Mercurial > hg > graal-jvmci-8
annotate src/share/vm/utilities/hashtable.hpp @ 6162:e9140bf80b4a
7158800: Improve storage of symbol tables
Summary: Use an alternate version of hashing algorithm for symbol string tables and after a certain bucket size to improve performance
Reviewed-by: pbk, kamg, dlong, kvn, fparain
| author | coleenp |
|---|---|
| date | Wed, 13 Jun 2012 19:52:59 -0400 |
| parents | b2cd0ee8f778 |
| children | 246d977b51f2 |
| rev | line source |
|---|---|
| 0 | 1 /* |
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2 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved. |
| 0 | 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 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 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" | |
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30 #include "oops/symbol.hpp" |
| 1972 | 31 #include "runtime/handles.hpp" |
| 32 | |
| 0 | 33 // This is a generic hashtable, designed to be used for the symbol |
| 34 // and string tables. | |
| 35 // | |
| 36 // It is implemented as an open hash table with a fixed number of buckets. | |
| 37 // | |
| 38 // %note: | |
| 39 // - TableEntrys are allocated in blocks to reduce the space overhead. | |
| 40 | |
| 41 | |
| 42 | |
| 43 class BasicHashtableEntry : public CHeapObj { | |
| 44 friend class VMStructs; | |
| 45 private: | |
| 46 unsigned int _hash; // 32-bit hash for item | |
| 47 | |
| 48 // Link to next element in the linked list for this bucket. EXCEPT | |
| 49 // bit 0 set indicates that this entry is shared and must not be | |
| 50 // unlinked from the table. Bit 0 is set during the dumping of the | |
| 51 // archive. Since shared entries are immutable, _next fields in the | |
| 52 // shared entries will not change. New entries will always be | |
| 53 // unshared and since pointers are align, bit 0 will always remain 0 | |
| 54 // with no extra effort. | |
| 55 BasicHashtableEntry* _next; | |
| 56 | |
| 57 // Windows IA64 compiler requires subclasses to be able to access these | |
| 58 protected: | |
| 59 // Entry objects should not be created, they should be taken from the | |
| 60 // free list with BasicHashtable.new_entry(). | |
| 61 BasicHashtableEntry() { ShouldNotReachHere(); } | |
| 62 // Entry objects should not be destroyed. They should be placed on | |
| 63 // the free list instead with BasicHashtable.free_entry(). | |
| 64 ~BasicHashtableEntry() { ShouldNotReachHere(); } | |
| 65 | |
| 66 public: | |
| 67 | |
| 68 unsigned int hash() const { return _hash; } | |
| 69 void set_hash(unsigned int hash) { _hash = hash; } | |
| 70 unsigned int* hash_addr() { return &_hash; } | |
| 71 | |
| 72 static BasicHashtableEntry* make_ptr(BasicHashtableEntry* p) { | |
| 73 return (BasicHashtableEntry*)((intptr_t)p & -2); | |
| 74 } | |
| 75 | |
| 76 BasicHashtableEntry* next() const { | |
| 77 return make_ptr(_next); | |
| 78 } | |
| 79 | |
| 80 void set_next(BasicHashtableEntry* next) { | |
| 81 _next = next; | |
| 82 } | |
| 83 | |
| 84 BasicHashtableEntry** next_addr() { | |
| 85 return &_next; | |
| 86 } | |
| 87 | |
| 88 bool is_shared() const { | |
| 89 return ((intptr_t)_next & 1) != 0; | |
| 90 } | |
| 91 | |
| 92 void set_shared() { | |
| 93 _next = (BasicHashtableEntry*)((intptr_t)_next | 1); | |
| 94 } | |
| 95 }; | |
| 96 | |
| 97 | |
| 98 | |
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99 template <class T> class HashtableEntry : public BasicHashtableEntry { |
| 0 | 100 friend class VMStructs; |
| 101 private: | |
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102 T _literal; // ref to item in table. |
| 0 | 103 |
| 104 public: | |
| 105 // Literal | |
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106 T literal() const { return _literal; } |
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107 T* literal_addr() { return &_literal; } |
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108 void set_literal(T s) { _literal = s; } |
| 0 | 109 |
| 110 HashtableEntry* next() const { | |
| 111 return (HashtableEntry*)BasicHashtableEntry::next(); | |
| 112 } | |
| 113 HashtableEntry** next_addr() { | |
