Introduce Streams as the domain language for the pubsub channels Channels redeliver messages from

1 files changed, 40 insertions, 0 deletions

diff --git a/lib/action_cable/channel/streams.rb b/lib/action_cable/channel/streams.rb
new file mode 100644
index 0000000000..3eac776e61
--- /dev/null
+++ b/lib/action_cable/channel/streams.rb
@@ -0,0 +1,40 @@
+module ActionCable
+  module Channel
+    module Streams
+      extend ActiveSupport::Concern
+
+      included do
+        on_unsubscribe :stop_all_streams
+      end
+
+      def stream_from(broadcasting, callback = nil)
+        callback ||= default_stream_callback(broadcasting)
+
+        streams << [ broadcasting, callback ]
+        pubsub.subscribe broadcasting, &callback
+
+        logger.info "#{channel_name} is streaming from #{broadcasting}"
+      end
+
+      def stop_all_streams
+        streams.each do |broadcasting, callback|
+          pubsub.unsubscribe_proc broadcasting, callback
+          logger.info "#{channel_name} stopped streaming from #{broadcasting}"
+        end
+      end
+
+      private
+        delegate :pubsub, to: :connection
+
+        def streams
+          @_streams ||= []
+        end
+
+        def default_stream_callback(broadcasting)
+          -> (message) do
+            transmit ActiveSupport::JSON.decode(message), via: "streamed from #{broadcasting}"
+          end
+        end
+    end
+  end
+end