//
// Copyright (C) 2012 United States Government as represented by the
// Administrator of the National Aeronautics and Space Administration
// (NASA). All Rights Reserved.
//
// This software is distributed under the NASA Open Source Agreement
// (NOSA), version 1.3. The NOSA has been approved by the Open Source
// Initiative. See the file NOSA-1.3-JPF at the top of the distribution
// directory tree for the complete NOSA document.
//
// THE SUBJECT SOFTWARE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY OF ANY
// KIND, EITHER EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT
// LIMITED TO, ANY WARRANTY THAT THE SUBJECT SOFTWARE WILL CONFORM TO
// SPECIFICATIONS, ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR
// A PARTICULAR PURPOSE, OR FREEDOM FROM INFRINGEMENT, ANY WARRANTY THAT
// THE SUBJECT SOFTWARE WILL BE ERROR FREE, OR ANY WARRANTY THAT
// DOCUMENTATION, IF PROVIDED, WILL CONFORM TO THE SUBJECT SOFTWARE.
//
package gov.nasa.jpf.vm;
import gov.nasa.jpf.Config;
/**
* abstraction for configured policy object that is responsible for detecting shared objects and classes
* The interface has to support both
* <ul>
* <li> tracking (actual access) based policies
* ("what <em>is</em> shared")</li>
* <li> conservative reachability based policies
* ("what <em>could be</em> shared")</li>
* </ul>
*
* The interface is intentionally kept generic to support both policies since tracking - while being
* far more efficient in terms of states and speed - can either miss some paths or cause state spaces
* to depend on search history, thus leading to different search graphs for randomized searches.
* Missed paths only happen in cases where there is very little interaction between threads and
* defects only happen along single paths. The second case is mostly of interest for comparative
* studies and not very relevant for bug finding
*/
public abstract class SharedObjectPolicy {
protected static SharedObjectPolicy singleton;
public static boolean init (Config config) {
singleton = config.getEssentialInstance("vm.por.shared.class", SharedObjectPolicy.class);
return true;
}
public static SharedObjectPolicy getPolicy() {
return singleton;
}
//--- creators
public abstract ThreadInfoSet getThreadInfoSet (ThreadInfo allocThread, DynamicElementInfo ei);
public abstract ThreadInfoSet getThreadInfoSet (ThreadInfo allocThread, StaticElementInfo ei);
//--- sharedness check
public abstract boolean isShared (ThreadInfo ti, ElementInfo ei, ThreadInfoSet set);
//--- state management
public abstract Memento<ThreadInfoSet> getMemento (ThreadInfoSet set);
//--- housekeeping
public abstract void cleanupThreadTermination (ThreadInfo ti);
}