build: Fix pipe stuck without --verbose and better progress indicator

Steepfile

@@ -13,6 +13,7 @@ target :lib do
   library "open-uri"
   library "uri"
   library "shellwords"
+  library "io-console"
 
   configure_code_diagnostics(D::Ruby.default)
 end

lib/ruby_wasm/build.rb

@@ -10,34 +10,67 @@ def initialize(verbose: false)
       @github_actions_markup = ENV["ENABLE_GITHUB_ACTIONS_MARKUP"] != nil
     end
 
-    def system(*args, chdir: nil, out: nil, env: nil)
+    def system(*args, chdir: nil, env: nil)
+      require "open3"
+
       _print_command(args, env)
 
-      if @verbose
-        out ||= $stdout
-      else
-        # Capture stdout by default
-        out_pipe = IO.pipe
-        out = out_pipe[1]
-      end
       # @type var kwargs: Hash[Symbol, untyped]
-      kwargs = { exception: true, out: out }
+      kwargs = {}
       kwargs[:chdir] = chdir if chdir
-      begin
-        if env
-          Kernel.system(env, *args.to_a.map(&:to_s), **kwargs)
+
+      args = args.to_a.map(&:to_s)
+      # TODO: Remove __skip__ once we have open3 RBS definitions.
+      __skip__ =
+        if @verbose || !$stdout.tty?
+          kwargs[:exception] = true
+          if env
+            Kernel.system(env, *args, **kwargs)
+          else
+            Kernel.system(*args, **kwargs)
+          end
         else
-          Kernel.system(*args.to_a.map(&:to_s), **kwargs)
+          printer = StatusPrinter.new
+          block =
+            proc do |stdin, stdout, stderr, wait_thr|
+              mux = Mutex.new
+              out = String.new
+              err = String.new
+              readers =
+                [
+                  [stdout, :stdout, out],
+                  [stderr, :stderr, err]
+                ].map do |io, name, str|
+                  reader =
+                    Thread.new do
+                      while (line = io.gets)
+                        mux.synchronize do
+                          printer.send(name, line)
+                          str << line
+                        end
+                      end
+                    end
+                  reader.report_on_exception = false
+                  reader
+                end
+
+              readers.each(&:join)
+
+              [out, err, wait_thr.value]
+            end
+          begin
+            if env
+              Open3.popen3(env, *args, **kwargs, &block)
+            else
+              Open3.popen3(*args, **kwargs, &block)
+            end
+          ensure
+            printer.done
+          end
         end
-      ensure
-        out.close if out_pipe
-      end
     rescue => e
-      if out_pipe
-        # Print the output of the failed command
-        puts out_pipe[0].read
-      end
       $stdout.flush
+      $stderr.puts "Try running with `rake --verbose` for more complete output."
       raise e
     end
 
@@ -58,9 +91,7 @@ def begin_section(klass, name, note)
 
     def end_section(klass, name)
       took = Time.now - @start_times[[klass, name]]
-      if @github_actions_markup
-        puts "::endgroup::"
-      end
+      puts "::endgroup::" if @github_actions_markup
       puts "\e[1;36m==>\e[0m \e[1m#{klass}(#{name}) -- done in #{took.round(2)}s\e[0m"
     end
 
@@ -98,4 +129,46 @@ def _print_command(args, env)
       print args.map { |arg| Shellwords.escape(arg.to_s) }.join(" ") + "\n"
     end
   end
+
+  # Human readable status printer for the build.
+  class StatusPrinter
+    def initialize
+      @mutex = Mutex.new
+      @counter = 0
+      @indicators = "|/-\\"
+    end
+
+    def stdout(message)
+      require "io/console"
+      @mutex.synchronize do
+        $stdout.print "\e[K"
+        first_line = message.lines(chomp: true).first || ""
+
+        # Make sure we don't line-wrap the output
+        size =
+          __skip__ =
+            IO.respond_to?(:console_size) ? IO.console_size : IO.console.winsize
+        terminal_width = size[1].to_i.nonzero? || 80
+        width_limit = terminal_width / 2 - 3
+
+        if first_line.length > width_limit
+          first_line = (first_line[0..width_limit - 5] || "") + "..."
+        end
+        indicator = @indicators[@counter] || " "
+        to_print = "  " + indicator + " " + first_line
+        $stdout.print to_print
+        $stdout.print "\e[1A\n"
+        @counter += 1
+        @counter = 0 if @counter >= @indicators.length
+      end
+    end
+
+    def stderr(message)
+      @mutex.synchronize { $stdout.print message }
+    end
+
+    def done
+      @mutex.synchronize { $stdout.print "\e[K" }
+    end
+  end
 end

lib/ruby_wasm/build/product/wasi_vfs.rb

@@ -48,7 +48,11 @@ def build(executor)
       lib_wasi_vfs_url =
         "https://github.com/kateinoigakukun/wasi-vfs/releases/download/v#{WASI_VFS_VERSION}/libwasi_vfs-wasm32-unknown-unknown.zip"
       Dir.mktmpdir do |tmpdir|
-        executor.system "curl", "-L", lib_wasi_vfs_url, "-o", "#{tmpdir}/libwasi_vfs.zip"
+        executor.system "curl",
+                        "-L",
+                        lib_wasi_vfs_url,
+                        "-o",
+                        "#{tmpdir}/libwasi_vfs.zip"
         executor.system "unzip", "#{tmpdir}/libwasi_vfs.zip", "-d", tmpdir
         executor.mkdir_p File.dirname(lib_wasi_vfs_a)
         executor.mv File.join(tmpdir, "libwasi_vfs.a"), lib_wasi_vfs_a

sig/ruby_wasm/build.rbs

@@ -227,7 +227,7 @@ module RubyWasm
     @start_times: Hash[[Class, String], Time]
 
     def initialize: (?verbose: bool) -> void
-    def system: (*_ToS args, ?chdir: String?, ?out: Kernel::redirect_fd?, ?env: Hash[String, String]?) -> void
+    def system: (*_ToS args, ?chdir: String?, ?env: Hash[String, String]?) -> void
     def rm_rf: (FileUtils::pathlist list) -> void
     def rm_f: (FileUtils::pathlist list) -> void
     def cp_r: (FileUtils::pathlist src, path dest) -> void
@@ -241,6 +241,17 @@ module RubyWasm
     private def _print_command: (Array[_ToS] command, Hash[String, String]? env) -> void
   end
 
+  class StatusPrinter
+    @mutex: Mutex
+    @counter: Integer
+    @indicators: String
+
+    def initialize: () -> void
+    def stdout: (String message) -> void
+    def stderr: (String message) -> void
+    def done: () -> void
+  end
+
   class Downloader
     def format_size: (Integer size) -> String