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 // 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 = 17, // 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