1 /*
2 * Copyright (c) 2012, 2019, 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 */
24 #ifndef SHARE_MEMORY_METASPACE_METACHUNK_HPP
25 #define SHARE_MEMORY_METASPACE_METACHUNK_HPP
26
27 #include "memory/metaspace/metabase.hpp"
28 #include "memory/metaspace/metaspaceCommon.hpp"
29 #include "utilities/debug.hpp"
30 #include "utilities/globalDefinitions.hpp"
31
32 class MetachunkTest;
33
34 namespace metaspace {
35
36 class VirtualSpaceNode;
37
38 // Metachunk - Quantum of allocation from a Virtualspace
39 // Metachunks are reused (when freed are put on a global freelist) and
40 // have no permanent association to a SpaceManager.
41
42 // +--------------+ <- end --+ --+
43 // | | | |
44 // | | | free |
45 // | | | |
46 // | | | | size | capacity
47 // | | | |
48 // | | <- top -- + |
49 // | | | |
50 // | | | used |
51 // | | | |
52 // | | | |
53 // +--------------+ <- bottom --+ --+
54
55 enum ChunkOrigin {
56 // Chunk normally born (via take_from_committed)
57 origin_normal = 1,
58 // Chunk was born as padding chunk
59 origin_pad = 2,
60 // Chunk was born as leftover chunk in VirtualSpaceNode::retire
61 origin_leftover = 3,
62 // Chunk was born as result of a merge of smaller chunks
63 origin_merge = 4,
64 // Chunk was born as result of a split of a larger chunk
65 origin_split = 5,
66
67 origin_minimum = origin_normal,
68 origin_maximum = origin_split,
69 origins_count = origin_maximum + 1
70 };
71
is_valid_chunkorigin(ChunkOrigin origin)72 inline bool is_valid_chunkorigin(ChunkOrigin origin) {
73 return origin == origin_normal ||
74 origin == origin_pad ||
75 origin == origin_leftover ||
76 origin == origin_merge ||
77 origin == origin_split;
78 }
79
80 class Metachunk : public Metabase<Metachunk> {
81
82 friend class ::MetachunkTest;
83
84 // The VirtualSpaceNode containing this chunk.
85 VirtualSpaceNode* const _container;
86
87 // Current allocation top.
88 MetaWord* _top;
89
90 // A 32bit sentinel for debugging purposes.
91 enum { CHUNK_SENTINEL = 0x4d4554EF, // "MET"
92 CHUNK_SENTINEL_INVALID = 0xFEEEEEEF
93 };
94
95 uint32_t _sentinel;
96
97 const ChunkIndex _chunk_type;
98 const bool _is_class;
99 // Whether the chunk is free (in freelist) or in use by some class loader.
100 bool _is_tagged_free;
101
102 ChunkOrigin _origin;
103 int _use_count;
104
initial_top() const105 MetaWord* initial_top() const { return (MetaWord*)this + overhead(); }
top() const106 MetaWord* top() const { return _top; }
107
108 public:
109 // Metachunks are allocated out of a MetadataVirtualSpace and
110 // and use some of its space to describe itself (plus alignment
111 // considerations). Metadata is allocated in the rest of the chunk.
112 // This size is the overhead of maintaining the Metachunk within
113 // the space.
114
115 // Alignment of each allocation in the chunks.
116 static size_t object_alignment();
117
118 // Size of the Metachunk header, in words, including alignment.
119 static size_t overhead();
120
121 Metachunk(ChunkIndex chunktype, bool is_class, size_t word_size, VirtualSpaceNode* container);
122
123 MetaWord* allocate(size_t word_size);
124
container() const125 VirtualSpaceNode* container() const { return _container; }
126
bottom() const127 MetaWord* bottom() const { return (MetaWord*) this; }
128
129 // Reset top to bottom so chunk can be reused.
reset_empty()130 void reset_empty() { _top = initial_top(); clear_next(); clear_prev(); }
is_empty()131 bool is_empty() { return _top == initial_top(); }
132
133 // used (has been allocated)
134 // free (available for future allocations)
word_size() const135 size_t word_size() const { return size(); }
136 size_t used_word_size() const;
137 size_t free_word_size() const;
138
is_tagged_free()139 bool is_tagged_free() { return _is_tagged_free; }
set_is_tagged_free(bool v)140 void set_is_tagged_free(bool v) { _is_tagged_free = v; }
141
contains(const void * ptr)142 bool contains(const void* ptr) { return bottom() <= ptr && ptr < _top; }
143
144 void print_on(outputStream* st) const;
145
is_valid_sentinel() const146 bool is_valid_sentinel() const { return _sentinel == CHUNK_SENTINEL; }
remove_sentinel()147 void remove_sentinel() { _sentinel = CHUNK_SENTINEL_INVALID; }
148
get_use_count() const149 int get_use_count() const { return _use_count; }
inc_use_count()150 void inc_use_count() { _use_count ++; }
151
get_origin() const152 ChunkOrigin get_origin() const { return _origin; }
set_origin(ChunkOrigin orig)153 void set_origin(ChunkOrigin orig) { _origin = orig; }
154
get_chunk_type() const155 ChunkIndex get_chunk_type() const { return _chunk_type; }
is_class() const156 bool is_class() const { return _is_class; }
157
158 DEBUG_ONLY(void mangle(juint word_value);)
159 DEBUG_ONLY(void verify() const;)
160
161 };
162
163
164 // Helper function that does a bunch of checks for a chunk.
165 DEBUG_ONLY(void do_verify_chunk(Metachunk* chunk);)
166
167 // Given a Metachunk, update its in-use information (both in the
168 // chunk and the occupancy map).
169 void do_update_in_use_info_for_chunk(Metachunk* chunk, bool inuse);
170
171 } // namespace metaspace
172
173 #endif // SHARE_MEMORY_METASPACE_METACHUNK_HPP
174