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lib/Acrux/FileLock.pm  view on Meta::CPAN

Serż Minus (Sergey Lepenkov) L<https://www.serzik.com> E<lt>abalama@cpan.orgE<gt>

=head1 COPYRIGHT

Copyright (C) 1998-2026 D&D Corporation

=head1 LICENSE

This program is distributed under the terms of the Artistic License Version 2.0

See the C<LICENSE> file or L<https://opensource.org/license/artistic-2-0> for details

=cut

use Carp qw/croak/;
use File::Spec;
use File::stat qw//;
use File::Basename qw/basename/;
use Cwd qw/getcwd/;

use constant {
        RETRIES     => 5,
        DELAY       => 60,
    };

sub new {
    my $class = shift;
    my $args = @_ ? @_ > 1 ? {@_} : {%{$_[0]}} : {};
    my $self  = bless {%$args}, $class;
    $self->{debug}      ||= 0;
    $self->{error}      = "";
    $self->{file}       //= File::Spec->catfile(getcwd, sprintf("%s.lock", basename($0)));
    $self->{pid}        ||= $$; # Current PID by default
    $self->{own}        ||= 0; # Owner PID
    $self->{auto}       //= 0;
    $self->{retries}    //= RETRIES;
    $self->{delay}      //= DELAY;
    $self->{_is_locked} = 0;
    croak("Incorrect pid attribute") unless $self->{pid} =~ /^[0-9]{1,11}$/;
    croak("Incorrect retries attribute") unless $self->{retries} =~ /^[0-9]{1,5}$/;
    croak("Incorrect delay attribute") unless $self->{delay} =~ /^[0-9]{1,5}$/;

    # Lock file
    return $self->lock if $self->{auto};
    return $self;
}

sub file { shift->{file} }
sub pid { shift->{pid} }
sub own { # own pid
    my $self = shift;
    if (scalar(@_) >= 1) {
        $self->{own} = shift;
        return $self;
    }
    return $self->{own};
}
sub owner { # numeric user ID of file's owner
    my $self = shift;
    return unless length($self->file) && -f $self->file;
    return File::stat::stat($self->file)->uid;
}
sub error {
    my $self = shift;
    if (scalar(@_) >= 1) {
        $self->{error} = shift;
        return $self;
    }
    return $self->{error};
}
sub lock {
    my $self = shift;
    if ($self->_is_locked) {
        $self->_debug(sprintf("File %s already locked", $self->file));
        return $self;
    }

    # Signals
    $SIG{HUP} = $SIG{QUIT} = $SIG{INT} = $SIG{TERM} = sub {
        $self->_debug( "Caught SIG$_[0]" );
        exit;
    };

    # Save temp file
    my $tmp_file = sprintf("%s.%d", $self->file, $self->pid);
    if (open(my $fh, '>', $tmp_file)) {
        printf $fh "%d\n", $self->pid || $$;
        close $fh;

        # Rename temp file to lock file
        for my $try (0 .. $self->{retries}) {
            unless ($self->check()) { # not exists, ok
                if (rename($tmp_file, $self->file)) {
                    $self->{_is_locked} = 1;
                    $self->_debug("Got lock file");
                    return $self;
                }
            }
            if ($self->{retries} && ($try != $self->{retries})) {
                $self->_debug(sprintf("Retrying in %d seconds", $self->{delay}));
                sleep $self->{delay} unless ($try == $self->{retries});
            }
        }

    } else {
        $self->error(sprintf("Could not write to %s: $!", $tmp_file))->_debug($self->error);
    }

    # Remove temp file in silent mode
    unlink $tmp_file if -f $tmp_file;

    # Ok
    return $self;
}
sub check {
    my $self = shift;
    return 0 unless -f $self->file;

    # Load file
    if (open(my $fh, $self->file)) {