gistfile1.diff

diff --git a/lib/timeout.rb b/lib/timeout.rb
index 7fd87ff..148fb76 100644
--- a/lib/timeout.rb
+++ b/lib/timeout.rb
@@ -47,39 +47,41 @@ module Timeout
   # Note that this is both a method of module Timeout, so you can <tt>include
   # Timeout</tt> 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+
-    return yield(sec) if sec == nil or sec.zero?
-    exception = klass || Class.new(ExitException)
-    begin
+  def timeout(sec, klass = nil, immediate: true)   #:yield: +sec+
+      return yield(sec) if sec == nil or sec.zero?
+    Thread.async_interrupt_timing(klass ? klass : ExitException => immediate ? :immediate : :on_blocking) do
+      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"
+        begin
+          x = Thread.current
+          y = Thread.start {
+            begin
+              sleep sec
+            rescue => e
+              x.raise e
+            else
+              x.raise exception, "execution expired"
+            end
+          }
+          return yield(sec)
+        ensure
+          if y
+            y.kill
+            y.join # make sure y is dead.
           end
-        }
-        return yield(sec)
-      ensure
-        if y
-          y.kill
-          y.join # make sure y is dead.
         end
+      rescue exception => e
+        rej = /\A#{Regexp.quote(__FILE__)}:#{__LINE__-4}\z/o
+        (bt = e.backtrace).reject! {|m| rej =~ m}
+        level = -caller(CALLER_OFFSET).size
+        while THIS_FILE =~ bt[level]
+          bt.delete_at(level)
+          level += 1
+        end
+        raise if klass            # if exception class is specified, it
+                                  # would be expected outside.
+        raise Error, e.message, e.backtrace
       end
-    rescue exception => e
-      rej = /\A#{Regexp.quote(__FILE__)}:#{__LINE__-4}\z/o
-      (bt = e.backtrace).reject! {|m| rej =~ m}
-      level = -caller(CALLER_OFFSET).size
-      while THIS_FILE =~ bt[level]
-        bt.delete_at(level)
-        level += 1
-      end
-      raise if klass            # if exception class is specified, it
-                                # would be expected outside.
-      raise Error, e.message, e.backtrace
     end
   end