Wed, 18 Jan 2012 09:50:16 -0800
7129514: time warp warnings after 7117303
Summary: Replace calls to os::javaTimeMillis() that are used to update the milliseconds since the last GC to an equivalent that uses a monotonically non-decreasing time source.
Reviewed-by: ysr, jmasa
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.
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23 */
25 #ifndef SHARE_VM_MEMORY_MEMREGION_HPP
26 #define SHARE_VM_MEMORY_MEMREGION_HPP
28 #include "memory/allocation.hpp"
29 #include "utilities/debug.hpp"
30 #include "utilities/globalDefinitions.hpp"
32 // A very simple data structure representing a contigous region
33 // region of address space.
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.
39 class MemRegion VALUE_OBJ_CLASS_SPEC {
40 friend class VMStructs;
41 private:
42 HeapWord* _start;
43 size_t _word_size;
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 }
54 MemRegion(const MemRegion& mr): _start(mr._start), _word_size(mr._word_size) {}
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;
63 HeapWord* start() const { return _start; }
64 HeapWord* end() const { return _start + _word_size; }
65 HeapWord* last() const { return _start + _word_size - 1; }
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 }
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 }
85 size_t byte_size() const { return _word_size * sizeof(HeapWord); }
86 size_t word_size() const { return _word_size; }
88 bool is_empty() const { return word_size() == 0; }
89 };
91 // For iteration over MemRegion's.
93 class MemRegionClosure : public StackObj {
94 public:
95 virtual void do_MemRegion(MemRegion mr) = 0;
96 };
98 // A ResourceObj version of MemRegionClosure
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 }
112 void operator delete(void* p) {} // nothing to do
113 };
115 #endif // SHARE_VM_MEMORY_MEMREGION_HPP