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TakTuk.3pm

NAME

TakTuk - Perl module that provides an interface to taktuk(1) communication facilities

SYNOPSIS

   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";
       }
   }
 
 

DESCRIPTION

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 $TakTuk::error to the numeric code of the error that occured. A textual description of the error is provided by the function TakTuk::error_msg($) 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
 
 

SEE ALSO

tatkuk(1), taktukcomm(3), TakTuk::Pilot(3)

AUTHOR

The original concept of TakTuk has been proposed by Cyrille Martin in his PhD thesis. People involved in this work include Jacques Briat, Olivier Richard, Thierry Gautier and Guillaume Huard.

The author of the version 3 (perl version) and current maintainer of the package is Guillaume Huard.

COPYRIGHT

The "TakTuk" communication interface library is provided under the terms of the GNU General Public License version 2 or later.