thread.c: avoid busy looping on rb_thread_fd_close

We no longer use it this function, but extensions do, and
we need to ensure it continues to work for them.

* thread.c (rb_thread_fd_close): schedule other threads in loop
* ext/-test-/thread_fd_close/thread_fd_close.c: new file
* ext/-test-/thread_fd_close/depend: ditto
* ext/-test-/thread_fd_close/extconf.rb: ditto
* test/-ext-/thread_fd_close/test_thread_fd_close.rb: new test

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59030 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/-test-/thread_fd_close/depend

@@ -0,0 +1,16 @@
+# AUTOGENERATED DEPENDENCIES START
+thread_fd_close.o: $(RUBY_EXTCONF_H)
+thread_fd_close.o: $(arch_hdrdir)/ruby/config.h
+thread_fd_close.o: $(hdrdir)/ruby/backward.h
+thread_fd_close.o: $(hdrdir)/ruby/defines.h
+thread_fd_close.o: $(hdrdir)/ruby/encoding.h
+thread_fd_close.o: $(hdrdir)/ruby/intern.h
+thread_fd_close.o: $(hdrdir)/ruby/io.h
+thread_fd_close.o: $(hdrdir)/ruby/missing.h
+thread_fd_close.o: $(hdrdir)/ruby/onigmo.h
+thread_fd_close.o: $(hdrdir)/ruby/oniguruma.h
+thread_fd_close.o: $(hdrdir)/ruby/ruby.h
+thread_fd_close.o: $(hdrdir)/ruby/st.h
+thread_fd_close.o: $(hdrdir)/ruby/subst.h
+thread_fd_close.o: thread_fd_close.c
+# AUTOGENERATED DEPENDENCIES END

ext/-test-/thread_fd_close/extconf.rb

@@ -0,0 +1,2 @@
+# frozen_string_literal: true
+create_makefile('-test-/thread_fd_close')

ext/-test-/thread_fd_close/thread_fd_close.c

@@ -0,0 +1,14 @@
+#include "ruby/ruby.h"
+
+static VALUE
+thread_fd_close(VALUE ign, VALUE fd)
+{
+    rb_thread_fd_close(NUM2INT(fd));
+    return Qnil;
+}
+
+void
+Init_thread_fd_close(void)
+{
+    rb_define_singleton_method(rb_cIO, "thread_fd_close", thread_fd_close, 1);
+}

test/-ext-/thread_fd_close/test_thread_fd_close.rb

@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+require 'test/unit'
+require '-test-/thread_fd_close'
+require 'io/wait'
+
+class TestThreadFdClose < Test::Unit::TestCase
+
+  def test_thread_fd_close
+    IO.pipe do |r, w|
+      th = Thread.new do
+        begin
+          r.read(4)
+        ensure
+          w.syswrite('done')
+        end
+      end
+      Thread.pass until th.stop?
+      IO.thread_fd_close(r.fileno)
+      assert_equal 'done', r.read(4)
+      assert_raise(IOError) { th.join }
+    end
+  end
+end

thread.c

@@ -2230,7 +2230,7 @@ rb_notify_fd_close(int fd)
 void
 rb_thread_fd_close(int fd)
 {
-    while (rb_notify_fd_close(fd));
+    while (rb_notify_fd_close(fd)) rb_thread_schedule();
 }
 
 /*