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# Copyright (c) 1997-2024
# Ewgenij Gawrilow, Michael Joswig, and the polymake team
# Technische Universität Berlin, Germany
# https://polymake.org
#
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2, or (at your option) any
# later version: http://www.gnu.org/licenses/gpl.txt.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#-------------------------------------------------------------------------------
use strict;
use namespaces;
use warnings qw(FATAL void syntax misc);
package Polymake::Background;
use POSIX qw( :sys_wait_h );
my %active; # pid => something to destroy on termination
my $init;
sub gather_zombies {
my $flag=shift // 0;
if (!$flag) {
foreach (grep { ref($_) eq "CODE" } values %active) {
eval { $_->() };
if ($@) {
warn_print( "cleanup after background process failed: $@\n" );
}
}
}
while (keys(%active) && (my $pid=waitpid(-1, $flag)) > 0) {
delete $active{$pid};
}
}
sub wait_for_active {
my $rc=0;
foreach my $pid (keys %active) {
waitpid($pid, 0);
$rc ||= $?;
delete $active{$pid};
}
return $rc;
}
sub add_process {
if ($init) {
gather_zombies(WNOHANG);
} else {
add AtEnd("Background", \&gather_zombies, before => "tempdir");
$init=1;
}
$active{$_[0]}=$_[1];
}
package Polymake::Background::Process;
sub new {
shift;
my $options=shift if ref($_[0]) eq "HASH";
my ($cleanup, $redirect);
if ($options) {
$cleanup=delete $options->{CLEANUP};
$redirect=delete $options->{REDIRECT};
if (keys %$options) {
croak( "unknown option(s) for Background::Process: ", join(",", keys %$options) );
}
}
my $pid=launch($redirect, 1, @_);
add_process($pid, $cleanup);
return $pid;
}
sub launch {
my ($redirect, $hide, @cmdline)=@_;
dbg_print( "starting @cmdline" ) if $Verbose::external;
my $pid=fork;
if (!$pid) {
die "Background::Process: fork failed: $!\n" if !defined($pid);
if (defined($redirect)) {
POSIX::dup2(fileno($redirect->[0]), 0);
POSIX::dup2(fileno($redirect->[1]), 1);
} else {
STDIN->close;
}
if ($hide) {
POSIX::setsid();
$SIG{INT}='IGNORE';
$SIG{ALRM}='IGNORE';
}
if (ref($cmdline[0]) eq "ARRAY") {
# internal subprocess: [ \&sub, leading arguments ], further arguments
my $lead=shift @cmdline;
my $sub=shift @$lead;
if (ref($sub) eq "CODE") {
eval { $sub->(@$lead, @cmdline) };
} else {
$@="wrong use: a CODE reference expected\n";
}
if ($@) {
print STDERR "internal subprocess terminated with an error: $@";
POSIX::_exit(1);
} else {
POSIX::_exit(0); # avoid executing global destructors
}
} else {
exec "@cmdline"
or do {
my ($progname)= @cmdline==1 ? $cmdline[0] =~ /^\s*(\S+)/ : @cmdline;
print STDERR "could not start $progname: $!\n";
POSIX::_exit(1); # avoid executing global destructors
}
}
}
return $pid;
}
1
# Local Variables:
# cperl-indent-level:3
# indent-tabs-mode:nil
# End:
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