Add benchmarks, get the baseline

Gemfile

@@ -1,7 +1,5 @@
 source "https://rubygems.org"
 
-git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
-
 gem 'coveralls', require: false
 
 # Specify your gem's dependencies in batch-loader.gemspec

batch-loader.gemspec

@@ -28,4 +28,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rspec", "~> 3.0"
   spec.add_development_dependency "graphql", "~> 1.6"
   spec.add_development_dependency "pry-byebug", "~> 3.4"
+  spec.add_development_dependency "benchmark-ips", "~> 2.7"
 end

spec/benchmarks/loading.rb

@@ -0,0 +1,41 @@
+# frozen_string_literal: true
+
+# Usage: ruby spec/benchmarks/loading.rb
+
+require 'benchmark/ips'
+require "batch_loader"
+
+require_relative "../fixtures/models"
+
+User.save(id: 1)
+
+batch_loader_with_cache = BatchLoader.for(1).batch do |ids, loader|
+  User.where(id: ids).each { |user| loader.call(user.id, user) }
+end
+
+batch_loader_without_cache = BatchLoader.for(1).batch(cache: false) do |ids, loader|
+  User.where(id: ids).each { |user| loader.call(user.id, user) }
+end
+
+Benchmark.ips do |x|
+  x.config(time: 5, warmup: 0)
+  x.report("without BatchLoader") { User.where(id: [1]).first.id }
+  x.report("with BatchLoader with cache") { batch_loader_with_cache.id }
+  x.report("with BatchLoader without cache") { batch_loader_without_cache.id }
+  x.compare!
+end
+
+# Warming up --------------------------------------
+# without BatchLoader            1.000  i/100ms
+# with BatchLoader with cache    1.000  i/100ms
+# with BatchLoader without cache 1.000  i/100ms
+
+# Calculating -------------------------------------
+# without BatchLoader            965.088k (±15.1%) i/s - 3.399M   in 3.864552s
+# with BatchLoader with cache    991.089k (± 8.0%) i/s - 3.272M
+# with BatchLoader without cache 75.239k (±18.1%) i/s  - 345.350k in 4.883875s
+
+# Comparison:
+# with BatchLoader with cache:    991089.2 i/s
+# without BatchLoader:            965088.1 i/s - same-ish: difference falls within error
+# with BatchLoader without cache: 75238.7 i/s  - 13.17x slower