Fix incorrectly cached content after editing

lib/pleroma/activity/html.ex

@@ -8,6 +8,40 @@ defmodule Pleroma.Activity.HTML do
 
   @cachex Pleroma.Config.get([:cachex, :provider], Cachex)
 
+  # We store a list of cache keys related to an activity in a
+  # separate cache, scrubber_management_cache. It has the same
+  # size as scrubber_cache (see application.ex). Every time we add
+  # a cache to scrubber_cache, we update scrubber_management_cache.
+  #
+  # The most recent write of a certain key in the management cache
+  # is the same as the most recent write of any record related to that
+  # key in the main cache.
+  # Assuming LRW ( https://hexdocs.pm/cachex/Cachex.Policy.LRW.html ),
+  # this means when the management cache is evicted by cachex, all
+  # related records in the main cache will also have been evicted.
+
+  defp get_cache_keys_for(activity_id) do
+    with {:ok, list} when is_list(list) <- @cachex.get(:scrubber_management_cache, activity_id) do
+      list
+    else
+      _ -> []
+    end
+  end
+
+  defp add_cache_key_for(activity_id, additional_key) do
+    current = get_cache_keys_for(activity_id)
+
+    unless additional_key in current do
+      @cachex.put(:scrubber_management_cache, activity_id, [additional_key | current])
+    end
+  end
+
+  def invalidate_cache_for(activity_id) do
+    keys = get_cache_keys_for(activity_id)
+    Enum.map(keys, &@cachex.del(:scrubber_cache, &1))
+    @cachex.del(:scrubber_management_cache, activity_id)
+  end
+
   def get_cached_scrubbed_html_for_activity(
         content,
         scrubbers,
@@ -19,6 +53,8 @@ def get_cached_scrubbed_html_for_activity(
 
     @cachex.fetch!(:scrubber_cache, key, fn _key ->
       object = Object.normalize(activity, fetch: false)
+
+      add_cache_key_for(activity.id, key)
       HTML.ensure_scrubbed_html(content, scrubbers, object.data["fake"] || false, callback)
     end)
   end

lib/pleroma/application.ex

@@ -149,6 +149,7 @@ defp cachex_children do
       build_cachex("object", default_ttl: 25_000, ttl_interval: 1000, limit: 2500),
       build_cachex("rich_media", default_ttl: :timer.minutes(120), limit: 5000),
       build_cachex("scrubber", limit: 2500),
+      build_cachex("scrubber_management", limit: 2500),
       build_cachex("idempotency", expiration: idempotency_expiration(), limit: 2500),
       build_cachex("web_resp", limit: 2500),
       build_cachex("emoji_packs", expiration: emoji_packs_expiration(), limit: 10),

lib/pleroma/web/activity_pub/side_effects.ex

@@ -460,7 +460,8 @@ defp handle_update_object(
          %{data: %{"type" => "Update", "object" => updated_object}} = object,
          meta
        ) do
-    orig_object = Object.get_by_ap_id(updated_object["id"])
+    orig_object_ap_id = updated_object["id"]
+    orig_object = Object.get_by_ap_id(orig_object_ap_id)
     orig_object_data = orig_object.data
 
     if orig_object_data["type"] in @updatable_object_types do
@@ -473,15 +474,21 @@ defp handle_update_object(
         |> Object.maybe_update_history(orig_object_data, updated)
         |> maybe_update_poll(updated_object)
 
-      orig_object
-      |> Repo.preload(:hashtags)
-      |> Object.change(%{data: updated_object_data})
-      |> Object.update_and_set_cache()
+      changeset =
+        orig_object
+        |> Repo.preload(:hashtags)
+        |> Object.change(%{data: updated_object_data})
 
-      if updated do
-        object
-        |> Activity.normalize()
-        |> ActivityPub.notify_and_stream()
+      with {:ok, new_object} <- Repo.update(changeset),
+           {:ok, _} <- Object.invalid_object_cache(new_object),
+           {:ok, _} <- Object.set_cache(new_object),
+           # The metadata/utils.ex uses the object id for the cache.
+           {:ok, _} <- Pleroma.Activity.HTML.invalidate_cache_for(new_object.id) do
+        if updated do
+          object
+          |> Activity.normalize()
+          |> ActivityPub.notify_and_stream()
+        end
       end
     end
 

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

@@ -271,6 +271,16 @@ def render("show.json", %{activity: %{data: %{"object" => _object}} = activity}
 
     reply_to_user = reply_to && CommonAPI.get_user(reply_to.data["actor"])
 
