metaspace.hpp revision 3602:da91efe96a93 
1/*
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23 */
24#ifndef SHARE_VM_MEMORY_METASPACE_HPP
25#define SHARE_VM_MEMORY_METASPACE_HPP
26
27#include "memory/allocation.hpp"
28#include "memory/memRegion.hpp"
29#include "runtime/virtualspace.hpp"
30#include "utilities/exceptions.hpp"
31
32// Metaspace
33//
34// Metaspaces are Arenas for the VM's metadata.
35// They are allocated one per class loader object, and one for the null
36// bootstrap class loader
37// Eventually for bootstrap loader we'll have a read-only section and read-write
38// to write for DumpSharedSpaces and read for UseSharedSpaces
39//
40//    block X ---+       +-------------------+
41//               |       |  Virtualspace     |
42//               |       |                   |
43//               |       |                   |
44//               |       |-------------------|
45//               |       || Chunk            |
46//               |       ||                  |
47//               |       ||----------        |
48//               +------>||| block 0 |       |
49//                       ||----------        |
50//                       ||| block 1 |       |
51//                       ||----------        |
52//                       ||                  |
53//                       |-------------------|
54//                       |                   |
55//                       |                   |
56//                       +-------------------+
57//
58
59class ClassLoaderData;
60class MetaWord;
61class Mutex;
62class outputStream;
63class FreeChunk;
64template <class Chunk_t> class FreeList;
65template <class Chunk_t> class BinaryTreeDictionary;
66class SpaceManager;
67
68// Metaspaces each have a  SpaceManager and allocations
69// are done by the SpaceManager.  Allocations are done
70// out of the current Metachunk.  When the current Metachunk
71// is exhausted, the SpaceManager gets a new one from
72// the current VirtualSpace.  When the VirtualSpace is exhausted
73// the SpaceManager gets a new one.  The SpaceManager
74// also manages freelists of available Chunks.
75//
76// Currently the space manager maintains the list of
77// virtual spaces and the list of chunks in use.  Its
78// allocate() method returns a block for use as a
79// quantum of metadata.
80
81class VirtualSpaceList;
82
83class Metaspace : public CHeapObj<mtClass> {
84  friend class VMStructs;
85  friend class SpaceManager;
86  friend class VM_CollectForMetadataAllocation;
87  friend class MetaspaceGC;
88  friend class MetaspaceAux;
89
90 public:
91  enum MetadataType {ClassType, NonClassType};
92
93 private:
94  void initialize(Mutex* lock, size_t initial_size = 0);
95
96  static size_t _first_chunk_word_size;
97
98  SpaceManager* _vsm;
99  SpaceManager* vsm() const { return _vsm; }
100
101  SpaceManager* _class_vsm;
102  SpaceManager* class_vsm() const { return _class_vsm; }
103
104  MetaWord* allocate(size_t word_size, MetadataType mdtype);
105
106  // Virtual Space lists for both classes and other metadata
107  static VirtualSpaceList* _space_list;
108  static VirtualSpaceList* _class_space_list;
109
110  static VirtualSpaceList* space_list()       { return _space_list; }
111  static VirtualSpaceList* class_space_list() { return _class_space_list; }
112
113 public:
114
115  Metaspace(Mutex* lock, size_t initial_size);
116  Metaspace(Mutex* lock);
117  ~Metaspace();
118
119  // Initialize globals for Metaspace
120  static void global_initialize();
121  static void initialize_class_space(ReservedSpace rs);
122
123  static size_t first_chunk_word_size() { return _first_chunk_word_size; }
124
125  char*  bottom() const;
126  size_t used_words(MetadataType mdtype) const;
127  size_t free_words(MetadataType mdtype) const;
128  size_t capacity_words(MetadataType mdtype) const;
129  size_t waste_words(MetadataType mdtype) const;
130
131  static MetaWord* allocate(ClassLoaderData* loader_data, size_t size,
132                            bool read_only, MetadataType mdtype, TRAPS);
133
134  void deallocate(MetaWord* ptr, size_t byte_size, bool is_class);
135
136#ifndef PRODUCT
137  bool contains(const void *ptr) const;
138  bool contains_class(const void *ptr) const;
139#endif
140
141  void dump(outputStream* const out) const;
142
143  void print_on(outputStream* st) const;
144  // Debugging support
145  void verify();
146};
147
148class MetaspaceAux : AllStatic {
149
150  // Statistics for class space and data space in metaspace.
