1 /* 2 * Copyright (c) 2003, 2019, 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 #include "precompiled.hpp" 26 #include "classfile/altHashing.hpp" 27 #include "classfile/dictionary.hpp" 28 #include "classfile/javaClasses.inline.hpp" 29 #include "classfile/moduleEntry.hpp" 30 #include "classfile/packageEntry.hpp" 31 #include "classfile/placeholders.hpp" 32 #include "classfile/protectionDomainCache.hpp" 33 #include "classfile/stringTable.hpp" 34 #include "code/nmethod.hpp" 35 #include "logging/log.hpp" 36 #include "memory/allocation.inline.hpp" 37 #include "memory/resourceArea.hpp" 38 #include "oops/oop.inline.hpp" 39 #include "oops/weakHandle.inline.hpp" 40 #include "runtime/safepoint.hpp" 41 #include "utilities/dtrace.hpp" 42 #include "utilities/hashtable.hpp" 43 #include "utilities/hashtable.inline.hpp" 44 #include "utilities/numberSeq.hpp" 45 46 47 // This hashtable is implemented as an open hash table with a fixed number of buckets. 48 49 template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry_free_list() { 50 BasicHashtableEntry<F>* entry = NULL; 51 if (_free_list != NULL) { 52 entry = _free_list; 53 _free_list = _free_list->next(); 54 } 55 return entry; 56 } 57 58 // HashtableEntrys are allocated in blocks to reduce the space overhead. 59 template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry(unsigned int hashValue) { 60 BasicHashtableEntry<F>* entry = new_entry_free_list(); 61 62 if (entry == NULL) { 63 if (_first_free_entry + _entry_size >= _end_block) { 64 int block_size = MIN2(512, MAX2((int)_table_size / 2, (int)_number_of_entries)); 65 int len = _entry_size * block_size; 66 len = 1 << log2_int(len); // round down to power of 2 67 assert(len >= _entry_size, ""); 68 _first_free_entry = NEW_C_HEAP_ARRAY2(char, len, F, CURRENT_PC); 69 _entry_blocks->append(_first_free_entry); 70 _end_block = _first_free_entry + len; 71 } 72 entry = (BasicHashtableEntry<F>*)_first_free_entry; 73 _first_free_entry += _entry_size; 74 } 75 76 assert(_entry_size % HeapWordSize == 0, ""); 77 entry->set_hash(hashValue); 78 return entry; 79 } 80 81 82 template <class T, MEMFLAGS F> HashtableEntry<T, F>* Hashtable<T, F>::new_entry(unsigned int hashValue, T obj) { 83 HashtableEntry<T, F>* entry; 84 85 entry = (HashtableEntry<T, F>*)BasicHashtable<F>::new_entry(hashValue); 86 entry->set_literal(obj); 87 return entry; 88 } 89 90 // Version of hashtable entry allocation that allocates in the C heap directly. 91 // The block allocator in BasicHashtable has less fragmentation, but the memory is not freed until 92 // the whole table is freed. Use allocate_new_entry() if you want to individually free the memory 93 // used by each entry 94 template <class T, MEMFLAGS F> HashtableEntry<T, F>* Hashtable<T, F>::allocate_new_entry(unsigned int hashValue, T obj) { 95 HashtableEntry<T, F>* entry = (HashtableEntry<T, F>*) NEW_C_HEAP_ARRAY(char, this->entry_size(), F); 96 97 entry->set_hash(hashValue); 98 entry->set_literal(obj); 99 entry->set_next(NULL); 100 return entry; 101 } 102 103 template <MEMFLAGS F> void BasicHashtable<F>::free_buckets() { 104 if (NULL != _buckets) { 105 FREE_C_HEAP_ARRAY(HashtableBucket, _buckets); 106 _buckets = NULL; 107 } 108 } 109 110 // For oops and Strings the size of the literal is interesting. For other types, nobody cares. 111 static int literal_size(ConstantPool*) { return 0; } 112 static int literal_size(Klass*) { return 0; } 113 static int literal_size(nmethod*) { return 0; } 114 115 static int literal_size(Symbol *symbol) { 116 return symbol->size() * HeapWordSize; 117 } 118 119 static int literal_size(oop obj) { 120 // NOTE: this would over-count if (pre-JDK8) java_lang_Class::has_offset_field() is true, 121 // and the String.value array is shared by several Strings. However, starting from JDK8, 122 // the String.value array is not shared anymore. 