/*

 * Copyright (c) 2018, 2019, 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_UTILITIES_GLOBALCOUNTER_INLINE_HPP

#define SHARE_UTILITIES_GLOBALCOUNTER_INLINE_HPP

#include "runtime/atomic.hpp"

#include "runtime/thread.inline.hpp"

#include "utilities/globalCounter.hpp"

inline GlobalCounter::CSContext

GlobalCounter::critical_section_begin(Thread *thread) {

  assert(thread == Thread::current(), "must be current thread");

  uintx old_cnt = Atomic::load(thread->get_rcu_counter());

  // Retain the old counter value if already active, e.g. nested.

  // Otherwise, set the counter to the current version + active bit.

  uintx new_cnt = old_cnt;

  if ((new_cnt & COUNTER_ACTIVE) == 0) {

    new_cnt = Atomic::load(&_global_counter._counter) | COUNTER_ACTIVE;

  }

  Atomic::release_store_fence(thread->get_rcu_counter(), new_cnt);

  return static_cast<CSContext>(old_cnt);

}

inline void

GlobalCounter::critical_section_end(Thread *thread, CSContext context) {

  assert(thread == Thread::current(), "must be current thread");

  assert((*thread->get_rcu_counter() & COUNTER_ACTIVE) == COUNTER_ACTIVE, "must be in critical section");

  // Restore the counter value from before the associated begin.

  Atomic::release_store(thread->get_rcu_counter(),

                        static_cast<uintx>(context));

}

class GlobalCounter::CriticalSection {

 private:

  Thread* _thread;

  CSContext _context;

 public:

  inline CriticalSection(Thread* thread) :

    _thread(thread),

    _context(GlobalCounter::critical_section_begin(_thread))

  {}

  inline  ~CriticalSection() {

    GlobalCounter::critical_section_end(_thread, _context);

  }

};

#endif // SHARE_UTILITIES_GLOBALCOUNTER_INLINE_HPP