提交嵌套事务

Question

假设我有一个方法可以在用户范围内提供对 API 客户端的访问，并且 API 客户端会在用户 OAuth 令牌过期时自动更新它们。

class User < ActiveRecord::Base

  def api
    ApiClient.new access_token: oauth_access_token,
                  refresh_token: oauth_refresh_token,
                  on_oauth_refresh: -> (tokens) {
                    # This proc will be called by the API client when an 
                    # OAuth refresh occurs
                    update_attributes({
                      oauth_access_token: tokens[:access_token],
                      oauth_refresh_token: tokens[:refresh_token]
                     })
                   }
  end

end

如果我在 Rails 事务中使用此 API 并发生刷新，然后发生错误 - 我无法保留新的 OAuth 令牌（因为上面的 proc 也被视为事务的一部分）：

u = User.first

User.transaction { 
  local_info = Info.create!

  # My tokens are expired so the client automatically
  # refreshes them and calls the proc that updates them locally.
  external_info = u.api.get_external_info(local_info.id)

  # Now when I try to locally save the info returned by the API an exception
  # occurs (for example due to validation). This rolls back the entire 
  # transaction (including the update of the user's new tokens.)
  local_info.info = external_info 
  local_info.save!
}

我正在简化示例，但基本上 API 的使用和 API 返回的数据的持久性需要在事务中发生。即使父事务失败，我如何确保对用户令牌的更新得到提交。

Answer 1

你有没有试过在新线程中打开一个新的数据库连接，并在这个线程中执行更新

u = User.first

User.transaction { 
   local_info = Info.create!

   # My tokens are expired so the client automatically
   # refreshes them and calls the proc that updates them locally.
   external_info = u.api.get_external_info(local_info.id)

   # Now when I try to locally save the info returned by the API an exception
   # occurs (for example due to validation). This rolls back the entire 
   # transaction (including the update of the user's new tokens.)
   local_info.info = external_info 
   local_info.save!

   # Now open new thread
   # In the new thread open new db connection, separate from the one already opened
   # In the new connection execute update only for the tokens
   # Close new connection and new thread
   Thread.new do
      ActiveRecord::Base.connection_pool.with_connection do |connection|
         connection.execute("Your SQL statement that will update the user tokens")        
      end
   end.join
}

希望对你有帮助

Answer 2

Nermin 的（接受的）答案是正确的。这是 Rails >= 5.0 的更新

Thread.new do
  Rails.application.executor.wrap do
    record.save
  end
  # Note: record probably won't be updated here yet since it's async
end

在此处记录：Rails guides threading and concurrency

Answer 3

上一个问题中的discussion 可能会对您有所帮助。看起来您可以设置一个requires_new: true 标志并将子事务实质上标记为子事务。

User.transaction { 
  User.transaction(requires_new: true) { 
    u.update_attribute(:name, 'test') 
  }; 

  u.update_attribute(:name, 'test2'); 

  raise 'boom' 
}