1 /*
2 * Copyright (c) 2003, 2010, 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.
22 *
23 */
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 // List of klassOops whose vtbl entries are used to patch others.
100 static void** _vtbl_list;
101
102 // Performance Counters
103 GenerationCounters* _gen_counters;
104 CSpaceCounters* _space_counters;
105
106 void initialize_performance_counters();
107
108 public:
109
110 enum {
111 vtbl_list_size = 16, // number of entries in the shared space vtable list.
112 num_virtuals = 200 // number of virtual methods in Klass (or
113 // subclass) objects, or greater.
114 };
115
116 enum {
117 ro = 0, // read-only shared space in the heap
118 rw = 1, // read-write shared space in the heap
119 md = 2, // miscellaneous data for initializing tables, etc.
120 mc = 3, // miscellaneous code - vtable replacement.
121 n_regions = 4
122 };
123
124 CompactingPermGenGen(ReservedSpace rs, ReservedSpace shared_rs,
125 size_t initial_byte_size, int level, GenRemSet* remset,
126 ContiguousSpace* space,
127 PermanentGenerationSpec* perm_spec);
128
129 const char* name() const {
130 return "compacting perm gen";
131 }
132
133 const char* short_name() const {
134 return "Perm";
135 }
136
137 // Return the maximum capacity for the object space. This
138 // explicitly does not include the shared spaces.
139 size_t max_capacity() const;
140
141 void update_counters();
142
143 void compute_new_size() {
144 assert(false, "Should not call this -- handled at PermGen level.");
145 }
146
147 bool must_be_youngest() const { return false; }
148 bool must_be_oldest() const { return false; }
149
150 OffsetTableContigSpace* ro_space() const { return _ro_space; }
151 OffsetTableContigSpace* rw_space() const { return _rw_space; }
152 VirtualSpace* md_space() { return &_md_vs; }
153 VirtualSpace* mc_space() { return &_mc_vs; }
154 ContiguousSpace* unshared_space() const { return _the_space; }
155
156 static bool inline is_shared(const oopDesc* p) {
157 return (HeapWord*)p >= shared_bottom && (HeapWord*)p < shared_end;
158 }
159 // RedefineClasses note: this tester is used to check residence of
160 // the specified oop in the shared readonly space and not whether
161 // the oop is readonly.
162 static bool inline is_shared_readonly(const oopDesc* p) {
163 return (HeapWord*)p >= readonly_bottom && (HeapWord*)p < readonly_end;
164 }
165 // RedefineClasses note: this tester is used to check residence of
166 // the specified oop in the shared readwrite space and not whether
167 // the oop is readwrite.
168 static bool inline is_shared_readwrite(const oopDesc* p) {
169 return (HeapWord*)p >= readwrite_bottom && (HeapWord*)p < readwrite_end;
170 }
171
172 bool is_in_unshared(const void* p) const {
173 return OneContigSpaceCardGeneration::is_in(p);
174 }
175
176 bool is_in_shared(const void* p) const {
177 return p >= shared_bottom && p < shared_end;
178 }
179
180 inline bool is_in(const void* p) const {
181 return is_in_unshared(p) || is_in_shared(p);
182 }
183
184 inline PermanentGenerationSpec* spec() const { return _spec; }
185 inline void set_spec(PermanentGenerationSpec* spec) { _spec = spec; }
186
187 void pre_adjust_pointers();
188 void adjust_pointers();
189 void space_iterate(SpaceClosure* blk, bool usedOnly = false);
190 void print_on(outputStream* st) const;
191 void younger_refs_iterate(OopsInGenClosure* blk);
192 void compact();
193 void post_compact();
194 size_t contiguous_available() const;
195
196 void clear_remembered_set();
197 void invalidate_remembered_set();
198
199 inline bool block_is_obj(const HeapWord* addr) const {
200 if (addr < the_space()->top()) return true;
201 else if (addr < the_space()->end()) return false;
202 else if (addr < ro_space()->top()) return true;
203 else if (addr < ro_space()->end()) return false;
204 else if (addr < rw_space()->top()) return true;
205 else return false;
206 }
207
208
209 inline size_t block_size(const HeapWord* addr) const {
210 if (addr < the_space()->top()) {
211 return oop(addr)->size();
212 }
213 else if (addr < the_space()->end()) {
214 assert(addr == the_space()->top(), "non-block head arg to block_size");
215 return the_space()->end() - the_space()->top();
216 }
217
218 else if (addr < ro_space()->top()) {
219 return oop(addr)->size();
220 }
221 else if (addr < ro_space()->end()) {
222 assert(addr == ro_space()->top(), "non-block head arg to block_size");
223 return ro_space()->end() - ro_space()->top();
224 }
225
226 else if (addr < rw_space()->top()) {
227 return oop(addr)->size();
228 }
229 else {
230 assert(addr == rw_space()->top(), "non-block head arg to block_size");
231 return rw_space()->end() - rw_space()->top();
232 }
233 }
234
235 static void generate_vtable_methods(void** vtbl_list,
236 void** vtable,
237 char** md_top, char* md_end,
238 char** mc_top, char* mc_end);
239
240 void verify(bool allow_dirty);
241
242 // Serialization
243 static void initialize_oops() KERNEL_RETURN;
244 static void serialize_oops(SerializeOopClosure* soc);
245 void serialize_bts(SerializeOopClosure* soc);
246
247 // Initiate dumping of shared file.
248 static jint dump_shared(GrowableArray<oop>* class_promote_order, TRAPS);
249
250 // JVM/TI RedefineClasses() support:
251 // Remap the shared readonly space to shared readwrite, private if
252 // sharing is enabled. Simply returns true if sharing is not enabled
253 // or if the remapping has already been done by a prior call.
254 static bool remap_shared_readonly_as_readwrite();
255 };
256
257 #endif // SHARE_VM_MEMORY_COMPACTINGPERMGENGEN_HPP