/*

 * 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 "memory/allocation.hpp"

#include "memory/metachunk.hpp"

#include "utilities/copy.hpp"

#include "utilities/debug.hpp"

class VirtualSpaceNode;

const size_t metadata_chunk_initialize = 0xf7f7f7f7;

size_t Metachunk::object_alignment() {

  // Must align pointers and sizes to 8,

  // so that 64 bit types get correctly aligned.

  const size_t alignment = 8;

  // Make sure that the Klass alignment also agree.

  STATIC_ASSERT(alignment == (size_t)KlassAlignmentInBytes);

  return alignment;

}

size_t Metachunk::overhead() {

  return align_size_up(sizeof(Metachunk), object_alignment()) / BytesPerWord;

}

// Metachunk methods

Metachunk::Metachunk(size_t word_size,

                     VirtualSpaceNode* container)

    : Metabase<Metachunk>(word_size),

    _top(NULL),

    _container(container)

{

  _top = initial_top();

#ifdef ASSERT

  set_is_tagged_free(false);

  size_t data_word_size = pointer_delta(end(),

                                        _top,

                                        sizeof(MetaWord));

  Copy::fill_to_words((HeapWord*)_top,

                      data_word_size,

                      metadata_chunk_initialize);

#endif

}

MetaWord* Metachunk::allocate(size_t word_size) {

  MetaWord* result = NULL;

  // If available, bump the pointer to allocate.

  if (free_word_size() >= word_size) {

    result = _top;

    _top = _top + word_size;

  }

  return result;

}

// _bottom points to the start of the chunk including the overhead.

size_t Metachunk::used_word_size() const {

  return pointer_delta(_top, bottom(), sizeof(MetaWord));

}

size_t Metachunk::free_word_size() const {

  return pointer_delta(end(), _top, sizeof(MetaWord));

}

void Metachunk::print_on(outputStream* st) const {

  st->print_cr("Metachunk:"

               " bottom " PTR_FORMAT " top " PTR_FORMAT

               " end " PTR_FORMAT " size " SIZE_FORMAT,

               bottom(), _top, end(), word_size());

  if (Verbose) {

    st->print_cr("    used " SIZE_FORMAT " free " SIZE_FORMAT,

                 used_word_size(), free_word_size());

  }

}

#ifndef PRODUCT

void Metachunk::mangle() {

  // Mangle the payload of the chunk and not the links that

  // maintain list of chunks.

  HeapWord* start = (HeapWord*)(bottom() + overhead());

  size_t size = word_size() - overhead();

  Copy::fill_to_words(start, size, metadata_chunk_initialize);

}

#endif // PRODUCT

void Metachunk::verify() {

#ifdef ASSERT

  // Cannot walk through the blocks unless the blocks have

  // headers with sizes.

  assert(bottom() <= _top &&

         _top <= (MetaWord*)end(),

         "Chunk has been smashed");

#endif

  return;

}

/////////////// Unit tests ///////////////

#ifndef PRODUCT

class TestMetachunk {

 public:

  static void test() {

    size_t size = 2 * 1024 * 1024;

    void* memory = malloc(size);

    assert(memory != NULL, "Failed to malloc 2MB");

    Metachunk* metachunk = ::new (memory) Metachunk(size / BytesPerWord, NULL);

    assert(metachunk->bottom() == (MetaWord*)metachunk, "assert");

    assert(metachunk->end() == (uintptr_t*)metachunk + metachunk->size(), "assert");

    // Check sizes

    assert(metachunk->size() == metachunk->word_size(), "assert");

    assert(metachunk->word_size() == pointer_delta(metachunk->end(), metachunk->bottom(),

        sizeof(MetaWord*)), "assert");

    // Check usage

    assert(metachunk->used_word_size() == metachunk->overhead(), "assert");

    assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");

    assert(metachunk->top() == metachunk->initial_top(), "assert");

    assert(metachunk->is_empty(), "assert");

    // Allocate

    size_t alloc_size = 64; // Words

    assert(is_size_aligned(alloc_size, Metachunk::object_alignment()), "assert");

    MetaWord* mem = metachunk->allocate(alloc_size);

    // Check post alloc

    assert(mem == metachunk->initial_top(), "assert");

    assert(mem + alloc_size == metachunk->top(), "assert");

    assert(metachunk->used_word_size() == metachunk->overhead() + alloc_size, "assert");

    assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");

    assert(!metachunk->is_empty(), "assert");

    // Clear chunk

    metachunk->reset_empty();

    // Check post clear

    assert(metachunk->used_word_size() == metachunk->overhead(), "assert");

    assert(metachunk->free_word_size() == metachunk->word_size() - metachunk->used_word_size(), "assert");

    assert(metachunk->top() == metachunk->initial_top(), "assert");

    assert(metachunk->is_empty(), "assert");

    free(memory);

  }

};

void TestMetachunk_test() {

  TestMetachunk::test();

}

#endif