2 IPC::MorseSignals - Communicate between processes with Morse signals.
8 use IPC::MorseSignals qw/msend mrecv/;
12 die "fork() failed: $!";
14 local @SIG{qw/USR1 USR2/} = mrecv sub {
15 print STDERR "received $_[0]!\n";
20 msend "hello!\n" => $pid;
24 This module implements a rare form of IPC by sending Morse-like signals
25 through "SIGUSR1" and "SIGUSR2". Both of those signals are used, so you
26 won't be able to keep them for something else when you use this module.
28 But, seriously, use something else for your IPC. :)
32 msend $msg, $pid [, speed => $speed, utf8 => $utf8 ]
34 Sends the string $msg to the process $pid (or to all the processes @$pid
35 if $pid is an array ref) at $speed bits per second. If the "utf8" flag
36 is set, the string will first be encoded in UTF-8. In this case, you
37 must turn it on for "mrecv" as well. Default speed is 512, don't set it
38 too low or the target will miss bits and the whole message will be
39 crippled. The "utf8" flag is turned off by default;
42 mrecv $callback [, utf => $utf8 ]
44 Takes as its first argument the callback triggered when a complete
45 message is received, and returns two code references that should replace
46 SIGUSR1 and SIGUSR2 signal handlers. Basically, you want to use it like
49 local @SIG{qw/USR1 USR2/} = mrecv sub { ... };
51 Turn on the utf8 flag if you know that the incoming strings are expected
52 to be in UTF-8. This flag is turned off by default.
55 This module exports on request its two only functions, "msend" and
59 Each byte of the data string is converted into its bits sequence, with
60 bits of highest weight coming first. All those bits sequences are put
61 into the same order as the characters occur in the string. The emitter
62 computes then the longuest sequence of successives 0 (say, "m") and 1
63 ("n"). A signature is then chosen :
65 If C(m > n), we take "n+1" times 1 follewed by 1 0 ;
66 Otherwise, we take "m+1" times 0 follewed by 1 1.
68 The signal is then formed by concatenating the signature, the data bits
69 and the reversed signature (i.e. the bits of the signature in the
72 The receiver knows that the signature has been sent when it has catched
73 at least one 0 and one 1. The signal is completely transferred when it
74 has received for the first time the whole reversed signature.
77 This type of IPC is highly unreliable. Send little data at slow speed if
78 you want it to reach its goal.
80 SIGUSR{1,2} seem to interrupt sleep, so it's not a good idea to transfer
81 data to a sleeping process.
84 POSIX (standard since perl 5) and Time::HiRes (standard since perl
88 perlipc for information about signals in perl.
90 For truly useful IPC, search for shared memory, pipes and semaphores.
93 Vincent Pit, "<perl at profvince.com>"
95 You can contact me by mail or on #perl @ FreeNode (Prof_Vince).
98 Please report any bugs or feature requests to "bug-ipc-morsesignals at
99 rt.cpan.org", or through the web interface at
100 <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=IPC-MorseSignals>. I
101 will be notified, and then you'll automatically be notified of progress
102 on your bug as I make changes.
105 You can find documentation for this module with the perldoc command.
107 perldoc IPC::MorseSignals
110 Thanks for the inspiration, mofino ! I hope this module will fill all
114 Copyright 2007 Vincent Pit, all rights reserved.
116 This program is free software; you can redistribute it and/or modify it
117 under the same terms as Perl itself.