Parallel subroutines...

How to?

[MonkeeSage]

I'm a relative newbie to Perl, but I'm doing pretty well I think, mainly because I have an OK understanding of JavaScript and in alot of places they share the same syntax (or very close to the same at least).

But I'm having a problem trying to execute a subroutine while at the same time executing a (blocking) library method, until the library method returns.

Here is what I mean ($svr is an instance of $ftp, which is a NET::FTP object)...

-----------------------

sub download { 
  my ($svr, $file) = @_; 
  print "Downloading..."; 
  if ($svr->get($file)) { 
   return 1; 
  } 
  else { 
   return 0; 
  } 
} 
  
sub dodownload { 
  my ($srv, $file) = @_; 
   
  &removefile($file); 
  $started = 1; 
   
  if (&download($srv, $file)) { 
   print "\n\nDownloaded file: $file\!\n\n"; 
   $srv->quit(); 
  } 
  else { 
   $srv->quit(); 
   &dienice("Failed to download file: $file\!\n"); 
  } 
} 

-----------------------

And I want to do this...

sub checkdone { 
  print '.'; 
  sleep(1); 
  &checkdone; 
}

...until

$svr->get($file)

-----------------------

I tried using fork(), like so...

my $done = 0; 
  
sub checkdone { 
  print '.'; 
  sleep(1); 
  if ($done ne 1) { 
   &checkdone; 
  } 
} 
  
sub download { 
  my ($svr, $file) = @_; 
  print "Downloading..."; 
  # if called here, download never starts, 
  # because the sub never returns 
  # &checkdone; 
  my $forkID = fork(); 
  if ($forkID eq 0) { 
   if ($svr->get($file)) { 
     return 1; 
   } 
   else { 
     return 0; 
   } 
  } 
  else { 
   # if called here, download starts, 
   # but sub still never returns  
   # (does it also get fork()'d or 
   # something?) 
   &checkdone; 
  } 
} 
  
sub dodownload { 
  my ($srv, $file) = @_; 
   
  &removefile($file); 
  $started = 1; 
   
  if (&download($srv, $file)) { 
   print "\n\nDownloaded file: $file\!\n\n"; 
   $srv->quit(); 
   $done = 1; 
  } 
  else { 
   $srv->quit(); 
   $done = 1; 
   &dienice("Failed to download file: $file\!\n"); 
  } 
} 

...but it just keeps on doing

&checkdone;

, even after

$done eq 1

(which I checked by printing out

$done

).

-----------------------

How can I do what I'm trying to do? Thanks in advance!

Jordan

Ps. This script will be run locally, so modules are no problem; I can install any that are needed.

[MonkeeSage]

Pss. I also tried an explicit kill($forkID) (and $$) but the checkdone sub just happily continues to spit out dots...

Jordan

[MonkeeSage]

I got it to work using 5.8's threads module and having

$done

as a ': shared'. Here's what I've got now...

use threads; 
use threads::shared; 
  
my $done : shared = 0; 
  
... 
  
sub checkdone { 
  my ($file) = @_; 
  if ($done ne 1) { 
   if (-e $file) { 
     print substr((stat $file)[7]/1048576, 0, 4); 
     print " mB done...\n"; 
   } 
   else { 
     print "Start Data...\n"; 
   } 
   $count = $count + 3; 
   sleep(3); 
   return &checkdone($file); 
  } 
  else { 
   print substr((stat $file)[7]/1048576, 0, 4); 
   print " mB done...\n"; 
   if ($count > 60) { 
     $count = $count/60 . " minute(s)"; 
   } 
   else { 
     $count = $count . " second(s)"; 
   } 
  } 
} 
  
sub download {  
  my ($svr, $file) = @_; 
  print "\nDownloading...\n"; 
  if ($svr->get($file)) {  
   $svr->quit();  
   $done = 1; 
   return 1;  
  }  
  else { 
   $svr->quit();  
   $done = 1; 
   return 0;  
  }  
}  
  
sub dodownload {  
  my ($svr, $file) = @_;  
  &removefile($file);  
  $started = 1; 
  my $thr; 
  $thr = threads->new(\&download, $svr, $file); 
  &checkdone($file); 
  my ($ret) = $thr->join; 
  if ($ret eq 1) {  
   print "\nDownloaded file: $file in $count\!\n\n"; 
  }  
  else {  
   &dienice("\nFailed to download file: $file\!\n"); 
  } 
}

Jordan