/*

 * Copyright (c) 2018, 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 "runtime/os.hpp"

#include "utilities/ostream.hpp"

#include "utilities/spinYield.hpp"

SpinYield::SpinYield(uint spin_limit, uint yield_limit, uint sleep_ns) :

  _sleep_time(),

  _spins(0),

  _yields(0),

  _spin_limit(os::is_MP() ? spin_limit : 0),

  _yield_limit(yield_limit),

  _sleep_ns(sleep_ns)

{}

void SpinYield::yield_or_sleep() {

  if (_yields < _yield_limit) {

    ++_yields;

    os::naked_yield();

  } else {

    Ticks sleep_start = Ticks::now();

    os::naked_short_nanosleep(_sleep_ns);

    _sleep_time += Ticks::now() - sleep_start;

  }

}

static const char* print_separator(outputStream* s, const char* separator) {

  s->print("%s", separator);

  return ", ";

}

void SpinYield::report(outputStream* s) const {

  const char* initial_separator = "";

  const char* separator = initial_separator;

  if (_spins > 0) {             // Report spins, if any.

    separator = print_separator(s, separator);

    s->print("spins = %u", _spins);

  }

  if (_yields > 0) {            // Report yields, if any.

    separator = print_separator(s, separator);

    s->print("yields = %u", _yields);

  }

  if (_sleep_time.value() != 0) { // Report sleep duration, if slept.

    separator = print_separator(s, separator);

    s->print("sleep = " UINT64_FORMAT " usecs",

             _sleep_time.milliseconds());

  }

  if (separator == initial_separator) {

    s->print("no waiting");

  }

}