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.
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
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23 */
24
25 #ifndef SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
26 #define SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP
27
28 #include "memory/metaspace/constants.hpp"
29 #include "memory/metaspace/counter.hpp"
30 #include "memory/metaspace/chunkTree.hpp"
31 #include "memory/metaspace/commitMask.hpp"
32 #include "memory/virtualspace.hpp"
33 #include "memory/memRegion.hpp"
34 #include "utilities/debug.hpp"
35 #include "utilities/bitMap.hpp"
36 #include "utilities/globalDefinitions.hpp"
37
38
39 class outputStream;
40
41 namespace metaspace {
42
43 class CommitLimiter;
44
45 // VirtualSpaceNode manage a single address range of the Metaspace.
46 //
47 // That address range may contain interleaved committed and uncommitted
48 // regions. It keeps track of which regions have committed and offers
49 // functions to commit and uncommit regions.
50 //
51 // It allocates and hands out memory ranges, starting at the bottom.
52 //
53 // Address range must be aligned to root chunk size.
54 //
55 class VirtualSpaceNode : public CHeapObj<mtClass> {
56
57 // Link to next VirtualSpaceNode
58 VirtualSpaceNode* _next;
59
60 ReservedSpace _rs;
61
62 // Start pointer of the area.
63 MetaWord* const _base;
64
65 // Size, in words, of the whole node
66 const size_t _word_size;
67
68 // Size, in words, of the range of this node which has been handed out in
69 // the form of chunks.
70 size_t _used_words;
71
72 // The bitmap describing the commit state of the region:
73 // Each bit covers a region of 64K (see constants::commit_granule_size).
74 CommitMask _commit_mask;
75
76 // An array of chunk trees. Each one describes fragmentation inside the associated root chunk.
77 ChunkTreeArray _chunk_tree_array;
78
79 // Limiter object to ask before expanding the committed size of this node.
80 CommitLimiter* const _commit_limiter;
81
82 // Points to outside size counters which we are to increase/decrease when we commit/uncommit
83 // space from this node.
84 SizeCounter* const _total_reserved_words_counter;
85 SizeCounter* const _total_committed_words_counter;
86
87 /// committing, uncommitting ///
88
89 // Given a pointer into this node, calculate the start of the commit granule
90 // the pointer points into.
91 MetaWord* calc_start_of_granule(MetaWord* p) const {
92 DEBUG_ONLY(check_pointer(p));
93 return align_down(p, constants::commit_granule_bytes);
94 }
95
96 // Given an address range, ensure it is committed.
97 //
98 // The range has to be aligned to granule size.
99 //
100 // Function will:
101 // - check how many granules in that region are uncommitted; If all are committed, it
102 // returns true immediately.
103 // - check if committing those uncommitted granules would bring us over the commit limit
104 // (GC threshold, MaxMetaspaceSize). If true, it returns false.
105 // - commit the memory.
106 // - mark the range as committed in the commit mask
107 //
108 // Returns true if success, false if it did hit a commit limit.
109 bool commit_range(MetaWord* p, size_t word_size);
110
111 //// creation ////
112
113 // Create a new empty node spanning the given reserved space.
114 VirtualSpaceNode(ReservedSpace rs,
115 CommitLimiter* limiter,
116 SizeCounter* reserve_counter,
117 SizeCounter* commit_counter);
118
119 MetaWord* base() const { return _base; }
120
121 // Reserved size of the whole node.
122 size_t word_size() const { return _word_size; }
123
124 public:
125
126 // Create a node of a given size
127 static VirtualSpaceNode* create_node(size_t word_size,
128 CommitLimiter* limiter,
129 SizeCounter* reserve_counter,
130 SizeCounter* commit_counter);
131
132 // Create a node over an existing space
133 static VirtualSpaceNode* create_node(ReservedSpace rs,
134 CommitLimiter* limiter,
135 SizeCounter* reserve_counter,
136 SizeCounter* commit_counter);
137
138 ~VirtualSpaceNode();
139
140 //// Chunk allocation, splitting, merging /////
141
142 // Allocate a root chunk from this node. Will fail and return NULL
143 // if the node is full.
