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. 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 // 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 };