+    history_len =
+      1 +
+        (Object.history_for(object.data)
+         |> Map.get("orderedItems")
+         |> length())
+
+    # See render("history.json", ...) for more details
+    # Here the implicit index of the current content is 0
+    chrono_order = history_len - 1
+
     content =
       object
       |> render_content()
@@ -280,14 +290,14 @@ def render("show.json", %{activity: %{data: %{"object" => _object}} = activity}
       |> Activity.HTML.get_cached_scrubbed_html_for_activity(
         User.html_filter_policy(opts[:for]),
         activity,
-        "mastoapi:content"
+        "mastoapi:content:#{chrono_order}"
       )
 
     content_plaintext =
       content
       |> Activity.HTML.get_cached_stripped_html_for_activity(
         activity,
-        "mastoapi:content"
+        "mastoapi:content:#{chrono_order}"
       )
 
     summary = object.data["summary"] || ""
@@ -416,9 +426,25 @@ def render("history.json", %{activity: %{data: %{"object" => _object}} = activit
 
     history = [object | past_history]
 
+    history_len = length(history)
+
+    history =
+      Enum.with_index(
+        history,
+        fn object, index ->
+          %{
+            # The history is prepended every time there is a new edit.
+            # In chrono_order, the oldest item is always at 0, and so on.
+            # The chrono_order is an invariant kept between edits.
+            chrono_order: history_len - 1 - index,
+            object: object
+          }
+        end
+      )
+
     individual_opts =
       opts
-      |> Map.put(:as, :object)
+      |> Map.put(:as, :item)
       |> Map.put(:user, user)
       |> Map.put(:hashtags, hashtags)
 
@@ -427,7 +453,12 @@ def render("history.json", %{activity: %{data: %{"object" => _object}} = activit
 
   def render(
         "history_item.json",
-        %{activity: activity, user: user, object: object, hashtags: hashtags} = opts
+        %{
+          activity: activity,
+          user: user,
+          item: %{object: object, chrono_order: chrono_order},
+          hashtags: hashtags
+        } = opts
       ) do
     sensitive = object.data["sensitive"] || Enum.member?(hashtags, "nsfw")
 
@@ -445,7 +476,7 @@ def render(
       |> Activity.HTML.get_cached_scrubbed_html_for_activity(
         User.html_filter_policy(opts[:for]),
         activity,
-        "mastoapi:content"
+        "mastoapi:content:#{chrono_order}"
       )
 
     summary = object.data["summary"] || ""

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

@@ -2113,9 +2113,15 @@ test "it returns the source", %{conn: conn} do
       oauth_access(["write:statuses"])
     end
 
-    test "it updates the status", %{conn: conn, user: user} do
+    test "it updates the status" do
+      %{conn: conn, user: user} = oauth_access(["write:statuses", "read:statuses"])
+
       {:ok, activity} = CommonAPI.post(user, %{status: "mew mew #abc", spoiler_text: "#def"})
 
+      conn
+      |> get("/api/v1/statuses/#{activity.id}")
+      |> json_response_and_validate_schema(200)
+
       response =
         conn
         |> put_req_header("content-type", "application/json")
@@ -2127,6 +2133,14 @@ test "it updates the status", %{conn: conn, user: user} do
 
       assert response["content"] == "edited"
       assert response["spoiler_text"] == "lol"
+
+      response =
+        conn
+        |> get("/api/v1/statuses/#{activity.id}")
+        |> json_response_and_validate_schema(200)
+
+      assert response["content"] == "edited"
+      assert response["spoiler_text"] == "lol"
     end
 
     test "it updates the attachments", %{conn: conn, user: user} do

test/pleroma/web/metadata/utils_test.exs

@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.Metadata.UtilsTest do
-  use Pleroma.DataCase, async: true
+  use Pleroma.DataCase, async: false
   import Pleroma.Factory
   alias Pleroma.Web.Metadata.Utils
 
@@ -22,6 +22,20 @@ test "it returns text without encode HTML" do
 
       assert Utils.scrub_html_and_truncate(note) == "Pleroma's really cool!"
     end
+
+    test "it does not return old content after editing" do
+      user = insert(:user)
+
+      {:ok, activity} = Pleroma.Web.CommonAPI.post(user, %{status: "mew mew #def"})
+
+      object = Pleroma.Object.normalize(activity)
+      assert Utils.scrub_html_and_truncate(object) == "mew mew #def"
+
+      {:ok, update} = Pleroma.Web.CommonAPI.update(user, activity, %{status: "mew mew #abc"})
+      update = Pleroma.Activity.normalize(update)
+      object = Pleroma.Object.normalize(update)
+      assert Utils.scrub_html_and_truncate(object) == "mew mew #abc"
+    end
   end
 
   describe "scrub_html_and_truncate/2" do