134 lines
4.9 KiB
C++
134 lines
4.9 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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#ifndef SHARE_VM_MEMORY_METACHUNK_HPP
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#define SHARE_VM_MEMORY_METACHUNK_HPP
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// Metachunk - Quantum of allocation from a Virtualspace
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// Metachunks are reused (when freed are put on a global freelist) and
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// have no permanent association to a SpaceManager.
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// +--------------+ <- end
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// | | --+ ---+
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// | | | free |
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// | | | |
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// | | | | capacity
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// | | | |
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// | | <- top --+ |
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// | | ---+ |
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// | | | used |
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// | | | |
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// | | | |
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// +--------------+ <- bottom ---+ ---+
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class Metachunk VALUE_OBJ_CLASS_SPEC {
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// link to support lists of chunks
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Metachunk* _next;
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Metachunk* _prev;
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MetaWord* _bottom;
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MetaWord* _end;
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MetaWord* _top;
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size_t _word_size;
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// Used in a guarantee() so included in the Product builds
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// even through it is only for debugging.
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bool _is_free;
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// Metachunks are allocated out of a MetadataVirtualSpace and
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// and use some of its space to describe itself (plus alignment
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// considerations). Metadata is allocated in the rest of the chunk.
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// This size is the overhead of maintaining the Metachunk within
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// the space.
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static size_t _overhead;
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void set_bottom(MetaWord* v) { _bottom = v; }
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void set_end(MetaWord* v) { _end = v; }
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void set_top(MetaWord* v) { _top = v; }
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void set_word_size(size_t v) { _word_size = v; }
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public:
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#ifdef ASSERT
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Metachunk() : _bottom(NULL), _end(NULL), _top(NULL), _is_free(false) {}
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#else
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Metachunk() : _bottom(NULL), _end(NULL), _top(NULL) {}
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#endif
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// Used to add a Metachunk to a list of Metachunks
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void set_next(Metachunk* v) { _next = v; assert(v != this, "Boom");}
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void set_prev(Metachunk* v) { _prev = v; assert(v != this, "Boom");}
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MetaWord* allocate(size_t word_size);
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static Metachunk* initialize(MetaWord* ptr, size_t word_size);
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// Accessors
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Metachunk* next() const { return _next; }
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Metachunk* prev() const { return _prev; }
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MetaWord* bottom() const { return _bottom; }
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MetaWord* end() const { return _end; }
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MetaWord* top() const { return _top; }
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size_t word_size() const { return _word_size; }
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size_t size() const volatile { return _word_size; }
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void set_size(size_t v) { _word_size = v; }
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bool is_free() { return _is_free; }
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void set_is_free(bool v) { _is_free = v; }
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static size_t overhead() { return _overhead; }
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void clear_next() { set_next(NULL); }
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void link_prev(Metachunk* ptr) { set_prev(ptr); }
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uintptr_t* end() { return ((uintptr_t*) this) + size(); }
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bool cantCoalesce() const { return false; }
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void link_next(Metachunk* ptr) { set_next(ptr); }
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void link_after(Metachunk* ptr){
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link_next(ptr);
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if (ptr != NULL) ptr->link_prev(this);
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}
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// Reset top to bottom so chunk can be reused.
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void reset_empty() { _top = (_bottom + _overhead); }
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bool is_empty() { return _top == (_bottom + _overhead); }
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// used (has been allocated)
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// free (available for future allocations)
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// capacity (total size of chunk)
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size_t used_word_size();
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size_t free_word_size();
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size_t capacity_word_size();
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// Debug support
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#ifdef ASSERT
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void* prev_addr() const { return (void*)&_prev; }
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void* next_addr() const { return (void*)&_next; }
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void* size_addr() const { return (void*)&_word_size; }
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#endif
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bool verify_chunk_in_free_list(Metachunk* tc) const { return true; }
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bool verify_par_locked() { return true; }
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void assert_is_mangled() const {/* Don't check "\*/}
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#ifdef ASSERT
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void mangle();
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#endif // ASSERT
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void print_on(outputStream* st) const;
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void verify();
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};
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#endif // SHARE_VM_MEMORY_METACHUNK_HPP
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