Add IO#timeout attribute and use it for blocking IO operations. (#5653)

Merged-By: ioquatix <samuel@codeotaku.com>

test/ruby/test_io.rb

@@ -3960,6 +3960,9 @@ __END__
       noex = Thread.new do # everything right and never see exceptions :)
         until sig_rd.wait_readable(0)
           IO.pipe do |r, w|
+            assert_nil r.timeout
+            assert_nil w.timeout
+
             th = Thread.new { r.read(1) }
             w.write(dot)
 

test/ruby/test_io_timeout.rb

@@ -0,0 +1,64 @@
+# frozen_string_literal: false
+
+require 'io/nonblock'
+
+class TestIOTimeout < Test::Unit::TestCase
+  def with_pipe
+    omit "UNIXSocket is not defined!" unless defined?(UNIXSocket)
+
+    begin
+      i, o = UNIXSocket.pair
+
+      unless i.nonblock? && o.nonblock?
+        i.close
+        o.close
+        omit "I/O is not non-blocking!"
+      end
+
+      yield i, o
+    ensure
+      i.close
+      o.close
+    end
+  end
+
+  def test_timeout_attribute
+    with_pipe do |i, o|
+      assert_nil i.timeout
+
+      i.timeout = 10
+      assert_equal 10, i.timeout
+      assert_nil o.timeout
+
+      o.timeout = 20
+      assert_equal 20, o.timeout
+      assert_equal 10, i.timeout
+    end
+  end
+
+  def test_timeout_read_exception
+    with_pipe do |i, o|
+      i.timeout = 0.0001
+
+      assert_raise(IO::TimeoutError) {i.read}
+    end
+  end
+
+  def test_timeout_gets_exception
+    with_pipe do |i, o|
+      i.timeout = 0.0001
+
+      assert_raise(IO::TimeoutError) {i.gets}
+    end
+  end
+
+  def test_timeout_puts
+    with_pipe do |i, o|
+      i.timeout = 0.0001
+      o.puts("Hello World")
+      o.close
+
+      assert_equal "Hello World", i.gets.chomp
+    end
+  end
+end