property of the select() function, Net::Server::SIG attempts to
    fix the unsafe problem. If a process is blocking on select() any signal
    will short circuit the select. Using this concept, Net::Server::SIG does
    the least work possible (changing one bit from 0 to 1). And depends upon
    the actual processing of the signals to take place immediately after the
    select call via the "check_sigs" function. See the example shown above
    and also see the sigtest.pl script located in the examples directory of
    this distribution.

FUNCTIONS
    "register_sig($SIG => \&code_ref)"
        Takes key/value pairs where the key is the signal name, and the
        argument is either a code ref, or the words 'DEFAULT' or 'IGNORE'.
        The function register_sig must be used in conjunction with
        check_sigs, and with a blocking select() function call -- otherwise,
        you will observe the registered signal mysteriously vanish.

    "unregister_sig($SIG)"
        Takes the name of a signal as an argument. Calls register_sig with a
        this signal name and 'DEFAULT' as arguments (same as
        register_sig(SIG,'DEFAULT')

    "check_sigs()"
        Checks to see if any registered signals have occurred. If so, it
        will play the registered code ref for that signal. Return value is
        array containing any SIGNAL names that had occurred.

    "sig_is_registered($SIG)"
        Takes a signal name and returns any registered code_ref for that
        signal.

AUTHORS
    Paul Seamons (paul AT seamons.com)

    Rob B Brown (rob AT roobik.com) - Provided a sounding board and feedback in
    creating Net::Server::SIG and sigtest.pl.

LICENSE
      This package may be distributed under the terms of either the
      GNU General Public License
        or the
      Perl Artistic License

      All rights reserved.