1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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).
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24
25 #ifndef SHARE_VM_MEMORY_COMPACTINGPERMGENGEN_HPP
26 #define SHARE_VM_MEMORY_COMPACTINGPERMGENGEN_HPP
27
28 #include "gc_implementation/shared/generationCounters.hpp"
29 #include "memory/space.hpp"
30
31 // All heaps contains a "permanent generation," containing permanent
32 // (reflective) objects. This is like a regular generation in some ways,
33 // but unlike one in others, and so is split apart.
34
35 class PermanentGenerationSpec;
36
37 // This is the "generation" view of a CompactingPermGen.
38 // NOTE: the shared spaces used for CDS are here handled in
39 // a somewhat awkward and potentially buggy fashion, see CR 6801625.
40 // This infelicity should be fixed, see CR 6897789.
41 class CompactingPermGenGen: public OneContigSpaceCardGeneration {
42 friend class VMStructs;
43 // Abstractly, this is a subtype that gets access to protected fields.
44 friend class CompactingPermGen;
45
46 private:
47 // Shared spaces
48 PermanentGenerationSpec* _spec;
49 size_t _shared_space_size;
50 VirtualSpace _ro_vs;
51 VirtualSpace _rw_vs;
52 VirtualSpace _md_vs;
53 VirtualSpace _mc_vs;
54 BlockOffsetSharedArray* _ro_bts;
55 BlockOffsetSharedArray* _rw_bts;
56 OffsetTableContigSpace* _ro_space;
57 OffsetTableContigSpace* _rw_space;
58
59 // With shared spaces there is a dichotomy in the use of the
60 // _virtual_space of the generation. There is a portion of the
61 // _virtual_space that is used for the unshared part of the
62 // permanent generation and a portion that is reserved for the shared part.
63 // The _reserved field in the generation represents both the
64 // unshared and shared parts of the generation. The _reserved
65 // variable is initialized for only the unshared part but is
66 // later extended to include the shared part during initialization
67 // if shared spaces are being used.
68 // The reserved size for the _virtual_space for CompactingPermGenGen
69 // is the size of the space for the permanent generation including the
70 // the shared spaces. This can be seen by the use of MaxPermSize
71 // in the allocation of PermanentGenerationSpec. The space for the
72 // shared spaces is committed separately (???).
73 // In general at initialization only a part of the
74 // space for the unshared part of the permanent generation is
75 // committed and more is committed as the permanent generation is
76 // grown. In growing the permanent generation the capacity() and
77 // max_capacity() of the generation are used. For the permanent
78 // generation (implemented with a CompactingPermGenGen) the capacity()
79 // is taken from the capacity of the space (_the_space variable used for the
80 // unshared part of the generation) and the max_capacity() is based
81 // on the size of the _reserved variable (which includes the size of the
82 // shared spaces) minus the size of the shared spaces.
83
84 // These values are redundant, but are called out separately to avoid
85 // going through heap/space/gen pointers for performance.
86 static HeapWord* unshared_bottom;
87 static HeapWord* unshared_end;
88 static HeapWord* shared_bottom;
89 static HeapWord* readonly_bottom;
90 static HeapWord* readonly_end;
91 static HeapWord* readwrite_bottom;
92 static HeapWord* readwrite_end;
93 static HeapWord* miscdata_bottom;
94 static HeapWord* miscdata_end;
95 static HeapWord* misccode_bottom;
96 static HeapWord* misccode_end;
97 static HeapWord* shared_end;
98
99 // Performance Counters
100 GenerationCounters* _gen_counters;
101 CSpaceCounters* _space_counters;
102
103 void initialize_performance_counters();
104
105 public:
106
107 enum {
108 vtbl_list_size = 16, // number of entries in the shared space vtable list.
109 num_virtuals = 200 // number of virtual methods in Klass (or
110 // subclass) objects, or greater.
111 };
112
113 enum {
114 ro = 0, // read-only shared space in the heap
115 rw = 1, // read-write shared space in the heap
116 md = 2, // miscellaneous data for initializing tables, etc.
117 mc = 3, // miscellaneous code - vtable replacement.
118 n_regions = 4
119 };
120
121 CompactingPermGenGen(ReservedSpace rs, ReservedSpace shared_rs,
122 size_t initial_byte_size, int level, GenRemSet* remset,
123 ContiguousSpace* space,
124 PermanentGenerationSpec* perm_spec);
125
126 const char* name() const {
127 return "compacting perm gen";
128 }
129
130 const char* short_name() const {
131 return "Perm";
132 }
133
134 // Return the maximum capacity for the object space. This
135 // explicitly does not include the shared spaces.
