1 /* 2 * Copyright (c) 2000, 2010, 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_MEMREGION_HPP 26 #define SHARE_VM_MEMORY_MEMREGION_HPP 27 28 #include "memory/allocation.hpp" 29 #include "utilities/debug.hpp" 30 #include "utilities/globalDefinitions.hpp" 31 32 // A very simple data structure representing a contigous region 33 // region of address space. 34 35 // Note that MemRegions are passed by value, not by reference. 36 // The intent is that they remain very small and contain no 37 // objects. 38 39 class MemRegion VALUE_OBJ_CLASS_SPEC { 40 friend class VMStructs; 41 private: 42 HeapWord* _start; 43 size_t _word_size; 44 45 public: 46 MemRegion() : _start(NULL), _word_size(0) {}; 47 MemRegion(HeapWord* start, size_t word_size) : 48 _start(start), _word_size(word_size) {}; 49 MemRegion(HeapWord* start, HeapWord* end) : 50 _start(start), _word_size(pointer_delta(end, start)) { 51 assert(end >= start, "incorrect constructor arguments"); 52 } 53 54 MemRegion(const MemRegion& mr): _start(mr._start), _word_size(mr._word_size) {} 55 56 MemRegion intersection(const MemRegion mr2) const; 57 // regions must overlap or be adjacent 58 MemRegion _union(const MemRegion mr2) const; 59 // minus will fail a guarantee if mr2 is interior to this, 60 // since there's no way to return 2 disjoint regions. 61 MemRegion minus(const MemRegion mr2) const; 62 63 HeapWord* start() const { return _start; } 64 HeapWord* end() const { return _start + _word_size; } 65 HeapWord* last() const { return _start + _word_size - 1; } 66 67 void set_start(HeapWord* start) { _start = start; } 68 void set_end(HeapWord* end) { _word_size = pointer_delta(end, _start); } 69 void set_word_size(size_t word_size) { 70 _word_size = word_size; 71 } 72 73 bool contains(const MemRegion mr2) const { 74 return _start <= mr2._start && end() >= mr2.end(); 75 } 76 bool contains(const void* addr) const { 77 return addr >= (void*)_start && addr < (void*)end(); 78 } 79 bool equals(const MemRegion mr2) const { 80 // first disjunct since we do not have a canonical empty set 81 return ((is_empty() && mr2.is_empty()) || 82 (start() == mr2.start() && end() == mr2.end())); 83 } 84 85 size_t byte_size() const { return _word_size * sizeof(HeapWord); } 86 size_t word_size() const { return _word_size; } 87 88 bool is_empty() const { return word_size() == 0; } 89 }; 90 91 // For iteration over MemRegion's. 92 93 class MemRegionClosure : public StackObj { 94 public: 95 virtual void do_MemRegion(MemRegion mr) = 0; 96 }; 97 98 // A ResourceObj version of MemRegionClosure 99 100 class MemRegionClosureRO: public MemRegionClosure { 101 public: 102 void* operator new(size_t size, ResourceObj::allocation_type type) { 103 return ResourceObj::operator new(size, type); 104 } 105 void* operator new(size_t size, Arena *arena) { 106 return ResourceObj::operator new(size, arena); 107 } 108 void* operator new(size_t size) { 109 return ResourceObj::operator new(size); 110 } 111 112 void operator delete(void* p) {} // nothing to do 113 }; 114 115 #endif // SHARE_VM_MEMORY_MEMREGION_HPP