Allow disabling of page numbers using Flipperpagination-without-count-flag

This allows page numbers to be disabled globally by enabling the
feature "paginate_without_count". This allows us to test the performance
impact of not having to run COUNT(*) queries, while still being able to
revert easily if necessary.

See https://gitlab.com/gitlab-org/gitlab-ce/issues/36077 for more
information.

5 files changed, 56 insertions, 46 deletions

diff --git a/app/helpers/pagination_helper.rb b/app/helpers/pagination_helper.rb
deleted file mode 100644
index 83dd76a01dd..00000000000
--- a/app/helpers/pagination_helper.rb
+++ /dev/null
@@ -1,21 +0,0 @@
-module PaginationHelper
-  def paginate_collection(collection, remote: nil)
-    if collection.is_a?(Kaminari::PaginatableWithoutCount)
-      paginate_without_count(collection)
-    elsif collection.respond_to?(:total_pages)
-      paginate_with_count(collection, remote: remote)
-    end
-  end
-
-  def paginate_without_count(collection)
-    render(
-      'kaminari/gitlab/without_count',
-      previous_path: path_to_prev_page(collection),
-      next_path: path_to_next_page(collection)
-    )
-  end
-
-  def paginate_with_count(collection, remote: nil)
-    paginate(collection, remote: remote, theme: 'gitlab')
-  end
-end
diff --git a/app/views/dashboard/todos/index.html.haml b/app/views/dashboard/todos/index.html.haml
index a5686002328..4c4e9dabdaa 100644
--- a/app/views/dashboard/todos/index.html.haml
+++ b/app/views/dashboard/todos/index.html.haml
@@ -72,7 +72,7 @@
 .js-todos-all
   - if @todos.any?
     .js-todos-list-container
-      .js-todos-options{ data: { per_page: @todos.limit_value, current_page: @todos.current_page, total_pages: @todos.total_pages } }
+      .js-todos-options{ data: { per_page: @todos.limit_value, current_page: @todos.current_page } }
         .panel.panel-default.panel-without-border.panel-without-margin
           %ul.content-list.todos-list
             = render @todos
diff --git a/app/views/shared/projects/_list.html.haml b/app/views/shared/projects/_list.html.haml
index 0bedfea3502..109c99b0dda 100644
--- a/app/views/shared/projects/_list.html.haml
+++ b/app/views/shared/projects/_list.html.haml
@@ -23,6 +23,6 @@
           = icon('lock fw', base: 'circle', class: 'fa-lg private-fork-icon')
           %strong= pluralize(@private_forks_count, 'private fork')
           %span  you have no access to.
-    = paginate_collection(projects, remote: remote)
+    = paginate(projects, remote: remote)
   - else
     .nothing-here-block No projects found
diff --git a/config/initializers/kaminari_config.rb b/config/initializers/kaminari_config.rb
index 3cbe9a058d7..b6e7d07ea2e 100644
--- a/config/initializers/kaminari_config.rb
+++ b/config/initializers/kaminari_config.rb
@@ -1,6 +1,7 @@
 Kaminari.configure do |config|
   config.default_per_page = 20
   config.max_per_page = 100
+  config.page_method_name = :page_with_count
   # config.window = 4
   # config.outer_window = 0
   # config.left = 0
@@ -8,3 +9,56 @@ Kaminari.configure do |config|
   # config.page_method_name = :page
   # config.param_name = :page
 end
+
+ar_module = Module.new do
+  def page(*args)
+    relation = page_with_count(*args)
+
+    if Feature.enabled?(:paginate_without_count)
+      relation.without_count
+    else
+      relation
+    end
+  end
+end
+
+av_module = Module.new do
+  def paginate(collection, options = {})
+    options[:theme] ||= 'gitlab'
+
+    if collection.is_a?(Kaminari::PaginatableWithoutCount)
+      paginate_without_count(collection, param_name: options[:param_name])
+    elsif collection.respond_to?(:total_pages)
+      super(collection, options)
+    end
+  end
+
+  def paginate_without_count(collection, param_name: nil)
+    render(
+      'kaminari/gitlab/without_count',
+      previous_path: path_to_prev_page(collection, param_name: param_name),
+      next_path: path_to_next_page(collection, param_name: param_name)
+    )
+  end
+end
+
+ActiveSupport.on_load :active_record do
+  ActiveRecord::Base.singleton_class.prepend(ar_module)
+
+  # When paginating without a COUNT(*) we still want to allow one to explicitly
+  # request the total number of pages.
+  module Kaminari::PaginatableWithoutCount
+    remove_method :total_count
+
+    total_count =
+      Kaminari::ActiveRecordRelationMethods.instance_method(:total_count)
+
+    total_count.bind(self)
+  end
+end
+
+ActiveSupport.on_load :action_view do
+  # We can not use regular helpers for this because Kaminari is loaded after
+  # them, thus it would overwrite our custom "paginate" method.
+  ActionView::Base.prepend(av_module)
+end
diff --git a/spec/helpers/pagination_helper_spec.rb b/spec/helpers/pagination_helper_spec.rb
deleted file mode 100644
index e235475fb47..00000000000
--- a/spec/helpers/pagination_helper_spec.rb
+++ /dev/null
@@ -1,23 +0,0 @@
-require 'spec_helper'
-
-describe PaginationHelper do
-  describe '#paginate_collection' do
-    let(:collection) { User.all.page(1) }
-
-    it 'paginates a collection without using a COUNT' do
-      without_count = collection.without_count
-
-      expect(helper).to receive(:paginate_without_count)
-        .with(without_count)
-        .and_call_original
-
-      helper.paginate_collection(without_count)
-    end
-
-    it 'paginates a collection using a COUNT' do
-      expect(helper).to receive(:paginate_with_count).and_call_original
-
-      helper.paginate_collection(collection)
-    end
-  end
-end