[2.0] Auto-configure job count

lib/bundler/feature_flag.rb

@@ -30,6 +30,7 @@ def self.settings_method(name, key, &default)
     settings_flag(:allow_bundler_dependency_conflicts) { bundler_2_mode? }
     settings_flag(:allow_offline_install) { bundler_2_mode? }
     settings_flag(:auto_clean_without_path) { bundler_2_mode? }
+    settings_flag(:auto_config_jobs) { bundler_2_mode? }
     settings_flag(:cache_all) { bundler_2_mode? }
     settings_flag(:cache_command_is_package) { bundler_2_mode? }
     settings_flag(:console_command) { !bundler_2_mode? }

lib/bundler/installer.rb

@@ -178,14 +178,36 @@ def generate_standalone_bundler_executable_stubs(spec)
     # installation is SO MUCH FASTER. so we let people opt in.
     def install(options)
       force = options["force"]
-      jobs = options.delete(:jobs) do
-        if can_install_in_parallel?
-          [Bundler.settings[:jobs].to_i - 1, 1].max
+      jobs = installation_parallelization(options)
+      install_in_parallel jobs, options[:standalone], force
+    end
+
+    def installation_parallelization(options)
+      if jobs = options.delete(:jobs)
+        return jobs
+      end
+
+      return 1 unless can_install_in_parallel?
+
+      auto_config_jobs = Bundler.feature_flag.auto_config_jobs?
+      if jobs = Bundler.settings[:jobs]
+        if auto_config_jobs
+          jobs
         else
-          1
+          [jobs.pred, 1].max
         end
+      elsif auto_config_jobs
+        processor_count
+      else
+        1
       end
-      install_in_parallel jobs, options[:standalone], force
+    end
+
+    def processor_count
+      require "etc"
+      Etc.nprocessors
+    rescue
+      1
     end
 
     def load_plugins

lib/bundler/installer/parallel_installer.rb

@@ -87,6 +87,7 @@ def initialize(installer, all_specs, size, standalone, force)
       @force = force
       @specs = all_specs.map {|s| SpecInstallation.new(s) }
       @spec_set = all_specs
+      @rake = @specs.find {|s| s.name == "rake" }
     end
 
     def call
@@ -218,6 +219,8 @@ def require_tree_for_spec(spec)
     # are installed.
     def enqueue_specs
       @specs.select(&:ready_to_enqueue?).each do |spec|
+        next if @rake && !@rake.installed? && spec.name != @rake.name
+
         if spec.dependencies_installed? @specs
           spec.state = :enqueued
           worker_pool.enq spec

lib/bundler/settings.rb

@@ -14,6 +14,7 @@ class Settings
       allow_offline_install
       auto_clean_without_path
       auto_install
+      auto_config_jobs
       cache_all
       cache_all_platforms
       cache_command_is_package
@@ -58,6 +59,7 @@ class Settings
     ].freeze
 
     NUMBER_KEYS = %w[
+      jobs
       redirect
       retry
       ssl_verify_mode

spec/quality_spec.rb

@@ -169,22 +169,21 @@ def check_for_specific_pronouns(filename)
 
   it "documents all used settings" do
     exemptions = %w[
+      auto_config_jobs
       cache_command_is_package
       console_command
-      default_cli_command
       deployment_means_frozen
       forget_cli_options
       gem.coc
       gem.mit
       inline
       lockfile_uses_separate_rubygems_sources
       use_gem_version_promoter_for_major_updates
-      warned_version
       viz_command
     ]
 
     all_settings = Hash.new {|h, k| h[k] = [] }
-    documented_settings = exemptions
+    documented_settings = []
 
     Bundler::Settings::BOOL_KEYS.each {|k| all_settings[k] << "in Bundler::Settings::BOOL_KEYS" }
     Bundler::Settings::NUMBER_KEYS.each {|k| all_settings[k] << "in Bundler::Settings::NUMBER_KEYS" }
@@ -200,8 +199,14 @@ def check_for_specific_pronouns(filename)
       documented_settings = File.read("man/bundle-config.ronn")[/LIST OF AVAILABLE KEYS.*/m].scan(/^\* `#{key_pattern}`/).flatten
     end
 
-    documented_settings.each {|s| all_settings.delete(s) }
-    exemptions.each {|s| all_settings.delete(s) }
+    documented_settings.each do |s|
+      all_settings.delete(s)
+      expect(exemptions.delete(s)).to be_nil, "setting #{s} was exempted but was actually documented"
+    end
+
+    exemptions.each do |s|
+      expect(all_settings.delete(s)).to be_truthy, "setting #{s} was exempted but unused"
+    end
     error_messages = all_settings.map do |setting, refs|
       "The `#{setting}` setting is undocumented\n\t- #{refs.join("\n\t- ")}\n"
     end