--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/main/gov/nasa/jpf/util/CountDown.java	Fri Jan 23 10:14:01 2015 -0800
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2014, United States Government, as represented by the
+ * Administrator of the National Aeronautics and Space Administration.
+ * All rights reserved.
+ *
+ * The Java Pathfinder core (jpf-core) platform is licensed under the
+ * Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ * 
+ *        http://www.apache.org/licenses/LICENSE-2.0. 
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and 
+ * limitations under the License.
+ */
+
+package gov.nasa.jpf.util;
+
+final class CountDown extends RuntimeException {
+  private int remaining;
+  
+  CountDown (int remaining){
+    this.remaining = remaining;
+  }
+  
+  public final int dec(){
+    if (remaining <= 0){
+      throw this;
+    }
+    remaining--;
+    return remaining;
+  }
+  
+  public final void expire (){
+    remaining = 0;
+  }
+  
+  public final void set(int remaining){
+    this.remaining = remaining;
+  }
+}
\ No newline at end of file