Reconnect on READONLY error

[Yenya]

When the Redis server does failover to a replica using master-slave replication, the old master is demoted to read-only (either manually or by a sentinel), read operations can continue, but writers receive a READONLY error message, and are expected to reconnect to a newly promoted replica. In Redis::Fast, this can be handled by setting up a hook on the READONLY error message. From their documentation:

my $r = Redis::Fast->new(
  reconnect          => 1, # The value greater than 0 is required
  reconnect_on_error => sub {
    my ($error, $ret, $command) = @_;
    if ($error =~ /READONLY You can't write against a read only slave/) {
      # force reconnect
      return 1;
    }
    # do nothing
    return -1;
  },
);

In Mojo::Redis this is not possible, because the Mojo::Redis::Connection->on(error => ...) event gets emitted only when the current request is not a promise, and it is called for a single connection out of many in the connection pool. Also, I am not sure whether the event handler can lead to resubmitting the current request.

Please support a sane way how to detect a server failover to another replica, and reconnect in case the server goes read-only. So far it seems that Mojo::Redis stays connected to the old master indefinitely, and keeps getting the READONLY errors for write requests.

Thanks!