123 if (obj == NULL) { 124 return 0; 125 } else if (obj->klass() == SystemDictionary::String_klass()) { 126 return (obj->size() + java_lang_String::value(obj)->size()) * HeapWordSize; 127 } else { 128 return obj->size(); 129 } 130 } 131 132 static int literal_size(WeakHandle<vm_class_loader_data> v) { 133 return literal_size(v.peek()); 134 } 135 136 template <MEMFLAGS F> bool BasicHashtable<F>::resize(int new_size) { 137 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 138 139 // Allocate new buckets 140 HashtableBucket<F>* buckets_new = NEW_C_HEAP_ARRAY2_RETURN_NULL(HashtableBucket<F>, new_size, F, CURRENT_PC); 141 if (buckets_new == NULL) { 142 return false; 143 } 144 145 // Clear the new buckets 146 for (int i = 0; i < new_size; i++) { 147 buckets_new[i].clear(); 148 } 149 150 int table_size_old = _table_size; 151 // hash_to_index() uses _table_size, so switch the sizes now 152 _table_size = new_size; 153 154 // Move entries from the old table to a new table 155 for (int index_old = 0; index_old < table_size_old; index_old++) { 156 for (BasicHashtableEntry<F>* p = _buckets[index_old].get_entry(); p != NULL; ) { 157 BasicHashtableEntry<F>* next = p->next(); 158 bool keep_shared = p->is_shared(); 159 int index_new = hash_to_index(p->hash()); 160 161 p->set_next(buckets_new[index_new].get_entry()); 162 buckets_new[index_new].set_entry(p); 163 164 if (keep_shared) { 165 p->set_shared(); 166 } 167 p = next; 168 } 169 } 170 171 // The old backets now can be released 172 BasicHashtable<F>::free_buckets(); 173 174 // Switch to the new storage 175 _buckets = buckets_new; 176 177 return true; 178 } 179 180 template <MEMFLAGS F> bool BasicHashtable<F>::maybe_grow(int max_size, int load_factor) { 181 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); 182 183 if (table_size() >= max_size) { 184 return false; 185 } 186 if (number_of_entries() / table_size() > load_factor) { 187 resize(MIN2<int>(table_size() * 2, max_size)); 188 return true; 189 } else { 190 return false; 191 } 192 } 193 194 template <class T, MEMFLAGS F> TableStatistics Hashtable<T, F>::statistics_calculate(T (*literal_load_barrier)(HashtableEntry<T, F>*)) { 195 NumberSeq summary; 196 int literal_bytes = 0; 197 for (int i = 0; i < this->table_size(); ++i) { 198 int count = 0; 199 for (HashtableEntry<T, F>* e = this->bucket(i); 200 e != NULL; e = e->next()) { 201 count++; 202 T l = (literal_load_barrier != NULL) ? literal_load_barrier(e) : e->literal(); 203 literal_bytes += literal_size(l); 204 } 205 summary.add((double)count); 206 } 207 return TableStatistics(this->_stats_rate, summary, literal_bytes, sizeof(HashtableBucket<F>), sizeof(HashtableEntry<T, F>)); 208 } 209 210 // Dump footprint and bucket length statistics 211 // 212 // Note: if you create a new subclass of Hashtable<MyNewType, F>, you will need to 213 // add a new function static int literal_size(MyNewType lit) 214 // because I can't get template <class T> int literal_size(T) to pick the specializations for Symbol and oop. 215 template <class T, MEMFLAGS F> void Hashtable<T, F>::print_table_statistics(outputStream* st, 216 const char *table_name, 217 T (*literal_load_barrier)(HashtableEntry<T, F>*)) { 218 TableStatistics ts = statistics_calculate(literal_load_barrier); 219 ts.print(st, table_name); 220 } 221 222 #ifndef PRODUCT 223 template <class T> void print_literal(T l) { 224 l->print(); 225 } 226 227 