136 size_t max_capacity() const;
137
138 void update_counters();
139
140 void compute_new_size() {
141 assert(false, "Should not call this -- handled at PermGen level.");
142 }
143
144 bool must_be_youngest() const { return false; }
145 bool must_be_oldest() const { return false; }
146
147 OffsetTableContigSpace* ro_space() const { return _ro_space; }
148 OffsetTableContigSpace* rw_space() const { return _rw_space; }
149 VirtualSpace* md_space() { return &_md_vs; }
150 VirtualSpace* mc_space() { return &_mc_vs; }
151 ContiguousSpace* unshared_space() const { return _the_space; }
152
153 static bool inline is_shared(const void* p) {
154 return p >= shared_bottom && p < shared_end;
155 }
156 // RedefineClasses note: this tester is used to check residence of
157 // the specified oop in the shared readonly space and not whether
158 // the oop is readonly.
159 static bool inline is_shared_readonly(const void* p) {
160 return p >= readonly_bottom && p < readonly_end;
161 }
162 // RedefineClasses note: this tester is used to check residence of
163 // the specified oop in the shared readwrite space and not whether
164 // the oop is readwrite.
165 static bool inline is_shared_readwrite(const void* p) {
166 return p >= readwrite_bottom && p < readwrite_end;
167 }
168
169 // Checks if the pointer is either in unshared space or in shared space
170 inline bool is_in(const void* p) const {
171 return OneContigSpaceCardGeneration::is_in(p) || is_shared(p);
172 }
173
174 inline PermanentGenerationSpec* spec() const { return _spec; }
175 inline void set_spec(PermanentGenerationSpec* spec) { _spec = spec; }
176
177 void pre_adjust_pointers();
178 void adjust_pointers();
179 void space_iterate(SpaceClosure* blk, bool usedOnly = false);
180 void print_on(outputStream* st) const;
181 void younger_refs_iterate(OopsInGenClosure* blk);
182 void compact();
183 void post_compact();
184 size_t contiguous_available() const;
185
186 void clear_remembered_set();
187 void invalidate_remembered_set();
188
189 inline bool block_is_obj(const HeapWord* addr) const {
190 if (addr < the_space()->top()) return true;
191 else if (addr < the_space()->end()) return false;
192 else if (addr < ro_space()->top()) return true;
193 else if (addr < ro_space()->end()) return false;
194 else if (addr < rw_space()->top()) return true;
195 else return false;
196 }
197
198
199 inline size_t block_size(const HeapWord* addr) const {
200 if (addr < the_space()->top()) {
201 return oop(addr)->size();
202 }
203 else if (addr < the_space()->end()) {
204 assert(addr == the_space()->top(), "non-block head arg to block_size");
205 return the_space()->end() - the_space()->top();
206 }
207
208 else if (addr < ro_space()->top()) {
209 return oop(addr)->size();
210 }
211 else if (addr < ro_space()->end()) {
212 assert(addr == ro_space()->top(), "non-block head arg to block_size");
213 return ro_space()->end() - ro_space()->top();
214 }
215
216 else if (addr < rw_space()->top()) {
217 return oop(addr)->size();
218 }
219 else {
220 assert(addr == rw_space()->top(), "non-block head arg to block_size");
221 return rw_space()->end() - rw_space()->top();
222 }
223 }
224
225 static void generate_vtable_methods(void** vtbl_list,
226 void** vtable,
227 char** md_top, char* md_end,
228 char** mc_top, char* mc_end);
229 static void* find_matching_vtbl_ptr(void** vtbl_list,
230 void* new_vtable_start,
231 void* obj);
232
233 void verify(bool allow_dirty);
234
235 // Serialization
236 static void initialize_oops() KERNEL_RETURN;
237 static void serialize_oops(SerializeOopClosure* soc);
238 void serialize_bts(SerializeOopClosure* soc);
239
240 // Initiate dumping of shared file.
241 static jint dump_shared(GrowableArray<oop>* class_promote_order, TRAPS);
242
243 // JVM/TI RedefineClasses() support:
244 // Remap the shared readonly space to shared readwrite, private if
245 // sharing is enabled. Simply returns true if sharing is not enabled
246 // or if the remapping has already been done by a prior call.
247 static bool remap_shared_readonly_as_readwrite();
248 };
249
250 #endif // SHARE_VM_MEMORY_COMPACTINGPERMGENGEN_HPP