| 114 return (HashtableEntry**)BasicHashtableEntry::next_addr(); | |
| 115 } | |
| 116 }; | |
| 117 | |
| 118 | |
| 119 | |
| 120 class HashtableBucket : public CHeapObj { | |
| 121 friend class VMStructs; | |
| 122 private: | |
| 123 // Instance variable | |
| 124 BasicHashtableEntry* _entry; | |
| 125 | |
| 126 public: | |
| 127 // Accessing | |
| 128 void clear() { _entry = NULL; } | |
| 129 | |
| 130 // The following methods use order access methods to avoid race | |
| 131 // conditions in multiprocessor systems. | |
| 132 BasicHashtableEntry* get_entry() const; | |
| 133 void set_entry(BasicHashtableEntry* l); | |
| 134 | |
| 135 // The following method is not MT-safe and must be done under lock. | |
| 136 BasicHashtableEntry** entry_addr() { return &_entry; } | |
| 137 }; | |
| 138 | |
| 139 | |
| 140 class BasicHashtable : public CHeapObj { | |
| 141 friend class VMStructs; | |
| 142 | |
| 143 public: | |
| 144 BasicHashtable(int table_size, int entry_size); | |
| 145 BasicHashtable(int table_size, int entry_size, | |
| 146 HashtableBucket* buckets, int number_of_entries); | |
| 147 | |
| 148 // Sharing support. | |
| 149 void copy_buckets(char** top, char* end); | |
| 150 void copy_table(char** top, char* end); | |
| 151 | |
| 152 // Bucket handling | |
| 153 int hash_to_index(unsigned int full_hash) { | |
| 154 int h = full_hash % _table_size; | |
| 155 assert(h >= 0 && h < _table_size, "Illegal hash value"); | |
| 156 return h; | |
| 157 } | |
| 158 | |
| 159 // Reverse the order of elements in each of the buckets. | |
| 160 void reverse(); | |
| 161 | |
| 162 private: | |
| 163 // Instance variables | |
| 164 int _table_size; | |
| 165 HashtableBucket* _buckets; | |
| 166 BasicHashtableEntry* _free_list; | |
| 167 char* _first_free_entry; | |
| 168 char* _end_block; | |
| 169 int _entry_size; | |
| 170 int _number_of_entries; | |
| 171 | |
| 172 protected: | |
| 173 | |
| 174 #ifdef ASSERT | |
| 175 int _lookup_count; | |
| 176 int _lookup_length; | |
| 177 void verify_lookup_length(double load); | |
| 178 #endif | |
| 179 | |
| 6162 | 180 enum { |
| 181 rehash_count = 100, | |
| 182 rehash_multiple = 60 | |
| 183 }; | |
| 184 | |
| 0 | 185 void initialize(int table_size, int entry_size, int number_of_entries); |
| 186 | |
| 187 // Accessor | |
| 188 int entry_size() const { return _entry_size; } | |
| 189 | |
| 190 // The following method is MT-safe and may be used with caution. | |
| 191 BasicHashtableEntry* bucket(int i); | |
| 192 | |
| 193 // The following method is not MT-safe and must be done under lock. | |
| 194 BasicHashtableEntry** bucket_addr(int i) { return _buckets[i].entry_addr(); } | |
| 195 | |
| 196 // Table entry management | |
| 197 BasicHashtableEntry* new_entry(unsigned int hashValue); | |
| 198 | |
| 6162 | 199 // Check that the table is unbalanced |
| 200 bool check_rehash_table(int count); | |
| 201 | |
| 202 // Used when moving the entry to another table | |
| 203 // Clean up links, but do not add to free_list | |
| 204 void unlink_entry(BasicHashtableEntry* entry) { | |
| 205 entry->set_next(NULL); | |
| 206 --_number_of_entries; | |
| 207 } | |
| 208 | |
| 209 // Move over freelist and free block for allocation | |
| 210 void copy_freelist(BasicHashtable* src) { | |
| 211 _free_list = src->_free_list; | |
| 212 src->_free_list = NULL; | |
| 213 _first_free_entry = src->_first_free_entry; | |
| 214 src->_first_free_entry = NULL; | |
| 215 _end_block = src->_end_block; | |
| 216 src->_end_block = NULL; | |
| 217 } | |
| 218 | |
| 219 // Free the buckets in this hashtable | |
| 220 void free_buckets() { | |
| 221 if (NULL != _buckets) { | |
| 222 FREE_C_HEAP_ARRAY(HashtableBucket, _buckets); | |
| 223 _buckets = NULL; | |
| 224 } | |
| 225 } | |
| 226 | |
| 0 | 227 public: |
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228 int table_size() { return _table_size; } |
| 0 | 229 void set_entry(int index, BasicHashtableEntry* entry); |
| 230 | |
| 231 void add_entry(int index, BasicHashtableEntry* entry); | |
| 232 | |
| 233 void free_entry(BasicHashtableEntry* entry); | |
| 234 | |