144 // Note: this just returns a chunk whose memory is reserved; no memory is committed yet.
145 // Hence, before using this chunk, it must be committed.
146 // Also, no limits are checked, since no committing takes place.
147 Metachunk* allocate_root_chunk();
148
149 // Given a chunk c, split it recursively until you get a chunk of the given target_level.
150 //
151 // The original chunk must not be part of a freelist.
152 //
153 // Returns pointer to the result chunk; returns split off chunks in splinters array.
154 //
155 // Returns NULL if chunk cannot be split at least once.
156 Metachunk* split(chklvl_t target_level, Metachunk* c, Metachunk* splinters[chklvl::NUM_CHUNK_LEVELS]);
157
158 // Given a chunk, attempt to merge it recursively with its neighboring chunks.
159 //
160 // If successful (merged at least once), returns address of
161 // the merged chunk; NULL otherwise.
162 //
163 // The merged chunks are removed from their freelist; the number of merged chunks is
164 // returned, split by level, in num_merged array. Note that these numbers does not
165 // include the original chunk.
166 //
167 // !!! Please note that if this method returns a non-NULL value, the
168 // original chunk will be invalid and should not be accessed anymore! !!!
169 Metachunk* merge(Metachunk* c, int num_merged[chklvl::NUM_CHUNK_LEVELS]);
170
171
172 /// misc /////
173
174 // Returns size, in words, of the used space in this node alone.
175 // (Notes:
176 // - This is the space handed out to the ChunkManager, so it is "used" from the viewpoint of this node,
177 // but not necessarily used for Metadata.
178 // - This may or may not be committed memory.
179 size_t used_words() const { return _used_words; }
180
181 // Returns size, in words, of how much space is left in this node alone.
182 size_t free_words() const { return _word_size - _used_words; }
183
184 // Returns size, in words, of committed space in this node alone.
185 size_t committed_words() const;
186
187 //// Committing/uncommitting memory /////
188
189 // Given an address range, ensure it is committed.
190 //
191 // The range does not have to be aligned to granule size. However, the function will always commit
192 // whole granules.
193 //
194 // Function will:
195 // - check how many granules in that region are uncommitted; If all are committed, it
196 // returns true immediately.
197 // - check if committing those uncommitted granules would bring us over the commit limit
198 // (GC threshold, MaxMetaspaceSize). If true, it returns false.
199 // - commit the memory.
200 // - mark the range as committed in the commit mask
201 //
202 // Returns true if success, false if it did hit a commit limit.
203 bool ensure_range_is_committed(MetaWord* p, size_t word_size);
204
205 // Given an address range (which has to be aligned to commit granule size):
206 // - uncommit it
207 // - mark it as uncommitted in the commit mask
208 bool uncommit_range(MetaWord* p, size_t word_size);
209
210 //// List stuff ////
211 VirtualSpaceNode* next() const { return _next; }
212 void set_next(VirtualSpaceNode* vsn) { _next = vsn; }
213
214
215 /// Debug stuff ////
216
217 // Print a description about this node.
218 void print_on(outputStream* st) const { print_on(st, K); }
219 void print_on(outputStream* st, size_t scale) const;
220
221 // Verify counters and basic structure. Slow mode: verify all chunks in depth
222 bool contains(const MetaWord* p) const {
223 return p >= _base && p < _base + _used_words;
224 }
225
226 #ifdef ASSERT
227 void check_pointer(const MetaWord* p) const {
228 assert(contains(p), "invalid pointer");
229 }
230 void verify(bool slow) const;
231 #endif
232
233 };
234
235
236 } // namespace metaspace
237
238 #endif // SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP