1 /* 2 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 #ifndef SHARE_VM_MEMORY_METACHUNK_HPP 25 #define SHARE_VM_MEMORY_METACHUNK_HPP 26 27 #include "memory/allocation.hpp" 28 #include "utilities/debug.hpp" 29 #include "utilities/globalDefinitions.hpp" 30 31 class VirtualSpaceNode; 32 33 // Super class of Metablock and Metachunk to allow them to 34 // be put on the FreeList and in the BinaryTreeDictionary. 35 template <class T> 36 class Metabase VALUE_OBJ_CLASS_SPEC { 37 size_t _word_size; 38 T* _next; 39 T* _prev; 40 41 protected: 42 Metabase(size_t word_size) : _word_size(word_size), _next(NULL), _prev(NULL) {} 43 44 public: 45 T* next() const { return _next; } 46 T* prev() const { return _prev; } 47 void set_next(T* v) { _next = v; assert(v != this, "Boom");} 48 void set_prev(T* v) { _prev = v; assert(v != this, "Boom");} 49 void clear_next() { set_next(NULL); } 50 void clear_prev() { set_prev(NULL); } 51 52 size_t size() const volatile { return _word_size; } 53 void set_size(size_t v) { _word_size = v; } 54 55 void link_next(T* ptr) { set_next(ptr); } 56 void link_prev(T* ptr) { set_prev(ptr); } 57 void link_after(T* ptr) { 58 link_next(ptr); 59 if (ptr != NULL) ptr->link_prev((T*)this); 60 } 61 62 uintptr_t* end() const { return ((uintptr_t*) this) + size(); } 63 64 bool cantCoalesce() const { return false; } 65 66 // Debug support 67 #ifdef ASSERT 68 void* prev_addr() const { return (void*)&_prev; } 69 void* next_addr() const { return (void*)&_next; } 70 void* size_addr() const { return (void*)&_word_size; } 71 #endif 72 bool verify_chunk_in_free_list(T* tc) const { return true; } 73 bool verify_par_locked() { return true; } 74 75 void assert_is_mangled() const {/* Don't check "\*/} 76 77 bool is_free() { return true; } 78 }; 79 80 // Metachunk - Quantum of allocation from a Virtualspace 81 // Metachunks are reused (when freed are put on a global freelist) and 82 // have no permanent association to a SpaceManager. 83 84 // +--------------+ <- end --+ --+ 85 // | | | | 86 // | | | free | 87 // | | | | 88 // | | | | size | capacity 89 // | | | | 90 // | | <- top -- + | 91 // | | | | 92 // | | | used | 93 // | | | | 94 // | | | | 95 // +--------------+ <- bottom --+ --+ 96 97 class Metachunk : public Metabase<Metachunk> { 98 friend class TestMetachunk; 99 // The VirtualSpaceNode containing this chunk. 100 VirtualSpaceNode* _container; 101 102 // Current allocation top. 103 MetaWord* _top; 104 105 DEBUG_ONLY(bool _is_tagged_free;) 106 107 MetaWord* initial_top() const { return (MetaWord*)this + overhead(); } 108 MetaWord* top() const { return _top; } 109 110 public: 111 // Metachunks are allocated out of a MetadataVirtualSpace and 112 // and use some of its space to describe itself (plus alignment 113 // considerations). Metadata is allocated in the rest of the chunk. 114 // This size is the overhead of maintaining the Metachunk within 115 // the space. 116 117 // Alignment of each allocation in the chunks. 118 static size_t object_alignment(); 119 120 // Size of the Metachunk header, including alignment. 121 static size_t overhead(); 122 123 Metachunk(size_t word_size , VirtualSpaceNode* container); 124 125 MetaWord* allocate(size_t word_size); 126 127 VirtualSpaceNode* container() const { return _container; } 128 129 MetaWord* bottom() const { return (MetaWord*) this; } 130 131 // Reset top to bottom so chunk can be reused. 132 void reset_empty() { _top = initial_top(); clear_next(); clear_prev(); } 133 bool is_empty() { return _top == initial_top(); } 134 135 // used (has been allocated) 136 // free (available for future allocations) 137 size_t word_size() const { return size(); } 138 size_t used_word_size() const; 139 size_t free_word_size() const; 140 141 #ifdef ASSERT 142 bool is_tagged_free() { return _is_tagged_free; } 143 void set_is_tagged_free(bool v) { _is_tagged_free = v; } 144 #endif 145 146 bool contains(const void* ptr) { return bottom() <= ptr && ptr < _top; } 147 148 NOT_PRODUCT(void mangle();) 149 150 void print_on(outputStream* st) const; 151 void verify(); 152 }; 153 154 // Metablock is the unit of allocation from a Chunk. 155 // 156 // A Metablock may be reused by its SpaceManager but are never moved between 157 // SpaceManagers. There is no explicit link to the Metachunk 158 // from which it was allocated. Metablock may be deallocated and 159 // put on a freelist but the space is never freed, rather 160 // the Metachunk it is a part of will be deallocated when it's 161 // associated class loader is collected. 162 163 class Metablock : public Metabase<Metablock> { 164 friend class VMStructs; 165 public: 166 Metablock(size_t word_size) : Metabase<Metablock>(word_size) {} 167 }; 168 169 #endif // SHARE_VM_MEMORY_METACHUNK_HPP