Sat, 23 Nov 2013 12:25:13 +0100
8028128: Add a type safe alternative for working with counter based data
Reviewed-by: dholmes, egahlin
1 /*
2 * Copyright (c) 2003, 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
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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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_ADJOININGVIRTUALSPACES_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_ADJOININGVIRTUALSPACES_HPP
28 #include "gc_implementation/parallelScavenge/psVirtualspace.hpp"
31 // Contains two virtual spaces that each can individually span
32 // most of the reserved region but committed parts of which
33 // cannot overlap.
34 //
35 // +-------+ <--- high_boundary for H
36 // | |
37 // | H |
38 // | |
39 // | |
40 // | |
41 // --------- <--- low for H
42 // | |
43 // ========= <--- low_boundary for H, high_boundary for L
44 // | |
45 // | |
46 // | |
47 // --------- <--- high for L
48 // | |
49 // | L |
50 // | |
51 // | |
52 // | |
53 // +-------+ <--- low_boundary for L
54 //
55 // Each virtual space in the AdjoiningVirtualSpaces grows and shrink
56 // within its reserved region (between the low_boundary and the
57 // boundary) independently. If L want to grow above its high_boundary,
58 // then the high_boundary of L and the low_boundary of H must be
59 // moved up consistently. AdjoiningVirtualSpaces provide the
60 // interfaces for moving the this boundary.
62 class AdjoiningVirtualSpaces {
63 // space at the high end and the low end, respectively
64 PSVirtualSpace* _high;
65 PSVirtualSpace* _low;
67 // The reserved space spanned by the two spaces.
68 ReservedSpace _reserved_space;
70 // The minimum byte size for the low space. It will not
71 // be shrunk below this value.
72 size_t _min_low_byte_size;
73 // Same for the high space
74 size_t _min_high_byte_size;
76 const size_t _alignment;
78 public:
79 // Allocates two virtual spaces that will be located at the
80 // high and low ends. Does no initialization.
81 AdjoiningVirtualSpaces(ReservedSpace rs,
82 size_t min_low_byte_size,
83 size_t min_high_byte_size,
84 size_t alignment);
86 // accessors
87 PSVirtualSpace* high() { return _high; }
88 PSVirtualSpace* low() { return _low; }
89 ReservedSpace reserved_space() { return _reserved_space; }
90 size_t min_low_byte_size() { return _min_low_byte_size; }
91 size_t min_high_byte_size() { return _min_high_byte_size; }
92 size_t alignment() const { return _alignment; }
94 // move boundary between the two spaces up
95 bool adjust_boundary_up(size_t size_in_bytes);
96 // and down
97 bool adjust_boundary_down(size_t size_in_bytes);
99 // Maximum byte size for the high space.
100 size_t high_byte_size_limit() {
101 return _reserved_space.size() - _min_low_byte_size;
102 }
103 // Maximum byte size for the low space.
104 size_t low_byte_size_limit() {
105 return _reserved_space.size() - _min_high_byte_size;
106 }
108 // Sets the boundaries for the virtual spaces and commits and
109 // initial size;
110 void initialize(size_t max_low_byte_size,
111 size_t init_low_byte_size,
112 size_t init_high_byte_size);
113 };
115 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_ADJOININGVIRTUALSPACES_HPP