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`

3 files changed, 7 insertions, 3 deletions

diff --git a/actioncable/CHANGELOG.md b/actioncable/CHANGELOG.md
index 560ee89846..3952887b61 100644
--- a/actioncable/CHANGELOG.md
+++ b/actioncable/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Support redis-rb 4.0.
+
+    *Jeremy Daer*
+
 *   Hash long stream identifiers when using PostgreSQL adapter.
 
     PostgreSQL has a limit on identifiers length (63 chars, [docs](https://www.postgresql.org/docs/current/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS)).
diff --git a/actioncable/lib/action_cable/subscription_adapter/evented_redis.rb b/actioncable/lib/action_cable/subscription_adapter/evented_redis.rb
index 07774810ce..1227c793a9 100644
--- a/actioncable/lib/action_cable/subscription_adapter/evented_redis.rb
+++ b/actioncable/lib/action_cable/subscription_adapter/evented_redis.rb
@@ -3,7 +3,7 @@
 require "thread"
 
 gem "em-hiredis", "~> 0.3.0"
-gem "redis", "~> 3.0"
+gem "redis", ">= 3", "< 5"
 require "em-hiredis"
 require "redis"
 
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|