/*

 * Copyright (c) 2012, 2013, 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 "memory/allocation.hpp"

#include "memory/metablock.hpp"

#include "utilities/copy.hpp"

#include "utilities/debug.hpp"

// Blocks of space for metadata are allocated out of Metachunks.

//

// Metachunk are allocated out of MetadataVirtualspaces and once

// allocated there is no explicit link between a Metachunk and

// the MetadataVirtualspaces from which it was allocated.

//

// Each SpaceManager maintains a

// list of the chunks it is using and the current chunk.  The current

// chunk is the chunk from which allocations are done.  Space freed in

// a chunk is placed on the free list of blocks (BlockFreelist) and

// reused from there.

//

// Future modification

//

// The Metachunk can conceivable be replaced by the Chunk in

// allocation.hpp.  Note that the latter Chunk is the space for

// allocation (allocations from the chunk are out of the space in

// the Chunk after the header for the Chunk) where as Metachunks

// point to space in a VirtualSpace.  To replace Metachunks with

// Chunks, change Chunks so that they can be allocated out of a VirtualSpace.

size_t Metablock::_min_block_byte_size = sizeof(Metablock);

#ifdef ASSERT

size_t Metablock::_overhead =

  Chunk::aligned_overhead_size(sizeof(Metablock)) / BytesPerWord;

#else

size_t Metablock::_overhead = 0;

#endif

// New blocks returned by the Metaspace are zero initialized.

// We should fix the constructors to not assume this instead.

Metablock* Metablock::initialize(MetaWord* p, size_t word_size) {

  if (p == NULL) {

    return NULL;

  }

  Metablock* result = (Metablock*) p;

  // Clear the memory

  Copy::fill_to_aligned_words((HeapWord*)result, word_size);

#ifdef ASSERT

  result->set_word_size(word_size);

#endif

  return result;

}