Fix deletes not reaching every server that interacted with status (#15200)

Extract logic for determining ActivityPub inboxes to send deletes
to to its own class and explicitly include the person the status
replied to (even if not mentioned), people who favourited it, and
people who replied to it (though that one is still not recursive)

app/lib/status_reach_finder.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+class StatusReachFinder
+  def initialize(status)
+    @status = status
+  end
+
+  def inboxes
+    Account.where(id: reached_account_ids).inboxes
+  end
+
+  private
+
+  def reached_account_ids
+    [
+      replied_to_account_id,
+      reblog_of_account_id,
+      mentioned_account_ids,
+      reblogs_account_ids,
+      favourites_account_ids,
+      replies_account_ids,
+    ].tap do |arr|
+      arr.flatten!
+      arr.compact!
+      arr.uniq!
+    end
+  end
+
+  def replied_to_account_id
+    @status.in_reply_to_account_id
+  end
+
+  def reblog_of_account_id
+    @status.reblog.account_id if @status.reblog?
+  end
+
+  def mentioned_account_ids
+    @status.mentions.pluck(:account_id)
+  end
+
+  def reblogs_account_ids
+    @status.reblogs.pluck(:account_id)
+  end
+
+  def favourites_account_ids
+    @status.favourites.pluck(:account_id)
+  end
+
+  def replies_account_ids
+    @status.replies.pluck(:account_id)
+  end
+end

app/services/remove_status_service.rb

@@ -14,39 +14,42 @@ class RemoveStatusService < BaseService
     @payload  = Oj.dump(event: :delete, payload: status.id.to_s)
     @status   = status
     @account  = status.account
-    @tags     = status.tags.pluck(:name).to_a
-    @mentions = status.active_mentions.includes(:account).to_a
-    @reblogs  = status.reblogs.includes(:account).to_a
     @options  = options
 
     RedisLock.acquire(lock_options) do |lock|
       if lock.acquired?
-        remove_from_self if status.account.local?
+        remove_from_self if @account.local?
         remove_from_followers
         remove_from_lists
-        remove_from_affected
+
+        # There is no reason to send out Undo activities when the
+        # cause is that the original object has been removed, since
+        # original object being removed implicitly removes reblogs
+        # of it. The Delete activity of the original is forwarded
+        # separately.
+        if @account.local? && !@options[:original_removed]
+          remove_from_remote_followers
+          remove_from_remote_reach
+        end
+
+        # Since reblogs don't mention anyone, don't get reblogged,
+        # favourited and don't contain their own media attachments
+        # or hashtags, this can be skipped
+        unless @status.reblog?
+          remove_from_mentions
           remove_reblogs
           remove_from_hashtags
           remove_from_public
-        remove_from_media if status.media_attachments.any?
+          remove_from_media if @status.media_attachments.any?
           remove_from_spam_check
           remove_media
+        end
 
         @status.destroy! if @options[:immediate] || !@status.reported?
       else
         raise Mastodon::RaceConditionError
       end
     end
-
-    # There is no reason to send out Undo activities when the
-    # cause is that the original object has been removed, since
-    # original object being removed implicitly removes reblogs
-    # of it. The Delete activity of the original is forwarded
-    # separately.
-    return if !@account.local? || @options[:original_removed]
-
-    remove_from_remote_followers
-    remove_from_remote_affected
   end
 
   private
@@ -67,31 +70,35 @@ class RemoveStatusService < BaseService
     end
   end
 
-  def remove_from_affected
-    @mentions.map(&:account).select(&:local?).each do |account|
-      redis.publish("timeline:#{account.id}", @payload)
+  def remove_from_mentions
+    # For limited visibility statuses, the mentions that determine
+    # who receives them in their home feed are a subset of followers
+    # and therefore the delete is already handled by sending it to all
+    # followers. Here we send a delete to actively mentioned accounts
+    # that may not follow the account
+
+    @status.active_mentions.find_each do |mention|
+      redis.publish("timeline:#{mention.account_id}", @payload)
     end
   end
 
-  def remove_from_remote_affected
+  def remove_from_remote_reach
+    return if @status.reblog?
+
     # People who got mentioned in the status, or who
     # reblogged it from someone else might not follow
     # the author and wouldn't normally receive the
     # delete notification - so here, we explicitly
     # send it to them
 
-    target_accounts = (@mentions.map(&:account).reject(&:local?) + @reblogs.map(&:account).reject(&:local?))
-    target_accounts << @status.reblog.account if @status.reblog? && !@status.reblog.account.local?
-    target_accounts.uniq!(&:id)
+    status_reach_finder = StatusReachFinder.new(@status)
 
-    # ActivityPub
-    ActivityPub::DeliveryWorker.push_bulk(target_accounts.select(&:activitypub?).uniq(&:preferred_inbox_url)) do |target_account|
-      [signed_activity_json, @account.id, target_account.preferred_inbox_url]
+    ActivityPub::DeliveryWorker.push_bulk(status_reach_finder.inboxes) do |inbox_url|
+      [signed_activity_json, @account.id, inbox_url]
     end
   end
 
   def remove_from_remote_followers
-    # ActivityPub
     ActivityPub::DeliveryWorker.push_bulk(@account.followers.inboxes) do |inbox_url|
       [signed_activity_json, @account.id, inbox_url]
     end
@@ -118,19 +125,19 @@ class RemoveStatusService < BaseService
     # because once original status is gone, reblogs will disappear
     # without us being able to do all the fancy stuff
 
-    @reblogs.each do |reblog|
+    @status.reblogs.includes(:account).find_each do |reblog|
       RemoveStatusService.new.call(reblog, original_removed: true)
     end
   end
 
   def remove_from_hashtags
-    @account.featured_tags.where(tag_id: @status.tags.pluck(:id)).each do |featured_tag|
+    @account.featured_tags.where(tag_id: @status.tags.map(&:id)).each do |featured_tag|
       featured_tag.decrement(@status.id)
     end
 
     return unless @status.public_visibility?
 
-    @tags.each do |hashtag|
+    @status.tags.map(&:name).each do |hashtag|
       redis.publish("timeline:hashtag:#{hashtag.mb_chars.downcase}", @payload)
       redis.publish("timeline:hashtag:#{hashtag.mb_chars.downcase}:local", @payload) if @status.local?
     end
@@ -140,22 +147,14 @@ class RemoveStatusService < BaseService
     return unless @status.public_visibility?
 
     redis.publish('timeline:public', @payload)
-    if @status.local?
-      redis.publish('timeline:public:local', @payload)
-    else
-      redis.publish('timeline:public:remote', @payload)
-    end
+    redis.publish(@status.local? ? 'timeline:public:local' : 'timeline:public:remote', @payload)
   end
 
   def remove_from_media
     return unless @status.public_visibility?
 
     redis.publish('timeline:public:media', @payload)
-    if @status.local?
-      redis.publish('timeline:public:local:media', @payload)
-    else
-      redis.publish('timeline:public:remote:media', @payload)
-    end
+    redis.publish(@status.local? ? 'timeline:public:local:media' : 'timeline:public:remote:media', @payload)
   end
 
   def remove_media