table of contents
Mojo::Pg::PubSub(3) | User Contributed Perl Documentation | Mojo::Pg::PubSub(3) |
NAME¶
Mojo::Pg::PubSub - Publish/Subscribe
SYNOPSIS¶
use Mojo::Pg::PubSub; my $pubsub = Mojo::Pg::PubSub->new(pg => $pg); my $cb = $pubsub->listen(foo => sub ($pubsub, $payload) { say "Received: $payload"; }); $pubsub->notify(foo => 'I ♥ Mojolicious!'); $pubsub->unlisten(foo => $cb);
DESCRIPTION¶
Mojo::Pg::PubSub is a scalable implementation of the publish/subscribe pattern used by Mojo::Pg. It is based on PostgreSQL notifications and allows many consumers to share the same database connection, to avoid many common scalability problems.
EVENTS¶
Mojo::Pg::PubSub inherits all events from Mojo::EventEmitter and can emit the following new ones.
disconnect¶
$pubsub->on(disconnect => sub ($pubsub, $db) { ... });
Emitted after the current database connection is lost.
reconnect¶
$pubsub->on(reconnect => sub ($pubsub, $db) { ... });
Emitted after switching to a new database connection for sending and receiving notifications.
ATTRIBUTES¶
Mojo::Pg::PubSub implements the following attributes.
pg¶
my $pg = $pubsub->pg; $pubsub = $pubsub->pg(Mojo::Pg->new);
Mojo::Pg object this publish/subscribe container belongs to. Note that this attribute is weakened.
reconnect_interval¶
my $interval = $pubsub->reconnect_interval; $pubsub = $pubsub->reconnect_interval(0.1);
Amount of time in seconds to wait to reconnect after disconnecting, defaults to 1.
METHODS¶
Mojo::Pg::PubSub inherits all methods from Mojo::EventEmitter and implements the following new ones.
db¶
my $db = $pubsub->db;
Build and cache or get cached Mojo::Pg::Database connection from "pg". Used to reconnect if disconnected.
# Reconnect immediately $pubsub->unsubscribe('disconnect')->on(disconnect => sub ($pubsub, $db) { pubsub->db });
json¶
$pubsub = $pubsub->json('foo');
Activate automatic JSON encoding and decoding with "to_json" in Mojo::JSON and "from_json" in Mojo::JSON for a channel.
# Send and receive data structures $pubsub->json('foo')->listen(foo => sub ($pubsub, $payload) { say $payload->{bar}; }); $pubsub->notify(foo => {bar => 'I ♥ Mojolicious!'});
listen¶
my $cb = $pubsub->listen(foo => sub {...});
Subscribe to a channel, there is no limit on how many subscribers a channel can have. Automatic decoding of JSON text to Perl values can be activated with "json".
# Subscribe to the same channel twice $pubsub->listen(foo => sub ($pubsub, $payload) { say "One: $payload"; }); $pubsub->listen(foo => sub ($pubsub, $payload) { say "Two: $payload"; });
new¶
my $pubsub = Mojo::Pg::PubSub->new; my $pubsub = Mojo::Pg::PubSub->new(pg => Mojo::Pg->new); my $pubsub = Mojo::Pg::PubSub->new({pg => Mojo::Pg->new});
Construct a new Mojo::Pg::PubSub object and subscribe to the "disconnect" event with default reconnect logic.
notify¶
$pubsub = $pubsub->notify('foo'); $pubsub = $pubsub->notify(foo => 'I ♥ Mojolicious!'); $pubsub = $pubsub->notify(foo => {bar => 'baz'});
Notify a channel. Automatic encoding of Perl values to JSON text can be activated with "json".
reset¶
$pubsub->reset;
Reset all subscriptions and the database connection. This is usually done after a new process has been forked, to prevent the child process from stealing notifications meant for the parent process.
unlisten¶
$pubsub = $pubsub->unlisten('foo'); $pubsub = $pubsub->unlisten(foo => $cb);
Unsubscribe from a channel.
SEE ALSO¶
Mojo::Pg, Mojolicious::Guides, <https://mojolicious.org>.
2022-03-16 | perl v5.40.0 |