--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/main/gov/nasa/jpf/vm/ThreadInfoSet.java	Fri Jan 23 10:14:01 2015 -0800
@@ -0,0 +1,50 @@
+/*
+ * 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.vm;
+
+/**
+ * interface to abstract the referencing set of threadinfos per object/class
+ * Used to detect shared objects/classes 
+ * Instances are created through a configured factory (SharedObjectPolicy)
+ * 
+ * We abstract the container so that the way we identify threads is not exposed
+ * to the client, and implementations can use either ThreadInfo references or
+ * global ids.
+ */
+public interface ThreadInfoSet extends Cloneable {
+
+  /**
+   * @return true if the thread wasn't in the set yet and was added
+   */
+  ThreadInfoSet add (ThreadInfo ti);
+  
+  ThreadInfoSet remove (ThreadInfo ti);
+  
+  boolean contains (ThreadInfo ti);
+  
+  boolean isShared (ThreadInfo ti, ElementInfo ei);
+  
+  
+  boolean hasMultipleLiveThreads ();
+  boolean hasMultipleRunnableThreads ();
+  
+  Memento<ThreadInfoSet> getMemento();
+  
+  int size();
+}