1 /*
2 * Copyright (c) 2018, 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.
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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
25 #ifndef SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
26 #define SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
27
28
29 #include "memory/allocation.hpp"
30 #include "memory/metaspace/constants.hpp"
31 #include "memory/metaspace/counter.hpp"
32 #include "memory/metaspace/chunkTree.hpp"
33 #include "memory/metaspace/commitMask.hpp"
34 #include "memory/virtualspace.hpp"
35 #include "memory/memRegion.hpp"
36 #include "utilities/debug.hpp"
37 #include "utilities/bitMap.hpp"
38 #include "utilities/globalDefinitions.hpp"
39
40
41 class outputStream;
42
43 namespace metaspace {
44
45 class CommitLimiter;
46
47 // VirtualSpaceNode manage a single address range of the Metaspace.
48 //
49 // That address range may contain interleaved committed and uncommitted
50 // regions. It keeps track of which regions have committed and offers
51 // functions to commit and uncommit regions.
52 //
53 // It allocates and hands out memory ranges, starting at the bottom.
54 //
55 // Address range must be aligned to root chunk size.
56 //
57 class VirtualSpaceNode : public CHeapObj<mtClass> {
58
59 // Link to next VirtualSpaceNode
60 VirtualSpaceNode* _next;
61
62 ReservedSpace _rs;
63
64 // Start pointer of the area.
65 MetaWord* const _base;
66
67 // Size, in words, of the whole node
68 const size_t _word_size;
69
70 // Size, in words, of the range of this node which has been handed out in
71 // the form of chunks.
72 size_t _used_words;
73
74 // The bitmap describing the commit state of the region:
75 // Each bit covers a region of 64K (see constants::commit_granule_size).
76 CommitMask _commit_mask;
77
78 // An array of chunk trees. Each one describes fragmentation inside the associated root chunk.
79 ChunkTreeArray _chunk_tree_array;
80
81 // Limiter object to ask before expanding the committed size of this node.
82 CommitLimiter* const _commit_limiter;
83
84 // Points to outside size counters which we are to increase/decrease when we commit/uncommit
85 // space from this node.
86 SizeCounter* const _total_reserved_words_counter;
87 SizeCounter* const _total_committed_words_counter;
88
89 /// committing, uncommitting ///
90
91 // Given a pointer into this node, calculate the start of the commit granule
92 // the pointer points into.
93 MetaWord* calc_start_of_granule(MetaWord* p) const {
94 DEBUG_ONLY(check_pointer(p));
95 return align_down(p, constants::commit_granule_bytes);
96 }
97
98 // Given an address range, ensure it is committed.
99 //
100 // The range has to be aligned to granule size.
101 //
102 // Function will:
103 // - check how many granules in that region are uncommitted; If all are committed, it
104 // returns true immediately.
105 // - check if committing those uncommitted granules would bring us over the commit limit
106 // (GC threshold, MaxMetaspaceSize). If true, it returns false.
107 // - commit the memory.
108 // - mark the range as committed in the commit mask
109 //
110 // Returns true if success, false if it did hit a commit limit.
111 bool commit_range(MetaWord* p, size_t word_size);
112
113 //// creation ////
114
115 // Create a new empty node spanning the given reserved space.
116 VirtualSpaceNode(ReservedSpace rs,
117 CommitLimiter* limiter,
118 SizeCounter* reserve_counter,
119 SizeCounter* commit_counter);
120
121 MetaWord* base() const { return _base; }
122
123 public:
124
125 // Create a node of a given size
126 static VirtualSpaceNode* create_node(size_t word_size,
127 CommitLimiter* limiter,
128 SizeCounter* reserve_counter,
129 SizeCounter* commit_counter);
130
131 // Create a node over an existing space
132 static VirtualSpaceNode* create_node(ReservedSpace rs,
133 CommitLimiter* limiter,
134 SizeCounter* reserve_counter,
135 SizeCounter* commit_counter);
136
137 ~VirtualSpaceNode();
138
139
140 // Reserved size of the whole node.
