memRegion.hpp revision 0:a61af66fc99e 
1/*
2 * Copyright 2000-2004 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
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23 */
24
25// A very simple data structure representing a contigous region
26// region of address space.
27
28// Note that MemRegions are passed by value, not by reference.
29// The intent is that they remain very small and contain no
30// objects.
31
32class MemRegion VALUE_OBJ_CLASS_SPEC {
33  friend class VMStructs;
34private:
35  HeapWord* _start;
36  size_t    _word_size;
37
38public:
39  MemRegion() : _start(NULL), _word_size(0) {};
40  MemRegion(HeapWord* start, size_t word_size) :
41    _start(start), _word_size(word_size) {};
42  MemRegion(HeapWord* start, HeapWord* end) :
43    _start(start), _word_size(pointer_delta(end, start)) {
44    assert(end >= start, "incorrect constructor arguments");
45  }
46
47  MemRegion(const MemRegion& mr): _start(mr._start), _word_size(mr._word_size) {}
48
49  MemRegion intersection(const MemRegion mr2) const;
50  // regions must overlap or be adjacent
51  MemRegion _union(const MemRegion mr2) const;
52  // minus will fail a guarantee if mr2 is interior to this,
53  // since there's no way to return 2 disjoint regions.
54  MemRegion minus(const MemRegion mr2) const;
55
56  HeapWord* start() const { return _start; }
57  HeapWord* end() const   { return _start + _word_size; }
58  HeapWord* last() const  { return _start + _word_size - 1; }
59
60  void set_start(HeapWord* start) { _start = start; }
61  void set_end(HeapWord* end)     { _word_size = pointer_delta(end, _start); }
62  void set_word_size(size_t word_size) {
63    _word_size = word_size;
64  }
65
66  bool contains(const MemRegion mr2) const {
67    return _start <= mr2._start && end() >= mr2.end();
68  }
69  bool contains(const void* addr) const {
70    return addr >= (void*)_start && addr < (void*)end();
71  }
72  bool equals(const MemRegion mr2) const {
73    // first disjunct since we do not have a canonical empty set
74    return ((is_empty() && mr2.is_empty()) ||
75            (start() == mr2.start() && end() == mr2.end()));
76  }
77
78  size_t byte_size() const { return _word_size * sizeof(HeapWord); }
79  size_t word_size() const { return _word_size; }
80
81  bool is_empty() const { return word_size() == 0; }
82};
83
84// For iteration over MemRegion's.
85
86class MemRegionClosure : public StackObj {
87public:
88  virtual void do_MemRegion(MemRegion mr) = 0;
89};
90
91// A ResourceObj version of MemRegionClosure
92
93class MemRegionClosureRO: public MemRegionClosure {
94public:
95  void* operator new(size_t size, ResourceObj::allocation_type type) {
96        return ResourceObj::operator new(size, type);
97  }
98  void* operator new(size_t size, Arena *arena) {
99        return ResourceObj::operator new(size, arena);
100  }
101  void* operator new(size_t size) {
102        return ResourceObj::operator new(size);
103  }
104
105  void  operator delete(void* p) {} // nothing to do
106};
107