Mercurial > hg > truffle
diff src/share/vm/memory/metablock.hpp @ 6885:685df3c6f84b
7045397: NPG: Add freelists to class loader arenas.
Reviewed-by: coleenp, stefank, jprovino, ohair
author | jmasa |
---|---|
date | Tue, 18 Sep 2012 23:35:42 -0700 |
parents | |
children | 335b388c4b28 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/memory/metablock.hpp Tue Sep 18 23:35:42 2012 -0700 @@ -0,0 +1,103 @@ +/* + * Copyright (c) 2012, 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. + * + */ +#ifndef SHARE_VM_MEMORY_METABLOCK_HPP +#define SHARE_VM_MEMORY_METABLOCK_HPP + +// Metablock are the unit of allocation from a Chunk. It is initialized +// with the size of the requested allocation. That size is overwritten +// once the allocation returns. +// +// A Metablock may be reused by its SpaceManager but are never moved between +// SpaceManagers. There is no explicit link to the Metachunk +// from which it was allocated. Metablock may be deallocated and +// put on a freelist but the space is never freed, rather +// the Metachunk it is a part of will be deallocated when it's +// associated class loader is collected. + +class Metablock VALUE_OBJ_CLASS_SPEC { + friend class VMStructs; + private: + // Used to align the allocation (see below). + union block_t { + void* _data[3]; + struct header_t { + size_t _word_size; + Metablock* _next; + Metablock* _prev; + } _header; + } _block; + static size_t _min_block_byte_size; + static size_t _overhead; + + typedef union block_t Block; + typedef struct header_t Header; + const Block* block() const { return &_block; } + const Block::header_t* header() const { return &(block()->_header); } + public: + + static Metablock* initialize(MetaWord* p, size_t word_size); + + // This places the body of the block at a 2 word boundary + // because every block starts on a 2 word boundary. Work out + // how to make the body on a 2 word boundary if the block + // starts on a arbitrary boundary. JJJ + + size_t word_size() const { return header()->_word_size; } + void set_word_size(size_t v) { _block._header._word_size = v; } + size_t size() const volatile { return _block._header._word_size; } + void set_size(size_t v) { _block._header._word_size = v; } + Metablock* next() const { return header()->_next; } + void set_next(Metablock* v) { _block._header._next = v; } + Metablock* prev() const { return header()->_prev; } + void set_prev(Metablock* v) { _block._header._prev = v; } + + static size_t min_block_byte_size() { return _min_block_byte_size; } + static size_t overhead() { return _overhead; } + + bool is_free() { return header()->_word_size != 0; } + void clear_next() { set_next(NULL); } + void link_prev(Metablock* ptr) { set_prev(ptr); } + uintptr_t* end() { return ((uintptr_t*) this) + size(); } + bool cantCoalesce() const { return false; } + void link_next(Metablock* ptr) { set_next(ptr); } + void link_after(Metablock* ptr){ + link_next(ptr); + if (ptr != NULL) ptr->link_prev(this); + } + + // Should not be needed in a free list of Metablocks + void markNotFree() { ShouldNotReachHere(); } + + // Debug support +#ifdef ASSERT + void* prev_addr() const { return (void*)&_block._header._prev; } + void* next_addr() const { return (void*)&_block._header._next; } + void* size_addr() const { return (void*)&_block._header._word_size; } +#endif + bool verify_chunk_in_free_list(Metablock* tc) const { return true; } + bool verify_par_locked() { return true; } + + void assert_is_mangled() const {/* Don't check "\*/} +}; +#endif // SHARE_VM_MEMORY_METABLOCK_HPP