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 #ifndef SHARE_UTILITIES_HASHTABLE_HPP 26 #define SHARE_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 #include "utilities/tableStatistics.hpp" 34 35 // This is a generic hashtable, designed to be used for the symbol 36 // and string tables. 37 // 38 // It is implemented as an open hash table with a fixed number of buckets. 39 // 40 // %note: 41 // - TableEntrys are allocated in blocks to reduce the space overhead. 42 43 44 45 template <MEMFLAGS F> class BasicHashtableEntry : public CHeapObj<F> { 46 friend class VMStructs; 47 private: 48 unsigned int _hash; // 32-bit hash for item 49 50 // Link to next element in the linked list for this bucket. EXCEPT 51 // bit 0 set indicates that this entry is shared and must not be 52 // unlinked from the table. Bit 0 is set during the dumping of the 53 // archive. Since shared entries are immutable, _next fields in the 54 // shared entries will not change. New entries will always be 55 // unshared and since pointers are align, bit 0 will always remain 0 56 // with no extra effort. 57 BasicHashtableEntry<F>* _next; 58 59 // Windows IA64 compiler requires subclasses to be able to access these 60 protected: 61 // Entry objects should not be created, they should be taken from the 62 // free list with BasicHashtable.new_entry(). BasicHashtableEntry()63 BasicHashtableEntry() { ShouldNotReachHere(); } 64 // Entry objects should not be destroyed. They should be placed on 65 // the free list instead with BasicHashtable.free_entry(). ~BasicHashtableEntry()66 ~BasicHashtableEntry() { ShouldNotReachHere(); } 67 68 public: 69 hash() const70 unsigned int hash() const { return _hash; } set_hash(unsigned int hash)71 void set_hash(unsigned int hash) { _hash = hash; } hash_addr()72 unsigned int* hash_addr() { return &_hash; } 73 make_ptr(BasicHashtableEntry<F> * p)74 static BasicHashtableEntry<F>* make_ptr(BasicHashtableEntry<F>* p) { 75 return (BasicHashtableEntry*)((intptr_t)p & -2); 76 } 77 next() const78 BasicHashtableEntry<F>* next() const { 79 return make_ptr(_next); 80 } 81 set_next(BasicHashtableEntry<F> * next)82 void set_next(BasicHashtableEntry<F>* next) { 83 _next = next; 84 } 85 next_addr()86 BasicHashtableEntry<F>** next_addr() { 87 return &_next; 88 } 89 is_shared() const90 bool is_shared() const { 91 return ((intptr_t)_next & 1) != 0; 92 } 93 set_shared()94 void set_shared() { 95 _next = (BasicHashtableEntry<F>*)((intptr_t)_next | 1); 96 } 97 }; 98 99 100 101 template <class T, MEMFLAGS F> class HashtableEntry : public BasicHashtableEntry<F> { 102 friend class VMStructs; 103 private: 104 T _literal; // ref to item in table. 105 106 public: 107 // Literal literal() const108 T literal() const { return _literal; } literal_addr()109 T* literal_addr() { return &_literal; } set_literal(T s)110 void set_literal(T s) { _literal = s; } 111 next() const112 HashtableEntry* next() const { 113 return (HashtableEntry*)BasicHashtableEntry<F>::next(); 114 } next_addr()115 HashtableEntry** next_addr() { 116 return (HashtableEntry**)BasicHashtableEntry<F>::next_addr(); 117 } 118 }; 119 120 121 122 template <MEMFLAGS F> class HashtableBucket : public CHeapObj<F> { 123 friend class VMStructs; 124 private: 125 // Instance variable 126 BasicHashtableEntry<F>* _entry; 127 128 public: 129 // Accessing clear()130 void clear() { _entry = NULL; } 131 132 // The following methods use order access methods to avoid race 133 // conditions in multiprocessor systems. 134 BasicHashtableEntry<F>* get_entry() const; 135 void set_entry(BasicHashtableEntry<F>* l); 136 137 // The following method is not MT-safe and must be done under lock. entry_addr()138 BasicHashtableEntry<F>** entry_addr() { return &_entry; } 139 140 }; 141 142 143 template <MEMFLAGS F> class BasicHashtable : public CHeapObj<F> { 144 friend class VMStructs; 145 146 public: 147 BasicHashtable(int table_size, int entry_size); 148 BasicHashtable(int table_size, int entry_size, 149 HashtableBucket<F>* buckets, int number_of_entries); 150 ~BasicHashtable(); 151 152 // Bucket handling hash_to_index(unsigned int full_hash) const153 int hash_to_index(unsigned int full_hash) const { 154 int h = full_hash % _table_size; 155 assert(h >= 0 && h < _table_size, "Illegal hash value"); 156 return h; 157 } 158 159 private: 160 // Instance variables 161 int _table_size; 162 HashtableBucket<F>* _buckets; 163 BasicHashtableEntry<F>* volatile _free_list; 164 char* _first_free_entry; 165 char* _end_block; 166 int _entry_size; 167 volatile int _number_of_entries; 168 GrowableArray<char*>* _entry_blocks; 169 170 protected: 171 172 TableRateStatistics _stats_rate; 173 174 void initialize(int table_size, int entry_size, int number_of_entries); 175 176 // Accessor entry_size() const177 int entry_size() const { return _entry_size; } 178 179 // The following method is MT-safe and may be used with caution. 