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
21 * questions.
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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/chunkTree.hpp"
30 #include "memory/metaspace/commitMask.hpp"
31 #include "memory/virtualspace.hpp"
32 #include "memory/memRegion.hpp"
33 #include "utilities/debug.hpp"
34 #include "utilities/bitMap.hpp"
35 #include "utilities/globalDefinitions.hpp"
36
37 class outputStream;
38
39 namespace metaspace {
40
41 // VirtualSpaceNode manage a single address range of the Metaspace.
42 //
43 // That address range may contain interleaved committed and uncommitted
44 // regions. It keeps track of which regions have committed and offers
45 // functions to commit and uncommit regions.
46 //
47 // It allocates and hands out memory ranges, starting at the bottom.
48 //
49 // Address range must be aligned to root chunk size.
50 //
51 class VirtualSpaceNode : public CHeapObj<mtClass> {
52
53 // Link to next VirtualSpaceNode
54 VirtualSpaceNode* _next;
55
56 ReservedSpace _rs;
57
58 // Start pointer of the area.
59 MetaWord* const _base;
60
61 // Size, in words, of the whole node
62 const size_t _word_size;
63
64 // Size, in words, of the used portion of the node
65 size_t _used_words;
66
67 // The bitmap describing the commit state of the region:
68 // Each bit covers a region of 64K (see constants::commit_granule_size).
69 CommitMask _commit_mask;
70
71 // An array of chunk trees. Each one describes fragmentation inside the associated root chunk.
72 ChunkTreeArray _chunk_tree_array;
73
74 /// committing, uncommitting ///
75
76 // Given a pointer into this node, calculate the start of the commit granule
77 // the pointer points into.
78 MetaWord* calc_start_of_granule(MetaWord* p) const {
79 DEBUG_ONLY(check_pointer(p));
80 return align_down(p, constants::commit_granule_bytes);
81 }
82
83 // Given an address range (which has to be aligned to commit granule size):
84 // - commit it
85 // - mark it as committed in the commit mask
86 // May fail and return NULL if we hit a global commit limit (GC threshold, MaxMetaspaceSize).
87 // Will assert if we run out of memory.
88 bool commit_range(MetaWord* p, size_t word_size);
89
90 //// creation ////
91
92 // Create a new empty node spanning the given reserved space.
93 VirtualSpaceNode(ReservedSpace rs);
94
95 public:
96
97 // Create a node of a given size
98 static VirtualSpaceNode* create_node(size_t word_size);
99
100 // Create a node over an existing space
101 static VirtualSpaceNode* create_node(ReservedSpace rs);
102
103 ~VirtualSpaceNode();
104
105 //// Chunk allocation, splitting, merging /////
106
107 // Allocate a root chunk from this node. Will fail and return NULL
108 // if the node is full.
109 // Note that the chunk memory may or may not be committed. Commit its payload
110 // area before using it.
111 Metachunk* allocate_root_chunk();
112
113 // Given a chunk c, split it recursively until you get a chunk of the given target_level.
114 // Returns pointer to the result chunk; returns split off chunks in p_splinters as linked list.
115 // Returns NULL if chunk cannot be split at least once.
116 Metachunk* split(chklvl_t target_level, Metachunk* c, Metachunk** p_splinters);
117
118 // Given a chunk, attempt to merge it recursively with its neighboring chunks.
119 // If successful (merged at least once), returns address of
120 // the merged chunk; NULL otherwise.
121 //
122 // !!! Please note that if this method returns a non-NULL value, the
123 // original chunk will be invalid and should not be accessed anymore! !!!
124 Metachunk* merge(Metachunk* c);
125
126
127 //// Committing/uncommitting memory /////
128
129 // Given an address range (which has to be aligned to commit granule size), ensure
130 // it is committed.
131 // - commit it
132 // - mark it as committed in the commit mask
133 // May fail and return NULL if we hit a global commit limit (GC threshold, MaxMetaspaceSize).
134 // Will assert if we run out of memory.
135 bool ensure_range_is_committed(MetaWord* p, size_t word_size);
136
137 // Given an address range (which has to be aligned to commit granule size):
138 // - uncommit it
139 // - mark it as uncommitted in the commit mask
140 bool uncommit_range(MetaWord* p, size_t word_size);
141
142
143 /// Debug stuff ////
144
145 // Verify counters and basic structure. Slow mode: verify all chunks in depth
146 bool contains(const MetaWord* p) const {
147 return p >= _base && p < _base + _used_words;
148 }
149
150 #ifdef ASSERT
151 void check_pointer(const MetaWord* p) const {
152 assert(contains(p), "invalid pointer");
153 }
154 void verify(bool slow);
155 #endif
156
157 };
158
159
160 } // namespace metaspace
161
162 #endif // SHARE_MEMORY_METASPACE_VIRTUALSPACENODE_HPP