TakTuk3pm

Usage

  use TakTuk;
  
  my $rank = TakTuk::get('rank');
  my $count = TakTuk::get('count');
  
  print "I'm process $rank among $count\n";
  
  if ($rank > 1) {
      my ($from, $message) = TakTuk::recv();
      if (not defined($message)) {
          print "Trying to recv: ",
                TakTuk::error_msg($TakTuk::error), "\n";
      } else {
          print "$rank received $message from $from\n";
      }
  }
  
  sleep 1;
  my $next = $rank+1;
  $next = 1 if ($next > $count);
  if (not TakTuk::send(to=>$next, body=>"[Salut numero $rank]")) {
      print "Trying to send to $next: ",
            TakTuk::error_msg($TakTuk::error), "\n";
  }
  
  if ($rank == 1) {
      my ($from, $message) = TakTuk::recv(timeout=>5);
      if (not defined($message)) {
          print "Trying to recv :",
                TakTuk::error_msg($TakTuk::error), "\n";
      } else {
          print "$rank received $message from $from\n";
      }
  }

Overview

The TakTuk communication layer Perl interface provides a way for programs executed using the taktuk(1) command to exchange data. It is based on a simple send/receive model using multicast-like sends and optionally timeouted receives. This is only designed to be a control facility, in particular this is not a high performance communication library.

The Perl communication interface for TakTuk is made of functions that can be called by scripts executed using the "taktuk_perl" command of the TakTuk engine (preferred way, less installation requirements on remote machines) or using the TakTuk Perl module provided with the TakTuk distribution. These functions are:

TakTuk::get($)

gets some information from TakTuk. Currently available information includes 'target', 'rank', 'count', 'father', 'child_min' and 'child_max'. This is a better way to get this information than environment variables as its takes into account renumbering that might occur after process spawn.

TakTuk::send(%)

sends a scalar to a single peer or a set specification (see taktuk(1) for information about set specifications). The two mandatory fields in the arguments are "to" (with a set specification) and "body". Optionally, a field "target" might be given. Returns an undefined value upon error.

TakTuk::recv(%)

blocks until the reception of a message. Returns a list of two elements: the logical number of the source of the message and the message itself. Accepts an optional "timeout" argument with a numeric value. Returns an empty list upon error.

When an error occur, all these functions set the variable $TakTuk::error to the numeric code of the error that occurred. A textual description of the error is provided by the function TakTuk::error_msg($) that takes the error code as an argument.

Error codes are the following :

TakTuk::ESWRIT

a call to "TakTuk::syswrite" failed. This is due to a "syswrite" error different than "EAGAIN". The code should be accessible using $!.

TakTuk::EFCLSD

the communication channel to the TakTuk engine has been closed. This typically occur when shutting down the logical network (using Ctrl-C on root node for instance).

TakTuk::ESREAD ("TakTuk::recv" only)

a call to "sysread" failed (the code should be accessible using $!).

TakTuk::EARGTO ("TakTuk::send" only)

"to" field missing in the arguments.

TakTuk::EARGBD ("TakTuk::send" only)

"body" field missing in the arguments.

TakTuk::ETMOUT ("TakTuk::recv" only)

The call to "TakTuk::recv" timeouted. This only occur when giving a "timeout" field as "TakTuk::recv" argument.

Finally, the TakTuk Perl module defines some constants which value match the different states reported by the stream "state" (see taktuk(1) for details about this stream). These constant are the following:

  TakTuk::TAKTUK_READY
  TakTuk::TAKTUK_NUMBERED
  TakTuk::TAKTUK_TERMINATED
  TakTuk::CONNECTION_FAILED
  TakTuk::CONNECTION_INITIALIZED
  TakTuk::CONNECTION_LOST
  TakTuk::COMMAND_STARTED
  TakTuk::COMMAND_FAILED
  TakTuk::COMMAND_TERMINATED
  TakTuk::UPDATE_FAILED
  TakTuk::PIPE_STARTED
  TakTuk::PIPE_FAILED
  TakTuk::PIPE_TERMINATED
  TakTuk::FILE_RECEPTION_STARTED
  TakTuk::FILE_RECEPTION_FAILED
  TakTuk::FILE_RECEPTION_TERMINATED
  TakTuk::FILE_SEND_FAILED
  TakTuk::INVALID_TARGET
  TakTuk::NO_TARGET
  TakTuk::MESSAGE_DELIVERED
  TakTuk::INVALID_DESTINATION
  TakTuk::UNAVAILABLE_DESTINATION