IPC::PubSub(3pm)

💖 IPC::PubSub — interprocess publish/subscribe channels, bestie 💖

okay so this is the manual page for IPC::PubSub, a Perl module (that's the 3pm part, it lives in the User Contributed Perl Documentation corner of the universe 🫶). If you've ever wanted processes to ~gossip~ with each other through named channels, this is literally the whole vibe. No cap.

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✨ SYNOPSIS ✨

Like, here's the whole thing in action, copy-paste energy, go off:

# A new message bus with the DBM::Deep backend
# (Other possible backends include Memcached and PlainHash)
my $bus = IPC::PubSub->new(DBM_Deep => '/tmp/pubsub.db');

# A channel is any arbitrary string
my $channel = '#perl6';

# Register a new publisher (you can publish to multiple channels)
my $pub = $bus->new_publisher("#perl6", "#moose");

# Publish a message (may be a complex object) to those channels
$pub->msg("This is a message");

# Register a new subscriber (you can subscribe to multiple channels)
my $sub = $bus->new_subscriber("#moose");

# Publish an object to channels
$pub->msg("This is another message");

# Set all subsequent messages from this publisher to expire in 30 seconds
$pub->expiry(30);
$pub->msg("This message will go away in 30 seconds");

# Simple get: Returns the messages sent since the previous get,
# but only for the first channel.
my @msgs = $sub->get;

# Simple get, with an explicit channel key (must be among the ones
# it initially subscribed to)
my @moose_msgs = $sub->get("#moose");

# Complex get: Returns a hash reference from channels to array
# references of [timestamp, message].
my $hash_ref = $sub->get_all;

# Changing the list of channels we subscribe to
$sub->subscribe('some-other-channel');
$sub->unsubscribe('some-other-channel');

# Changing the list of channels we publish to
$pub->publish('some-other-channel');
$pub->unpublish('some-other-channel');

# Listing and checking if we are in a channel
my @sub_channels = $sub->channels;
my @pub_channels = $pub->channels;
print "Sub is in #moose" if $sub->channels->{'#moose'};
print "Pub is in #moose" if $pub->channels->{'#moose'};

# Raw cache manipulation APIs (not advised; use ->modify instead)
$bus->lock('channel');
$bus->unlock('channel');
my @timed_msgs = $bus->fetch('key1', 'key2', 'key3');
$bus->store('key', 'value', time, 30);

# Atomic updating of cache content; $_ is stored back on the
# end of the callback.
my $rv = $bus->modify('key' => sub { delete $_->{foo} });

# Shorthand for $bus->modify('key' => sub { $_ = 'val' });
$bus->modify('key' => 'val');

# Shorthand for $bus->modify('key' => sub { $_ });
$bus->modify('key');

# Disconnect the backend connection explicitly
$bus->disconnect;

⚠️ heads up bestie: the raw cache manipulation APIs ($bus->lock, $bus->unlock, $bus->fetch, $bus->store) are not advised — the docs themselves say use ->modify instead. So like, respectfully, don't. 🙈

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🌸 DESCRIPTION 🌸

So this module gives you a simple API for publishing messages to channels and for subscribing to them. That's it, that's the whole plot. 📢

When a message gets published on a channel, all subscribers currently in that channel will get it on their next get or get_all call. Like a group chat where nobody's muted and everyone reads on their own time. 👑

Right now it ships with four backends, each with its own little personality:

• DBM_Deep — for on-disk storage 💾
• Memcached — for possibly multi-host storage 🌐
• Jifty::DBI — for database-backed storage 🗄️
• PlainHash — for single-process storage 🧠

Also, please go look at the tests in t/ for this distribution, plus the SYNOPSIS up above, for some usage examples — because detailed documentation is not yet available. Yeah, it said that. Not me, the module said that. 😭

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🦋 SEE ALSO 🦋

• IPC::DirQueue — where the subscribers divide the published messages among themselves, so different subscribers never see the same message. Completely different energy: that one's a divide and conquer situation, this one's a everybody gets a copy situation. Both iconic, just different. 💅

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🎀 AUTHORS 🎀

• Audrey Tang <cpan@audreyt.org> 👑

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💜 COPYRIGHT 💜

Copyright 2006, 2007 by Audrey Tang <cpan@audreyt.org>.

This software is released under the MIT license cited below. 🫶

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🌈 The MIT License 🌈

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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and that's the whole page, bestie 💖 this little gem is documented as part of perl v5.36.0, dated 2022-11-27, and it's filed under IPC::PubSub(3pm). mwah, go build something cute with it 🎀✨🦋