--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/jfr/leakprofiler/chains/objectSampleMarker.hpp	Tue May 15 20:24:34 2018 +0200
@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2017, 2018, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_JFR_LEAKPROFILER_CHAINS_OBJECTSAMPLEMARKER_HPP
+#define SHARE_VM_JFR_LEAKPROFILER_CHAINS_OBJECTSAMPLEMARKER_HPP
+
+#include "memory/allocation.hpp"
+#include "oops/markOop.hpp"
+#include "utilities/growableArray.hpp"
+//
+// This class will save the original mark oop of a object sample object.
+// It will then install an "identifier" mark oop to be used for
+// identification purposes in the search for reference chains.
+// The destructor will restore each modified oop with its original mark oop.
+//
+class ObjectSampleMarker : public StackObj {
+ private:
+  class ObjectSampleMarkOop : public ResourceObj {
+    friend class ObjectSampleMarker;
+   private:
+    oop _obj;
+    markOop _mark_oop;
+    ObjectSampleMarkOop(const oop obj,
+                        const markOop mark_oop) : _obj(obj),
+                                                  _mark_oop(mark_oop) {}
+   public:
+    ObjectSampleMarkOop() : _obj(NULL), _mark_oop(NULL) {}
+  };
+
+  GrowableArray<ObjectSampleMarkOop>* _store;
+
+ public:
+  ObjectSampleMarker() :
+       _store(new GrowableArray<ObjectSampleMarkOop>(16)) {}
+  ~ObjectSampleMarker() {
+    assert(_store != NULL, "invariant");
+    // restore the saved, original, markOop for sample objects
+    while (_store->is_nonempty()) {
+      ObjectSampleMarkOop sample_oop = _store->pop();
+      sample_oop._obj->set_mark(sample_oop._mark_oop);
+      assert(sample_oop._obj->mark() == sample_oop._mark_oop, "invariant");
+    }
+  }
+
+  void mark(oop obj) {
+    assert(obj != NULL, "invariant");
+    // save the original markOop
+    _store->push(ObjectSampleMarkOop(obj, obj->mark()));
+    // now we will "poison" the mark word of the sample object
+    // to the intermediate monitor INFLATING state.
+    // This is an "impossible" state during a safepoint,
+    // hence we will use it to quickly identify sample objects
+    // during the reachability search from gc roots.
+    assert(NULL == markOopDesc::INFLATING(), "invariant");
+    obj->set_mark(markOopDesc::INFLATING());
+    assert(NULL == obj->mark(), "invariant");
+  }
+};
+
+#endif // SHARE_VM_JFR_LEAKPROFILER_CHAINS_OBJECTSAMPLEMARKER_HPP