lib/monitor.rb: avoid race conditions by Thread.handle_interrupt

Suggested by Benoit Daloze.  [ruby-core:88502] [Bug #14998]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@66061 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/monitor.rb

@@ -103,15 +103,19 @@ module MonitorMixin
     # even if no other thread doesn't signal.
     #
     def wait(timeout = nil)
+      Thread.handle_interrupt(Exception => :never) do
         @monitor.__send__(:mon_check_owner)
         count = @monitor.__send__(:mon_exit_for_cond)
         begin
+          Thread.handle_interrupt(Exception => :immediate) do
             @cond.wait(@monitor.instance_variable_get(:@mon_mutex), timeout)
+          end
           return true
         ensure
           @monitor.__send__(:mon_enter_for_cond, count)
         end
       end
+    end
 
     #
     # Calls wait repeatedly while the given block yields a truthy value.

test/monitor/test_monitor.rb

@@ -269,4 +269,26 @@ class TestMonitor < Test::Unit::TestCase
 #     end
 #     cumber_thread.kill
   end
+
+  def test_wait_interruption
+    queue = Queue.new
+    cond = @monitor.new_cond
+    @monitor.define_singleton_method(:mon_enter_for_cond) do |*args|
+      queue.deq
+      super(*args)
+    end
+    th = Thread.start {
+      @monitor.synchronize do
+        begin
+          cond.wait(0.1)
+        rescue Interrupt
+          @monitor.instance_variable_get(:@mon_owner)
+        end
+      end
+    }
+    sleep(0.1)
+    th.raise(Interrupt)
+    queue.enq(nil)
+    assert_equal th, th.value
+  end
 end