Adds the ability to force a new connection to Redis

[markhuot]

When using Redis' SUBSCRIBE the recommendation is to open a second connection for any key modification you need to do. E.g. Laravel does not currently allow you to modify keys why subscribed, causing the following to error,

Redis::subscribe('queue-notifications', function ($msg) {
  $job = Redis::rpoplpush('queue-jobs', 'working-jobs');
});

The exact error is,

ERR only (P)SUBSCRIBE / (P)UNSUBSCRIBE / PING / QUIT allowed in this context

This PR allows you to work around this by forcing a new connection to Redis, when necessary,

Redis::subscribe('queue-notifications', function ($msg) {
  $redis = Redis::connection(null, true);
  $job = $redis->rpoplpush('queue-jobs', 'working-jobs');
});

The need for a second connection is also stated here,

http://stackoverflow.com/questions/22668244/should-i-use-separate-connections-for-pub-and-sub-with-redis

Note, this could probably be more expressive with Redis::newConnection() but I wanted to start here.

[taylorotwell]

Sounds kinda more intuitive to have a disconnect() method like DB?

[markhuot]

I don't want to disconnect either connection. I actually need both connections to be active so I can continue to listen on one connection while interacting with Redis over the second connection.

Some additional reports of similar needs on other frameworks,

• Can't Pub/Sub On Same Client clue/reactphp-redis#39
• https://groups.google.com/forum/#!topic/lettuce-redis-client-users/Jszb0siSPpw
• https://laracasts.com/discuss/channels/laravel/unable-to-fire-a-laravel-event-from-within-a-laravel-redis-pubsub-subscriber-only-happens-when-im-interacting-with-queues

[taylorotwell]

Easier for me to just make resolve public. I can't change the interface on a point release.

[markhuot]

👍 makes sense. Thank you.

Would you like another PR based on master that adds Redis::newConnection($name = null) for a later release? Or, is resolve the way to go for this?