1/*
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24#ifndef SHARE_MEMORY_METASPACE_METACHUNK_HPP
25#define SHARE_MEMORY_METASPACE_METACHUNK_HPP
26
27#include "memory/metaspace/metabase.hpp"
28#include "memory/metaspace/metaspaceCommon.hpp"
29#include "utilities/debug.hpp"
30#include "utilities/globalDefinitions.hpp"
31
32class MetachunkTest;
33
34namespace metaspace {
35
36class VirtualSpaceNode;
37
38// Metachunk - Quantum of allocation from a Virtualspace
39// Metachunks are reused (when freed are put on a global freelist) and
40// have no permanent association to a SpaceManager.
41
42// +--------------+ <- end --+ --+
43// | | | |
44// | | | free |
45// | | | |
46// | | | | size | capacity
47// | | | |
48// | | <- top -- + |
49// | | | |
50// | | | used |
51// | | | |
52// | | | |
53// +--------------+ <- bottom --+ --+
54
55enum ChunkOrigin {
56 // Chunk normally born (via take_from_committed)
57 origin_normal = 1,
58 // Chunk was born as padding chunk
59 origin_pad = 2,
60 // Chunk was born as leftover chunk in VirtualSpaceNode::retire
61 origin_leftover = 3,
62 // Chunk was born as result of a merge of smaller chunks
63 origin_merge = 4,
64 // Chunk was born as result of a split of a larger chunk
65 origin_split = 5,
66
67 origin_minimum = origin_normal,
68 origin_maximum = origin_split,
69 origins_count = origin_maximum + 1
70};
71
72inline bool is_valid_chunkorigin(ChunkOrigin origin) {
73 return origin == origin_normal ||
74 origin == origin_pad ||
75 origin == origin_leftover ||
76 origin == origin_merge ||
77 origin == origin_split;
78}
79
80class Metachunk : public Metabase<Metachunk> {
81
82 friend class ::MetachunkTest;
83
84 // The VirtualSpaceNode containing this chunk.
85 VirtualSpaceNode* const _container;
86
87 // Current allocation top.
88 MetaWord* _top;
89
90 // A 32bit sentinel for debugging purposes.
91 enum { CHUNK_SENTINEL = 0x4d4554EF, // "MET"
92 CHUNK_SENTINEL_INVALID = 0xFEEEEEEF
93 };
94
95 uint32_t _sentinel;
96
97 const ChunkIndex _chunk_type;
98 const bool _is_class;
99 // Whether the chunk is free (in freelist) or in use by some class loader.
100 bool _is_tagged_free;
101
102 ChunkOrigin _origin;
103 int _use_count;
104
105 MetaWord* initial_top() const { return (MetaWord*)this + overhead(); }
106 MetaWord* top() const { return _top; }
107
108 public:
109 // Metachunks are allocated out of a MetadataVirtualSpace and
110 // and use some of its space to describe itself (plus alignment
111 // considerations). Metadata is allocated in the rest of the chunk.
112 // This size is the overhead of maintaining the Metachunk within
113 // the space.
114
115 // Alignment of each allocation in the chunks.
116 static size_t object_alignment();
117
118 // Size of the Metachunk header, in words, including alignment.
119 static size_t overhead();
120
121 Metachunk(ChunkIndex chunktype, bool is_class, size_t word_size, VirtualSpaceNode* container);
122
123 MetaWord* allocate(size_t word_size);
124
125 VirtualSpaceNode* container() const { return _container; }
126
127 MetaWord* bottom() const { return (MetaWord*) this; }
128
129 // Reset top to bottom so chunk can be reused.
130 void reset_empty() { _top = initial_top(); clear_next(); clear_prev(); }
131 bool is_empty() { return _top == initial_top(); }
132
133 // used (has been allocated)
134 // free (available for future allocations)
135 size_t word_size() const { return size(); }
136 size_t used_word_size() const;
137 size_t free_word_size() const;
138
139 bool is_tagged_free() { return _is_tagged_free; }
140 void set_is_tagged_free(bool v) { _is_tagged_free = v; }
141
142 bool contains(const void* ptr) { return bottom() <= ptr && ptr < _top; }
143
144 void print_on(outputStream* st) const;
145
146 bool is_valid_sentinel() const { return _sentinel == CHUNK_SENTINEL; }
147 void remove_sentinel() { _sentinel = CHUNK_SENTINEL_INVALID; }
148
149 int get_use_count() const { return _use_count; }
150 void inc_use_count() { _use_count ++; }
151
152 ChunkOrigin get_origin() const { return _origin; }
153 void set_origin(ChunkOrigin orig) { _origin = orig; }
154
155 ChunkIndex get_chunk_type() const { return _chunk_type; }
156 bool is_class() const { return _is_class; }
157
158 DEBUG_ONLY(void mangle(juint word_value);)
159 DEBUG_ONLY(void verify() const;)
160
161};
162
163
164// Helper function that does a bunch of checks for a chunk.
165DEBUG_ONLY(void do_verify_chunk(Metachunk* chunk);)
166
167// Given a Metachunk, update its in-use information (both in the
168// chunk and the occupancy map).
169void do_update_in_use_info_for_chunk(Metachunk* chunk, bool inuse);
170
171} // namespace metaspace
172
173#endif // SHARE_MEMORY_METASPACE_METACHUNK_HPP
174