Add a bootsnap command to allow to precompile gems without booting th…

…e application

bootsnap.gemspec

@@ -26,6 +26,9 @@ Gem::Specification.new do |spec|
   spec.files = %x(git ls-files -z ext lib).split("\x0") + %w(CHANGELOG.md LICENSE.txt README.md)
   spec.require_paths = %w(lib)
 
+  spec.bindir        = 'exe'
+  spec.executables   = %w(bootsnap)
+
   spec.required_ruby_version = '>= 2.3.0'
 
   if RUBY_PLATFORM =~ /java/

exe/bootsnap

@@ -0,0 +1,5 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'bootsnap/cli'
+exit Bootsnap::CLI.new(ARGV).run

lib/bootsnap/cli.rb

@@ -0,0 +1,118 @@
+# frozen_string_literal: true
+
+require 'bootsnap'
+require 'optparse'
+require 'fileutils'
+
+module Bootsnap
+  class CLI
+    unless Regexp.method_defined?(:match?)
+      module RegexpMatchBackport
+        refine Regepx do
+          def match?(string)
+            !!match(string)
+          end
+        end
+      end
+      using RegexpMatchBackport
+    end
+
+    attr_reader :cache_dir, :argv
+
+    attr_accessor :compile_gemfile, :exclude
+
+    def initialize(argv)
+      @argv = argv
+      self.cache_dir = 'tmp/cache'
+      self.compile_gemfile = false
+      self.exclude = nil
+    end
+
+    def precompile_command(*sources)
+      require 'bootsnap/compile_cache/iseq'
+
+      sources.each do |source|
+        if !File.directory?(source) && File.exist?(source)
+          STDERR.puts "#{source} is not a directory"
+          return 1
+        end
+      end
+
+      if compile_gemfile
+        sources += $LOAD_PATH
+      end
+
+      CompileCache::ISeq.compile_option_updated
+      iseq_cache_dir = File.join(cache_dir, 'bootsnap-compile-cache')
+
+      source.map { |d| File.expand_path(d) }.each do |path|
+        Dir[File.join(path, '**/*.rb')].each do |ruby_file|
+          if !exclude || !exclude.match?(ruby_file)
+            CompileCache::Native.fetch(
+              iseq_cache_dir,
+              ruby_file,
+              CompileCache::ISeq,
+              nil,
+            )
+          end
+        end
+      end
+      0
+    end
+
+    def run
+      parser.parse!(argv)
+      command = argv.shift
+      method = "#{command}_command"
+      if respond_to?(method)
+        public_send(method, *argv)
+      else
+        invalid_usage!("Unknown command: #{command}")
+      end
+    end
+
+    private
+
+    def invalid_usage!(message)
+      STDERR.puts message
+      STDERR.puts
+      STDERR.puts parser
+      1
+    end
+
+    def cache_dir=(dir)
+      @cache_dir = File.expand_path(dir)
+    end
+
+    def parser
+      @parser ||= OptionParser.new do |opts|
+        opts.banner = "Usage: bootsnap COMMAND [ARGS]"
+        opts.separator ""
+        opts.separator "GLOBAL OPTIONS"
+        opts.separator ""
+
+        help = <<~EOS
+          Path to the bootsnap cache directory. Defaults to tmp/cache
+        EOS
+        opts.on('--cache-dir DIR', help.strip) do |dir|
+          self.cache_dir = dir
+        end
+
+        opts.separator ""
+        opts.separator "COMMANDS"
+        opts.separator ""
+        opts.separator "    precompile [DIRECTORIES...]: Precompile all .rb files in the passed directories"
+
+        help = <<~EOS
+          Precompile the gems in Gemfile
+        EOS
+        opts.on('--gemfile', help) { self.compile_gemfile = true }
+
+        help = <<~EOS
+          Path pattern to not precompile. e.g. --exclude 'aws-sdk|google-api'
+        EOS
+        opts.on('--exclude PATTERN', help) { |pattern| self.exclude = Regexp.new(pattern) }
+      end
+    end
+  end
+end