hashtable.hpp revision 13059:cb443f7d564f
165285Siwasaki/* 265285Siwasaki * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved. 365285Siwasaki * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 465285Siwasaki * 565285Siwasaki * This code is free software; you can redistribute it and/or modify it 665285Siwasaki * under the terms of the GNU General Public License version 2 only, as 765285Siwasaki * published by the Free Software Foundation. 865285Siwasaki * 965285Siwasaki * This code is distributed in the hope that it will be useful, but WITHOUT 1065285Siwasaki * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 1165285Siwasaki * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 1265285Siwasaki * version 2 for more details (a copy is included in the LICENSE file that 1365285Siwasaki * accompanied this code). 1465285Siwasaki * 1565285Siwasaki * You should have received a copy of the GNU General Public License version 1665285Siwasaki * 2 along with this work; if not, write to the Free Software Foundation, 1765285Siwasaki * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 1865285Siwasaki * 1965285Siwasaki * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 2065285Siwasaki * or visit www.oracle.com if you need additional information or have any 2165285Siwasaki * questions. 2265285Siwasaki * 2365285Siwasaki */ 2465285Siwasaki 2565285Siwasaki#ifndef SHARE_VM_UTILITIES_HASHTABLE_HPP 2665285Siwasaki#define SHARE_VM_UTILITIES_HASHTABLE_HPP 2765285Siwasaki 2865285Siwasaki#include "classfile/classLoaderData.hpp" 2965285Siwasaki#include "memory/allocation.hpp" 3065285Siwasaki#include "oops/oop.hpp" 31196555Sjhb#include "oops/symbol.hpp" 3265285Siwasaki#include "runtime/handles.hpp" 33196555Sjhb 34196555Sjhb// This is a generic hashtable, designed to be used for the symbol 35196555Sjhb// and string tables. 3668475Siwasaki// 37196555Sjhb// It is implemented as an open hash table with a fixed number of buckets. 38196555Sjhb// 39196555Sjhb// %note: 40196555Sjhb// - TableEntrys are allocated in blocks to reduce the space overhead. 41196555Sjhb 42196555Sjhb 43196555Sjhb 44196555Sjhbtemplate <MEMFLAGS F> class BasicHashtableEntry : public CHeapObj<F> { 45196555Sjhb friend class VMStructs; 46196555Sjhbprivate: 4768475Siwasaki unsigned int _hash; // 32-bit hash for item 48196555Sjhb 49196555Sjhb // Link to next element in the linked list for this bucket. EXCEPT 50196555Sjhb // bit 0 set indicates that this entry is shared and must not be 51196555Sjhb // unlinked from the table. Bit 0 is set during the dumping of the 52196555Sjhb // archive. Since shared entries are immutable, _next fields in the 53196555Sjhb // shared entries will not change. New entries will always be 5468475Siwasaki // unshared and since pointers are align, bit 0 will always remain 0 55119515Snjl // with no extra effort. 56196555Sjhb BasicHashtableEntry<F>* _next; 57119515Snjl 58211196Stakawata // Windows IA64 compiler requires subclasses to be able to access these 59211196Stakawataprotected: 60211196Stakawata // Entry objects should not be created, they should be taken from the 61211196Stakawata // free list with BasicHashtable.new_entry(). 62211196Stakawata BasicHashtableEntry() { ShouldNotReachHere(); } 63211196Stakawata // Entry objects should not be destroyed. They should be placed on 64211196Stakawata // the free list instead with BasicHashtable.free_entry(). 65211196Stakawata ~BasicHashtableEntry() { ShouldNotReachHere(); } 66211196Stakawata 67211196Stakawatapublic: 68211196Stakawata 69211196Stakawata unsigned int hash() const { return _hash; } 70211196Stakawata void set_hash(unsigned int hash) { _hash = hash; } 71211196Stakawata unsigned int* hash_addr() { return &_hash; } 72211196Stakawata 73211196Stakawata static BasicHashtableEntry<F>* make_ptr(BasicHashtableEntry<F>* p) { 74211196Stakawata return (BasicHashtableEntry*)((intptr_t)p & -2); 75211196Stakawata } 76211196Stakawata 77211196Stakawata BasicHashtableEntry<F>* next() const { 78211196Stakawata return make_ptr(_next); 79211196Stakawata } 80211196Stakawata 81211196Stakawata void set_next(BasicHashtableEntry<F>* next) { 82211196Stakawata _next = next; 83211196Stakawata } 84211196Stakawata 85211196Stakawata BasicHashtableEntry<F>** next_addr() { 86211196Stakawata return &_next; 87211196Stakawata } 88211196Stakawata 89211196Stakawata bool is_shared() const { 90211196Stakawata return ((intptr_t)_next & 1) != 0; 91211196Stakawata } 92211196Stakawata 93211196Stakawata void set_shared() { 94211196Stakawata _next = (BasicHashtableEntry<F>*)((intptr_t)_next | 1); 95211196Stakawata } 96211196Stakawata}; 97211196Stakawata 98211196Stakawata 99211196Stakawata 100211196Stakawatatemplate <class T, MEMFLAGS F> class HashtableEntry : public BasicHashtableEntry<F> { 101211196Stakawata friend class VMStructs; 102211196Stakawataprivate: 103211196Stakawata T _literal; // ref to item in table. 