jmasa@4327: /*
jmasa@4327:  * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
jmasa@4327:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jmasa@4327:  *
jmasa@4327:  * This code is free software; you can redistribute it and/or modify it
jmasa@4327:  * under the terms of the GNU General Public License version 2 only, as
jmasa@4327:  * published by the Free Software Foundation.
jmasa@4327:  *
jmasa@4327:  * This code is distributed in the hope that it will be useful, but WITHOUT
jmasa@4327:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jmasa@4327:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jmasa@4327:  * version 2 for more details (a copy is included in the LICENSE file that
jmasa@4327:  * accompanied this code).
jmasa@4327:  *
jmasa@4327:  * You should have received a copy of the GNU General Public License version
jmasa@4327:  * 2 along with this work; if not, write to the Free Software Foundation,
jmasa@4327:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jmasa@4327:  *
jmasa@4327:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jmasa@4327:  * or visit www.oracle.com if you need additional information or have any
jmasa@4327:  * questions.
jmasa@4327:  *
jmasa@4327:  */
jmasa@4327: 
jmasa@4327: #include "precompiled.hpp"
jmasa@4327: #include "memory/allocation.hpp"
jmasa@4327: #include "memory/metablock.hpp"
jmasa@4327: #include "utilities/copy.hpp"
jmasa@4327: #include "utilities/debug.hpp"
jmasa@4327: 
jmasa@4327: // Blocks of space for metadata are allocated out of Metachunks.
jmasa@4327: //
jmasa@4327: // Metachunk are allocated out of MetadataVirtualspaces and once
jmasa@4327: // allocated there is no explicit link between a Metachunk and
jmasa@4327: // the MetadataVirtualspaces from which it was allocated.
jmasa@4327: //
jmasa@4327: // Each SpaceManager maintains a
jmasa@4327: // list of the chunks it is using and the current chunk.  The current
jmasa@4327: // chunk is the chunk from which allocations are done.  Space freed in
jmasa@4327: // a chunk is placed on the free list of blocks (BlockFreelist) and
jmasa@4327: // reused from there.
jmasa@4327: //
jmasa@4327: // Future modification
jmasa@4327: //
jmasa@4327: // The Metachunk can conceivable be replaced by the Chunk in
jmasa@4327: // allocation.hpp.  Note that the latter Chunk is the space for
jmasa@4327: // allocation (allocations from the chunk are out of the space in
jmasa@4327: // the Chunk after the header for the Chunk) where as Metachunks
jmasa@4327: // point to space in a VirtualSpace.  To replace Metachunks with
jmasa@4327: // Chunks, change Chunks so that they can be allocated out of a VirtualSpace.
jmasa@4327: size_t Metablock::_min_block_byte_size = sizeof(Metablock);
jmasa@4327: 
jmasa@4327: #ifdef ASSERT
jmasa@4327: size_t Metablock::_overhead =
jmasa@4327:   Chunk::aligned_overhead_size(sizeof(Metablock)) / BytesPerWord;
jmasa@4327: #else
jmasa@4327: size_t Metablock::_overhead = 0;
jmasa@4327: #endif
jmasa@4327: 
jmasa@4327: // New blocks returned by the Metaspace are zero initialized.
jmasa@4327: // We should fix the constructors to not assume this instead.
jmasa@4327: Metablock* Metablock::initialize(MetaWord* p, size_t word_size) {
jmasa@4327:   if (p == NULL) {
jmasa@4327:     return NULL;
jmasa@4327:   }
jmasa@4327: 
jmasa@4327:   Metablock* result = (Metablock*) p;
jmasa@4327: 
jmasa@4327:   // Clear the memory
jmasa@4327:   Copy::fill_to_aligned_words((HeapWord*)result, word_size);
jmasa@4327: #ifdef ASSERT
jmasa@4327:   result->set_word_size(word_size);
jmasa@4327: #endif
jmasa@4327:   return result;
jmasa@4327: }