Wrap commonly-repeated calls to Spree::Config to reduce unnecessary cache reads

These config values are relatively static but in some cases they can be called many times in the same request (like rendering a report or a large list of line_items in BOM). These values will now only get fetched from Redis/Postgres once at most per request/job.

app/helpers/admin/injection_helper.rb

@@ -162,7 +162,7 @@ module Admin
     def admin_inject_available_units
       admin_inject_json "admin.products",
                         "availableUnits",
-                        Spree::Config.available_units
+                        CurrentConfig.get(:available_units)
     end
 
     def admin_inject_json(ng_module, name, data)

app/models/current_config.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+# Wraps repeatedly-called configs in a CurrentAttributes object so they only get fetched once
+# per request at most, eg: CurrentConfig.get(:available_units) for Spree::Config[:available_units]
+
+class CurrentConfig < ActiveSupport::CurrentAttributes
+  attribute :display_currency, :hide_cents, :currency_decimal_mark,
+            :currency_thousands_separator, :currency_symbol_position, :available_units
+
+  def get(config_key)
+    return public_send(config_key) unless public_send(config_key).nil?
+
+    public_send("#{config_key}=", Spree::Config.public_send(config_key))
+  end
+
+  def currency
+    ENV.fetch("CURRENCY")
+  end
+end

app/models/spree/adjustment.rb

@@ -120,7 +120,7 @@ module Spree
     end
 
     def currency
-      adjustable ? adjustable.currency : Spree::Config[:currency]
+      adjustable ? adjustable.currency : CurrentConfig.get(:currency)
     end
 
     def display_amount

app/models/spree/order.rb

@@ -186,7 +186,7 @@ module Spree
     end
 
     def currency
-      self[:currency] || Spree::Config[:currency]
+      self[:currency] || CurrentConfig.get(:currency)
     end
 
     def display_item_total
@@ -689,7 +689,7 @@ module Spree
     end
 
     def set_currency
-      self.currency = Spree::Config[:currency] if self[:currency].nil?
+      self.currency = CurrentConfig.get(:currency) if self[:currency].nil?
     end
 
     def using_guest_checkout?

app/models/spree/price.rb

@@ -37,7 +37,7 @@ module Spree
     def check_price
       return unless currency.nil?
 
-      self.currency = Spree::Config[:currency]
+      self.currency = CurrentConfig.get(:currency)
     end
 
     # strips all non-price-like characters from the price, taking into account locale settings

app/models/spree/return_authorization.rb

@@ -29,7 +29,7 @@ module Spree
     end
 
     def currency
-      order.nil? ? Spree::Config[:currency] : order.currency
+      order.nil? ? CurrentConfig.get(:currency) : order.currency
     end
 
     def display_amount

app/models/spree/shipment.rb

@@ -163,7 +163,7 @@ module Spree
     end
 
     def currency
-      order ? order.currency : Spree::Config[:currency]
+      order ? order.currency : CurrentConfig.get(:currency)
     end
 
     def display_cost

app/models/spree/variant.rb

@@ -42,7 +42,7 @@ module Spree
     accepts_nested_attributes_for :images
 
     has_one :default_price,
-            -> { with_deleted.where(currency: Spree::Config[:currency]) },
+            -> { with_deleted.where(currency: CurrentConfig.get(:currency)) },
             class_name: 'Spree::Price',
             dependent: :destroy
     has_many :prices,
@@ -162,7 +162,7 @@ module Spree
       where("spree_variants.id in (?)", joins(:prices).
                                           where(deleted_at: nil).
                                           where('spree_prices.currency' =>
-                                            currency || Spree::Config[:currency]).
+                                            currency || CurrentConfig.get(:currency)).
                                           where.not(spree_prices: { amount: nil }).
                                           select("spree_variants.id"))
     end
@@ -211,7 +211,7 @@ module Spree
     def check_currency
       return unless currency.nil?
 
-      self.currency = Spree::Config[:currency]
+      self.currency = CurrentConfig.get(:currency)
     end
 
     def save_default_price
@@ -223,7 +223,7 @@ module Spree
     end
 
     def set_cost_currency
-      self.cost_currency = Spree::Config[:currency] if cost_currency.blank?
+      self.cost_currency = CurrentConfig.get(:currency) if cost_currency.blank?
     end
 
     def create_stock_items

app/serializers/api/admin/customer_with_balance_serializer.rb

@@ -12,7 +12,7 @@ module Api
       delegate :balance_value, to: :object
 
       def balance
-        Spree::Money.new(balance_value, currency: Spree::Config[:currency]).to_s
+        Spree::Money.new(balance_value, currency: CurrentConfig.get(:currency)).to_s
       end
 
       def balance_status

app/serializers/api/currency_config_serializer.rb

@@ -4,22 +4,22 @@ class Api::CurrencyConfigSerializer < ActiveModel::Serializer
   attributes :currency, :display_currency, :symbol, :symbol_position, :hide_cents
 
   def currency
-    Spree::Config[:currency]
+    CurrentConfig.get(:currency)
   end
 
   def display_currency
-    Spree::Config[:display_currency]
+    CurrentConfig.get(:display_currency)
   end
 
