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 * Copyright (c) 2018, 2026, 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.
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#ifndef SHARE_UTILITIES_GLOBALCOUNTER_INLINE_HPP
#define SHARE_UTILITIES_GLOBALCOUNTER_INLINE_HPP

#include "utilities/globalCounter.hpp"

#include "runtime/atomic.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/safepointVerifiers.hpp"

inline GlobalCounter::CSContext
GlobalCounter::critical_section_begin(Thread *thread) {
  assert(thread == Thread::current(), "must be current thread");
  uintx old_cnt = thread->get_rcu_counter()->load_relaxed();
  // 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 = _global_counter._counter.load_relaxed() | COUNTER_ACTIVE;
  }
  thread->get_rcu_counter()->release_store_fence(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()->load_relaxed() & COUNTER_ACTIVE) == COUNTER_ACTIVE, "must be in critical section");
  // Restore the counter value from before the associated begin.
  thread->get_rcu_counter()->release_store(static_cast<uintx>(context));
}

class GlobalCounter::CriticalSection {
  NoSafepointVerifier _nsv;
  Thread* _thread;
  CSContext _context;

public:
  inline CriticalSection(Thread* thread) :
    _nsv(),
    _thread(thread),
    _context(GlobalCounter::critical_section_begin(_thread))
  {}

  inline  ~CriticalSection() {
    GlobalCounter::critical_section_end(_thread, _context);
  }
};

#endif // SHARE_UTILITIES_GLOBALCOUNTER_INLINE_HPP
