/usr/share/perl5/Net/Server/Fork.pm is in libnet-server-perl 0.99-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#
# Net::Server::Fork - Net::Server personality
#
# $Id: Fork.pm,v 1.22 2007/02/03 05:41:29 rhandom Exp $
#
# Copyright (C) 2001-2007
#
# Paul Seamons
# paul@seamons.com
# http://seamons.com/
#
# This package may be distributed under the terms of either the
# GNU General Public License
# or the
# Perl Artistic License
#
# All rights reserved.
#
################################################################
package Net::Server::Fork;
use base qw(Net::Server);
use strict;
use vars qw($VERSION);
use Net::Server::SIG qw(register_sig check_sigs);
use Socket qw(SO_TYPE SOL_SOCKET SOCK_DGRAM);
use POSIX qw(WNOHANG);
$VERSION = $Net::Server::VERSION; # done until separated
### override-able options for this package
sub options {
my $self = shift;
my $prop = $self->{server};
my $ref = shift;
$self->SUPER::options($ref);
foreach ( qw(max_servers max_dequeue
check_for_dead check_for_dequeue) ){
$prop->{$_} = undef unless exists $prop->{$_};
$ref->{$_} = \$prop->{$_};
}
}
### make sure some defaults are set
sub post_configure {
my $self = shift;
my $prop = $self->{server};
### let the parent do the rest
$self->SUPER::post_configure;
### what are the max number of processes
$prop->{max_servers} = 256
unless defined $prop->{max_servers};
### how often to see if children are alive
### only used when max_servers is reached
$prop->{check_for_dead} = 60
unless defined $prop->{check_for_dead};
### I need to know who is the parent
$prop->{ppid} = $$;
### let the post bind set up a select handle for us
$prop->{multi_port} = 1;
}
### loop, fork, and process connections
sub loop {
my $self = shift;
my $prop = $self->{server};
### get ready for children
$prop->{children} = {};
if ($ENV{HUP_CHILDREN}) {
my %children = map {/^(\w+)$/; $1} split(/\s+/, $ENV{HUP_CHILDREN});
$children{$_} = {status => $children{$_}, hup => 1} foreach keys %children;
$prop->{children} = \%children;
}
### register some of the signals for safe handling
register_sig(PIPE => 'IGNORE',
INT => sub { $self->server_close() },
TERM => sub { $self->server_close() },
QUIT => sub { $self->server_close() },
HUP => sub { $self->sig_hup() },
CHLD => sub {
while ( defined(my $chld = waitpid(-1, WNOHANG)) ){
last unless $chld > 0;
$self->delete_child($chld);
}
},
);
my ($last_checked_for_dead, $last_checked_for_dequeue) = (time(), time());
### this is the main loop
while( 1 ){
### make sure we don't use too many processes
my $n_children = grep { $_->{status} !~ /dequeue/ } (values %{ $prop->{children} });
while ($n_children > $prop->{max_servers}){
### block for a moment (don't look too often)
select(undef,undef,undef,5);
&check_sigs();
### periodically see which children are alive
my $time = time();
if( $time - $last_checked_for_dead > $prop->{check_for_dead} ){
$last_checked_for_dead = $time;
$self->log(2,"Max number of children reached ($prop->{max_servers}) -- checking for alive.");
foreach (keys %{ $prop->{children} }){
### see if the child can be killed
kill(0,$_) or $self->delete_child($_);
}
}
$n_children = grep { $_->{status} !~ /dequeue/ } (values %{ $prop->{children} });
}
### periodically check to see if we should clear a queue
if( defined $prop->{check_for_dequeue} ){
my $time = time();
if( $time - $last_checked_for_dequeue
> $prop->{check_for_dequeue} ){
$last_checked_for_dequeue = $time;
if( defined($prop->{max_dequeue}) ){
my $n_dequeue = grep { $_->{status} =~ /dequeue/ } (values %{ $prop->{children} });
if( $n_dequeue < $prop->{max_dequeue} ){
$self->run_dequeue();
}
}
}
}
$self->pre_accept_hook;
### try to call accept
### accept will check signals as appropriate
if( ! $self->accept() ){
last if $prop->{_HUP};
last if $prop->{done};
next;
}
$self->pre_fork_hook;
### fork a child so the parent can go back to listening
my $pid = fork;
### trouble
if( not defined $pid ){
$self->log(1,"Bad fork [$!]");
sleep(5);
### parent
}elsif( $pid ){
close($prop->{client}) if ! $prop->{udp_true};
$prop->{children}->{$pid}->{status} = 'processing';
### child
}else{
### the child will call post_accept_hook
$self->run_client_connection;
exit;
}
}
### fall back to the main run routine
}
sub pre_accept_hook {};
### Net::Server::Fork's own accept method which
### takes advantage of safe signals
sub accept {
