1 /*
2 * Copyright (c) 2012, 2018, 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_VM_MEMORY_METACHUNK_HPP
25 #define SHARE_VM_MEMORY_METACHUNK_HPP
26
27 #include "memory/allocation.hpp"
28 #include "utilities/debug.hpp"
29 #include "utilities/globalDefinitions.hpp"
30
31 class VirtualSpaceNode;
32
33 // Super class of Metablock and Metachunk to allow them to
34 // be put on the FreeList and in the BinaryTreeDictionary.
35 template <class T>
36 class Metabase {
37 size_t _word_size;
38 T* _next;
39 T* _prev;
40
41 protected:
42 Metabase(size_t word_size) : _word_size(word_size), _next(NULL), _prev(NULL) {}
43
44 public:
45 T* next() const { return _next; }
46 T* prev() const { return _prev; }
47 void set_next(T* v) { _next = v; assert(v != this, "Boom");}
48 void set_prev(T* v) { _prev = v; assert(v != this, "Boom");}
49 void clear_next() { set_next(NULL); }
50 void clear_prev() { set_prev(NULL); }
51
52 size_t size() const volatile { return _word_size; }
53 void set_size(size_t v) { _word_size = v; }
54
55 void link_next(T* ptr) { set_next(ptr); }
56 void link_prev(T* ptr) { set_prev(ptr); }
57 void link_after(T* ptr) {
58 link_next(ptr);
59 if (ptr != NULL) ptr->link_prev((T*)this);
60 }
61
62 uintptr_t* end() const { return ((uintptr_t*) this) + size(); }
63
64 bool cantCoalesce() const { return false; }
65
66 // Debug support
67 #ifdef ASSERT
68 void* prev_addr() const { return (void*)&_prev; }
69 void* next_addr() const { return (void*)&_next; }
70 void* size_addr() const { return (void*)&_word_size; }
71 #endif
72 bool verify_chunk_in_free_list(T* tc) const { return true; }
73 bool verify_par_locked() { return true; }
74
75 void assert_is_mangled() const {/* Don't check "\*/}
76
77 bool is_free() { return true; }
78 };
79
80 // Metachunk - Quantum of allocation from a Virtualspace
81 // Metachunks are reused (when freed are put on a global freelist) and
82 // have no permanent association to a SpaceManager.
83
84 // +--------------+ <- end --+ --+
85 // | | | |
86 // | | | free |
87 // | | | |
88 // | | | | size | capacity
89 // | | | |
90 // | | <- top -- + |
91 // | | | |
92 // | | | used |
93 // | | | |
94 // | | | |
95 // +--------------+ <- bottom --+ --+
96
97 // ChunkIndex defines the type of chunk.
98 // Chunk types differ by size: specialized < small < medium, chunks
99 // larger than medium are humongous chunks of varying size.
100 enum ChunkIndex {
101 ZeroIndex = 0,
102 SpecializedIndex = ZeroIndex,
103 SmallIndex = SpecializedIndex + 1,
104 MediumIndex = SmallIndex + 1,
105 HumongousIndex = MediumIndex + 1,
106 NumberOfFreeLists = 3,
107 NumberOfInUseLists = 4
108 };
109
110 // Utility functions.
111 size_t get_size_for_nonhumongous_chunktype(ChunkIndex chunk_type, bool is_class);
112 ChunkIndex get_chunk_type_by_size(size_t size, bool is_class);
113
114 // Returns a descriptive name for a chunk type.
115 const char* chunk_size_name(ChunkIndex index);
116
117 // Verify chunk type.
118 inline bool is_valid_chunktype(ChunkIndex index) {
119 return index == SpecializedIndex || index == SmallIndex ||
120 index == MediumIndex || index == HumongousIndex;
121 }
122
123 inline bool is_valid_nonhumongous_chunktype(ChunkIndex index) {
124 return is_valid_chunktype(index) && index != HumongousIndex;
125 }
126
127 enum ChunkOrigin {
128 // Chunk normally born (via take_from_committed)
129 origin_normal = 1,
130 // Chunk was born as padding chunk
131 origin_pad = 2,
132 // Chunk was born as leftover chunk in VirtualSpaceNode::retire
133 origin_leftover = 3,
134 // Chunk was born as result of a merge of smaller chunks
135 origin_merge = 4,
136 // Chunk was born as result of a split of a larger chunk
137 origin_split = 5,
138
139 origin_minimum = origin_normal,
140 origin_maximum = origin_split,
141 origins_count = origin_maximum + 1
142 };
143
144 inline bool is_valid_chunkorigin(ChunkOrigin origin) {
145 return origin == origin_normal ||
146 origin == origin_pad ||
147 origin == origin_leftover ||
148 origin == origin_merge ||
149 origin == origin_split;
150 }
151
152 class Metachunk : public Metabase<Metachunk> {
153 friend class MetachunkTest;
154 // The VirtualSpaceNode containing this chunk.
