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comparison src/share/vm/gc_implementation/parallelScavenge/adjoiningVirtualSpaces.hpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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1 /*
2 * Copyright 2003 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
21 * have any questions.
22 *
23 */
24
25
26 // Contains two virtual spaces that each can individually span
27 // most of the reserved region but committed parts of which
28 // cannot overlap.
29 //
30 // +-------+ <--- high_boundary for H
31 // | |
32 // | H |
33 // | |
34 // | |
35 // | |
36 // --------- <--- low for H
37 // | |
38 // ========= <--- low_boundary for H, high_boundary for L
39 // | |
40 // | |
41 // | |
42 // --------- <--- high for L
43 // | |
44 // | L |
45 // | |
46 // | |
47 // | |
48 // +-------+ <--- low_boundary for L
49 //
50 // Each virtual space in the AdjoiningVirtualSpaces grows and shrink
51 // within its reserved region (between the low_boundary and the
52 // boundary) independently. If L want to grow above its high_boundary,
53 // then the high_boundary of L and the low_boundary of H must be
54 // moved up consistently. AdjoiningVirtualSpaces provide the
55 // interfaces for moving the this boundary.
56
57 class AdjoiningVirtualSpaces {
58 // space at the high end and the low end, respectively
59 PSVirtualSpace* _high;
60 PSVirtualSpace* _low;
61
62 // The reserved space spanned by the two spaces.
63 ReservedSpace _reserved_space;
64
65 // The minimum byte size for the low space. It will not
66 // be shrunk below this value.
67 size_t _min_low_byte_size;
68 // Same for the high space
69 size_t _min_high_byte_size;
70
71 const size_t _alignment;
72
73 public:
74 // Allocates two virtual spaces that will be located at the
75 // high and low ends. Does no initialization.
76 AdjoiningVirtualSpaces(ReservedSpace rs,
77 size_t min_low_byte_size,
78 size_t min_high_byte_size,
79 size_t alignment);
80
81 // accessors
82 PSVirtualSpace* high() { return _high; }
83 PSVirtualSpace* low() { return _low; }
84 ReservedSpace reserved_space() { return _reserved_space; }
85 size_t min_low_byte_size() { return _min_low_byte_size; }
86 size_t min_high_byte_size() { return _min_high_byte_size; }
87 size_t alignment() const { return _alignment; }
88
89 // move boundary between the two spaces up
90 bool adjust_boundary_up(size_t size_in_bytes);
91 // and down
92 bool adjust_boundary_down(size_t size_in_bytes);
93
94 // Maximum byte size for the high space.
95 size_t high_byte_size_limit() {
96 return _reserved_space.size() - _min_low_byte_size;
97 }
98 // Maximum byte size for the low space.
99 size_t low_byte_size_limit() {
100 return _reserved_space.size() - _min_high_byte_size;
101 }
102
103 // Sets the boundaries for the virtual spaces and commits and
104 // initial size;
105 void initialize(size_t max_low_byte_size,
106 size_t init_low_byte_size,
107 size_t init_high_byte_size);
108 };