From 6cf57c676550068a59149ca82d63fcb5b5431158 Mon Sep 17 00:00:00 2001
From: Eugen Rochko <eugen@zeonfederated.com>
Date: Fri, 13 May 2022 00:02:35 +0200
Subject: Refactor how Redis locks are created (#18400)

* Refactor how Redis locks are created

* Fix autorelease duration on account deletion lock
---
 app/models/account_migration.rb  | 13 +++----------
 app/models/concerns/lockable.rb  | 19 +++++++++++++++++++
 app/models/concerns/redisable.rb |  8 ++++----
 3 files changed, 26 insertions(+), 14 deletions(-)
 create mode 100644 app/models/concerns/lockable.rb

(limited to 'app/models')

diff --git a/app/models/account_migration.rb b/app/models/account_migration.rb
index ded32c9c6..06291c9f3 100644
--- a/app/models/account_migration.rb
+++ b/app/models/account_migration.rb
@@ -15,6 +15,7 @@
 
 class AccountMigration < ApplicationRecord
   include Redisable
+  include Lockable
 
   COOLDOWN_PERIOD = 30.days.freeze
 
@@ -41,12 +42,8 @@ class AccountMigration < ApplicationRecord
 
     return false unless errors.empty?
 
-    RedisLock.acquire(lock_options) do |lock|
-      if lock.acquired?
-        save
-      else
-        raise Mastodon::RaceConditionError
-      end
+    with_lock("account_migration:#{account.id}") do
+      save
     end
   end
 
@@ -83,8 +80,4 @@ class AccountMigration < ApplicationRecord
   def validate_migration_cooldown
     errors.add(:base, I18n.t('migrations.errors.on_cooldown')) if account.migrations.within_cooldown.exists?
   end
-
-  def lock_options
-    { redis: redis, key: "account_migration:#{account.id}" }
-  end
 end
diff --git a/app/models/concerns/lockable.rb b/app/models/concerns/lockable.rb
new file mode 100644
index 000000000..55a9714ca
--- /dev/null
+++ b/app/models/concerns/lockable.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+module Lockable
+  # @param [String] lock_name
+  # @param [ActiveSupport::Duration] autorelease Automatically release the lock after this time
+  # @param [Boolean] raise_on_failure Raise an error if a lock cannot be acquired, or fail silently
+  # @raise [Mastodon::RaceConditionError]
+  def with_lock(lock_name, autorelease: 15.minutes, raise_on_failure: true)
+    with_redis do |redis|
+      RedisLock.acquire(redis: redis, key: "lock:#{lock_name}", autorelease: autorelease.seconds) do |lock|
+        if lock.acquired?
+          yield
+        elsif raise_on_failure
+          raise Mastodon::RaceConditionError, "Could not acquire lock for #{lock_name}, try again later"
+        end
+      end
+    end
+  end
+end
diff --git a/app/models/concerns/redisable.rb b/app/models/concerns/redisable.rb
index 8d76b6b82..0dad3abb2 100644
--- a/app/models/concerns/redisable.rb
+++ b/app/models/concerns/redisable.rb
@@ -1,11 +1,11 @@
 # frozen_string_literal: true
 
 module Redisable
-  extend ActiveSupport::Concern
-
-  private
-
   def redis
     Thread.current[:redis] ||= RedisConfiguration.pool.checkout
   end
+
+  def with_redis(&block)
+    RedisConfiguration.with(&block)
+  end
 end
-- 
cgit