180 BasicHashtableEntry<F>* bucket(int i) const; 181 182 // The following method is not MT-safe and must be done under lock. bucket_addr(int i)183 BasicHashtableEntry<F>** bucket_addr(int i) { return _buckets[i].entry_addr(); } 184 185 // Attempt to get an entry from the free list 186 BasicHashtableEntry<F>* new_entry_free_list(); 187 188 // Table entry management 189 BasicHashtableEntry<F>* new_entry(unsigned int hashValue); 190 191 // Used when moving the entry to another table 192 // Clean up links, but do not add to free_list unlink_entry(BasicHashtableEntry<F> * entry)193 void unlink_entry(BasicHashtableEntry<F>* entry) { 194 entry->set_next(NULL); 195 --_number_of_entries; 196 } 197 198 // Move over freelist and free block for allocation copy_freelist(BasicHashtable * src)199 void copy_freelist(BasicHashtable* src) { 200 _free_list = src->_free_list; 201 src->_free_list = NULL; 202 _first_free_entry = src->_first_free_entry; 203 src->_first_free_entry = NULL; 204 _end_block = src->_end_block; 205 src->_end_block = NULL; 206 } 207 208 // Free the buckets in this hashtable 209 void free_buckets(); 210 public: table_size() const211 int table_size() const { return _table_size; } 212 void set_entry(int index, BasicHashtableEntry<F>* entry); 213 214 void add_entry(int index, BasicHashtableEntry<F>* entry); 215 216 void free_entry(BasicHashtableEntry<F>* entry); 217 number_of_entries() const218 int number_of_entries() const { return _number_of_entries; } 219 220 bool resize(int new_size); 221 222 // Grow the number of buckets if the average entries per bucket is over the load_factor 223 bool maybe_grow(int max_size, int load_factor = 8); 224 225 template <class T> void verify_table(const char* table_name) PRODUCT_RETURN; 226 }; 227 228 229 template <class T, MEMFLAGS F> class Hashtable : public BasicHashtable<F> { 230 friend class VMStructs; 231 232 public: Hashtable(int table_size,int entry_size)233 Hashtable(int table_size, int entry_size) 234 : BasicHashtable<F>(table_size, entry_size) { } 235 Hashtable(int table_size,int entry_size,HashtableBucket<F> * buckets,int number_of_entries)236 Hashtable(int table_size, int entry_size, 237 HashtableBucket<F>* buckets, int number_of_entries) 238 : BasicHashtable<F>(table_size, entry_size, buckets, number_of_entries) { } 239 240 // Debugging 241 void print() PRODUCT_RETURN; 242 compute_hash(const Symbol * name) const243 unsigned int compute_hash(const Symbol* name) const { 244 return (unsigned int) name->identity_hash(); 245 } 246 index_for(const Symbol * name) const247 int index_for(const Symbol* name) const { 248 return this->hash_to_index(compute_hash(name)); 249 } 250 251 TableStatistics statistics_calculate(T (*literal_load_barrier)(HashtableEntry<T, F>*) = NULL); 252 void print_table_statistics(outputStream* st, const char *table_name, T (*literal_load_barrier)(HashtableEntry<T, F>*) = NULL); 253 254 protected: 255 256 // Table entry management 257 HashtableEntry<T, F>* new_entry(unsigned int hashValue, T obj); 258 // Don't create and use freelist of HashtableEntry. 259 HashtableEntry<T, F>* allocate_new_entry(unsigned int hashValue, T obj); 260 261 // The following method is MT-safe and may be used with caution. bucket(int i) const262 HashtableEntry<T, F>* bucket(int i) const { 263 return (HashtableEntry<T, F>*)BasicHashtable<F>::bucket(i); 264 } 265 266 // The following method is not MT-safe and must be done under lock. bucket_addr(int i)267 HashtableEntry<T, F>** bucket_addr(int i) { 268 return (HashtableEntry<T, F>**)BasicHashtable<F>::bucket_addr(i); 269 } 270 }; 271 272 // A subclass of BasicHashtable that allows you to do a simple K -> V mapping 273 // without using tons of boilerplate code. 274 template< 275 typename K, typename V, MEMFLAGS F, 276 unsigned (*HASH) (K const&) = primitive_hash<K>, 277 bool (*EQUALS)(K const&, K const&) = primitive_equals<K> 278 > 279 class KVHashtable : public BasicHashtable<F> { 280 class KVHashtableEntry : public BasicHashtableEntry<F> { 281 public: 282 K _key; 283 V _value; next()284 KVHashtableEntry* next() { 285 return (KVHashtableEntry*)BasicHashtableEntry<F>::next(); 286 } 287 }; 288 289 protected: bucket(int i) const290 KVHashtableEntry* bucket(int i) const { 291 return (KVHashtableEntry*)BasicHashtable<F>::bucket(i); 292 } 293 new_entry(unsigned int hashValue,K key,V value)294 KVHashtableEntry* new_entry(unsigned int hashValue, K key, V value) { 295 KVHashtableEntry* entry = (KVHashtableEntry*)BasicHashtable<F>::new_entry(hashValue); 296 entry->_key = key; 297 entry->_value = value; 298 return entry; 299 } 300 301 public: KVHashtable(int table_size)302 KVHashtable(int table_size) : BasicHashtable<F>(table_size, sizeof(KVHashtableEntry)) {} 303 add(K key,V value)304 void add(K key, V value) { 305 unsigned int hash = HASH(key); 306 KVHashtableEntry* entry = new_entry(hash, key, value); 307 BasicHashtable<F>::add_entry(BasicHashtable<F>::hash_to_index(hash), entry); 308 } 309 lookup(K key)310 V* lookup(K key) { 311 unsigned int hash = HASH(key); 312 int index = BasicHashtable<F>::hash_to_index(hash); 313 for (KVHashtableEntry* e = bucket(index); e != NULL; e = e->next()) { 314 if (e->hash() == hash && e->_key == key) { 315 return &(e->_value); 316 } 317 } 318 return NULL; 319 } 320 }; 321 322 323 #endif // SHARE_UTILITIES_HASHTABLE_HPP 324