| 235 int number_of_entries() { return _number_of_entries; } | |
| 236 | |
| 237 void verify() PRODUCT_RETURN; | |
| 238 }; | |
| 239 | |
| 240 | |
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241 template <class T> class Hashtable : public BasicHashtable { |
| 0 | 242 friend class VMStructs; |
| 243 | |
| 244 public: | |
| 245 Hashtable(int table_size, int entry_size) | |
| 246 : BasicHashtable(table_size, entry_size) { } | |
| 247 | |
| 248 Hashtable(int table_size, int entry_size, | |
| 249 HashtableBucket* buckets, int number_of_entries) | |
| 250 : BasicHashtable(table_size, entry_size, buckets, number_of_entries) { } | |
| 251 | |
| 252 // Debugging | |
| 253 void print() PRODUCT_RETURN; | |
| 254 | |
| 255 // Reverse the order of elements in each of the buckets. Hashtable | |
| 256 // entries which refer to objects at a lower address than 'boundary' | |
| 257 // are separated from those which refer to objects at higher | |
| 258 // addresses, and appear first in the list. | |
| 259 void reverse(void* boundary = NULL); | |
| 260 | |
| 261 protected: | |
| 262 | |
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263 unsigned int compute_hash(Symbol* name) { |
| 0 | 264 return (unsigned int) name->identity_hash(); |
| 265 } | |
| 266 | |
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267 int index_for(Symbol* name) { |
| 0 | 268 return hash_to_index(compute_hash(name)); |
| 269 } | |
| 270 | |
| 271 // Table entry management | |
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272 HashtableEntry<T>* new_entry(unsigned int hashValue, T obj); |
| 0 | 273 |
| 274 // The following method is MT-safe and may be used with caution. | |
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275 HashtableEntry<T>* bucket(int i) { |
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276 return (HashtableEntry<T>*)BasicHashtable::bucket(i); |
| 0 | 277 } |
| 278 | |
| 279 // The following method is not MT-safe and must be done under lock. | |
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280 HashtableEntry<T>** bucket_addr(int i) { |
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281 return (HashtableEntry<T>**)BasicHashtable::bucket_addr(i); |
| 0 | 282 } |
| 6162 | 283 |
| 284 // Function to move these elements into the new table. | |
| 285 void move_to(Hashtable<T>* new_table); | |
| 286 virtual unsigned int new_hash(T) { ShouldNotReachHere(); return 0; } // should be overridden | |
| 0 | 287 }; |
| 288 | |
| 289 | |
| 290 // Verions of hashtable where two handles are used to compute the index. | |
| 291 | |
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292 template <class T> class TwoOopHashtable : public Hashtable<T> { |
| 0 | 293 friend class VMStructs; |
| 294 protected: | |
| 295 TwoOopHashtable(int table_size, int entry_size) | |
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296 : Hashtable<T>(table_size, entry_size) {} |
| 0 | 297 |
| 298 TwoOopHashtable(int table_size, int entry_size, HashtableBucket* t, | |
| 299 int number_of_entries) | |
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300 : Hashtable<T>(table_size, entry_size, t, number_of_entries) {} |
| 0 | 301 |
| 302 public: | |
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303 unsigned int compute_hash(Symbol* name, Handle loader) { |
| 0 | 304 // Be careful with identity_hash(), it can safepoint and if this |
| 305 // were one expression, the compiler could choose to unhandle each | |
| 306 // oop before calling identity_hash() for either of them. If the first | |
| 307 // causes a GC, the next would fail. | |
| 308 unsigned int name_hash = name->identity_hash(); | |
| 309 unsigned int loader_hash = loader.is_null() ? 0 : loader->identity_hash(); | |
| 310 return name_hash ^ loader_hash; | |
| 311 } | |
| 312 | |
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313 int index_for(Symbol* name, Handle loader) { |
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314 return this->hash_to_index(compute_hash(name, loader)); |
| 0 | 315 } |
| 316 }; | |
| 1972 | 317 |
| 318 #endif // SHARE_VM_UTILITIES_HASHTABLE_HPP |