Pipeline: Add a side effects step after the transaction finishes

This is to run things like streaming notifications out, which will
sometimes need data that is created by the transaction, but is
streamed out asynchronously.

lib/pleroma/notification.ex

@@ -334,30 +334,34 @@ defmodule Pleroma.Notification do
     end
   end
 
-  def create_notifications(%Activity{data: %{"to" => _, "type" => "Create"}} = activity) do
+  def create_notifications(activity, options \\ [])
+
+  def create_notifications(%Activity{data: %{"to" => _, "type" => "Create"}} = activity, options) do
     object = Object.normalize(activity, false)
 
     if object && object.data["type"] == "Answer" do
       {:ok, []}
     else
-      do_create_notifications(activity)
+      do_create_notifications(activity, options)
     end
   end
 
-  def create_notifications(%Activity{data: %{"type" => type}} = activity)
+  def create_notifications(%Activity{data: %{"type" => type}} = activity, options)
       when type in ["Follow", "Like", "Announce", "Move", "EmojiReact"] do
-    do_create_notifications(activity)
+    do_create_notifications(activity, options)
   end
 
-  def create_notifications(_), do: {:ok, []}
+  def create_notifications(_, _), do: {:ok, []}
+
+  defp do_create_notifications(%Activity{} = activity, options) do
+    do_send = Keyword.get(options, :do_send, true)
 
-  defp do_create_notifications(%Activity{} = activity) do
     {enabled_receivers, disabled_receivers} = get_notified_from_activity(activity)
     potential_receivers = enabled_receivers ++ disabled_receivers
 
     notifications =
       Enum.map(potential_receivers, fn user ->
-        do_send = user in enabled_receivers
+        do_send = do_send && user in enabled_receivers
         create_notification(activity, user, do_send)
       end)
 
@@ -623,4 +627,12 @@ defmodule Pleroma.Notification do
   end
 
   def skip?(_, _, _), do: false
+
+  def for_user_and_activity(user, activity) do
+    from(n in __MODULE__,
+      where: n.user_id == ^user.id,
+      where: n.activity_id == ^activity.id
+    )
+    |> Repo.one()
+  end
 end

lib/pleroma/web/activity_pub/pipeline.ex

@@ -17,6 +17,10 @@ defmodule Pleroma.Web.ActivityPub.Pipeline do
           {:ok, Activity.t() | Object.t(), keyword()} | {:error, any()}
   def common_pipeline(object, meta) do
     case Repo.transaction(fn -> do_common_pipeline(object, meta) end) do
+      {:ok, {:ok, activity, meta}} ->
+        SideEffects.handle_after_transaction(meta)
+        {:ok, activity, meta}
+
       {:ok, value} ->
         value
 

lib/pleroma/web/activity_pub/side_effects.ex

@@ -16,6 +16,7 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
   alias Pleroma.Web.ActivityPub.Pipeline
   alias Pleroma.Web.ActivityPub.Utils
   alias Pleroma.Web.Streamer
+  alias Pleroma.Web.Push
 
   def handle(object, meta \\ [])
 
@@ -37,7 +38,12 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
   # - Set up notifications
   def handle(%{data: %{"type" => "Create"}} = activity, meta) do
     with {:ok, _object, _meta} <- handle_object_creation(meta[:object_data], meta) do
-      Notification.create_notifications(activity)
+      {:ok, notifications} = Notification.create_notifications(activity, do_send: false)
+
+      meta =
+        meta
+        |> add_notifications(notifications)
+
       {:ok, activity, meta}
     else
       e -> Repo.rollback(e)
@@ -200,4 +206,26 @@ defmodule Pleroma.Web.ActivityPub.SideEffects do
   end
 
   def handle_undoing(object), do: {:error, ["don't know how to handle", object]}
+
+  defp send_notifications(meta) do
+    Keyword.get(meta, :created_notifications, [])
+    |> Enum.each(fn notification ->
+      Streamer.stream(["user", "user:notification"], notification)
+      Push.send(notification)
+    end)
+
+    meta
+  end
+
+  defp add_notifications(meta, notifications) do
+    existing = Keyword.get(meta, :created_notifications, [])
+
+    meta
+    |> Keyword.put(:created_notifications, notifications ++ existing)
+  end
+
+  def handle_after_transaction(meta) do
+    meta
+    |> send_notifications()
+  end
 end