1 /*
2 * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2020 SAP SE. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
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24 */
25
26 #ifndef SHARE_MEMORY_METASPACE_METASPACEARENA_HPP
27 #define SHARE_MEMORY_METASPACE_METASPACEARENA_HPP
28
29 #include "memory/allocation.hpp"
30 #include "memory/metaspace.hpp"
31 #include "memory/metaspace/chunkManager.hpp"
32 #include "memory/metaspace/counters.hpp"
33 #include "memory/metaspace/metachunk.hpp"
34 #include "memory/metaspace/metachunkList.hpp"
35 #include "memory/metaspace/metaspaceCommon.hpp"
36
37 class outputStream;
38 class Mutex;
39
40 namespace metaspace {
41
42 class ArenaGrowthPolicy;
43 class FreeBlocks;
44
45 struct ArenaStats;
46
47 // The MetaspaceArena is a growable metaspace memory pool belonging to a CLD;
48 // internally it consists of a list of metaspace chunks, of which the head chunk
49 // is the current chunk from which we allocate via pointer bump.
50 //
51 // +---------------+
52 // | Arena |
53 // +---------------+
54 // |
55 // | _chunks commit top
56 // | v
57 // +----------+ +----------+ +----------+ +----------+
58 // | retired | ---> | retired | ---> | retired | ---> | current |
59 // | chunk | | chunk | | chunk | | chunk |
60 // +----------+ +----------+ +----------+ +----------+
61 // ^
62 // used top
63 //
64 // +------------+
65 // | FreeBlocks | --> O -> O -> O -> O
66 // +------------+
67 //
68 //
69
70 // When the current chunk is used up, MetaspaceArena requestes a new chunk from
71 // the associated ChunkManager.
72 //
73 // MetaspaceArena also keeps a FreeBlocks structure to manage memory blocks which
74 // had been deallocated prematurely.
75 //
76
77 class MetaspaceArena : public CHeapObj<mtClass> {
78
79 // Reference to an outside lock to use for synchronizing access to this arena.
80 // This lock is normally owned by the CLD which owns the ClassLoaderMetaspace which
81 // owns this arena.
82 // Todo: This should be changed. Either the CLD should synchronize access to the
83 // CLMS and its arenas itself, or the arena should have an own lock. The latter
84 // would allow for more fine granular locking since it would allow access to
85 // both class- and non-class arena in the CLMS independently.
86 Mutex* const _lock;
87
88 // Reference to the chunk manager to allocate chunks from.
89 ChunkManager* const _chunk_manager;
90
91 // Reference to the growth policy to use.
92 const ArenaGrowthPolicy* const _growth_policy;
93
94 // List of chunks. Head of the list is the current chunk.
95 MetachunkList _chunks;
96
97 // Alignment alignment, in words.
98 const int _alignment_words;
99
100 // Structure to take care of leftover/deallocated space in used chunks.
101 // Owned by the Arena. Gets allocated on demand only.
102 FreeBlocks* _fbl;
103
104 Metachunk* current_chunk() { return _chunks.first(); }
105 const Metachunk* current_chunk() const { return _chunks.first(); }
106
107 // Reference to an outside counter to keep track of used space.
108 SizeAtomicCounter* const _total_used_words_counter;
109
110 // A name for purely debugging/logging purposes.
111 const char* const _name;
112
113 #ifdef ASSERT
114 // Allocation guards: When active, arena allocations are interleaved with
115 // fence allocations. An overwritten fence indicates a buffer overrun in either
116 // the preceding or the following user block. All fences are linked together;
117 // validating the fences just means walking that linked list.
118 // Note that for the Arena, fence blocks are just another form of user blocks.
119 class Fence {
120 static const uintx EyeCatcher =
121 NOT_LP64(0x77698465) LP64_ONLY(0x7769846577698465ULL); // "META" resp "METAMETA"
122 // Two eyecatchers to easily spot a corrupted _next pointer
123 const uintx _eye1;
124 const Fence* const _next;
125 const uintx _eye2;
126 public:
127 Fence(const Fence* next) : _eye1(EyeCatcher), _next(next), _eye2(EyeCatcher) {}
128 const Fence* next() const { return _next; }
129 void verify() const;
130 };
131 const Fence* _first_fence;
132 #endif // ASSERT
133
134 Mutex* lock() const { return _lock; }
135 ChunkManager* chunk_manager() const { return _chunk_manager; }
136
137 // free block list
138 FreeBlocks* fbl() const { return _fbl; }
139 void add_allocation_to_fbl(MetaWord* p, size_t word_size);
140
141 // Given a chunk, add its remaining free committed space to the free block list.
142 void salvage_chunk(Metachunk* c);
143
144 // Allocate a new chunk from the underlying chunk manager able to hold at least
145 // requested word size.
146 Metachunk* allocate_new_chunk(size_t requested_word_size);
147
148 // Returns the level of the next chunk to be added, acc to growth policy.
149 chunklevel_t next_chunk_level() const;
150
151 // Attempt to enlarge the current chunk to make it large enough to hold at least
152 // requested_word_size additional words.
153 //
154 // On success, true is returned, false otherwise.
155 bool attempt_enlarge_current_chunk(size_t requested_word_size);
156
157 // Prematurely returns a metaspace allocation to the _block_freelists
158 // because it is not needed anymore (requires CLD lock to be active).
159 void deallocate_locked(MetaWord* p, size_t word_size);
160
161 // Returns true if the area indicated by pointer and size have actually been allocated
162 // from this arena.
163 DEBUG_ONLY(bool is_valid_area(MetaWord* p, size_t word_size) const;)
164
165 // Allocate from the arena proper, once dictionary allocations and fencing are sorted out.
166 MetaWord* allocate_inner(size_t word_size);
167
168 public:
169
170 MetaspaceArena(ChunkManager* chunk_manager, const ArenaGrowthPolicy* growth_policy, int alignment_words,
171 Mutex* lock, SizeAtomicCounter* total_used_words_counter,
172 const char* name);
173
174 ~MetaspaceArena();
175
176 // Allocate memory from Metaspace.
177 // 1) Attempt to allocate from the dictionary of deallocated blocks.
178 // 2) Attempt to allocate from the current chunk.
179 // 3) Attempt to enlarge the current chunk in place if it is too small.
180 // 4) Attempt to get a new chunk and allocate from that chunk.
181 // At any point, if we hit a commit limit, we return NULL.
182 MetaWord* allocate(size_t word_size);
183
184 // Prematurely returns a metaspace allocation to the _block_freelists because it is not
185 // needed anymore.
186 void deallocate(MetaWord* p, size_t word_size);
187
188 // Update statistics. This walks all in-use chunks.
189 void add_to_statistics(ArenaStats* out) const;
190
191 // Convenience method to get the most important usage statistics.
192 // For deeper analysis use add_to_statistics().
193 void usage_numbers(size_t* p_used_words, size_t* p_committed_words, size_t* p_capacity_words) const;
194
195 DEBUG_ONLY(void verify() const;)
196 DEBUG_ONLY(void verify_locked() const;)
197 DEBUG_ONLY(void verify_allocation_guards() const;)
198
199 void print_on(outputStream* st) const;
200 void print_on_locked(outputStream* st) const;
201
202 };
203
204 } // namespace metaspace
205
206 #endif // SHARE_MEMORY_METASPACE_METASPACEARENA_HPP
207