123 lines
4.0 KiB
C++
123 lines
4.0 KiB
C++
/*
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* Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#include "precompiled.hpp"
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#include "memory/allocation.hpp"
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#include "memory/metachunk.hpp"
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#include "utilities/copy.hpp"
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#include "utilities/debug.hpp"
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//
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// Future modification
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//
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// The Metachunk can conceivable be replaced by the Chunk in
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// allocation.hpp. Note that the latter Chunk is the space for
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// allocation (allocations from the chunk are out of the space in
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// the Chunk after the header for the Chunk) where as Metachunks
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// point to space in a VirtualSpace. To replace Metachunks with
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// Chunks, change Chunks so that they can be allocated out of a VirtualSpace.
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const size_t metadata_chunk_initialize = 0xf7f7f7f7;
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size_t Metachunk::_overhead =
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Chunk::aligned_overhead_size(sizeof(Metachunk)) / BytesPerWord;
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// Metachunk methods
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Metachunk* Metachunk::initialize(MetaWord* ptr, size_t word_size) {
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// Set bottom, top, and end. Allow space for the Metachunk itself
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Metachunk* chunk = (Metachunk*) ptr;
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MetaWord* chunk_bottom = ptr + _overhead;
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chunk->set_bottom(ptr);
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chunk->set_top(chunk_bottom);
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MetaWord* chunk_end = ptr + word_size;
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assert(chunk_end > chunk_bottom, "Chunk must be too small");
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chunk->set_end(chunk_end);
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chunk->set_next(NULL);
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chunk->set_prev(NULL);
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chunk->set_word_size(word_size);
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#ifdef ASSERT
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size_t data_word_size = pointer_delta(chunk_end, chunk_bottom, sizeof(MetaWord));
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Copy::fill_to_words((HeapWord*) chunk_bottom, data_word_size, metadata_chunk_initialize);
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#endif
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return chunk;
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}
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MetaWord* Metachunk::allocate(size_t word_size) {
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MetaWord* result = NULL;
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// If available, bump the pointer to allocate.
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if (free_word_size() >= word_size) {
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result = _top;
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_top = _top + word_size;
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}
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return result;
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}
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// _bottom points to the start of the chunk including the overhead.
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size_t Metachunk::used_word_size() const {
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return pointer_delta(_top, _bottom, sizeof(MetaWord));
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}
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size_t Metachunk::free_word_size() const {
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return pointer_delta(_end, _top, sizeof(MetaWord));
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}
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size_t Metachunk::capacity_word_size() const {
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return pointer_delta(_end, _bottom, sizeof(MetaWord));
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}
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void Metachunk::print_on(outputStream* st) const {
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st->print_cr("Metachunk:"
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" bottom " PTR_FORMAT " top " PTR_FORMAT
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" end " PTR_FORMAT " size " SIZE_FORMAT,
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bottom(), top(), end(), word_size());
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if (Verbose) {
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st->print_cr(" used " SIZE_FORMAT " free " SIZE_FORMAT,
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used_word_size(), free_word_size());
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}
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}
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#ifndef PRODUCT
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void Metachunk::mangle() {
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// Mangle the payload of the chunk and not the links that
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// maintain list of chunks.
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HeapWord* start = (HeapWord*)(bottom() + overhead());
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size_t word_size = capacity_word_size() - overhead();
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Copy::fill_to_words(start, word_size, metadata_chunk_initialize);
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}
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#endif // PRODUCT
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void Metachunk::verify() {
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#ifdef ASSERT
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// Cannot walk through the blocks unless the blocks have
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// headers with sizes.
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assert(_bottom <= _top &&
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_top <= _end,
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"Chunk has been smashed");
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#endif
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return;
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}
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