my $self = shift;
my $prop = $self->{server};
### block on trying to get a handle (select created because we specified multi_port)
my (@socks) = $prop->{select}->can_read(2);
### see if any sigs occured
if( &check_sigs() ){
return undef if $prop->{_HUP};
return undef unless @socks; # don't continue unless we have a connection
}
### choose one at random (probably only one)
my $sock = $socks[rand @socks];
return undef unless defined $sock;
### check if this is UDP
if( SOCK_DGRAM == $sock->getsockopt(SOL_SOCKET,SO_TYPE) ){
$prop->{udp_true} = 1;
$prop->{client} = $sock;
$prop->{udp_true} = 1;
$prop->{udp_peer} = $sock->recv($prop->{udp_data},
$sock->NS_recv_len,
$sock->NS_recv_flags);
### Receive a SOCK_STREAM (TCP or UNIX) packet
}else{
delete $prop->{udp_true};
$prop->{client} = $sock->accept();
return undef unless defined $prop->{client};
}
}
### override a little to restore sigs
sub run_client_connection {
my $self = shift;
### close the main sock, we still have
### the client handle, this will allow us
### to HUP the parent at any time
$_ = undef foreach @{ $self->{server}->{sock} };
### restore sigs (for the child)
$SIG{HUP} = $SIG{CHLD}
= $SIG{INT} = $SIG{TERM} = $SIG{QUIT} = 'DEFAULT';
$SIG{PIPE} = 'IGNORE';
delete $self->{server}->{children};
$self->SUPER::run_client_connection;
}
### Stub function in case check_for_dequeue is used.
sub run_dequeue {
die "run_dequeue: virtual method not defined";
}
sub close_children {
my $self = shift;
$self->SUPER::close_children(@_);
check_sigs(); # since we have captured signals - make sure we handle them
register_sig(PIPE => 'DEFAULT',
INT => 'DEFAULT',
TERM => 'DEFAULT',
QUIT => 'DEFAULT',
HUP => 'DEFAULT',
CHLD => 'DEFAULT',
);
}
sub pre_fork_hook {}
1;
__END__
=head1 NAME
Net::Server::Fork - Net::Server personality
=head1 SYNOPSIS
use Net::Server::Fork;
@ISA = qw(Net::Server::Fork);
sub process_request {
#...code...
}
__PACKAGE__->run();
=head1 DESCRIPTION
Please read the pod on Net::Server first. This module
is a personality, or extension, or sub class, of the
Net::Server module.
This personality binds to one or more ports and then waits
for a client connection. When a connection is received,
the server forks a child. The child handles the request
and then closes.
With the exception of parent/child signaling, this module
will work (with basic functionality) on Win32 systems.
=head1 ARGUMENTS
=over 4
=item check_for_dead
Number of seconds to wait before looking for dead children.
This only takes place if the maximum number of child processes
(max_servers) has been reached. Default is 60 seconds.
=item max_servers
The maximum number of children to fork. The server will
not accept connections until there are free children. Default
is 256 children.
=item max_dequeue
The maximum number of dequeue processes to start. If a
value of zero or undef is given, no dequeue processes will
be started. The number of running dequeue processes will
be checked by the check_for_dead variable.
=item check_for_dequeue
Seconds to wait before forking off a dequeue process. It
is intended to use the dequeue process to take care of
items such as mail queues. If a value of undef is given,
no dequeue processes will be started.
=back
=head1 CONFIGURATION FILE
See L<Net::Server>.
=head1 PROCESS FLOW
Process flow follows Net::Server until the post_accept phase.
At this point a child is forked. The parent is immediately
able to wait for another request. The child handles the
request and then exits.
=head1 HOOKS
The Fork server has the following hooks in addition to
the hooks provided by the Net::Server base class.
See L<Net::Server>
=over 4
=item C<$self-E<gt>pre_accept_hook()>
This hook occurs just before the accept is called.
=item C<$self-E<gt>pre_fork_hook()>
This hook occurs just after accept but before the fork.
=item C<$self-E<gt>post_accept_hook()>
This hook occurs in the child after the accept and fork.
=item C<$self-E<gt>run_dequeue()>
This hook only gets called in conjunction with the
check_for_dequeue setting.
=back
=head1 TO DO
See L<Net::Server>
=head1 AUTHOR
Paul Seamons <paul@seamons.com>
Rob Brown <bbb@cpan.org>
=head1 SEE ALSO
Please see also
L<Net::Server::INET>,
L<Net::Server::PreFork>,
L<Net::Server::MultiType>,
L<Net::Server::SIG>
L<Net::Server::Single>
=cut
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