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/metachunk.hpp"
33 #include "memory/metaspace/metachunkList.hpp"
34 #include "memory/metaspace/metaspaceCommon.hpp"
35
36
37 class outputStream;
38 class Mutex;
39
40 namespace metaspace {
41
42
43 class ArenaGrowthPolicy;
44 class FreeBlocks;
45
46 struct arena_stats_t;
47
48
49 // The MetaspaceArena is a growable metaspace memory pool belonging to a CLD;
50 // internally it consists of a list of metaspace chunks, of which the head chunk
51 // is the current chunk from which we allocate via pointer bump.
52 //
53 // When the current chunk is used up, MetaspaceArena requestes a new chunk from
54 // the associated ChunkManager.
55 //
56 // MetaspaceArena also keeps a FreeBlocks structure to manage memory blocks which
57 // had been deallocated prematurely.
58 //
59
60 class MetaspaceArena : public CHeapObj<mtClass> {
61
62 // Reference to an outside lock to use for synchronizing access to this arena.
63 // This lock is normally owned by the CLD which owns the ClassLoaderMetaspace which
64 // owns this arena.
65 // Todo: This should be changed. Either the CLD should synchronize access to the
66 // CLMS and its arenas itself, or the arena should have an own lock. The latter
67 // would allow for more fine granular locking since it would allow access to
68 // both class- and non-class arena in the CLMS independently.
69 Mutex* const _lock;
70
71 // Reference to the chunk manager to allocate chunks from.
72 ChunkManager* const _chunk_manager;
73
74 // Reference to the growth policy to use.
75 const ArenaGrowthPolicy* const _growth_policy;
76
77 // List of chunks. Head of the list is the current chunk.
78 MetachunkList _chunks;
79
80 // Structure to take care of leftover/deallocated space in used chunks.
81 // Owned by the Arena. Gets allocated on demand only.
82 FreeBlocks* _fbl;
83
84 Metachunk* current_chunk() { return _chunks.first(); }
85 const Metachunk* current_chunk() const { return _chunks.first(); }
86
87 // Reference to an outside counter to keep track of used space.
88 SizeAtomicCounter* const _total_used_words_counter;
89
90 // A name for purely debugging/logging purposes.
91 const char* const _name;
92
93 Mutex* lock() const { return _lock; }
94 ChunkManager* chunk_manager() const { return _chunk_manager; }
95
96 // free block list
97 FreeBlocks* fbl() const { return _fbl; }
98 void add_allocation_to_fbl(MetaWord* p, size_t word_size);
99
100 // Given a chunk, add its remaining free committed space to the free block list.
101 void salvage_chunk(Metachunk* c);
102
103 // Allocate a new chunk from the underlying chunk manager able to hold at least
104 // requested word size.
105 Metachunk* allocate_new_chunk(size_t requested_word_size);
106
107 // Returns the level of the next chunk to be added, acc to growth policy.
108 chunklevel_t next_chunk_level() const;
109
110 // Attempt to enlarge the current chunk to make it large enough to hold at least
111 // requested_word_size additional words.
112 //
113 // On success, true is returned, false otherwise.
114 bool attempt_enlarge_current_chunk(size_t requested_word_size);
115
116 // Prematurely returns a metaspace allocation to the _block_freelists
117 // because it is not needed anymore (requires CLD lock to be active).
118 void deallocate_locked(MetaWord* p, size_t word_size);
119
120 // Returns true if the area indicated by pointer and size have actually been allocated
121 // from this arena.
122 DEBUG_ONLY(bool is_valid_area(MetaWord* p, size_t word_size) const;)
123
124 public:
125
126 MetaspaceArena(ChunkManager* chunk_manager,
127 const ArenaGrowthPolicy* growth_policy,
128 Mutex* lock,
129 SizeAtomicCounter* total_used_words_counter,
130 const char* name);
131
132 ~MetaspaceArena();
133
134 // Allocate memory from Metaspace.
135 // 1) Attempt to allocate from the dictionary of deallocated blocks.
136 // 2) Attempt to allocate from the current chunk.
137 // 3) Attempt to enlarge the current chunk in place if it is too small.
138 // 4) Attempt to get a new chunk and allocate from that chunk.
139 // At any point, if we hit a commit limit, we return NULL.
140 MetaWord* allocate(size_t word_size);
141
142 // Prematurely returns a metaspace allocation to the _block_freelists because it is not
143 // needed anymore.
144 void deallocate(MetaWord* p, size_t word_size);
145
146 // Update statistics. This walks all in-use chunks.
147 void add_to_statistics(arena_stats_t* out) const;
148
149 // Convenience method to get the most important usage statistics.
150 // For deeper analysis use add_to_statistics().
151 void usage_numbers(size_t* p_used_words, size_t* p_committed_words, size_t* p_capacity_words) const;
152
153 DEBUG_ONLY(void verify(bool slow) const;)
154 DEBUG_ONLY(void verify_locked(bool slow) const;)
155
156 void print_on(outputStream* st) const;
157 void print_on_locked(outputStream* st) const;
158
159 };
160
161 } // namespace metaspace
162
163 #endif // SHARE_MEMORY_METASPACE_METASPACEARENA_HPP
164