Use node views cache (#5338)

* Restore using node.views for unique impressions count

This should improve performance of various page loads, as it avoids
running COUNT() queries on the impressions table, and instead uses the
views value, which the impressions gem keeps up-to-date.

* Added a migration which updates node.views to the count of unique visits

app/models/node.rb

@@ -173,12 +173,10 @@ def setup
 
   public
 
-  is_impressionable counter_cache: true, column_name: :views
+  is_impressionable counter_cache: true, column_name: :views, unique: :ip_address
 
   def totalviews
-    # this doesn't filter out duplicate ip addresses as the line below does:
-    # self.views + self.legacy_views
-    impressionist_count(filter: :ip_address) + legacy_views
+    views + legacy_views
   end
 
   def self.weekly_tallies(type = 'note', span = 52, time = Time.now)

db/migrate/20190401093400_update_node_view_count.rb

@@ -0,0 +1,11 @@
+class UpdateNodeViewCount < ActiveRecord::Migration[5.2]
+  def up
+    Node.ids.each do |id|
+      node = Node.find(id)
+      node.update_columns(views: node.impressionist_count(filter: :ip_address))
+    end
+  end
+
+  def down
+  end
+end

db/schema.rb.example

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_03_30_043340) do
+ActiveRecord::Schema.define(version: 2019_04_01_093400) do
 
   create_table "answer_selections", force: true do |t|
     t.integer "user_id"

test/functional/notes_controller_test.rb

@@ -81,7 +81,7 @@ def teardown
     assert_equal '0.0.0.0', Impression.last.ip_address
     Impression.last.update_attribute('ip_address', '0.0.0.1')
 
-    assert_difference 'note.totalviews', 1 do
+    assert_difference 'note.reload.totalviews', 1 do
       get :show,
           params: {
           author: note.author.name,
@@ -90,10 +90,10 @@ def teardown
           }
     end
 
-    assert_equal 2, note.totalviews
+    assert_equal 2, note.reload.totalviews
 
     # same IP won't add to views twice
-    assert_difference 'note.totalviews', 0 do
+    assert_difference 'note.reload.totalviews', 0 do
       get :show,
           params: {
           author: note.author.name,

test/integration/node_unique_views_test.rb

@@ -12,7 +12,7 @@ class NodeInsertExtrasTest < ActionDispatch::IntegrationTest
       assert_response :success
     end
 
-    assert_difference 'nodes(:about).totalviews', 0 do
+    assert_difference 'nodes(:about).reload.totalviews', 0 do
       assert_difference 'Impression.count', 0 do
         get "/wiki/#{nodes(:about).slug}"
         assert_response :success
@@ -22,7 +22,7 @@ class NodeInsertExtrasTest < ActionDispatch::IntegrationTest
     assert_equal '127.0.0.1', Impression.last.ip_address
     assert Impression.last.update_attributes(ip_address: '0.0.0.0')
 
-    assert_difference 'nodes(:about).totalviews', 1 do
+    assert_difference 'nodes(:about).reload.totalviews', 1 do
       assert_difference 'Impression.count', 1 do
         get "/wiki/#{nodes(:about).slug}"
         assert_response :success