141 size_t word_size() const { return _word_size; }
142
143 //// Chunk allocation, splitting, merging /////
144
145 // Allocate a root chunk from this node. Will fail and return NULL
146 // if the node is full.
147 // Note: this just returns a chunk whose memory is reserved; no memory is committed yet.
148 // Hence, before using this chunk, it must be committed.
149 // Also, no limits are checked, since no committing takes place.
150 Metachunk* allocate_root_chunk();
151
152 // Given a chunk c, split it recursively until you get a chunk of the given target_level.
153 //
154 // The original chunk must not be part of a freelist.
155 //
156 // Returns pointer to the result chunk; returns split off chunks in splinters array.
157 //
158 // Returns NULL if chunk cannot be split at least once.
159 Metachunk* split(chklvl_t target_level, Metachunk* c, Metachunk* splinters[chklvl::NUM_CHUNK_LEVELS]);
160
161 // Given a chunk, attempt to merge it recursively with its neighboring chunks.
162 //
163 // If successful (merged at least once), returns address of
164 // the merged chunk; NULL otherwise.
165 //
166 // The merged chunks are removed from their freelist; the number of merged chunks is
167 // returned, split by level, in num_merged array. Note that these numbers does not
168 // include the original chunk.
169 //
170 // !!! Please note that if this method returns a non-NULL value, the
171 // original chunk will be invalid and should not be accessed anymore! !!!
172 Metachunk* merge(Metachunk* c, int num_merged[chklvl::NUM_CHUNK_LEVELS]);
173
174
175 /// misc /////
176
177 // Returns size, in words, of the used space in this node alone.
178 // (Notes:
179 // - This is the space handed out to the ChunkManager, so it is "used" from the viewpoint of this node,
180 // but not necessarily used for Metadata.
181 // - This may or may not be committed memory.
182 size_t used_words() const { return _used_words; }
183
184 // Returns size, in words, of how much space is left in this node alone.
185 size_t free_words() const { return _word_size - _used_words; }
186
187 // Returns size, in words, of committed space in this node alone.
188 size_t committed_words() const;
189
190 //// Committing/uncommitting memory /////
191
192 // Given an address range, ensure it is committed.
193 //
194 // The range does not have to be aligned to granule size. However, the function will always commit
195 // whole granules.
196 //
197 // Function will:
198 // - check how many granules in that region are uncommitted; If all are committed, it
199 // returns true immediately.
200 // - check if committing those uncommitted granules would bring us over the commit limit
201 // (GC threshold, MaxMetaspaceSize). If true, it returns false.
202 // - commit the memory.
203 // - mark the range as committed in the commit mask
204 //
205 // Returns true if success, false if it did hit a commit limit.
206 bool ensure_range_is_committed(MetaWord* p, size_t word_size);
207
208 // Given an address range (which has to be aligned to commit granule size):
209 // - uncommit it
210 // - mark it as uncommitted in the commit mask
211 bool uncommit_range(MetaWord* p, size_t word_size);
212
213 //// List stuff ////
214 VirtualSpaceNode* next() const { return _next; }
215 void set_next(VirtualSpaceNode* vsn) { _next = vsn; }
216
217
218 /// Debug stuff ////
219
220 // Print a description about this node.
221 void print_on(outputStream* st) const { print_on(st, K); }
222 void print_on(outputStream* st, size_t scale) const;
223
224 // Verify counters and basic structure. Slow mode: verify all chunks in depth
225 bool contains(const MetaWord* p) const {
226 return p >= _base && p < _base + _used_words;
227 }
228
229 #ifdef ASSERT
230 void check_pointer(const MetaWord* p) const {
231 assert(contains(p), "invalid pointer");
232 }
233 void verify(bool slow) const;
234 #endif
235
236 };
237
238
239 } // namespace metaspace
240
241 #endif // SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP