/*

 * Copyright (c) 2017, 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 "jfr/leakprofiler/sampling/objectSample.hpp"

#include "jfr/leakprofiler/sampling/sampleList.hpp"

#include "oops/oop.inline.hpp"

SampleList::SampleList(size_t limit, size_t cache_size) :

  _free_list(),

  _in_use_list(),

  _last_resolved(NULL),

  _allocated(0),

  _limit(limit),

  _cache_size(cache_size) {

}

SampleList::~SampleList() {

  deallocate_samples(_free_list);

  deallocate_samples(_in_use_list);

}

ObjectSample* SampleList::last() const {

  return _in_use_list.head();

}

ObjectSample* SampleList::first() const {

  return _in_use_list.tail();

}

const ObjectSample* SampleList::last_resolved() const {

  return _last_resolved;

}

void SampleList::set_last_resolved(const ObjectSample* sample) {

  assert(last() == sample, "invariant");

  _last_resolved = sample;

}

void SampleList::link(ObjectSample* sample) {

  assert(sample != NULL, "invariant");

  _in_use_list.prepend(sample);

}

void SampleList::unlink(ObjectSample* sample) {

  assert(sample != NULL, "invariant");

  if (_last_resolved == sample) {

    _last_resolved = sample->next();

  }

  reset(_in_use_list.remove(sample));

}

ObjectSample* SampleList::reuse(ObjectSample* sample) {

  assert(sample != NULL, "invariant");

  unlink(sample);

  link(sample);

  return sample;

}

void SampleList::populate_cache() {

  if (_free_list.count() < _cache_size) {

    const size_t cache_delta = _cache_size - _free_list.count();

    for (size_t i = 0; i < cache_delta; ++i) {

      ObjectSample* sample = newSample();

      if (sample != NULL) {

        _free_list.append(sample);

      }

    }

  }

}

ObjectSample* SampleList::newSample() const {

  if (_limit == _allocated) {

    return NULL;

  }

  ++_allocated;

  return new ObjectSample();

}

ObjectSample* SampleList::get() {

  ObjectSample* sample = _free_list.head();

  if (sample != NULL) {

    link(_free_list.remove(sample));

  } else {

    sample = newSample();

    if (sample != NULL) {

      _in_use_list.prepend(sample);

    }

  }

  if (_cache_size > 0 && sample != NULL) {

    populate_cache();

  }

  return sample;

}

void SampleList::release(ObjectSample* sample) {

  assert(sample != NULL, "invariant");

  unlink(sample);

  _free_list.append(sample);

}

void SampleList::deallocate_samples(List& list) {

  if (list.count() > 0) {

    ObjectSample* sample = list.head();

    while (sample != NULL) {

      list.remove(sample);

      delete sample;

      sample = list.head();

    }

  }

  assert(list.count() == 0, "invariant");

}

void SampleList::reset(ObjectSample* sample) {

  assert(sample != NULL, "invariant");

  sample->reset();

}

bool SampleList::is_full() const {

  return _in_use_list.count() == _limit;

}

size_t SampleList::count() const {

  return _in_use_list.count();

}