build: Parallelize make build by default

Author: kateinoigakukun

lib/ruby_wasm/build.rb

@@ -5,9 +5,17 @@
 module RubyWasm
   # Build executor to run the actual build commands.
   class BuildExecutor
-    def initialize(verbose: false)
+    attr_reader :process_count
+
+    def initialize(verbose: false, process_count: nil)
       @verbose = verbose
       @github_actions_markup = ENV["ENABLE_GITHUB_ACTIONS_MARKUP"] != nil
+      __skip__ = begin
+        require "etc"
+        @process_count = process_count || Etc.nprocessors
+      rescue LoadError
+        @process_count = process_count || 1
+      end
     end
 
     def system(*args, chdir: nil, env: nil)

lib/ruby_wasm/build/product/baseruby.rb

@@ -28,7 +28,10 @@ def build(executor)
                       "--prefix=#{install_dir}",
                       "--disable-install-doc",
                       chdir: product_build_dir
-      executor.system "make", "install", chdir: product_build_dir
+      executor.system "make",
+                      "-j#{executor.process_count}",
+                      "install",
+                      chdir: product_build_dir
     end
   end
 end

lib/ruby_wasm/build/product/crossruby.rb

@@ -33,6 +33,7 @@ def build(executor, crossruby)
       executor.mkdir_p objdir
       do_extconf executor, crossruby
       executor.system "make",
+                      "-j#{executor.process_count}",
                       "-C",
                       "#{objdir}",
                       *make_args(crossruby),

sig/ruby_wasm/build.rbs

@@ -224,8 +224,11 @@ module RubyWasm
   class BuildExecutor
     @verbose: bool
     @github_actions_markup: bool
+    @process_count: Integer
     @start_times: Hash[[Class, String], Time]
 
+    attr_reader process_count: Integer
+
     def initialize: (?verbose: bool) -> void
     def system: (*_ToS args, ?chdir: String?, ?env: Hash[String, String]?) -> void
     def rm_rf: (FileUtils::pathlist list) -> void