/*

 * Copyright (c) 1997, 2010, 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 "oops/markOop.hpp"

#ifdef TARGET_OS_FAMILY_linux

# include "thread_linux.inline.hpp"

#endif

#ifdef TARGET_OS_FAMILY_solaris

# include "thread_solaris.inline.hpp"

#endif

#ifdef TARGET_OS_FAMILY_windows

# include "thread_windows.inline.hpp"

#endif

void markOopDesc::print_on(outputStream* st) const {

  if (is_locked()) {

    st->print("locked(0x%lx)->", value());

    markOop(*(markOop*)value())->print_on(st);

  } else {

    assert(is_unlocked() || has_bias_pattern(), "just checking");

    st->print("mark(");

    if (has_bias_pattern())  st->print("biased,");

    st->print("hash %#lx,", hash());

    st->print("age %d)", age());

  }

}

// Give advice about whether the oop that contains this markOop

// should be cached or not.

bool markOopDesc::should_not_be_cached() const {

  // the cast is because decode_pointer() isn't marked const

  if (is_marked() && ((markOopDesc *)this)->decode_pointer() != NULL) {

    // If the oop containing this markOop is being forwarded, then

    // we are in the middle of GC and we do not want the containing

    // oop to be added to a cache. We have no way of knowing whether

    // the cache has already been visited by the current GC phase so

    // we don't know whether the forwarded oop will be properly

    // processed in this phase. If the forwarded oop is not properly

    // processed, then we'll see strange crashes or asserts during

    // the next GC run because the markOop will contain an unexpected

    // value.

    //

    // This situation has been seen when we are GC'ing a methodOop

    // because we use the methodOop while we're GC'ing it. Scary

    // stuff. Some of the uses the methodOop cause the methodOop to

    // be added to the OopMapCache in the instanceKlass as a side

    // effect. This check lets the cache maintainer know when a

    // cache addition would not be safe.

    return true;

  }

  // caching the containing oop should be just fine

  return false;

}