1 files changed, 26 insertions, 21 deletions

diff --git a/actioncable/lib/action_cable/channel/base.rb b/actioncable/lib/action_cable/channel/base.rb
index 845b747fc5..a866044f95 100644
--- a/actioncable/lib/action_cable/channel/base.rb
+++ b/actioncable/lib/action_cable/channel/base.rb
@@ -1,4 +1,4 @@
-require 'set'
+require "set"
 
 module ActionCable
   module Channel
@@ -144,13 +144,14 @@ module ActionCable
 
         # When a channel is streaming via pubsub, we want to delay the confirmation
         # transmission until pubsub subscription is confirmed.
-        @defer_subscription_confirmation = false
+        #
+        # The counter starts at 1 because it's awaiting a call to #subscribe_to_channel
+        @defer_subscription_confirmation_counter = Concurrent::AtomicFixnum.new(1)
 
         @reject_subscription = nil
         @subscription_confirmation_sent = nil
 
         delegate_connection_identifiers
-        subscribe_to_channel
       end
 
       # Extract the action name from the passed data and process it via the channel. The process will ensure
@@ -169,6 +170,17 @@ module ActionCable
         end
       end
 
+      # This method is called after subscription has been added to the connection
+      # and confirms or rejects the subscription.
+      def subscribe_to_channel
+        run_callbacks :subscribe do
+          subscribed
+        end
+
+        reject_subscription if subscription_rejected?
+        ensure_confirmation_sent
+      end
+
       # Called by the cable connection when it's cut, so the channel has a chance to cleanup with callbacks.
       # This method is not intended to be called directly by the user. Instead, overwrite the #unsubscribed callback.
       def unsubscribe_from_channel # :nodoc:
@@ -177,7 +189,6 @@ module ActionCable
         end
       end
 
-
       protected
         # Called once a consumer has become a subscriber of the channel. Usually the place to setup any streams
         # you want this channel to be sending to the subscriber.
@@ -202,12 +213,18 @@ module ActionCable
           end
         end
 
+        def ensure_confirmation_sent
+          return if subscription_rejected?
+          @defer_subscription_confirmation_counter.decrement
+          transmit_subscription_confirmation unless defer_subscription_confirmation?
+        end
+
         def defer_subscription_confirmation!
-          @defer_subscription_confirmation = true
+          @defer_subscription_confirmation_counter.increment
         end
 
         def defer_subscription_confirmation?
-          @defer_subscription_confirmation
+          @defer_subscription_confirmation_counter.value > 0
         end
 
         def subscription_confirmation_sent?
@@ -231,24 +248,12 @@ module ActionCable
           end
         end
 
-        def subscribe_to_channel
-          run_callbacks :subscribe do
-            subscribed
-          end
-
-          if subscription_rejected?
-            reject_subscription
-          else
-            transmit_subscription_confirmation unless defer_subscription_confirmation?
-          end
-        end
-
         def extract_action(data)
-          (data['action'].presence || :receive).to_sym
+          (data["action"].presence || :receive).to_sym
         end
 
         def processable_action?(action)
-          self.class.action_methods.include?(action.to_s)
+          self.class.action_methods.include?(action.to_s) unless subscription_rejected?
         end
 
         def dispatch_action(action, data)
@@ -263,7 +268,7 @@ module ActionCable
 
         def action_signature(action, data)
           "#{self.class.name}##{action}".tap do |signature|
-            if (arguments = data.except('action')).any?
+            if (arguments = data.except("action")).any?
               signature << "(#{arguments.inspect})"
             end
           end