1 /*
2 * Copyright (c) 2003, 2008, Oracle and/or its affiliates. All rights reserved.
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
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,
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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23 */
24
25 // All heaps contains a "permanent generation," containing permanent
26 // (reflective) objects. This is like a regular generation in some ways,
27 // but unlike one in others, and so is split apart.
28
29 class PermanentGenerationSpec;
30
31 // This is the "generation" view of a CompactingPermGen.
32 // NOTE: the shared spaces used for CDS are here handled in
33 // a somewhat awkward and potentially buggy fashion, see CR 6801625.
34 // This infelicity should be fixed, see CR 6897789.
35 class CompactingPermGenGen: public OneContigSpaceCardGeneration {
36 friend class VMStructs;
37 // Abstractly, this is a subtype that gets access to protected fields.
38 friend class CompactingPermGen;
39
40 private:
41 // Shared spaces
42 PermanentGenerationSpec* _spec;
43 size_t _shared_space_size;
44 VirtualSpace _ro_vs;
45 VirtualSpace _rw_vs;
46 VirtualSpace _md_vs;
47 VirtualSpace _mc_vs;
48 BlockOffsetSharedArray* _ro_bts;
49 BlockOffsetSharedArray* _rw_bts;
50 OffsetTableContigSpace* _ro_space;
51 OffsetTableContigSpace* _rw_space;
52
53 // With shared spaces there is a dichotomy in the use of the
54 // _virtual_space of the generation. There is a portion of the
55 // _virtual_space that is used for the unshared part of the
56 // permanent generation and a portion that is reserved for the shared part.
57 // The _reserved field in the generation represents both the
58 // unshared and shared parts of the generation. The _reserved
59 // variable is initialized for only the unshared part but is
60 // later extended to include the shared part during initialization
61 // if shared spaces are being used.
62 // The reserved size for the _virtual_space for CompactingPermGenGen
63 // is the size of the space for the permanent generation including the
64 // the shared spaces. This can be seen by the use of MaxPermSize
65 // in the allocation of PermanentGenerationSpec. The space for the
66 // shared spaces is committed separately (???).
67 // In general at initialization only a part of the
68 // space for the unshared part of the permanent generation is
69 // committed and more is committed as the permanent generation is
70 // grown. In growing the permanent generation the capacity() and
71 // max_capacity() of the generation are used. For the permanent
72 // generation (implemented with a CompactingPermGenGen) the capacity()
73 // is taken from the capacity of the space (_the_space variable used for the
74 // unshared part of the generation) and the max_capacity() is based
75 // on the size of the _reserved variable (which includes the size of the
76 // shared spaces) minus the size of the shared spaces.
77
78 // These values are redundant, but are called out separately to avoid
79 // going through heap/space/gen pointers for performance.
80 static HeapWord* unshared_bottom;
81 static HeapWord* unshared_end;
82 static HeapWord* shared_bottom;
83 static HeapWord* readonly_bottom;
84 static HeapWord* readonly_end;
85 static HeapWord* readwrite_bottom;
86 static HeapWord* readwrite_end;
87 static HeapWord* miscdata_bottom;
88 static HeapWord* miscdata_end;
89 static HeapWord* misccode_bottom;
90 static HeapWord* misccode_end;
91 static HeapWord* shared_end;
92
93 // List of klassOops whose vtbl entries are used to patch others.
94 static void** _vtbl_list;
95
96 // Performance Counters
97 GenerationCounters* _gen_counters;
98 CSpaceCounters* _space_counters;
99
100 void initialize_performance_counters();
101
102 public:
103
104 enum {
105 vtbl_list_size = 16, // number of entries in the shared space vtable list.
106 num_virtuals = 200 // number of virtual methods in Klass (or
107 // subclass) objects, or greater.
108 };
109
110 enum {
111 ro = 0, // read-only shared space in the heap
112 rw = 1, // read-write shared space in the heap
113 md = 2, // miscellaneous data for initializing tables, etc.
114 mc = 3, // miscellaneous code - vtable replacement.
115 n_regions = 4
116 };
117
118 CompactingPermGenGen(ReservedSpace rs, ReservedSpace shared_rs,
119 size_t initial_byte_size, int level, GenRemSet* remset,
120 ContiguousSpace* space,
121 PermanentGenerationSpec* perm_spec);
122
123 const char* name() const {
124 return "compacting perm gen";
125 }
126
127 const char* short_name() const {
128 return "Perm";
129 }
130
131 // Return the maximum capacity for the object space. This
132 // explicitly does not include the shared spaces.
