From b195956ecb07e9a3e47123a5bad95a664b257ffc Mon Sep 17 00:00:00 2001
From: David Roetzel <david@roetzel.de>
Date: Wed, 28 May 2025 14:34:37 +0200
Subject: [PATCH] Encapsulate redis key usage (#34840)

---
 app/models/home_feed.rb                 |  8 ++++++
 app/models/user.rb                      |  6 +++-
 app/services/follow_service.rb          |  2 +-
 app/services/precompute_feed_service.rb |  2 +-
 app/workers/merge_worker.rb             |  2 +-
 spec/models/home_feed_spec.rb           | 38 +++++++++++++++++++++++++
 6 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/app/models/home_feed.rb b/app/models/home_feed.rb
index d6ebb5fa6b..81730ac98f 100644
--- a/app/models/home_feed.rb
+++ b/app/models/home_feed.rb
@@ -9,4 +9,12 @@ class HomeFeed < Feed
   def regenerating?
     redis.exists?("account:#{@account.id}:regeneration")
   end
+
+  def regeneration_in_progress!
+    redis.set("account:#{@account.id}:regeneration", true, nx: true, ex: 1.day.seconds)
+  end
+
+  def regeneration_finished!
+    redis.del("account:#{@account.id}:regeneration")
+  end
 end
diff --git a/app/models/user.rb b/app/models/user.rb
index 8a9e27504d..86201f543f 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -531,7 +531,11 @@ class User < ApplicationRecord
   end
 
   def regenerate_feed!
-    RegenerationWorker.perform_async(account_id) if redis.set("account:#{account_id}:regeneration", true, nx: true, ex: 1.day.seconds)
+    home_feed = HomeFeed.new(account)
+    unless home_feed.regenerating?
+      home_feed.regeneration_in_progress!
+      RegenerationWorker.perform_async(account_id)
+    end
   end
 
   def needs_feed_update?
diff --git a/app/services/follow_service.rb b/app/services/follow_service.rb
index cff38b8e6e..2928c85390 100644
--- a/app/services/follow_service.rb
+++ b/app/services/follow_service.rb
@@ -46,7 +46,7 @@ class FollowService < BaseService
   private
 
   def mark_home_feed_as_partial!
-    redis.set("account:#{@source_account.id}:regeneration", true, nx: true, ex: 1.day.seconds)
+    HomeFeed.new(@source_account).regeneration_in_progress!
   end
 
   def following_not_possible?
diff --git a/app/services/precompute_feed_service.rb b/app/services/precompute_feed_service.rb
index a591c90913..3eb1d41d92 100644
--- a/app/services/precompute_feed_service.rb
+++ b/app/services/precompute_feed_service.rb
@@ -12,7 +12,7 @@ class PrecomputeFeedService < BaseService
       FeedManager.instance.populate_list(list) unless skip_timeline?(:list, list.id)
     end
   ensure
-    redis.del("account:#{account.id}:regeneration")
+    HomeFeed.new(account).regeneration_finished!
   end
 
   private
diff --git a/app/workers/merge_worker.rb b/app/workers/merge_worker.rb
index d4dcb326bc..4fdf5ba3f9 100644
--- a/app/workers/merge_worker.rb
+++ b/app/workers/merge_worker.rb
@@ -31,7 +31,7 @@ class MergeWorker
       FeedManager.instance.merge_into_home(@from_account, @into_account)
     end
   ensure
-    redis.del("account:#{into_account_id}:regeneration")
+    HomeFeed.new(@into_account).regeneration_finished!
   end
 
   def merge_into_list!(into_list_id)
diff --git a/spec/models/home_feed_spec.rb b/spec/models/home_feed_spec.rb
index 06bb63b1a4..7546fb7861 100644
--- a/spec/models/home_feed_spec.rb
+++ b/spec/models/home_feed_spec.rb
@@ -42,4 +42,42 @@ RSpec.describe HomeFeed do
       end
     end
   end
+
+  describe '#regenerating?' do
+    context 'when feed is being generated' do
+      before do
+        redis.set("account:#{account.id}:regeneration", true)
+      end
+
+      it 'returns `true`' do
+        expect(subject.regenerating?).to be true
+      end
+    end
+
+    context 'when feed is not being generated' do
+      it 'returns `false`' do
+        expect(subject.regenerating?).to be false
+      end
+    end
+  end
+
+  describe '#regeneration_in_progress!' do
+    it 'sets the corresponding key in redis' do
+      expect(redis.exists?("account:#{account.id}:regeneration")).to be false
+
+      subject.regeneration_in_progress!
+
+      expect(redis.exists?("account:#{account.id}:regeneration")).to be true
+    end
+  end
+
+  describe '#regeneration_finished!' do
+    it 'removes the corresponding key from redis' do
+      redis.set("account:#{account.id}:regeneration", true)
+
+      subject.regeneration_finished!
+
+      expect(redis.exists?("account:#{account.id}:regeneration")).to be false
+    end
+  end
 end