1 /* 2 * Copyright (c) 1997, 2012, 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 25 #ifndef SHARE_VM_MEMORY_HEAP_HPP 26 #define SHARE_VM_MEMORY_HEAP_HPP 27 28 #include "memory/allocation.hpp" 29 #include "runtime/virtualspace.hpp" 30 31 // Blocks 32 33 class HeapBlock VALUE_OBJ_CLASS_SPEC { 34 friend class VMStructs; 35 36 public: 37 struct Header { 38 size_t _length; // the length in segments 39 bool _used; // Used bit 40 }; 41 42 protected: 43 union { 44 Header _header; 45 int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ]; 46 // pad to 0 mod 8 47 }; 48 49 public: 50 // Initialization 51 void initialize(size_t length) { _header._length = length; set_used(); } 52 53 // Accessors 54 void* allocated_space() const { return (void*)(this + 1); } 55 size_t length() const { return _header._length; } 56 57 // Used/free 58 void set_used() { _header._used = true; } 59 void set_free() { _header._used = false; } 60 bool free() { return !_header._used; } 61 }; 62 63 class FreeBlock: public HeapBlock { 64 friend class VMStructs; 65 protected: 66 FreeBlock* _link; 67 68 public: 69 // Initialization 70 void initialize(size_t length) { HeapBlock::initialize(length); _link= NULL; } 71 72 // Merging 73 void set_length(size_t l) { _header._length = l; } 74 75 // Accessors 76 FreeBlock* link() const { return _link; } 77 void set_link(FreeBlock* link) { _link = link; } 78 }; 79 80 class CodeHeap : public CHeapObj<mtCode> { 81 friend class VMStructs; 82 private: 83 VirtualSpace _memory; // the memory holding the blocks 84 VirtualSpace _segmap; // the memory holding the segment map 85 86 size_t _number_of_committed_segments; 87 size_t _number_of_reserved_segments; 88 size_t _segment_size; 89 int _log2_segment_size; 90 91 size_t _next_segment; 92 93 FreeBlock* _freelist; 94 size_t _freelist_segments; // No. of segments in freelist 95 96 // Helper functions 97 size_t size_to_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; } 98 size_t segments_to_size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; } 99 100 size_t segment_for(void* p) const { return ((char*)p - _memory.low()) >> _log2_segment_size; } 101 HeapBlock* block_at(size_t i) const { return (HeapBlock*)(_memory.low() + (i << _log2_segment_size)); } 102 103 void mark_segmap_as_free(size_t beg, size_t end); 104 void mark_segmap_as_used(size_t beg, size_t end); 105 106 // Freelist management helpers 107 FreeBlock* following_block(FreeBlock *b); 108 void insert_after(FreeBlock* a, FreeBlock* b); 109 void merge_right (FreeBlock* a); 110 111 // Toplevel freelist management 112 void add_to_freelist(HeapBlock *b); 113 FreeBlock* search_freelist(size_t length, bool is_critical); 114 115 // Iteration helpers 116 void* next_free(HeapBlock* b) const; 117 HeapBlock* first_block() const; 118 HeapBlock* next_block(HeapBlock* b) const; 119 HeapBlock* block_start(void* p) const; 120 121 // to perform additional actions on creation of executable code 122 void on_code_mapping(char* base, size_t size); 123 124 public: 125 CodeHeap(); 126 127 // Heap extents 128 bool reserve(size_t reserved_size, size_t committed_size, size_t segment_size); 129 void release(); // releases all allocated memory 130 bool expand_by(size_t size); // expands commited memory by size 131 void shrink_by(size_t size); // shrinks commited memory by size 132 void clear(); // clears all heap contents 133 134 // Memory allocation 135 void* allocate (size_t size, bool is_critical); // allocates a block of size or returns NULL 136 void deallocate(void* p); // deallocates a block 137 138 // Attributes 139 char* low_boundary() const { return _memory.low_boundary (); } 140 char* high() const { return _memory.high(); } 141 char* high_boundary() const { return _memory.high_boundary(); } 142 143 bool contains(const void* p) const { return low_boundary() <= p && p < high(); } 144 void* find_start(void* p) const; // returns the block containing p or NULL 145 size_t alignment_unit() const; // alignment of any block 146 size_t alignment_offset() const; // offset of first byte of any block, within the enclosing alignment unit 147 static size_t header_size(); // returns the header size for each heap block 148 149 // Iteration 150 151 // returns the first block or NULL 152 void* first() const { return next_free(first_block()); } 153 // returns the next block given a block p or NULL 154 void* next(void* p) const { return next_free(next_block(block_start(p))); } 155 156 // Statistics 157 size_t capacity() const; 158 size_t max_capacity() const; 159 size_t allocated_capacity() const; 160 size_t unallocated_capacity() const { return max_capacity() - allocated_capacity(); } 161 162 private: 163 size_t heap_unallocated_capacity() const; 164 165 public: 166 // Debugging 167 void verify(); 168 void print() PRODUCT_RETURN; 169 }; 170 171 #endif // SHARE_VM_MEMORY_HEAP_HPP