#!perl -w
use strict;
use Fcntl qw(LOCK_EX LOCK_NB);

my $PID_FILE    = '/tmp/_pid_file';
my $TASK        = 'test_script';
my $EVENT_DELAY = 30 ;
my $DEBUG       = 'YES';


eval { main( @ARGV ) };
error( $@ ) if $@;

# ------------------------------------------------------------------------------
sub main
{
    my $start_mess = "===== Starting $TASK";
    $start_mess   .= " (@_)" if @_;
    $start_mess   .= " =====";
    error( $start_mess );

    open( HIGHLANDER, ">>$PID_FILE") or die( "Cannot write to $PID_FILE: $!" );
    {
	my $count = 0;
	{
	    flock HIGHLANDER, LOCK_EX | LOCK_NB and last;
	    sleep 1;
	    redo if ++$count < 3;
	    error( "Script is already running." );
            die( "Startup failed, PID file locked." );
        }
     }
     print HIGHLANDER $$;

    my $stopped;
    local $SIG{HUP} = sub { $stopped = 1 };

    while( not $stopped )
    {
	error( "DEBUG: Script Running" ) if $DEBUG;
	sleep $EVENT_DELAY;
    }

    my $finish_mess = "===== Stopping $TASK =====";
    error( $finish_mess );

    close HIGHLANDER;
}

# ------------------------------------------------------------------------------
sub error{ print "$TASK -> WARN: @_\n" }