static void print_literal(WeakHandle<vm_class_loader_data> l) { 228 l.print(); 229 } 230 231 template <class T, MEMFLAGS F> void Hashtable<T, F>::print() { 232 ResourceMark rm; 233 234 for (int i = 0; i < BasicHashtable<F>::table_size(); i++) { 235 HashtableEntry<T, F>* entry = bucket(i); 236 while(entry != NULL) { 237 tty->print("%d : ", i); 238 print_literal(entry->literal()); 239 tty->cr(); 240 entry = entry->next(); 241 } 242 } 243 } 244 245 template <MEMFLAGS F> 246 template <class T> void BasicHashtable<F>::verify_table(const char* table_name) { 247 int element_count = 0; 248 int max_bucket_count = 0; 249 int max_bucket_number = 0; 250 for (int index = 0; index < table_size(); index++) { 251 int bucket_count = 0; 252 for (T* probe = (T*)bucket(index); probe != NULL; probe = probe->next()) { 253 probe->verify(); 254 bucket_count++; 255 } 256 element_count += bucket_count; 257 if (bucket_count > max_bucket_count) { 258 max_bucket_count = bucket_count; 259 max_bucket_number = index; 260 } 261 } 262 guarantee(number_of_entries() == element_count, 263 "Verify of %s failed", table_name); 264 265 // Log some statistics about the hashtable 266 log_info(hashtables)("%s max bucket size %d bucket %d element count %d table size %d", table_name, 267 max_bucket_count, max_bucket_number, _number_of_entries, _table_size); 268 if (_number_of_entries > 0 && log_is_enabled(Debug, hashtables)) { 269 for (int index = 0; index < table_size(); index++) { 270 int bucket_count = 0; 271 for (T* probe = (T*)bucket(index); probe != NULL; probe = probe->next()) { 272 log_debug(hashtables)("bucket %d hash " INTPTR_FORMAT, index, (intptr_t)probe->hash()); 273 bucket_count++; 274 } 275 if (bucket_count > 0) { 276 log_debug(hashtables)("bucket %d count %d", index, bucket_count); 277 } 278 } 279 } 280 } 281 #endif // PRODUCT 282 283 // Explicitly instantiate these types 284 template class Hashtable<nmethod*, mtGC>; 285 template class HashtableEntry<nmethod*, mtGC>; 286 template class BasicHashtable<mtGC>; 287 template class Hashtable<ConstantPool*, mtClass>; 288 template class Hashtable<Symbol*, mtSymbol>; 289 template class Hashtable<Klass*, mtClass>; 290 template class Hashtable<InstanceKlass*, mtClass>; 291 template class Hashtable<WeakHandle<vm_class_loader_data>, mtClass>; 292 template class Hashtable<Symbol*, mtModule>; 293 template class Hashtable<oop, mtSymbol>; 294 template class Hashtable<Symbol*, mtClass>; 295 template class HashtableEntry<Symbol*, mtSymbol>; 296 template class HashtableEntry<Symbol*, mtClass>; 297 template class HashtableEntry<oop, mtSymbol>; 298 template class HashtableEntry<WeakHandle<vm_class_loader_data>, mtClass>; 299 template class HashtableBucket<mtClass>; 300 template class BasicHashtableEntry<mtSymbol>; 301 template class BasicHashtableEntry<mtCode>; 302 template class BasicHashtable<mtClass>; 303 template class BasicHashtable<mtClassShared>; 304 template class BasicHashtable<mtSymbol>; 305 template class BasicHashtable<mtCode>; 306 template class BasicHashtable<mtInternal>; 307 template class BasicHashtable<mtModule>; 308 template class BasicHashtable<mtCompiler>; 309 template class BasicHashtable<mtTracing>; 310 311 template void BasicHashtable<mtClass>::verify_table<DictionaryEntry>(char const*); 312 template void BasicHashtable<mtModule>::verify_table<ModuleEntry>(char const*); 313 template void BasicHashtable<mtModule>::verify_table<PackageEntry>(char const*); 314 template void BasicHashtable<mtClass>::verify_table<ProtectionDomainCacheEntry>(char const*); 315 template void BasicHashtable<mtClass>::verify_table<PlaceholderEntry>(char const*);