1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/memory/metablock.cpp Thu Nov 29 10:09:04 2012 -0800
1.3 @@ -0,0 +1,75 @@
1.4 +/*
1.5 + * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "precompiled.hpp"
1.29 +#include "memory/allocation.hpp"
1.30 +#include "memory/metablock.hpp"
1.31 +#include "utilities/copy.hpp"
1.32 +#include "utilities/debug.hpp"
1.33 +
1.34 +// Blocks of space for metadata are allocated out of Metachunks.
1.35 +//
1.36 +// Metachunk are allocated out of MetadataVirtualspaces and once
1.37 +// allocated there is no explicit link between a Metachunk and
1.38 +// the MetadataVirtualspaces from which it was allocated.
1.39 +//
1.40 +// Each SpaceManager maintains a
1.41 +// list of the chunks it is using and the current chunk. The current
1.42 +// chunk is the chunk from which allocations are done. Space freed in
1.43 +// a chunk is placed on the free list of blocks (BlockFreelist) and
1.44 +// reused from there.
1.45 +//
1.46 +// Future modification
1.47 +//
1.48 +// The Metachunk can conceivable be replaced by the Chunk in
1.49 +// allocation.hpp. Note that the latter Chunk is the space for
1.50 +// allocation (allocations from the chunk are out of the space in
1.51 +// the Chunk after the header for the Chunk) where as Metachunks
1.52 +// point to space in a VirtualSpace. To replace Metachunks with
1.53 +// Chunks, change Chunks so that they can be allocated out of a VirtualSpace.
1.54 +size_t Metablock::_min_block_byte_size = sizeof(Metablock);
1.55 +
1.56 +#ifdef ASSERT
1.57 +size_t Metablock::_overhead =
1.58 + Chunk::aligned_overhead_size(sizeof(Metablock)) / BytesPerWord;
1.59 +#else
1.60 +size_t Metablock::_overhead = 0;
1.61 +#endif
1.62 +
1.63 +// New blocks returned by the Metaspace are zero initialized.
1.64 +// We should fix the constructors to not assume this instead.
1.65 +Metablock* Metablock::initialize(MetaWord* p, size_t word_size) {
1.66 + if (p == NULL) {
1.67 + return NULL;
1.68 + }
1.69 +
1.70 + Metablock* result = (Metablock*) p;
1.71 +
1.72 + // Clear the memory
1.73 + Copy::fill_to_aligned_words((HeapWord*)result, word_size);
1.74 +#ifdef ASSERT
1.75 + result->set_word_size(word_size);
1.76 +#endif
1.77 + return result;
1.78 +}
