1 files changed, 59 insertions, 0 deletions
diff --git a/actioncable/lib/action_cable/subscription_adapter/subscriber_map.rb b/actioncable/lib/action_cable/subscription_adapter/subscriber_map.rb
new file mode 100644
index 0000000000..01cdc2dfa1
--- /dev/null
+++ b/actioncable/lib/action_cable/subscription_adapter/subscriber_map.rb
@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+module ActionCable
+  module SubscriptionAdapter
+    class SubscriberMap
+      def initialize
+        @subscribers = Hash.new { |h, k| h[k] = [] }
+        @sync = Mutex.new
+      end
+
+      def add_subscriber(channel, subscriber, on_success)
+        @sync.synchronize do
+          new_channel = !@subscribers.key?(channel)
+
+          @subscribers[channel] << subscriber
+
+          if new_channel
+            add_channel channel, on_success
+          elsif on_success
+            on_success.call
+          end
+        end
+      end
+
+      def remove_subscriber(channel, subscriber)
+        @sync.synchronize do
+          @subscribers[channel].delete(subscriber)
+
+          if @subscribers[channel].empty?
+            @subscribers.delete channel
+            remove_channel channel
+          end
+        end
+      end
+
+      def broadcast(channel, message)
+        list = @sync.synchronize do
+          return if !@subscribers.key?(channel)
+          @subscribers[channel].dup
+        end
+
+        list.each do |subscriber|
+          invoke_callback(subscriber, message)
+        end
+      end
+
+      def add_channel(channel, on_success)
+        on_success.call if on_success
+      end
+
+      def remove_channel(channel)
+      end
+
+      def invoke_callback(callback, message)
+        callback.call message
+      end
+    end
+  end
+end