/*

 * Copyright (c) 2019, SAP SE. All rights reserved.

 * Copyright (c) 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_MEMORY_METASPACE_COUNTER_HPP

#define SHARE_MEMORY_METASPACE_COUNTER_HPP

#include "metaprogramming/isSigned.hpp"

#include "runtime/atomic.hpp"

#include "utilities/debug.hpp"

#include "utilities/globalDefinitions.hpp"

namespace metaspace {

// A very simple helper class which counts something, offers decrement/increment

//

template <class T>

class AbstractCounter {

  T _c;

  // Optional name for easier reference

  const char* const _name;

  // Only allow unsigned values for now

  STATIC_ASSERT(IsSigned<T>::value == false);

public:

  AbstractCounter(const char* name) : _c(0), _name(name) {}

  AbstractCounter() : _c(0), _name("") {}

  T get() const           { return _c; }

  void increment() { increment_by(1); }

  void decrement() { decrement_by(1); }

  void increment_by(T v) {

    assert(_c + v >= _c,

        "%s overflow (" UINT64_FORMAT "+" UINT64_FORMAT ")",

        _name, (uint64_t)_c, (uint64_t)v);

    _c += v;

  }

  void decrement_by(T v) {

    assert(_c - v <= _c,

        "%s underflow (" UINT64_FORMAT "-" UINT64_FORMAT ")",

        _name, (uint64_t)_c, (uint64_t)v);

    _c -= v;

  }

  void reset()                { _c = 0; }

#ifdef ASSERT

  void check(T expected) const {

    assert(_c == expected, "Counter mismatch: %d, expected: %d.",

           (int)_c, (int)expected);

    }

#endif

};

typedef AbstractCounter<size_t>   SizeCounter;

typedef AbstractCounter<unsigned> IntCounter;

template <class T>

class AbstractAtomicCounter {

  volatile T _c;

  // Optional name for easier reference

  const char* const _name;

  // Only allow unsigned values for now

  STATIC_ASSERT(IsSigned<T>::value == false);

public:

  AbstractAtomicCounter(const char* name) : _c(0), _name(name) {}

  AbstractAtomicCounter() : _c(0), _name("") {}

  T get() const               { return _c; }

  void increment() {

    assert(_c + 1 != 0,

        "%s overflow (" UINT64_FORMAT "+1)",

        _name, (uint64_t)_c);

    Atomic::inc(&_c);

  }

  void decrement() {

    assert(_c >= 1,

        "%s underflow (" UINT64_FORMAT "-1)",

        _name, (uint64_t)_c);

    Atomic::dec(&_c);

  }

  void increment_by(T v) {

    T v1 = _c;

    T v2 = Atomic::add(v, &_c);

    assert(v2 > v1,

           "%s overflow (" UINT64_FORMAT "+" UINT64_FORMAT ")",

           _name, (uint64_t)v1, (uint64_t)v);

  }

  void decrement_by(T v) {

    assert(_c >= v,

           "%s underflow (" UINT64_FORMAT "-" UINT64_FORMAT ")",

           _name, (uint64_t)_c, (uint64_t)v);

    Atomic::sub(v, &_c);

  }

#ifdef ASSERT

  void check(T expected) const {

    assert(_c == expected, "Counter mismatch: %d, expected: %d.",

           (int)_c, (int)expected);

    }

#endif

};

typedef AbstractAtomicCounter<size_t> SizeAtomicCounter;

} // namespace metaspace

#endif // SHARE_MEMORY_METASPACE_WORDSIZECOUNTER_HPP