1 /* 2 * Copyright (c) 2003, 2018, 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_UTILITIES_HASHTABLE_HPP 26 #define SHARE_VM_UTILITIES_HASHTABLE_HPP 27 28 #include "memory/allocation.hpp" 29 #include "oops/oop.hpp" 30 #include "oops/symbol.hpp" 31 #include "runtime/handles.hpp" 32 #include "utilities/growableArray.hpp" 33 34 // This is a generic hashtable, designed to be used for the symbol 35 // and string tables. 36 // 37 // It is implemented as an open hash table with a fixed number of buckets. 38 // 39 // %note: 40 // - TableEntrys are allocated in blocks to reduce the space overhead. 41 42 43 44 template <MEMFLAGS F> class BasicHashtableEntry : public CHeapObj<F> { 45 friend class VMStructs; 46 private: 47 unsigned int _hash; // 32-bit hash for item 48 49 // Link to next element in the linked list for this bucket. EXCEPT 50 // bit 0 set indicates that this entry is shared and must not be 51 // unlinked from the table. Bit 0 is set during the dumping of the 52 // archive. Since shared entries are immutable, _next fields in the 53 // shared entries will not change. New entries will always be 54 // unshared and since pointers are align, bit 0 will always remain 0 55 // with no extra effort. 56 BasicHashtableEntry<F>* _next; 57 58 // Windows IA64 compiler requires subclasses to be able to access these 59 protected: 60 // Entry objects should not be created, they should be taken from the 61 // free list with BasicHashtable.new_entry(). 62 BasicHashtableEntry() { ShouldNotReachHere(); } 63 // Entry objects should not be destroyed. They should be placed on 64 // the free list instead with BasicHashtable.free_entry(). 65 ~BasicHashtableEntry() { ShouldNotReachHere(); } 66 67 public: 68 69 unsigned int hash() const { return _hash; } 70 void set_hash(unsigned int hash) { _hash = hash; } 71 unsigned int* hash_addr() { return &_hash; } 72 73 static BasicHashtableEntry<F>* make_ptr(BasicHashtableEntry<F>* p) { 74 return (BasicHashtableEntry*)((intptr_t)p & -2); 75 } 76 77 BasicHashtableEntry<F>* next() const { 78 return make_ptr(_next); 79 } 80 81 void set_next(BasicHashtableEntry<F>* next) { 82 _next = next; 83 } 84 85 BasicHashtableEntry<F>** next_addr() { 86 return &_next; 87 } 88 89 bool is_shared() const { 90 return ((intptr_t)_next & 1) != 0; 91 } 92 93 void set_shared() { 94 _next = (BasicHashtableEntry<F>*)((intptr_t)_next | 1); 95 } 96 }; 97 98 99 100 template <class T, MEMFLAGS F> class HashtableEntry : public BasicHashtableEntry<F> { 101 friend class VMStructs; 102 private: 103 T _literal; // ref to item in table. 104 105 public: 106 // Literal 107 T literal() const { return _literal; } 108 T* literal_addr() { return &_literal; } 109 void set_literal(T s) { _literal = s; } 110 111 HashtableEntry* next() const { 112 return (HashtableEntry*)BasicHashtableEntry<F>::next(); 113 } 114 HashtableEntry** next_addr() { 115 return (HashtableEntry**)BasicHashtableEntry<F>::next_addr(); 116 } 117 }; 118 119 120 121 template <MEMFLAGS F> class HashtableBucket : public CHeapObj<F> { 122 friend class VMStructs; 123 private: 124 // Instance variable 125 BasicHashtableEntry<F>* _entry; 126 127 public: 128 // Accessing 129 void clear() { _entry = NULL; } 130 131 // The following methods use order access methods to avoid race 132 // conditions in multiprocessor systems. 