--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/classes/java/util/concurrent/CyclicBarrier.java	Fri Jan 23 10:14:01 2015 -0800
@@ -0,0 +1,104 @@
+/*
+ * 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 java.util.concurrent;
+
+/**
+ * a simplistic CyclicBarrier implementation, required because the real one
+ * relies heavily on Sun infrastructure (including native methods)
+ */
+public class CyclicBarrier {
+
+  private Runnable action;
+  private int parties;
+  private int count;
+  private boolean isBroken;
+
+  // make sure nobody from the outside can interfere with our locking
+  private final Object lock = new Object();
+
+  
+  public CyclicBarrier (int parties) {
+    this(parties, null);
+  }
+
+  public CyclicBarrier (int parties, Runnable action) {
+    this.parties = parties;
+    count = parties;
+    
+    this.action = action;
+  }
+  
+  public int await () throws InterruptedException, BrokenBarrierException {
+    synchronized (lock) {
+      int arrival = parties - count;
+
+      if (--count == 0) {
+        if (action != null) {
+          action.run();
+        }
+        count = parties; // reset barrier
+        lock.notifyAll();
+      } else {
+        try {
+          lock.wait();
+          if (isBroken) {
+            throw new BrokenBarrierException();
+          }
+        } catch (InterruptedException ix) {
+          if (count > 0) {
+            isBroken = true;
+            lock.notifyAll();
+          }
+
+          throw ix;
+        }
+      }
+
+      return arrival;
+    }
+  }
+
+  public int getParties () {
+    return parties;
+  }
+
+  public void reset () {
+    synchronized (lock) {
+      if ((count != parties) && (count != 0)) {
+        // there are waiters
+        isBroken = true;
+        lock.notifyAll();
+      } else {
+        count = parties;
+        isBroken = false;
+      }
+    }
+  }
+
+  public boolean isBroken () {
+    // true if one of the parties got out of an await by being
+    // interrupted
+    return isBroken;
+  }
+
+  public int getNumberWaiting () {
+    synchronized (lock) {
+      return (parties - count);
+    }
+  }
+}