Add mini profiler to each page

It shows up in development always, and if you're logged in as Me
Specifically in production!

I'm using this to poke at memory usage for pages that seem suspicious.
I don't know why our app reliably grows so large in RAM, but my hunch is
that maybe there are some pages that just use a truly large amount to
begin with - and I've learned Ruby doesn't release memory back after
it's GC'd, it just grows the process and keeps the free space to itself
in its own heap!

So I'm just eyeing pages that I know *can* have a lot going on, and
seeing what I find!

Gemfile

@@ -65,3 +65,8 @@ gem 'record_tag_helper', '~> 1.0', '>= 1.0.1'
 
 # Reduces boot times through caching; required in config/boot.rb
 gem 'bootsnap', '~> 1.16', require: false
+
+# For investigating performance issues.
+gem "rack-mini-profiler", "~> 3.1"
+gem "memory_profiler", "~> 1.0"
+gem "stackprof", "~> 0.2.25"

Gemfile.lock

@@ -154,6 +154,7 @@ GEM
       net-pop
       net-smtp
     marcel (1.0.2)
+    memory_profiler (1.0.1)
     mime-types (3.4.1)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2023.0218.1)
@@ -189,6 +190,8 @@ GEM
     rack (2.2.8)
     rack-attack (6.7.0)
       rack (>= 1.0, < 4)
+    rack-mini-profiler (3.1.1)
+      rack (>= 1.2.0)
     rack-session (1.0.1)
       rack (< 3)
     rack-test (2.1.0)
@@ -273,6 +276,7 @@ GEM
       actionpack (>= 5.2)
       activesupport (>= 5.2)
       sprockets (>= 3.0.0)
+    stackprof (0.2.25)
     stringio (3.0.8)
     temple (0.8.2)
     terser (1.1.17)
@@ -314,11 +318,13 @@ DEPENDENCIES
   httparty (~> 0.21.0)
   jsbundling-rails (~> 1.1)
   letter_opener (~> 1.8, >= 1.8.1)
+  memory_profiler (~> 1.0)
   mysql2 (~> 0.5.5)
   nokogiri (~> 1.15, >= 1.15.3)
   parallel (~> 1.23)
   puma (~> 6.3, >= 6.3.1)
   rack-attack (~> 6.7)
+  rack-mini-profiler (~> 3.1)
   rails (~> 7.1, >= 7.1.1)
   rails-i18n (~> 7.0, >= 7.0.7)
   rdiscount (~> 2.2, >= 2.2.7.1)
@@ -328,6 +334,7 @@ DEPENDENCIES
   sanitize (~> 6.0, >= 6.0.2)
   sass-rails (~> 6.0)
   sprockets (~> 4.2)
+  stackprof (~> 0.2.25)
   terser (~> 1.1, >= 1.1.17)
   web-console (~> 4.2)
   will_paginate (~> 4.0)

app/controllers/application_controller.rb

@@ -13,6 +13,13 @@ class ApplicationController < ActionController::Base
   before_action :save_return_to_path,
     if: ->(c) { c.controller_name == 'sessions' && c.action_name == 'new' }
 
+  # Enable profiling tools if logged in as admin.
+  before_action do
+    if current_user && current_user.admin?
+      Rack::MiniProfiler.authorize_request
+    end
+  end
+
   def authenticate_user!
     redirect_to(new_auth_user_session_path) unless user_signed_in?
   end

config/initializers/rack_mini_profiler.rb

@@ -0,0 +1,3 @@
+Rails.configuration.to_prepare do
+	Rack::MiniProfiler.config.enable_advanced_debugging_tools = true
+end