133 size_t max_capacity() const;
134
135 void update_counters();
136
137 void compute_new_size() {
138 assert(false, "Should not call this -- handled at PermGen level.");
139 }
140
141 bool must_be_youngest() const { return false; }
142 bool must_be_oldest() const { return false; }
143
144 OffsetTableContigSpace* ro_space() const { return _ro_space; }
145 OffsetTableContigSpace* rw_space() const { return _rw_space; }
146 VirtualSpace* md_space() { return &_md_vs; }
147 VirtualSpace* mc_space() { return &_mc_vs; }
148 ContiguousSpace* unshared_space() const { return _the_space; }
149
150 static bool inline is_shared(const oopDesc* p) {
151 return (HeapWord*)p >= shared_bottom && (HeapWord*)p < shared_end;
152 }
153 // RedefineClasses note: this tester is used to check residence of
154 // the specified oop in the shared readonly space and not whether
155 // the oop is readonly.
156 static bool inline is_shared_readonly(const oopDesc* p) {
157 return (HeapWord*)p >= readonly_bottom && (HeapWord*)p < readonly_end;
158 }
159 // RedefineClasses note: this tester is used to check residence of
160 // the specified oop in the shared readwrite space and not whether
161 // the oop is readwrite.
162 static bool inline is_shared_readwrite(const oopDesc* p) {
163 return (HeapWord*)p >= readwrite_bottom && (HeapWord*)p < readwrite_end;
164 }
165
166 bool is_in_unshared(const void* p) const {
167 return OneContigSpaceCardGeneration::is_in(p);
168 }
169
170 bool is_in_shared(const void* p) const {
171 return p >= shared_bottom && p < shared_end;
172 }
173
174 inline bool is_in(const void* p) const {
175 return is_in_unshared(p) || is_in_shared(p);
176 }
177
178 inline PermanentGenerationSpec* spec() const { return _spec; }
179 inline void set_spec(PermanentGenerationSpec* spec) { _spec = spec; }
180
181 void pre_adjust_pointers();
182 void adjust_pointers();
183 void space_iterate(SpaceClosure* blk, bool usedOnly = false);
184 void print_on(outputStream* st) const;
185 void younger_refs_iterate(OopsInGenClosure* blk);
186 void compact();
187 void post_compact();
188 size_t contiguous_available() const;
189
190 void clear_remembered_set();
191 void invalidate_remembered_set();
192
193 inline bool block_is_obj(const HeapWord* addr) const {
194 if (addr < the_space()->top()) return true;
195 else if (addr < the_space()->end()) return false;
196 else if (addr < ro_space()->top()) return true;
197 else if (addr < ro_space()->end()) return false;
198 else if (addr < rw_space()->top()) return true;
199 else return false;
200 }
201
202
203 inline size_t block_size(const HeapWord* addr) const {
204 if (addr < the_space()->top()) {
205 return oop(addr)->size();
206 }
207 else if (addr < the_space()->end()) {
208 assert(addr == the_space()->top(), "non-block head arg to block_size");
209 return the_space()->end() - the_space()->top();
210 }
211
212 else if (addr < ro_space()->top()) {
213 return oop(addr)->size();
214 }
215 else if (addr < ro_space()->end()) {
216 assert(addr == ro_space()->top(), "non-block head arg to block_size");
217 return ro_space()->end() - ro_space()->top();
218 }
219
220 else if (addr < rw_space()->top()) {
221 return oop(addr)->size();
222 }
223 else {
224 assert(addr == rw_space()->top(), "non-block head arg to block_size");
225 return rw_space()->end() - rw_space()->top();
226 }
227 }
228
229 static void generate_vtable_methods(void** vtbl_list,
230 void** vtable,
231 char** md_top, char* md_end,
232 char** mc_top, char* mc_end);
233
234 void verify(bool allow_dirty);
235
236 // Serialization
237 static void initialize_oops() KERNEL_RETURN;
238 static void serialize_oops(SerializeOopClosure* soc);
239 void serialize_bts(SerializeOopClosure* soc);
240
241 // Initiate dumping of shared file.
242 static jint dump_shared(GrowableArray<oop>* class_promote_order, TRAPS);
243
244 // JVM/TI RedefineClasses() support:
245 // Remap the shared readonly space to shared readwrite, private if
246 // sharing is enabled. Simply returns true if sharing is not enabled
247 // or if the remapping has already been done by a prior call.
248 static bool remap_shared_readonly_as_readwrite();
249 };