Updating a GUI with tail???

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi all. In my code below, I have a perl/Tk application with a scalebar tracking the progress of another program. The problem is that the main GUI freezes up until the tail process detects new input.

Is there a cleaner way to do this? I have experimented with File::Tail, but I get the same results.

Any help appreciated.

Regards,
Stacy.

$tpid = open(MLOG,"tail -f $log_dir/mkisofs.log |");
&log("Started mkisofs.log tail: pid = $tpid");
  
while ($line = <MLOG>) {  
 if ($line =~ /estimate finish/) {
    $line =~ s/^\s+//; #remove leading whitespace
    $perc = (split(/\s+/, $line))[0];
    chop($perc); #get rid of the "%"
    $perc = sprintf("%3.0f", $perc);
    $progress_label -> configure(-text => "Completed: $perc%");
    $progress_scale -> set($perc);
    $main->update;
    }
    last if $line =~ /extents written/;
  }
  
kill('TERM', $tpid); #kill the tail process
close(MLOG);
[download]

Edit: chipmunk 2001-05-30

Comment on Updating a GUI with tail??? Download Code

Replies are listed 'Best First'.

Re: Updating a GUI with tail???
by chb (Deacon) on May 30, 2001 at 11:58 UTC

With fileevent, the process can tell when
data is present and only invoke gets or read when they
won't block
[download]

[reply]
[d/l]

Re: Updating a GUI with tail???
by stefan k (Curate) on May 30, 2001 at 13:14 UTC

Gtk::Gdk->input_add( $source, $condition, \&function, @data );???
[download]

Maybe some perl-gtk guru could verify this?

Regards... Stefan

[reply]
[d/l]

Re: Updating a GUI with tail???
by maderman (Beadle) on Jun 12, 2001 at 07:54 UTC


Here is a way to do it without the call to unix tail... My
GUI does not freeze up with this code... 

Regards,
    Stacy.


my $exit = 0;
  for (;;) {
    while ($line = <MLOG>) {
      
      $main->update; 
      
      if ($line =~ m/estimate finish/) {
        $line =~ s/^\s+//; #remove leading whitespace
        $perc = (split(/\s+/, $line))[0];
        chop($perc); #get rid of the "%"
        $perc = sprintf("%3.0f", $perc);
        $progress_label -> configure(-text => "Percent completed: $per
+c%");
        $progress_scale -> set($perc);
        $main->update; } 
      elsif ($line =~ /extents written/) { $exit = 1 }
      else { next }
       
    }#end of while
    last if $exit == 1;
    seek(MLOG,0,1);
    $main->update; 
  }
  close(MLOG);
[download]

[reply]
[d/l]