   def symbol
-    ::Money.new(1, Spree::Config[:currency]).symbol
+    ::Money.new(1, CurrentConfig.get(:currency)).symbol
   end
 
   def symbol_position
-    Spree::Config[:currency_symbol_position]
+    CurrentConfig.get(:currency_symbol_position)
   end
 
   def hide_cents
-    Spree::Config[:hide_cents]
+    CurrentConfig.get(:hide_cents)
   end
 end

app/services/weights_and_measures.rb

@@ -40,7 +40,7 @@ class WeightsAndMeasures
   end
 
   def self.available_units
-    Spree::Config.available_units.split(",")
+    CurrentConfig.get(:available_units).split(",")
   end
 
   def self.available_units_sorted

app/views/spree/admin/general_settings/edit.html.haml

@@ -79,7 +79,7 @@
           %fieldset.available_units.no-border-bottom
             %legend{:align => "center"}= t('admin.available_units')
             .field
-              - available_units = Spree::Config[:available_units].split(",")
+              - available_units = CurrentConfig.get(:available_units).split(",")
               - all_units.each do |unit|
                 - selected = available_units.include?(unit)
                 = preference_field_tag("available_units[#{unit}]", selected, { type: :boolean, selected: selected })

app/views/spree/admin/payments/paypal_refund.html.haml

@@ -18,8 +18,8 @@
           %small
             %em= Spree.t(:original_amount, scope: 'paypal', amount: @payment.display_amount)
           %br/
-          - symbol = ::Money.new(1, Spree::Config[:currency]).symbol
-          - if Spree::Config[:currency_symbol_position] == "before"
+          - symbol = ::Money.new(1, CurrentConfig.get(:currency)).symbol
+          - if CurrentConfig.get(:currency_symbol_position) == "before"
             = symbol
             = text_field_tag 'refund_amount', @payment.amount
           - else

lib/reporting/reports/xero_invoices/base.rb

@@ -189,7 +189,7 @@ module Reporting
            '',
            '',
            '',
-           Spree::Config.currency,
+           CurrentConfig.get(:currency),
            '',
            order.paid? ? I18n.t(:y) : I18n.t(:n)]
         end

lib/spree/core/controller_helpers/order.rb

@@ -79,7 +79,7 @@ module Spree
         end
 
         def current_currency
-          Spree::Config[:currency]
+          CurrentConfig.get(:currency)
         end
 
         def ip_address

lib/spree/money.rb

@@ -9,7 +9,7 @@ module Spree
     delegate :cents, to: :money
 
     def initialize(amount, options = {})
-      @money = ::Monetize.parse([amount, options[:currency] || Spree::Config[:currency]].join)
+      @money = ::Monetize.parse([amount, options[:currency] || CurrentConfig.get(:currency)].join)
 
       if options.key?(:symbol_position)
         options[:format] = position_to_format(options.delete(:symbol_position))
@@ -20,7 +20,7 @@ module Spree
 
     # Return the currency symbol (on its own) for the current default currency
     def self.currency_symbol
-      ::Money.new(0, Spree::Config[:currency]).symbol
+      ::Money.new(0, CurrentConfig.get(:currency)).symbol
     end
 
     def to_s
@@ -44,11 +44,11 @@ module Spree
 
     def defaults
       {
-        with_currency: Spree::Config[:display_currency],
-        no_cents: Spree::Config[:hide_cents],
-        decimal_mark: Spree::Config[:currency_decimal_mark],
-        thousands_separator: Spree::Config[:currency_thousands_separator],
-        format: position_to_format(Spree::Config[:currency_symbol_position])
+        with_currency: CurrentConfig.get(:display_currency),
+        no_cents: CurrentConfig.get(:hide_cents),
+        decimal_mark: CurrentConfig.get(:currency_decimal_mark),
+        thousands_separator: CurrentConfig.get(:currency_thousands_separator),
+        format: position_to_format(CurrentConfig.get(:currency_symbol_position))
       }
     end
 

spec/base_spec_helper.rb

@@ -194,6 +194,7 @@ RSpec.configure do |config|
       spree_config.currency = currency
       spree_config.shipping_instructions = true
     end
+    CurrentConfig.clear_all
   end
 
   # Don't validate our invalid test data with expensive network requests.

spec/lib/spree/money_spec.rb

@@ -24,6 +24,11 @@ describe Spree::Money do
   end
 
   context "with currency" do
+    before do
+      allow(ENV).to receive(:fetch).and_call_original
+      allow(ENV).to receive(:fetch).with("CURRENCY").and_return("USD")
+    end
+
     it "passed in option" do
       money = Spree::Money.new(10, with_currency: true, html_wrap: false)
       expect(money.to_s).to eq("$10.00 USD")
@@ -96,6 +101,9 @@ describe Spree::Money do
         config.currency_symbol_position = :after
         config.display_currency = false
       end
+
+      allow(ENV).to receive(:fetch).and_call_original
+      allow(ENV).to receive(:fetch).with("CURRENCY").and_return("EUR")
     end
 
     # Regression test for Spree #2634