155 VirtualSpaceNode* const _container;
156
157 // Current allocation top.
158 MetaWord* _top;
159
160 // A 32bit sentinel for debugging purposes.
161 enum { CHUNK_SENTINEL = 0x4d4554EF, // "MET"
162 CHUNK_SENTINEL_INVALID = 0xFEEEEEEF
163 };
164
165 uint32_t _sentinel;
166
167 const ChunkIndex _chunk_type;
168 const bool _is_class;
169 // Whether the chunk is free (in freelist) or in use by some class loader.
170 bool _is_tagged_free;
171
172 ChunkOrigin _origin;
173 int _use_count;
174
175 MetaWord* initial_top() const { return (MetaWord*)this + overhead(); }
176 MetaWord* top() const { return _top; }
177
178 public:
179 // Metachunks are allocated out of a MetadataVirtualSpace and
180 // and use some of its space to describe itself (plus alignment
181 // considerations). Metadata is allocated in the rest of the chunk.
182 // This size is the overhead of maintaining the Metachunk within
183 // the space.
184
185 // Alignment of each allocation in the chunks.
186 static size_t object_alignment();
187
188 // Size of the Metachunk header, including alignment.
189 static size_t overhead();
190
191 Metachunk(ChunkIndex chunktype, bool is_class, size_t word_size, VirtualSpaceNode* container);
192
193 MetaWord* allocate(size_t word_size);
194
195 VirtualSpaceNode* container() const { return _container; }
196
197 MetaWord* bottom() const { return (MetaWord*) this; }
198
199 // Reset top to bottom so chunk can be reused.
200 void reset_empty() { _top = initial_top(); clear_next(); clear_prev(); }
201 bool is_empty() { return _top == initial_top(); }
202
203 // used (has been allocated)
204 // free (available for future allocations)
205 size_t word_size() const { return size(); }
206 size_t used_word_size() const;
207 size_t free_word_size() const;
208
209 bool is_tagged_free() { return _is_tagged_free; }
210 void set_is_tagged_free(bool v) { _is_tagged_free = v; }
211
212 bool contains(const void* ptr) { return bottom() <= ptr && ptr < _top; }
213
214 void print_on(outputStream* st) const;
215
216 bool is_valid_sentinel() const { return _sentinel == CHUNK_SENTINEL; }
217 void remove_sentinel() { _sentinel = CHUNK_SENTINEL_INVALID; }
218
219 int get_use_count() const { return _use_count; }
220 void inc_use_count() { _use_count ++; }
221
222 ChunkOrigin get_origin() const { return _origin; }
223 void set_origin(ChunkOrigin orig) { _origin = orig; }
224
225 ChunkIndex get_chunk_type() const { return _chunk_type; }
226 bool is_class() const { return _is_class; }
227
228 DEBUG_ONLY(void mangle(juint word_value);)
229 DEBUG_ONLY(void verify();)
230
231 };
232
233 // Metablock is the unit of allocation from a Chunk.
234 //
235 // A Metablock may be reused by its SpaceManager but are never moved between
236 // SpaceManagers. There is no explicit link to the Metachunk
237 // from which it was allocated. Metablock may be deallocated and
238 // put on a freelist but the space is never freed, rather
239 // the Metachunk it is a part of will be deallocated when it's
240 // associated class loader is collected.
241
242 class Metablock : public Metabase<Metablock> {
243 friend class VMStructs;
244 public:
245 Metablock(size_t word_size) : Metabase<Metablock>(word_size) {}
246 };
247
248 #endif // SHARE_VM_MEMORY_METACHUNK_HPP