redis-rb 4.0 support

* Use `gem 'redis', '~> 4.0'` for new app Gemfiles
* Loosen Action Cable redis-rb dep to `>= 3.3, < 5`
* Bump redis-namespace for looser Redis version dep
* Avoid using the underlying `redis.client` directly
* Use `Redis.new` instead of `Redis.connect`

1 files changed, 2 insertions, 2 deletions

diff --git a/actioncable/lib/action_cable/subscription_adapter/redis.rb b/actioncable/lib/action_cable/subscription_adapter/redis.rb
index facea944ff..c28951608f 100644
--- a/actioncable/lib/action_cable/subscription_adapter/redis.rb
+++ b/actioncable/lib/action_cable/subscription_adapter/redis.rb
@@ -2,7 +2,7 @@
 
 require "thread"
 
-gem "redis", "~> 3.0"
+gem "redis", ">= 3", "< 5"
 require "redis"
 
 module ActionCable
@@ -76,7 +76,7 @@ module ActionCable
 
           def listen(conn)
             conn.without_reconnect do
-              original_client = conn.client
+              original_client = conn.respond_to?(:_client) ? conn._client : conn.client
 
               conn.subscribe("_action_cable_internal") do |on|
                 on.subscribe do |chan, count|