Hi,
I am not sure I fully understand your question, but if you already have
Redis and you want that only one spawned process receives an event, and
that on next event next spawned process do the same, you could use queue
commands from Redis for that (instead of PUB/SUB that would be addressed to
all childs that are listening to the published key).
So your "publisher" should send events to a queue using for instance, RPUSH
somelist someevent, and your mojo app should be listening with BLPOP
somelist 0 (0 means indefinitelly).
For the listening inside your Mojo app, you should take a look on
Mojo::Redis2.
Just as an example, you could do something like:
use Mojolicious::Lite;
use Mojo::Redis2;
helper redis => sub { shift->stash->{redis} ||= Mojo::Redis2->new; };
Mojo::IOLoop->next_tick(sub {
my $c = app->build_controller;
my $element_get;
$element_get = sub {
$c->redis->blpop('myqueue', 0, sub {
my ($self, $err, $res) = @_;
$c->app->log->info("Worker $$ received an event from $res->[0]: $res->[1]");
$element_get->(); # get next element from 'myqueue'
});
};
$c->app->log->info("Worker $$ started");
$element_get->();
});
get '/' => {text => 'Hello Word!!!'};
app->start;
That way, you will not block the ioloop, and only one child will take next
event.
The child that gets the event should rotate just because it is the way
Redis queues work.
As stated in the cookbook, you can use "next_tick" to run code whenever a
new process is spawned.
You can check this code running it with hypnotoad and opening on another
terminal a redis-cli instance and sending strings to the 'myqueue' list,
like:
> rpush myqueue whatever "whatever 2" "whatever 3" "whatever 4" "whatever 5"
Hope this helps,
El jueves, 13 de abril de 2017, 10:46:24 (UTC-3), Ганц Аккерман escribió:
>
> Hello!
>
> In my hypnotoad application i want to update cache (Cache::FastMmap) on
> some event, which fired by Redis subscription.
> But now i have to subscribe on Redis events and update local perl hash in
> every spawned process, which at the same time serve users requests.
> How to use only one process to support actualized cache state, so all
> workers can read information from that cache, but not update it?
>
> I think, i need to subscribe on Redis events and maintain cache in the
> main process, but Mojolicious Cookbook tell me that is impossible (IOLoop
> not running in the main process).
> I think Minion is not suitable for me because we use only Redis+MariaDB in
> our production environments and i cant install PostgreSQL for Minion.
> So i m in doubt, how to operate cache in traditional way (one auxiliary
> updater process - many frontend processes-readers).
>
> Tell me please, whether is it possible in Mojolicious application running
> on Mojolicious::Server::Prefork/hypnotoad?
>
> Thank you!
>
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