133 BasicHashtableEntry<F>* get_entry() const; 134 void set_entry(BasicHashtableEntry<F>* l); 135 136 // The following method is not MT-safe and must be done under lock. 137 BasicHashtableEntry<F>** entry_addr() { return &_entry; } 138 139 }; 140 141 142 template <MEMFLAGS F> class BasicHashtable : public CHeapObj<F> { 143 friend class VMStructs; 144 145 public: 146 BasicHashtable(int table_size, int entry_size); 147 BasicHashtable(int table_size, int entry_size, 148 HashtableBucket<F>* buckets, int number_of_entries); 149 ~BasicHashtable(); 150 151 // Bucket handling 152 int hash_to_index(unsigned int full_hash) const { 153 int h = full_hash % _table_size; 154 assert(h >= 0 && h < _table_size, "Illegal hash value"); 155 return h; 156 } 157 158 private: 159 // Instance variables 160 int _table_size; 161 HashtableBucket<F>* _buckets; 162 BasicHashtableEntry<F>* volatile _free_list; 163 char* _first_free_entry; 164 char* _end_block; 165 int _entry_size; 166 volatile int _number_of_entries; 167 GrowableArray<char*>* _entry_blocks; 168 169 protected: 170 171 void initialize(int table_size, int entry_size, int number_of_entries); 172 173 // Accessor 174 int entry_size() const { return _entry_size; } 175 176 // The following method is MT-safe and may be used with caution. 177 BasicHashtableEntry<F>* bucket(int i) const; 178 179 // The following method is not MT-safe and must be done under lock. 180 BasicHashtableEntry<F>** bucket_addr(int i) { return _buckets[i].entry_addr(); } 181 182 // Attempt to get an entry from the free list 183 BasicHashtableEntry<F>* new_entry_free_list(); 184 185 // Table entry management 186 BasicHashtableEntry<F>* new_entry(unsigned int hashValue); 187 188 // Used when moving the entry to another table 189 // Clean up links, but do not add to free_list 190 void unlink_entry(BasicHashtableEntry<F>* entry) { 191 entry->set_next(NULL); 192 --_number_of_entries; 193 } 194 195 // Move over freelist and free block for allocation 196 void copy_freelist(BasicHashtable* src) { 197 _free_list = src->_free_list; 198 src->_free_list = NULL; 199 _first_free_entry = src->_first_free_entry; 200 src->_first_free_entry = NULL; 201 _end_block = src->_end_block; 202 src->_end_block = NULL; 203 } 204 205 // Free the buckets in this hashtable 206 void free_buckets(); 207 208 // Helper data structure containing context for the bucket entry unlink process, 209 // storing the unlinked buckets in a linked list. 210 // Also avoids the need to pass around these four members as parameters everywhere. 211 struct BucketUnlinkContext { 212 int _num_processed; 213 int _num_removed; 214 // Head and tail pointers for the linked list of removed entries. 215 BasicHashtableEntry<F>* _removed_head; 216 BasicHashtableEntry<F>* _removed_tail; 217 218 BucketUnlinkContext() : _num_processed(0), _num_removed(0), _removed_head(NULL), _removed_tail(NULL) { 219 } 220 221 void free_entry(BasicHashtableEntry<F>* entry); 222 }; 223 // Add of bucket entries linked together in the given context to the global free list. This method 224 // is mt-safe wrt. to other calls of this method. 