--- /dev/null 2017-11-09 09:38:01.297999907 +0100 +++ new/src/hotspot/share/jfr/leakprofiler/chains/objectSampleMarker.hpp 2018-04-09 14:39:03.445069876 +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* _store; + + public: + ObjectSampleMarker() : + _store(new GrowableArray(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