104211196Stakawata 105211196Stakawatapublic: 106211196Stakawata // Literal 107211196Stakawata T literal() const { return _literal; } 108211196Stakawata T* literal_addr() { return &_literal; } 109211196Stakawata void set_literal(T s) { _literal = s; } 110211196Stakawata 111211196Stakawata HashtableEntry* next() const { 112211196Stakawata return (HashtableEntry*)BasicHashtableEntry<F>::next(); 113211196Stakawata } 114211196Stakawata HashtableEntry** next_addr() { 115211196Stakawata return (HashtableEntry**)BasicHashtableEntry<F>::next_addr(); 116211196Stakawata } 117211196Stakawata}; 118211196Stakawata 119211196Stakawata 120211196Stakawata 121211196Stakawatatemplate <MEMFLAGS F> class HashtableBucket : public CHeapObj<F> { 122211196Stakawata friend class VMStructs; 123211196Stakawataprivate: 124211196Stakawata // Instance variable 125211196Stakawata BasicHashtableEntry<F>* _entry; 126211196Stakawata 127211196Stakawata#ifdef ASSERT 128211196Stakawataprivate: 129211196Stakawata unsigned _hits; 130119515Snjlpublic: 131119515Snjl unsigned hits() { return _hits; } 132119515Snjl void count_hit() { _hits++; } 133119515Snjl#endif 134196555Sjhb 135119515Snjlpublic: 136119515Snjl // Accessing 137196555Sjhb void clear() { _entry = NULL; DEBUG_ONLY(_hits = 0); } 138119515Snjl 139119515Snjl // The following methods use order access methods to avoid race 140196555Sjhb // conditions in multiprocessor systems. 141119515Snjl BasicHashtableEntry<F>* get_entry() const; 142119515Snjl void set_entry(BasicHashtableEntry<F>* l); 143196555Sjhb 144119515Snjl // The following method is not MT-safe and must be done under lock. 145119515Snjl BasicHashtableEntry<F>** entry_addr() { return &_entry; } 146196555Sjhb 147196555Sjhb}; 148196555Sjhb 149196555Sjhb 150196555Sjhbtemplate <MEMFLAGS F> class BasicHashtable : public CHeapObj<F> { 151196555Sjhb friend class VMStructs; 152119515Snjl 153119515Snjlpublic: 154119515Snjl BasicHashtable(int table_size, int entry_size); 155119515Snjl BasicHashtable(int table_size, int entry_size, 156119515Snjl HashtableBucket<F>* buckets, int number_of_entries); 157119515Snjl 15865285Siwasaki // Sharing support. 159 void copy_buckets(char** top, char* end); 160 void copy_table(char** top, char* end); 161 162 // Bucket handling 163 int hash_to_index(unsigned int full_hash) const { 164 int h = full_hash % _table_size; 165 assert(h >= 0 && h < _table_size, "Illegal hash value"); 166 return h; 167 } 168 169private: 170 // Instance variables 171 int _table_size; 172 HashtableBucket<F>* _buckets; 173 BasicHashtableEntry<F>* _free_list; 174 char* _first_free_entry; 175 char* _end_block; 176 int _entry_size; 177 int _number_of_entries; 178 179protected: 180 181#ifdef ASSERT 182 bool _lookup_warning; 183 mutable int _lookup_count; 184 mutable int _lookup_length; 185 bool verify_lookup_length(double load, const char *table_name); 186#endif 187 188 void initialize(int table_size, int entry_size, int number_of_entries); 189 190 // Accessor 191 int entry_size() const { return _entry_size; } 192 193 // The following method is MT-safe and may be used with caution. 194 BasicHashtableEntry<F>* bucket(int i) const; 195 196 // The following method is not MT-safe and must be done under lock. 197 BasicHashtableEntry<F>** bucket_addr(int i) { return _buckets[i].entry_addr(); } 198 199 // Attempt to get an entry from the free list 200 BasicHashtableEntry<F>* new_entry_free_list(); 201 202 // Table entry management 203 BasicHashtableEntry<F>* new_entry(unsigned int hashValue); 204 205 // Used when moving the entry to another table 206 // Clean up links, but do not add to free_list 207 void unlink_entry(BasicHashtableEntry<F>* entry) { 208 entry->set_next(NULL); 209 --_number_of_entries; 210 } 211 212 // Move over freelist and free block for allocation 213 void copy_freelist(BasicHashtable* src) { 214 _free_list = src->_free_list; 215 src->_free_list = NULL; 216 _first_free_entry = src->_first_free_entry; 217 src->_first_free_entry = NULL; 