1 files changed, 75 insertions, 0 deletions
diff --git a/actioncable/lib/action_cable/subscription_adapter/evented_redis.rb b/actioncable/lib/action_cable/subscription_adapter/evented_redis.rb
new file mode 100644
index 0000000000..af04a58c70
--- /dev/null
+++ b/actioncable/lib/action_cable/subscription_adapter/evented_redis.rb
@@ -0,0 +1,75 @@
+require 'thread'
+
+gem 'em-hiredis', '~> 0.3.0'
+gem 'redis', '~> 3.0'
+require 'em-hiredis'
+require 'redis'
+
+EventMachine.epoll  if EventMachine.epoll?
+EventMachine.kqueue if EventMachine.kqueue?
+
+module ActionCable
+  module SubscriptionAdapter
+    class EventedRedis < Base # :nodoc:
+      @@mutex = Mutex.new
+
+      # Overwrite this factory method for EventMachine redis connections if you want to use a different Redis library than EM::Hiredis.
+      # This is needed, for example, when using Makara proxies for distributed Redis.
+      cattr_accessor(:em_redis_connector) { ->(config) { EM::Hiredis.connect(config[:url]) } }
+
+      # Overwrite this factory method for redis connections if you want to use a different Redis library than Redis.
+      # This is needed, for example, when using Makara proxies for distributed Redis.
+      cattr_accessor(:redis_connector) { ->(config) { ::Redis.new(url: config[:url]) } }
+
+      def initialize(*)
+        super
+        @redis_connection_for_broadcasts = @redis_connection_for_subscriptions = nil
+      end
+
+      def broadcast(channel, payload)
+        redis_connection_for_broadcasts.publish(channel, payload)
+      end
+
+      def subscribe(channel, message_callback, success_callback = nil)
+        redis_connection_for_subscriptions.pubsub.subscribe(channel, &message_callback).tap do |result|
+          result.callback { |reply| success_callback.call } if success_callback
+        end
+      end
+
+      def unsubscribe(channel, message_callback)
+        redis_connection_for_subscriptions.pubsub.unsubscribe_proc(channel, message_callback)
+      end
+
+      def shutdown
+        redis_connection_for_subscriptions.pubsub.close_connection
+        @redis_connection_for_subscriptions = nil
+      end
+
+      private
+        def redis_connection_for_subscriptions
+          ensure_reactor_running
+          @redis_connection_for_subscriptions || @server.mutex.synchronize do
+            @redis_connection_for_subscriptions ||= self.class.em_redis_connector.call(@server.config.cable).tap do |redis|
+              redis.on(:reconnect_failed) do
+                @logger.info "[ActionCable] Redis reconnect failed."
+              end
+            end
+          end
+        end
+
+        def redis_connection_for_broadcasts
+          @redis_connection_for_broadcasts || @server.mutex.synchronize do
+            @redis_connection_for_broadcasts ||= self.class.redis_connector.call(@server.config.cable)
+          end
+        end
+
+        def ensure_reactor_running
+          return if EventMachine.reactor_running?
+          @@mutex.synchronize do
+            Thread.new { EventMachine.run } unless EventMachine.reactor_running?
+            Thread.pass until EventMachine.reactor_running?
+          end
+        end
+    end
+  end
+end