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annotate src/share/vm/utilities/hashtable.hpp @ 2426:1d1603768966
7010070: Update all 2010 Oracle-changed OpenJDK files to have the proper copyright dates - second pass
Summary: Update the copyright to be 2010 on all changed files in OpenJDK
Reviewed-by: ohair
| author | trims |
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| date | Tue, 05 Apr 2011 14:12:31 -0700 |
| parents | 3adec115d40d |
| children | b2cd0ee8f778 |
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| 0 | 1 /* |
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2 * Copyright (c) 2003, 2011, 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 | |
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162 static unsigned int hash_symbol(const char* s, int len); |
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163 |
| 0 | 164 private: |
| 165 // Instance variables | |
| 166 int _table_size; | |
| 167 HashtableBucket* _buckets; | |
| 168 BasicHashtableEntry* _free_list; | |
| 169 char* _first_free_entry; | |
| 170 char* _end_block; | |
| 171 int _entry_size; | |
| 172 int _number_of_entries; | |
| 173 | |
| 174 protected: | |
| 175 | |
| 176 #ifdef ASSERT | |
| 177 int _lookup_count; | |
| 178 int _lookup_length; | |
| 179 void verify_lookup_length(double load); | |
| 180 #endif | |
| 181 | |
| 182 void initialize(int table_size, int entry_size, int number_of_entries); | |
| 183 | |
| 184 // Accessor | |
| 185 int entry_size() const { return _entry_size; } | |
| 186 int table_size() { return _table_size; } | |
| 187 | |
| 188 // The following method is MT-safe and may be used with caution. | |
| 189 BasicHashtableEntry* bucket(int i); | |
| 190 | |
| 191 // The following method is not MT-safe and must be done under lock. | |
| 192 BasicHashtableEntry** bucket_addr(int i) { return _buckets[i].entry_addr(); } | |
| 193 | |
| 194 // Table entry management | |
| 195 BasicHashtableEntry* new_entry(unsigned int hashValue); | |
| 196 | |
| 197 public: | |
| 198 void set_entry(int index, BasicHashtableEntry* entry); | |
| 199 | |
| 200 void add_entry(int index, BasicHashtableEntry* entry); | |
| 201 | |
| 202 void free_entry(BasicHashtableEntry* entry); | |
| 203 | |
| 204 int number_of_entries() { return _number_of_entries; } | |
| 205 | |
| 206 void verify() PRODUCT_RETURN; | |
| 207 }; | |
| 208 | |
| 209 | |
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210 template <class T> class Hashtable : public BasicHashtable { |
| 0 | 211 friend class VMStructs; |
| 212 | |
| 213 public: | |
| 214 Hashtable(int table_size, int entry_size) | |
| 215 : BasicHashtable(table_size, entry_size) { } | |
| 216 | |
| 217 Hashtable(int table_size, int entry_size, | |
| 218 HashtableBucket* buckets, int number_of_entries) | |
| 219 : BasicHashtable(table_size, entry_size, buckets, number_of_entries) { } | |
| 220 | |
| 221 // Debugging | |
| 222 void print() PRODUCT_RETURN; | |
| 223 | |
| 224 // Reverse the order of elements in each of the buckets. Hashtable | |
| 225 // entries which refer to objects at a lower address than 'boundary' | |
| 226 // are separated from those which refer to objects at higher | |
| 227 // addresses, and appear first in the list. | |
| 228 void reverse(void* boundary = NULL); | |
| 229 | |
| 230 protected: | |
| 231 | |
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232 unsigned int compute_hash(Symbol* name) { |
| 0 | 233 return (unsigned int) name->identity_hash(); |
| 234 } | |
| 235 | |
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236 int index_for(Symbol* name) { |
| 0 | 237 return hash_to_index(compute_hash(name)); |
| 238 } | |
| 239 | |
| 240 // Table entry management | |
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241 HashtableEntry<T>* new_entry(unsigned int hashValue, T obj); |
| 0 | 242 |
| 243 // The following method is MT-safe and may be used with caution. | |
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244 HashtableEntry<T>* bucket(int i) { |
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245 return (HashtableEntry<T>*)BasicHashtable::bucket(i); |
| 0 | 246 } |
| 247 | |
| 248 // The following method is not MT-safe and must be done under lock. | |
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249 HashtableEntry<T>** bucket_addr(int i) { |
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250 return (HashtableEntry<T>**)BasicHashtable::bucket_addr(i); |
| 0 | 251 } |
| 252 }; | |
| 253 | |
| 254 | |
| 255 // Verions of hashtable where two handles are used to compute the index. | |
| 256 | |
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257 template <class T> class TwoOopHashtable : public Hashtable<T> { |
| 0 | 258 friend class VMStructs; |
| 259 protected: | |
| 260 TwoOopHashtable(int table_size, int entry_size) | |
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261 : Hashtable<T>(table_size, entry_size) {} |
| 0 | 262 |
| 263 TwoOopHashtable(int table_size, int entry_size, HashtableBucket* t, | |
| 264 int number_of_entries) | |
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265 : Hashtable<T>(table_size, entry_size, t, number_of_entries) {} |
| 0 | 266 |
| 267 public: | |
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268 unsigned int compute_hash(Symbol* name, Handle loader) { |
| 0 | 269 // Be careful with identity_hash(), it can safepoint and if this |
| 270 // were one expression, the compiler could choose to unhandle each | |
| 271 // oop before calling identity_hash() for either of them. If the first | |
| 272 // causes a GC, the next would fail. | |
| 273 unsigned int name_hash = name->identity_hash(); | |
| 274 unsigned int loader_hash = loader.is_null() ? 0 : loader->identity_hash(); | |
| 275 return name_hash ^ loader_hash; | |
| 276 } | |
| 277 | |
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278 int index_for(Symbol* name, Handle loader) { |
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279 return this->hash_to_index(compute_hash(name, loader)); |
| 0 | 280 } |
| 281 }; | |
| 1972 | 282 |
| 283 #endif // SHARE_VM_UTILITIES_HASHTABLE_HPP |