gistfile1.diff

diff --git a/lib/timeout.rb b/lib/timeout.rb
index 297b769..8399639 100644
--- a/lib/timeout.rb
+++ b/lib/timeout.rb
@@ -40,21 +40,22 @@ module Timeout
   # Note that this is both a method of module Timeout, so you can 'include Timeout'
   # into your classes so they have a #timeout method, as well as a module method,
   # so you can call it directly as Timeout.timeout().
-  def timeout(sec, klass = nil)   #:yield: +sec+
+  def timeout(sec, klass = nil, &block)   #:yield: +sec+
     return yield(sec) if sec == nil or sec.zero?
     exception = klass || Class.new(ExitException)
     begin
-      x = Thread.current
-      y = Thread.start {
-        begin
-          sleep sec
-        rescue => e
-          x.raise e
-        else
-          x.raise exception, "execution expired" if x.alive?
+      @t = @ret = nil
+      @s = Dispatch::Semaphore.new(0)
+
+      Dispatch::Queue.concurrent.async do
+        @t = Thread.new do
+          @ret = block.call(sec)
+          @s.signal
         end
-      }
-      return yield(sec)
+      end
+      raise exception, "execution expired" if not @s.wait(sec)
+      return @ret
+
     rescue exception => e
       rej = /\A#{Regexp.quote(__FILE__)}:#{__LINE__-4}\z/o
       (bt = e.backtrace).reject! {|m| rej =~ m}
@@ -67,9 +68,8 @@ module Timeout
                                 # would be expected outside.
       raise Error, e.message, e.backtrace
     ensure
-      if y and y.alive?
-        y.kill
-        y.join # make sure y is dead.
+      if @t and @t.alive?
+        @t.kill
       end
     end
   end