151  static size_t used_in_bytes(Metaspace::MetadataType mdtype);
152  static size_t free_in_bytes(Metaspace::MetadataType mdtype);
153  static size_t capacity_in_bytes(Metaspace::MetadataType mdtype);
154  static size_t reserved_in_bytes(Metaspace::MetadataType mdtype);
155
156  static size_t free_chunks_total(Metaspace::MetadataType mdtype);
157  static size_t free_chunks_total_in_bytes(Metaspace::MetadataType mdtype);
158
159 public:
160  // Total of space allocated to metadata in all Metaspaces
161  static size_t used_in_bytes() {
162    return used_in_bytes(Metaspace::ClassType) +
163           used_in_bytes(Metaspace::NonClassType);
164  }
165
166  // Total of available space in all Metaspaces
167  // Total of capacity allocated to all Metaspaces.  This includes
168  // space in Metachunks not yet allocated and in the Metachunk
169  // freelist.
170  static size_t capacity_in_bytes() {
171    return capacity_in_bytes(Metaspace::ClassType) +
172           capacity_in_bytes(Metaspace::NonClassType);
173  }
174
175  // Total space reserved in all Metaspaces
176  static size_t reserved_in_bytes() {
177    return reserved_in_bytes(Metaspace::ClassType) +
178           reserved_in_bytes(Metaspace::NonClassType);
179  }
180
181  static size_t min_chunk_size();
182
183  // Print change in used metadata.
184  static void print_metaspace_change(size_t prev_metadata_used);
185  static void print_on(outputStream * out);
186  static void print_on(outputStream * out, Metaspace::MetadataType mdtype);
187
188  static void print_waste(outputStream* out);
189  static void dump(outputStream* out);
190};
191
192// Metaspace are deallocated when their class loader are GC'ed.
193// This class implements a policy for inducing GC's to recover
194// Metaspaces.
195
196class MetaspaceGC : AllStatic {
197
198  // The current high-water-mark for inducing a GC.  When
199  // the capacity of all space in the virtual lists reaches this value,
200  // a GC is induced and the value is increased.  This should be changed
201  // to the space actually used for allocations to avoid affects of
202  // fragmentation losses to partially used chunks.  Size is in words.
203  static size_t _capacity_until_GC;
204
205  // After a GC is done any allocation that fails should try to expand
206  // the capacity of the Metaspaces.  This flag is set during attempts
207  // to allocate in the VMGCOperation that does the GC.
208  static bool _expand_after_GC;
209
210  // For a CMS collection, signal that a concurrent collection should
211  // be started.
212  static bool _should_concurrent_collect;
213
214  static uint _shrink_factor;
215
216  static void set_capacity_until_GC(size_t v) { _capacity_until_GC = v; }
217
218  static size_t shrink_factor() { return _shrink_factor; }
219  void set_shrink_factor(uint v) { _shrink_factor = v; }
220
221 public:
222
223  static size_t capacity_until_GC() { return _capacity_until_GC; }
224  static size_t capacity_until_GC_in_bytes() { return _capacity_until_GC * BytesPerWord; }
225  static void inc_capacity_until_GC(size_t v) { _capacity_until_GC += v; }
226  static void dec_capacity_until_GC(size_t v) {
227    _capacity_until_GC = _capacity_until_GC > v ? _capacity_until_GC - v : 0;
228  }
229  static bool expand_after_GC()           { return _expand_after_GC; }
230  static void set_expand_after_GC(bool v) { _expand_after_GC = v; }
231
232  static bool should_concurrent_collect() { return _should_concurrent_collect; }
233  static void set_should_concurrent_collect(bool v) {
234    _should_concurrent_collect = v;
235  }
236
237  // The amount to increase the high-water-mark (_capacity_until_GC)
238  static size_t delta_capacity_until_GC(size_t word_size);
239
240  // It is expected that this will be called when the current capacity
241  // has been used and a GC should be considered.
242  static bool should_expand(VirtualSpaceList* vsl, size_t word_size);
243
244  // Calculate the new high-water mark at which to induce
245  // a GC.
246  static void compute_new_size();
247};
248
249#endif // SHARE_VM_MEMORY_METASPACE_HPP
250