mastodon/app/controllers/api/v1/favourites_controller.rb
Akihiko Odaki 552e886b64
Eagerly load statuses with the main query in Api::V1::FavouritesController (#14673)
The old implementation had two queries:
1. The query constructed in Api::V1::FavouritesController#results
2. The query constructed in #cached_favourites, which is merged with 1.

Both of them are issued againt PostgreSQL. The combination of the two
queries caused the following problems:
- The small window between the two queries involves race conditions.
- Minor performance inefficiency.

Moreover, the construction of query 2, which involves merging with query
1 has a bug. Query 1 is finalized with paginate_by_id, but paginate_by_id
returns an array when min_id parameter is specified. The behavior prevents
from merging the query, and in the real world, ActiveRecord simply ignores
the merge (!), which results in querying the entire scan of statuses and
favourites table.

This change fixes these issues by simply letting query 1 get all the works
done.
2020-08-28 09:27:33 +02:00

65 lines
1.4 KiB
Ruby

# frozen_string_literal: true
class Api::V1::FavouritesController < Api::BaseController
before_action -> { doorkeeper_authorize! :read, :'read:favourites' }
before_action :require_user!
after_action :insert_pagination_headers
def index
@statuses = load_statuses
render json: @statuses, each_serializer: REST::StatusSerializer, relationships: StatusRelationshipsPresenter.new(@statuses, current_user&.account_id)
end
private
def load_statuses
cached_favourites
end
def cached_favourites
cache_collection(results.map(&:status), Status)
end
def results
@_results ||= account_favourites.eager_load(:status).paginate_by_id(
limit_param(DEFAULT_STATUSES_LIMIT),
params_slice(:max_id, :since_id, :min_id)
)
end
def account_favourites
current_account.favourites
end
def insert_pagination_headers
set_pagination_headers(next_path, prev_path)
end
def next_path
if records_continue?
api_v1_favourites_url pagination_params(max_id: pagination_max_id)
end
end
def prev_path
unless results.empty?
api_v1_favourites_url pagination_params(min_id: pagination_since_id)
end
end
def pagination_max_id
results.last.id
end
def pagination_since_id
results.first.id
end
def records_continue?
results.size == limit_param(DEFAULT_STATUSES_LIMIT)
end
def pagination_params(core_params)
params.slice(:limit).permit(:limit).merge(core_params)
end
end