225 void bulk_free_entries(BucketUnlinkContext* context); 226 public: 227 int table_size() const { return _table_size; } 228 void set_entry(int index, BasicHashtableEntry<F>* entry); 229 230 void add_entry(int index, BasicHashtableEntry<F>* entry); 231 232 void free_entry(BasicHashtableEntry<F>* entry); 233 234 int number_of_entries() const { return _number_of_entries; } 235 236 bool resize(int new_size); 237 238 // Grow the number of buckets if the average entries per bucket is over the load_factor 239 bool maybe_grow(int load_factor = 8) { 240 if (number_of_entries() / table_size() > load_factor) { 241 resize(table_size() * 2); 242 return true; 243 } else { 244 return false; 245 } 246 } 247 248 template <class T> void verify_table(const char* table_name) PRODUCT_RETURN; 249 }; 250 251 252 template <class T, MEMFLAGS F> class Hashtable : public BasicHashtable<F> { 253 friend class VMStructs; 254 255 public: 256 Hashtable(int table_size, int entry_size) 257 : BasicHashtable<F>(table_size, entry_size) { } 258 259 Hashtable(int table_size, int entry_size, 260 HashtableBucket<F>* buckets, int number_of_entries) 261 : BasicHashtable<F>(table_size, entry_size, buckets, number_of_entries) { } 262 263 // Debugging 264 void print() PRODUCT_RETURN; 265 266 unsigned int compute_hash(const Symbol* name) const { 267 return (unsigned int) name->identity_hash(); 268 } 269 270 int index_for(const Symbol* name) const { 271 return this->hash_to_index(compute_hash(name)); 272 } 273 274 void print_table_statistics(outputStream* st, const char *table_name, T (*literal_load_barrier)(HashtableEntry<T, F>*) = NULL); 275 276 protected: 277 278 // Table entry management 279 HashtableEntry<T, F>* new_entry(unsigned int hashValue, T obj); 280 // Don't create and use freelist of HashtableEntry. 281 HashtableEntry<T, F>* allocate_new_entry(unsigned int hashValue, T obj); 282 283 // The following method is MT-safe and may be used with caution. 284 HashtableEntry<T, F>* bucket(int i) const { 285 return (HashtableEntry<T, F>*)BasicHashtable<F>::bucket(i); 286 } 287 288 // The following method is not MT-safe and must be done under lock. 289 HashtableEntry<T, F>** bucket_addr(int i) { 290 return (HashtableEntry<T, F>**)BasicHashtable<F>::bucket_addr(i); 291 } 292 }; 293 294 // A subclass of BasicHashtable that allows you to do a simple K -> V mapping 295 // without using tons of boilerplate code. 296 template< 297 typename K, typename V, MEMFLAGS F, 298 unsigned (*HASH) (K const&) = primitive_hash<K>, 299 bool (*EQUALS)(K const&, K const&) = primitive_equals<K> 300 > 301 class KVHashtable : public BasicHashtable<F> { 302 class KVHashtableEntry : public BasicHashtableEntry<F> { 303 public: 304 K _key; 305 V _value; 306 KVHashtableEntry* next() { 307 return (KVHashtableEntry*)BasicHashtableEntry<F>::next(); 308 } 309 }; 310 311 protected: 312 KVHashtableEntry* bucket(int i) const { 313 return (KVHashtableEntry*)BasicHashtable<F>::bucket(i); 314 } 315 316 KVHashtableEntry* new_entry(unsigned int hashValue, K key, V value) { 317 KVHashtableEntry* entry = (KVHashtableEntry*)BasicHashtable<F>::new_entry(hashValue); 318 entry->_key = key; 319 entry->_value = value; 320 return entry; 321 } 322 323 public: 324 KVHashtable(int table_size) : BasicHashtable<F>(table_size, sizeof(KVHashtableEntry)) {} 325 326 void add(K key, V value) { 327 unsigned int hash = HASH(key); 328 KVHashtableEntry* entry = new_entry(hash, key, value); 329 BasicHashtable<F>::add_entry(BasicHashtable<F>::hash_to_index(hash), entry); 330 } 331 332 V* lookup(K key) { 333 unsigned int hash = HASH(key); 334 int index = BasicHashtable<F>::hash_to_index(hash); 335 for (KVHashtableEntry* e = bucket(index); e != NULL; e = e->next()) { 336 if (e->hash() == hash && e->_key == key) { 337 return &(e->_value); 338 } 339 } 340 return NULL; 341 } 342 }; 343 344 345 #endif // SHARE_VM_UTILITIES_HASHTABLE_HPP