Introduce ApplicationController#cache_collection_paginated_by_id (#14677)

* Replace incorrect use of distinct with group

Some uses of ActiveRecord::QueryMethods#distinct pass field names but they
are incorrect for the current version of Rails.

ActiveRecord::QueryMethods#group provides the expected behavior and
benefits performance. See commit 6da24aad4cafdef8d8a2c92bac2002a5fc2fe9c8.

* Introduce ApplicationController#cache_collection_paginated_by_id

ApplicationController#cache_collection_paginated_by_id fuses
ApplicationController#cache_collection and Paginable.paginate_by_id.

An advantage of this method is that it prevents from modifying scope which
Paginable.paginate_by_id may provide.
ApplicationController#cache_collection always return an array and there
is no possibility of the scope modification. It is also clear for a
programmer, considering the implication of "cache".

This method can also emit more efficient queries by using
Cacheable.cache_ids before calling Paginable.paginate_by_id.

app/controllers/accounts_controller.rb

@@ -28,8 +28,7 @@ class AccountsController < ApplicationController
         end
 
         @pinned_statuses = cache_collection(@account.pinned_statuses, Status) if show_pinned_statuses?
-        @statuses        = filtered_status_page
-        @statuses        = cache_collection(@statuses, Status)
+        @statuses        = cached_filtered_status_page
         @rss_url         = rss_url
 
         unless @statuses.empty?
@@ -142,8 +141,13 @@ class AccountsController < ApplicationController
     request.path.split('.').first.ends_with?(Addressable::URI.parse("/tagged/#{params[:tag]}").normalize)
   end
 
-  def filtered_status_page
-    filtered_statuses.paginate_by_id(PAGE_SIZE, params_slice(:max_id, :min_id, :since_id))
+  def cached_filtered_status_page
+    cache_collection_paginated_by_id(
+      filtered_statuses,
+      Status,
+      PAGE_SIZE,
+      params_slice(:max_id, :min_id, :since_id)
+    )
   end
 
   def params_slice(*keys)

app/controllers/activitypub/outboxes_controller.rb

@@ -50,8 +50,12 @@ class ActivityPub::OutboxesController < ActivityPub::BaseController
     return unless page_requested?
 
     @statuses = @account.statuses.permitted_for(@account, signed_request_account)
-    @statuses = @statuses.paginate_by_id(LIMIT, params_slice(:max_id, :min_id, :since_id))
-    @statuses = cache_collection(@statuses, Status)
+    @statuses = cache_collection_paginated_by_id(
+      @statuses,
+      Status,
+      LIMIT,
+      params_slice(:max_id, :min_id, :since_id)
+    )
   end
 
   def page_requested?

app/controllers/api/v1/accounts/statuses_controller.rb

@@ -22,10 +22,6 @@ class Api::V1::Accounts::StatusesController < Api::BaseController
   end
 
   def cached_account_statuses
-    cache_collection account_statuses, Status
-  end
-
-  def account_statuses
     statuses = truthy_param?(:pinned) ? pinned_scope : permitted_account_statuses
 
     statuses.merge!(only_media_scope) if truthy_param?(:only_media)
@@ -33,7 +29,12 @@ class Api::V1::Accounts::StatusesController < Api::BaseController
     statuses.merge!(no_reblogs_scope) if truthy_param?(:exclude_reblogs)
     statuses.merge!(hashtag_scope)    if params[:tagged].present?
 
-    statuses.paginate_by_id(limit_param(DEFAULT_STATUSES_LIMIT), params_slice(:max_id, :since_id, :min_id))
+    cache_collection_paginated_by_id(
+      statuses,
+      Status,
+      limit_param(DEFAULT_STATUSES_LIMIT),
+      params_slice(:max_id, :since_id, :min_id)
+    )
   end
 
   def permitted_account_statuses

app/controllers/api/v1/notifications_controller.rb

@@ -31,11 +31,9 @@ class Api::V1::NotificationsController < Api::BaseController
   private
 
   def load_notifications
-    cache_collection paginated_notifications, Notification
-  end
-
-  def paginated_notifications
-    browserable_account_notifications.paginate_by_id(
+    cache_collection_paginated_by_id(
+      browserable_account_notifications,
+      Notification,
       limit_param(DEFAULT_NOTIFICATIONS_LIMIT),
       params_slice(:max_id, :since_id, :min_id)
     )

app/controllers/api/v1/timelines/public_controller.rb

@@ -16,18 +16,20 @@ class Api::V1::Timelines::PublicController < Api::BaseController
   end
 
   def load_statuses
-    cached_public_statuses
+    cached_public_statuses_page
   end
 
-  def cached_public_statuses
-    cache_collection public_statuses, Status
-  end
-
-  def public_statuses
-    statuses = public_timeline_statuses.paginate_by_id(
+  def cached_public_statuses_page
+    cache_collection_paginated_by_id(
+      public_statuses,
+      Status,
       limit_param(DEFAULT_STATUSES_LIMIT),
       params_slice(:max_id, :since_id, :min_id)
     )
+  end
+
+  def public_statuses
+    statuses = public_timeline_statuses
 
     if truthy_param?(:only_media)
       statuses.joins(:media_attachments).group(:id)

app/controllers/api/v1/timelines/tag_controller.rb

@@ -20,23 +20,18 @@ class Api::V1::Timelines::TagController < Api::BaseController
   end
 
   def cached_tagged_statuses
-    cache_collection tagged_statuses, Status
-  end
-
-  def tagged_statuses
     if @tag.nil?
       []
     else
-      statuses = tag_timeline_statuses.paginate_by_id(
+      statuses = tag_timeline_statuses
+      statuses = statuses.joins(:media_attachments) if truthy_param?(:only_media)
+
+      cache_collection_paginated_by_id(
+        statuses,
+        Status,
         limit_param(DEFAULT_STATUSES_LIMIT),
         params_slice(:max_id, :since_id, :min_id)
       )
-
-      if truthy_param?(:only_media)
-        statuses.joins(:media_attachments)
-      else
-        statuses
-      end
     end
   end
 

app/controllers/concerns/cache_concern.rb

@@ -47,4 +47,8 @@ module CacheConcern
 
     raw.map { |item| cached_keys_with_value[item.id] || uncached[item.id] }.compact
   end
+
+  def cache_collection_paginated_by_id(raw, klass, limit, options)
+    cache_collection raw.cache_ids.paginate_by_id(limit, options), klass
+  end
 end