Resolve rack.multithread/rack.multiprocess using config

lib/puma/binder.rb

@@ -6,6 +6,7 @@ require 'socket'
 require 'puma/const'
 require 'puma/util'
 require 'puma/minissl/context_builder'
+require 'puma/configuration'
 
 module Puma
   class Binder
@@ -13,18 +14,19 @@ module Puma
 
     RACK_VERSION = [1,6].freeze
 
-    def initialize(events)
+    def initialize(events, conf = Configuration.new)
       @events = events
       @listeners = []
       @inherited_fds = {}
       @activated_sockets = {}
       @unix_paths = []
+      @conf = conf
 
       @proto_env = {
         "rack.version".freeze => RACK_VERSION,
         "rack.errors".freeze => events.stderr,
-        "rack.multithread".freeze => true,
-        "rack.multiprocess".freeze => false,
+        "rack.multithread".freeze => resolve_option(:multithread, @conf),
+        "rack.multiprocess".freeze => resolve_option(:multiprocess, @conf),
         "rack.run_once".freeze => false,
         "SCRIPT_NAME".freeze => ENV['SCRIPT_NAME'] || "",
 
@@ -383,5 +385,14 @@ module Puma
     def socket_activation_fd(int)
       int + 3 # 3 is the magic number you add to follow the SA protocol
     end
+
+    def resolve_option(key, conf)
+      case key
+      when :multithread
+        conf.options[:max_threads] > 1
+      when :multiprocess
+        conf.options[:workers] >= 1
+      end
+    end
   end
 end

lib/puma/launcher.rb

@@ -47,7 +47,7 @@ module Puma
       @original_argv = @argv.dup
       @config        = conf
 
-      @binder        = Binder.new(@events)
+      @binder        = Binder.new(@events, conf)
       @binder.create_inherited_fds(ENV).each { |k| ENV.delete k }
       @binder.create_activated_fds(ENV).each { |k| ENV.delete k }
 

test/test_binder.rb

@@ -6,6 +6,7 @@ require_relative "helpers/ssl"
 require "puma/binder"
 require "puma/puma_http11"
 require "puma/events"
+require "puma/configuration"
 
 class TestBinderBase < Minitest::Test
   include SSLHelper
@@ -295,6 +296,34 @@ class TestBinder < TestBinderBase
     File.unlink(path) rescue nil # JRuby race?
   end
 
+  def test_rack_multithread_default_configuration
+    binder = Puma::Binder.new(@events)
+
+    assert binder.proto_env["rack.multithread"]
+  end
+
+  def test_rack_multithread_custom_configuration
+    conf = Puma::Configuration.new(max_threads: 1)
+
+    binder = Puma::Binder.new(@events, conf)
+
+    refute binder.proto_env["rack.multithread"]
+  end
+
+  def test_rack_multiprocess_default_configuration
+    binder = Puma::Binder.new(@events)
+
+    refute binder.proto_env["rack.multiprocess"]
+  end
+
+  def test_rack_multiprocess_custom_configuration
+    conf = Puma::Configuration.new(workers: 1)
+
+    binder = Puma::Binder.new(@events, conf)
+
+    assert binder.proto_env["rack.multiprocess"]
+  end
+
   private
 
   def assert_activates_sockets(path: nil, port: nil, url: nil, sock: nil)