218 _end_block = src->_end_block; 219 src->_end_block = NULL; 220 } 221 222 // Free the buckets in this hashtable 223 void free_buckets(); 224 225public: 226 int table_size() { return _table_size; } 227 void set_entry(int index, BasicHashtableEntry<F>* entry); 228 229 void add_entry(int index, BasicHashtableEntry<F>* entry); 230 231 void free_entry(BasicHashtableEntry<F>* entry); 232 233 int number_of_entries() { return _number_of_entries; } 234 235 void verify() PRODUCT_RETURN; 236 237#ifdef ASSERT 238 void bucket_count_hit(int i) const { 239 _buckets[i].count_hit(); 240 } 241 unsigned bucket_hits(int i) const { 242 return _buckets[i].hits(); 243 } 244#endif 245}; 246 247 248template <class T, MEMFLAGS F> class Hashtable : public BasicHashtable<F> { 249 friend class VMStructs; 250 251public: 252 Hashtable(int table_size, int entry_size) 253 : BasicHashtable<F>(table_size, entry_size) { } 254 255 Hashtable(int table_size, int entry_size, 256 HashtableBucket<F>* buckets, int number_of_entries) 257 : BasicHashtable<F>(table_size, entry_size, buckets, number_of_entries) { } 258 259 // Debugging 260 void print() PRODUCT_RETURN; 261 262protected: 263 264 unsigned int compute_hash(Symbol* name) { 265 return (unsigned int) name->identity_hash(); 266 } 267 268 int index_for(Symbol* name) { 269 return this->hash_to_index(compute_hash(name)); 270 } 271 272 // Table entry management 273 HashtableEntry<T, F>* new_entry(unsigned int hashValue, T obj); 274 275 // The following method is MT-safe and may be used with caution. 276 HashtableEntry<T, F>* bucket(int i) const { 277 return (HashtableEntry<T, F>*)BasicHashtable<F>::bucket(i); 278 } 279 280 // The following method is not MT-safe and must be done under lock. 281 HashtableEntry<T, F>** bucket_addr(int i) { 282 return (HashtableEntry<T, F>**)BasicHashtable<F>::bucket_addr(i); 283 } 284 285}; 286 287template <class T, MEMFLAGS F> class RehashableHashtable : public Hashtable<T, F> { 288 friend class VMStructs; 289 protected: 290 291 enum { 292 rehash_count = 100, 293 rehash_multiple = 60 294 }; 295 296 // Check that the table is unbalanced 297 bool check_rehash_table(int count); 298 299 public: 300 RehashableHashtable(int table_size, int entry_size) 301 : Hashtable<T, F>(table_size, entry_size) { } 302 303 RehashableHashtable(int table_size, int entry_size, 304 HashtableBucket<F>* buckets, int number_of_entries) 305 : Hashtable<T, F>(table_size, entry_size, buckets, number_of_entries) { } 306 307 308 // Function to move these elements into the new table. 309 void move_to(RehashableHashtable<T, F>* new_table); 310 static bool use_alternate_hashcode() { return _seed != 0; } 311 static juint seed() { return _seed; } 312 313 static int literal_size(Symbol *symbol); 314 static int literal_size(oop oop); 315 316 // The following two are currently not used, but are needed anyway because some 317 // C++ compilers (MacOS and Solaris) force the instantiation of 318 // Hashtable<ConstantPool*, mtClass>::dump_table() even though we never call this function 319 // in the VM code. 320 static int literal_size(ConstantPool *cp) {Unimplemented(); return 0;} 321 static int literal_size(Klass *k) {Unimplemented(); return 0;} 322 323 void dump_table(outputStream* st, const char *table_name); 324 325 private: 326 static juint _seed; 327}; 328 329 330// Versions of hashtable where two handles are used to compute the index. 331 332template <class T, MEMFLAGS F> class TwoOopHashtable : public Hashtable<T, F> { 333 friend class VMStructs; 334protected: 335 TwoOopHashtable(int table_size, int entry_size) 336 : Hashtable<T, F>(table_size, entry_size) {} 337 338 TwoOopHashtable(int table_size, int entry_size, HashtableBucket<F>* t, 339 int number_of_entries) 340 : Hashtable<T, F>(table_size, entry_size, t, number_of_entries) {} 341 342public: 343 unsigned int compute_hash(const Symbol* name, const ClassLoaderData* loader_data) const { 344 unsigned int name_hash = name->identity_hash(); 345 // loader is null with CDS 346 assert(loader_data != NULL || UseSharedSpaces || DumpSharedSpaces, 347 "only allowed with shared spaces"); 348 unsigned int loader_hash = loader_data == NULL ? 0 : loader_data->identity_hash(); 349 return name_hash ^ loader_hash; 350 } 351 352 int index_for(Symbol* name, ClassLoaderData* loader_data) { 353 return this->hash_to_index(compute_hash(name, loader_data)); 354 } 355}; 356 357#endif // SHARE_VM_UTILITIES_HASHTABLE_HPP 358