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comparison src/share/vm/memory/metachunk.hpp @ 6885:685df3c6f84b

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7045397: NPG: Add freelists to class loader arenas. Reviewed-by: coleenp, stefank, jprovino, ohair
author jmasa
date Tue, 18 Sep 2012 23:35:42 -0700
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children 90273fc0a981
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6877:d0e7716b179e 6885:685df3c6f84b
1 /*
2 * Copyright (c) 2012, 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 #ifndef SHARE_VM_MEMORY_METACHUNK_HPP
25 #define SHARE_VM_MEMORY_METACHUNK_HPP
26
27 // Metachunk - Quantum of allocation from a Virtualspace
28 // Metachunks are reused (when freed are put on a global freelist) and
29 // have no permanent association to a SpaceManager.
30
31 // +--------------+ <- end
32 // | | --+ ---+
33 // | | | free |
34 // | | | |
35 // | | | | capacity
36 // | | | |
37 // | | <- top --+ |
38 // | | ---+ |
39 // | | | used |
40 // | | | |
41 // | | | |
42 // +--------------+ <- bottom ---+ ---+
43
44 class Metachunk VALUE_OBJ_CLASS_SPEC {
45 // link to support lists of chunks
46 Metachunk* _next;
47 Metachunk* _prev;
48
49 MetaWord* _bottom;
50 MetaWord* _end;
51 MetaWord* _top;
52 size_t _word_size;
53 // Used in a guarantee() so included in the Product builds
54 // even through it is only for debugging.
55 bool _is_free;
56
57 // Metachunks are allocated out of a MetadataVirtualSpace and
58 // and use some of its space to describe itself (plus alignment
59 // considerations). Metadata is allocated in the rest of the chunk.
60 // This size is the overhead of maintaining the Metachunk within
61 // the space.
62 static size_t _overhead;
63
64 void set_bottom(MetaWord* v) { _bottom = v; }
65 void set_end(MetaWord* v) { _end = v; }
66 void set_top(MetaWord* v) { _top = v; }
67 void set_word_size(size_t v) { _word_size = v; }
68 public:
69 #ifdef ASSERT
70 Metachunk() : _bottom(NULL), _end(NULL), _top(NULL), _is_free(false) {}
71 #else
72 Metachunk() : _bottom(NULL), _end(NULL), _top(NULL) {}
73 #endif
74
75 // Used to add a Metachunk to a list of Metachunks
76 void set_next(Metachunk* v) { _next = v; assert(v != this, "Boom");}
77 void set_prev(Metachunk* v) { _prev = v; assert(v != this, "Boom");}
78
79 MetaWord* allocate(size_t word_size);
80 static Metachunk* initialize(MetaWord* ptr, size_t word_size);
81
82 // Accessors
83 Metachunk* next() const { return _next; }
84 Metachunk* prev() const { return _prev; }
85 MetaWord* bottom() const { return _bottom; }
86 MetaWord* end() const { return _end; }
87 MetaWord* top() const { return _top; }
88 size_t word_size() const { return _word_size; }
89 size_t size() const volatile { return _word_size; }
90 void set_size(size_t v) { _word_size = v; }
91 bool is_free() { return _is_free; }
92 void set_is_free(bool v) { _is_free = v; }
93 static size_t overhead() { return _overhead; }
94 void clear_next() { set_next(NULL); }
95 void link_prev(Metachunk* ptr) { set_prev(ptr); }
96 uintptr_t* end() { return ((uintptr_t*) this) + size(); }
97 bool cantCoalesce() const { return false; }
98 void link_next(Metachunk* ptr) { set_next(ptr); }
99 void link_after(Metachunk* ptr){
100 link_next(ptr);
101 if (ptr != NULL) ptr->link_prev(this);
102 }
103
104 // Reset top to bottom so chunk can be reused.
105 void reset_empty() { _top = (_bottom + _overhead); }
106 bool is_empty() { return _top == (_bottom + _overhead); }
107
108 // used (has been allocated)
109 // free (available for future allocations)
110 // capacity (total size of chunk)
111 size_t used_word_size();
112 size_t free_word_size();
113 size_t capacity_word_size();
114
115 // Debug support
116 #ifdef ASSERT
117 void* prev_addr() const { return (void*)&_prev; }
118 void* next_addr() const { return (void*)&_next; }
119 void* size_addr() const { return (void*)&_word_size; }
120 #endif
121 bool verify_chunk_in_free_list(Metachunk* tc) const { return true; }
122 bool verify_par_locked() { return true; }
123
124 void assert_is_mangled() const {/* Don't check "\*/}
125
126 #ifdef ASSERT
127 void mangle();
128 #endif // ASSERT
129
130 void print_on(outputStream* st) const;
131 void verify();
132 };
133 #endif // SHARE_VM_MEMORY_METACHUNK_HPP