feat: v2 user broadcast push metadata

lib/realtime_web/channels/realtime_channel/broadcast_handler.ex

@@ -129,7 +129,8 @@ defmodule RealtimeWeb.RealtimeChannel.BroadcastHandler do
   @dialyzer {:nowarn_function, build_broadcast: 2}
 
   # Message payload was built by V2 Serializer which was originally UserBroadcastPush
-  defp build_broadcast(topic, {user_event, user_payload_encoding, user_payload}) do
+  # We are not using the metadata for anything just yet.
+  defp build_broadcast(topic, {user_event, user_payload_encoding, user_payload, _metadata}) do
     %RealtimeWeb.Socket.UserBroadcast{
       topic: topic,
       user_event: user_event,

lib/realtime_web/socket/v2_serializer.ex

@@ -183,21 +183,30 @@ defmodule RealtimeWeb.Socket.V2Serializer do
          ref_size::size(8),
          topic_size::size(8),
          user_event_size::size(8),
+         metadata_size::size(8),
          user_payload_encoding::size(8),
          join_ref::binary-size(join_ref_size),
          ref::binary-size(ref_size),
          topic::binary-size(topic_size),
          user_event::binary-size(user_event_size),
+         metadata::binary-size(metadata_size),
          user_payload::binary
        >>) do
     user_payload_encoding = if user_payload_encoding == 0, do: :binary, else: :json
 
+    metadata =
+      if metadata_size > 0 do
+        Phoenix.json_library().decode!(metadata)
+      else
+        %{}
+      end
+
     # Encoding as Message because that's how Phoenix Socket and Channel.Server expects things to show up
-    # Here we abuse the payload field to carry a tuple of (user_event, user payload encoding, user payload)
+    # Here we abuse the payload field to carry a tuple of (user_event, user payload encoding, user payload, metadata)
     %Message{
       topic: topic,
       event: "broadcast",
-      payload: {user_event, user_payload_encoding, user_payload},
+      payload: {user_event, user_payload_encoding, user_payload, metadata},
       ref: ref,
       join_ref: join_ref
     }

mix.exs

@@ -4,7 +4,7 @@ defmodule Realtime.MixProject do
   def project do
     [
       app: :realtime,
-      version: "2.65.3",
+      version: "2.66.0",
       elixir: "~> 1.18",
       elixirc_paths: elixirc_paths(Mix.env()),
       start_permanent: Mix.env() == :prod,

test/realtime_web/channels/realtime_channel/broadcast_handler_test.exs

@@ -286,7 +286,7 @@ defmodule RealtimeWeb.RealtimeChannel.BroadcastHandlerTest do
       json_encoded_user_broadcast_payload = Jason.encode!(user_broadcast_payload)
 
       {:reply, :ok, _socket} =
-        BroadcastHandler.handle({"event123", :json, json_encoded_user_broadcast_payload}, db_conn, socket)
+        BroadcastHandler.handle({"event123", :json, json_encoded_user_broadcast_payload, %{}}, db_conn, socket)
 
       topic = "realtime:#{topic}"
       assert_receive {:socket_push, code, data}
@@ -327,7 +327,7 @@ defmodule RealtimeWeb.RealtimeChannel.BroadcastHandlerTest do
       user_broadcast_payload = <<123, 456, 789>>
 
       {:reply, :ok, _socket} =
-        BroadcastHandler.handle({"event123", :binary, user_broadcast_payload}, db_conn, socket)
+        BroadcastHandler.handle({"event123", :binary, user_broadcast_payload, %{}}, db_conn, socket)
 
       topic = "realtime:#{topic}"
 

test/realtime_web/socket/v2_serializer_test.exs

@@ -40,6 +40,8 @@ defmodule RealtimeWeb.Socket.V2SerializerTest do
     5,
     # user_event_size
     10,
+    # metadata_size
+    0,
     # binary encoding
     0::size(8),
     "12",
@@ -62,6 +64,8 @@ defmodule RealtimeWeb.Socket.V2SerializerTest do
     5,
     # user_event_size
     10,
+    # metadata_size
+    0,
     # json encoding
     1::size(8),
     "12",
@@ -79,6 +83,31 @@ defmodule RealtimeWeb.Socket.V2SerializerTest do
     125
   >>
 
+  @client_binary_user_broadcast_push_with_metadata <<
+    # user broadcast push
+    3::size(8),
+    # join_ref_size
+    2,
+    # ref_size
+    3,
+    # topic_size
+    5,
+    # user_event_size
+    10,
+    # metadata_size
+    14,
+    # binary encoding
+    0::size(8),
+    "12",
+    "123",
+    "topic",
+    "user_event",
+    ~s<{"store":true}>,
+    101,
+    102,
+    103
+  >>
+
   @reply <<
     # reply
     1::size(8),
@@ -490,13 +519,24 @@ defmodule RealtimeWeb.Socket.V2SerializerTest do
              }
     end
 
+    test "binary user pushed message with metadata" do
+      assert decode!(@serializer, @client_binary_user_broadcast_push_with_metadata, opcode: :binary) ==
+               %Phoenix.Socket.Message{
+                 join_ref: "12",
+                 ref: "123",
+                 topic: "topic",
+                 event: "broadcast",
+                 payload: {"user_event", :binary, <<101, 102, 103>>, %{"store" => true}}
+               }
+    end
+
     test "binary user pushed message" do
       assert decode!(@serializer, @client_binary_user_broadcast_push, opcode: :binary) == %Phoenix.Socket.Message{
                join_ref: "12",
                ref: "123",
                topic: "topic",
                event: "broadcast",
-               payload: {"user_event", :binary, <<101, 102, 103>>}
+               payload: {"user_event", :binary, <<101, 102, 103>>, %{}}
              }
     end
 
@@ -506,7 +546,7 @@ defmodule RealtimeWeb.Socket.V2SerializerTest do
                ref: "123",
                topic: "topic",
                event: "broadcast",
-               payload: {"user_event", :json, "{\"a\":\"b\"}"}
+               payload: {"user_event", :json, "{\"a\":\"b\"}", %{}}
              }
     end
   end