Don't create noop SearchIndexingWorker jobs for passive index

lib/pleroma/search/database_search.ex

@@ -40,12 +40,6 @@ def search(user, search_query, options \\ []) do
     end
   end
 
-  @impl true
-  def add_to_index(_activity), do: nil
-
-  @impl true
-  def remove_from_index(_object), do: nil
-
   def maybe_restrict_author(query, %User{} = author) do
     Activity.Queries.by_author(query, author)
   end

lib/pleroma/search/search_backend.ex

@@ -14,4 +14,6 @@ defmodule Pleroma.Search.SearchBackend do
   from index.
   """
   @callback remove_from_index(object :: Pleroma.Object.t()) :: {:ok, any()} | {:error, any()}
+
+  @optional_callbacks add_to_index: 1, remove_from_index: 1
 end

lib/pleroma/workers/search_indexing_worker.ex

@@ -1,23 +1,38 @@
 defmodule Pleroma.Workers.SearchIndexingWorker do
   use Pleroma.Workers.WorkerHelper, queue: "search_indexing"
 
-  @impl Oban.Worker
+  defp search_module(), do: Pleroma.Config.get!([Pleroma.Search, :module])
 
+  def enqueue("add_to_index", params, worker_args) do
+    if Kernel.function_exported?(search_module(), :add_to_index, 1) do
+      do_enqueue("add_to_index", params, worker_args)
+    else
+      # XXX: or {:ok, nil} to more closely match Oban.inset()'s {:ok, job}?
+      #      or similar to unique coflict: %Oban.Job{conflict?: true} (but omitting all other fileds...)
+      :ok
+    end
+  end
+
+  def enqueue("remove_from_index", params, worker_args) do
+    if Kernel.function_exported?(search_module(), :remove_from_index, 1) do
+      do_enqueue("remove_from_index", params, worker_args)
+    else
+      :ok
+    end
+  end
+
+  @impl Oban.Worker
   def perform(%Job{args: %{"op" => "add_to_index", "activity" => activity_id}}) do
     activity = Pleroma.Activity.get_by_id_with_object(activity_id)
 
-    search_module = Pleroma.Config.get([Pleroma.Search, :module])
-
-    search_module.add_to_index(activity)
+    search_module().add_to_index(activity)
 
     :ok
   end
 
   def perform(%Job{args: %{"op" => "remove_from_index", "object" => object_id}}) do
-    search_module = Pleroma.Config.get([Pleroma.Search, :module])
-
     # Fake the object so we can remove it from the index without having to keep it in the DB
-    search_module.remove_from_index(%Pleroma.Object{id: object_id})
+    search_module().remove_from_index(%Pleroma.Object{id: object_id})
 
     :ok
   end