/*

 * Copyright (c) 2013, 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.

 *

 */

#include "precompiled.hpp"

#include "classfile/metadataOnStackMark.hpp"

#include "code/codeCache.hpp"

#include "compiler/compileBroker.hpp"

#include "oops/metadata.hpp"

#include "runtime/synchronizer.hpp"

#include "runtime/thread.hpp"

#include "utilities/growableArray.hpp"

// Keep track of marked on-stack metadata so it can be cleared.

GrowableArray<Metadata*>* _marked_objects = NULL;

NOT_PRODUCT(bool MetadataOnStackMark::_is_active = false;)

// Walk metadata on the stack and mark it so that redefinition doesn't delete

// it.  Class unloading also walks the previous versions and might try to

// delete it, so this class is used by class unloading also.

MetadataOnStackMark::MetadataOnStackMark() {

  assert(SafepointSynchronize::is_at_safepoint(), "sanity check");

  NOT_PRODUCT(_is_active = true;)

  if (_marked_objects == NULL) {

    _marked_objects = new (ResourceObj::C_HEAP, mtClass) GrowableArray<Metadata*>(1000, true);

  }

  Threads::metadata_do(Metadata::mark_on_stack);

  CodeCache::alive_nmethods_do(nmethod::mark_on_stack);

  CompileBroker::mark_on_stack();

}

MetadataOnStackMark::~MetadataOnStackMark() {

  assert(SafepointSynchronize::is_at_safepoint(), "sanity check");

  // Unmark everything that was marked.   Can't do the same walk because

  // redefine classes messes up the code cache so the set of methods

  // might not be the same.

  for (int i = 0; i< _marked_objects->length(); i++) {

    _marked_objects->at(i)->set_on_stack(false);

  }

  _marked_objects->clear();   // reuse growable array for next time.

  NOT_PRODUCT(_is_active = false;)

}

// Record which objects are marked so we can unmark the same objects.

void MetadataOnStackMark::record(Metadata* m) {

  assert(_is_active, "metadata on stack marking is active");

  _marked_objects->push(m);

}