add caching for translations

CHANGELOG.md

@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - support for setting instance languages in metadata
 - support for reusing oauth tokens, and not requiring new authorizations
 - the ability to obfuscate domains in your MRF descriptions
+- automatic translation of statuses via DeepL or LibreTranslate
 
 ### Changed
 - MFM parsing is now done on the backend by a modified version of ilja's parser -> https://akkoma.dev/AkkomaGang/mfm-parser

lib/pleroma/application.ex

@@ -154,7 +154,8 @@ defp cachex_children do
       build_cachex("web_resp", limit: 2500),
       build_cachex("emoji_packs", expiration: emoji_packs_expiration(), limit: 10),
       build_cachex("failed_proxy_url", limit: 2500),
-      build_cachex("banned_urls", default_ttl: :timer.hours(24 * 30), limit: 5_000)
+      build_cachex("banned_urls", default_ttl: :timer.hours(24 * 30), limit: 5_000),
+      build_cachex("translations", default_ttl: :timer.hours(24 * 30), limit: 2500)
     ]
   end
 

lib/pleroma/web/mastodon_api/controllers/status_controller.ex

@@ -31,6 +31,7 @@ defmodule Pleroma.Web.MastodonAPI.StatusController do
   plug(:skip_public_check when action in [:index, :show])
 
   @unauthenticated_access %{fallback: :proceed_unauthenticated, scopes: []}
+  @cachex Pleroma.Config.get([:cachex, :provider], Cachex)
 
   plug(
     OAuthScopesPlug,
@@ -427,7 +428,12 @@ def translate(%{assigns: %{user: user}} = conn, %{id: id, language: language}) d
          {:visible, true} <- {:visible, Visibility.visible_for_user?(activity, user)},
          translation_module <- Config.get([:translator, :module]),
          {:ok, detected, translation} <-
-           translation_module.translate(activity.object.data["content"], language) do
+           fetch_or_translate(
+             activity.id,
+             activity.object.data["content"],
+             language,
+             translation_module
+           ) do
       json(conn, %{detected_language: detected, text: translation})
     else
       {:enabled, false} ->
@@ -443,6 +449,18 @@ def translate(%{assigns: %{user: user}} = conn, %{id: id, language: language}) d
     end
   end
 
+  defp fetch_or_translate(status_id, text, language, translation_module) do
+    @cachex.fetch!(:user_cache, "translations:#{status_id}:#{language}", fn _ ->
+      value = translation_module.translate(text, language)
+
+      with {:ok, _, _} <- value do
+        value
+      else
+        _ -> {:ignore, value}
+      end
+    end)
+  end
+
   defp put_application(params, %{assigns: %{token: %Token{user: %User{} = user} = token}} = _conn) do
     if user.disclose_client do
       %{client_name: client_name, website: website} = Repo.preload(token, :app).app

lib/pleroma/web/mastodon_api/views/instance_view.ex

@@ -81,6 +81,9 @@ def features do
       if Config.get([:instance, :profile_directory]) do
         "profile_directory"
       end,
+      if Config.get([:translator, :enabled], false) do
+        "akkoma:machine_translation"
+      end,
       "custom_emoji_reactions"
     ]
     |> Enum.filter(& &1)

test/pleroma/web/mastodon_api/controllers/status_controller_test.exs

@@ -2083,7 +2083,7 @@ test "posting a quote of a status that doesn't exist", %{conn: conn} do
     test "should return text and detected language", %{conn: conn} do
       clear_config([:deepl, :tier], :free)
 
-      Tesla.Mock.mock(fn
+      Tesla.Mock.mock_global(fn
         %{method: :post, url: "https://api-free.deepl.com/v2/translate"} ->
           %Tesla.Env{
             status: 200,
@@ -2116,7 +2116,7 @@ test "should return text and detected language", %{conn: conn} do
     test "should not allow translating of statuses you cannot see", %{conn: conn} do
       clear_config([:deepl, :tier], :free)
 
-      Tesla.Mock.mock(fn
+      Tesla.Mock.mock_global(fn
         %{method: :post, url: "https://api-free.deepl.com/v2/translate"} ->
           %Tesla.Env{
             status: 200,