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/metachunk.hpp"
jmasa@4327: #include "utilities/copy.hpp"
jmasa@4327: #include "utilities/debug.hpp"
jmasa@4327: 
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: 
jmasa@4327: const size_t metadata_chunk_initialize = 0xf7f7f7f7;
jmasa@4327: 
jmasa@4327: size_t Metachunk::_overhead =
jmasa@4327:   Chunk::aligned_overhead_size(sizeof(Metachunk)) / BytesPerWord;
jmasa@4327: 
jmasa@4327: // Metachunk methods
jmasa@4327: 
jmasa@4327: Metachunk* Metachunk::initialize(MetaWord* ptr, size_t word_size) {
jmasa@4327:   // Set bottom, top, and end.  Allow space for the Metachunk itself
jmasa@4327:   Metachunk* chunk = (Metachunk*) ptr;
jmasa@4327: 
jmasa@4327:   MetaWord* chunk_bottom = ptr + _overhead;
jmasa@4327:   chunk->set_bottom(ptr);
jmasa@4327:   chunk->set_top(chunk_bottom);
jmasa@4327:   MetaWord* chunk_end = ptr + word_size;
jmasa@4327:   assert(chunk_end > chunk_bottom, "Chunk must be too small");
jmasa@4327:   chunk->set_end(chunk_end);
jmasa@4327:   chunk->set_next(NULL);
jmasa@4382:   chunk->set_prev(NULL);
jmasa@4327:   chunk->set_word_size(word_size);
jmasa@4327: #ifdef ASSERT
jmasa@4327:   size_t data_word_size = pointer_delta(chunk_end, chunk_bottom, sizeof(MetaWord));
jmasa@4327:   Copy::fill_to_words((HeapWord*) chunk_bottom, data_word_size, metadata_chunk_initialize);
jmasa@4327: #endif
jmasa@4327:   return chunk;
jmasa@4327: }
jmasa@4327: 
jmasa@4327: 
jmasa@4327: MetaWord* Metachunk::allocate(size_t word_size) {
jmasa@4327:   MetaWord* result = NULL;
jmasa@4327:   // If available, bump the pointer to allocate.
jmasa@4327:   if (free_word_size() >= word_size) {
jmasa@4327:     result = _top;
jmasa@4327:     _top = _top + word_size;
jmasa@4327:   }
jmasa@4327:   return result;
jmasa@4327: }
jmasa@4327: 
jmasa@4327: // _bottom points to the start of the chunk including the overhead.
jmasa@4382: size_t Metachunk::used_word_size() const {
jmasa@4327:   return pointer_delta(_top, _bottom, sizeof(MetaWord));
jmasa@4327: }
jmasa@4327: 
jmasa@4382: size_t Metachunk::free_word_size() const {
jmasa@4327:   return pointer_delta(_end, _top, sizeof(MetaWord));
jmasa@4327: }
jmasa@4327: 
jmasa@4382: size_t Metachunk::capacity_word_size() const {
jmasa@4327:   return pointer_delta(_end, _bottom, sizeof(MetaWord));
jmasa@4327: }
jmasa@4327: 
jmasa@4327: void Metachunk::print_on(outputStream* st) const {
jmasa@4327:   st->print_cr("Metachunk:"
jmasa@4327:                " bottom " PTR_FORMAT " top " PTR_FORMAT
jmasa@4327:                " end " PTR_FORMAT " size " SIZE_FORMAT,
jmasa@4327:                bottom(), top(), end(), word_size());
jmasa@4382:   if (Verbose) {
jmasa@4382:     st->print_cr("    used " SIZE_FORMAT " free " SIZE_FORMAT,
jmasa@4382:                  used_word_size(), free_word_size());
jmasa@4382:   }
jmasa@4327: }
jmasa@4327: 
jmasa@4327: #ifndef PRODUCT
jmasa@4327: void Metachunk::mangle() {
jmasa@4327:   // Mangle the payload of the chunk and not the links that
jmasa@4327:   // maintain list of chunks.
jmasa@4327:   HeapWord* start = (HeapWord*)(bottom() + overhead());
jmasa@4327:   size_t word_size = capacity_word_size() - overhead();
jmasa@4327:   Copy::fill_to_words(start, word_size, metadata_chunk_initialize);
jmasa@4327: }
jmasa@4327: #endif // PRODUCT
jmasa@4327: 
jmasa@4327: void Metachunk::verify() {
jmasa@4327: #ifdef ASSERT
jmasa@4327:   // Cannot walk through the blocks unless the blocks have
jmasa@4327:   // headers with sizes.
jmasa@4327:   assert(_bottom <= _top &&
jmasa@4327:          _top <= _end,
jmasa@4327:          "Chunk has been smashed");
jmasa@4327: #endif
jmasa@4327:   return;
jmasa@4327: }