Mercurial > hg > graal-compiler
annotate src/share/vm/utilities/hashtable.cpp @ 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 | 436b4a3231bf |
| children | 246d977b51f2 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 6162 | 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 #include "precompiled.hpp" |
| 26 #include "memory/allocation.inline.hpp" | |
| 27 #include "memory/resourceArea.hpp" | |
| 28 #include "oops/oop.inline.hpp" | |
| 29 #include "runtime/safepoint.hpp" | |
| 30 #include "utilities/dtrace.hpp" | |
| 31 #include "utilities/hashtable.hpp" | |
| 32 #include "utilities/hashtable.inline.hpp" | |
| 0 | 33 |
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34 |
| 4006 | 35 #ifndef USDT2 |
| 0 | 36 HS_DTRACE_PROBE_DECL4(hs_private, hashtable__new_entry, |
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37 void*, unsigned int, void*, void*); |
| 4006 | 38 #endif /* !USDT2 */ |
| 0 | 39 |
| 40 // This is a generic hashtable, designed to be used for the symbol | |
| 41 // and string tables. | |
| 42 // | |
| 43 // It is implemented as an open hash table with a fixed number of buckets. | |
| 44 // | |
| 45 // %note: | |
| 46 // - HashtableEntrys are allocated in blocks to reduce the space overhead. | |
| 47 | |
| 48 BasicHashtableEntry* BasicHashtable::new_entry(unsigned int hashValue) { | |
| 49 BasicHashtableEntry* entry; | |
| 50 | |
| 51 if (_free_list) { | |
| 52 entry = _free_list; | |
| 53 _free_list = _free_list->next(); | |
| 54 } else { | |
| 432 | 55 if (_first_free_entry + _entry_size >= _end_block) { |
| 56 int block_size = MIN2(512, MAX2((int)_table_size / 2, (int)_number_of_entries)); | |
| 0 | 57 int len = _entry_size * block_size; |
| 432 | 58 len = 1 << log2_intptr(len); // round down to power of 2 |
| 59 assert(len >= _entry_size, ""); | |
| 0 | 60 _first_free_entry = NEW_C_HEAP_ARRAY(char, len); |
| 61 _end_block = _first_free_entry + len; | |
| 62 } | |
| 63 entry = (BasicHashtableEntry*)_first_free_entry; | |
| 64 _first_free_entry += _entry_size; | |
| 65 } | |
| 66 | |
| 432 | 67 assert(_entry_size % HeapWordSize == 0, ""); |
| 0 | 68 entry->set_hash(hashValue); |
| 69 return entry; | |
| 70 } | |
| 71 | |
| 72 | |
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73 template <class T> HashtableEntry<T>* Hashtable<T>::new_entry(unsigned int hashValue, T obj) { |
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74 HashtableEntry<T>* entry; |
| 0 | 75 |
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76 entry = (HashtableEntry<T>*)BasicHashtable::new_entry(hashValue); |
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77 entry->set_literal(obj); |
| 4006 | 78 #ifndef USDT2 |
| 0 | 79 HS_DTRACE_PROBE4(hs_private, hashtable__new_entry, |
| 80 this, hashValue, obj, entry); | |
| 4006 | 81 #else /* USDT2 */ |
| 82 HS_PRIVATE_HASHTABLE_NEW_ENTRY( | |
| 83 this, hashValue, (uintptr_t) obj, entry); | |
| 84 #endif /* USDT2 */ | |
| 0 | 85 return entry; |
| 86 } | |
| 87 | |
| 88 | |
| 6162 | 89 // Check to see if the hashtable is unbalanced. The caller set a flag to |
| 90 // rehash at the next safepoint. If this bucket is 60 times greater than the | |
| 91 // expected average bucket length, it's an unbalanced hashtable. | |
| 92 // This is somewhat an arbitrary heuristic but if one bucket gets to | |
| 93 // rehash_count which is currently 100, there's probably something wrong. | |
| 94 | |
| 95 bool BasicHashtable::check_rehash_table(int count) { | |
| 96 assert(table_size() != 0, "underflow"); | |
| 97 if (count > (((double)number_of_entries()/(double)table_size())*rehash_multiple)) { | |
| 98 // Set a flag for the next safepoint, which should be at some guaranteed | |
| 99 // safepoint interval. | |
| 100 return true; | |
| 101 } | |
| 102 return false; | |
| 103 } | |
| 104 | |
| 105 // Create a new table and using alternate hash code, populate the new table | |
| 106 // with the existing elements. This can be used to change the hash code | |
| 107 // and could in the future change the size of the table. | |
| 108 | |
| 109 template <class T> void Hashtable<T>::move_to(Hashtable<T>* new_table) { | |
| 110 int saved_entry_count = number_of_entries(); | |
| 111 | |
| 112 // Iterate through the table and create a new entry for the new table | |
| 113 for (int i = 0; i < new_table->table_size(); ++i) { | |
| 114 for (HashtableEntry<T>* p = bucket(i); p != NULL; ) { | |
| 115 HashtableEntry<T>* next = p->next(); | |
| 116 T string = p->literal(); | |
| 117 // Use alternate hashing algorithm on the symbol in the first table | |
| 118 unsigned int hashValue = new_hash(string); | |
| 119 // Get a new index relative to the new table (can also change size) | |
| 120 int index = new_table->hash_to_index(hashValue); | |
| 121 p->set_hash(hashValue); | |
| 122 unlink_entry(p); | |
| 123 new_table->add_entry(index, p); | |
| 124 p = next; | |
| 125 } | |
| 126 } | |
| 127 // give the new table the free list as well | |
| 128 new_table->copy_freelist(this); | |
| 129 assert(new_table->number_of_entries() == saved_entry_count, "lost entry on dictionary copy?"); | |
| 130 | |
| 131 // Destroy memory used by the buckets in the hashtable. The memory | |
| 132 // for the elements has been used in a new table and is not | |
| 133 // destroyed. The memory reuse will benefit resizing the SystemDictionary | |
| 134 // to avoid a memory allocation spike at safepoint. | |
| 135 free_buckets(); | |
| 136 } | |
| 137 | |
| 0 | 138 // Reverse the order of elements in the hash buckets. |
| 139 | |
| 140 void BasicHashtable::reverse() { | |
| 141 | |
| 142 for (int i = 0; i < _table_size; ++i) { | |
| 143 BasicHashtableEntry* new_list = NULL; | |
| 144 BasicHashtableEntry* p = bucket(i); | |
| 145 while (p != NULL) { | |
| 146 BasicHashtableEntry* next = p->next(); | |
| 147 p->set_next(new_list); | |
| 148 new_list = p; | |
| 149 p = next; | |
| 150 } | |
| 151 *bucket_addr(i) = new_list; | |
| 152 } | |
| 153 } | |
| 154 | |
| 155 | |
| 156 // Copy the table to the shared space. | |
| 157 | |
| 158 void BasicHashtable::copy_table(char** top, char* end) { | |
| 159 | |
| 160 // Dump the hash table entries. | |
| 161 | |
| 162 intptr_t *plen = (intptr_t*)(*top); | |
| 163 *top += sizeof(*plen); | |
| 164 | |
| 165 int i; | |
| 166 for (i = 0; i < _table_size; ++i) { | |
| 167 for (BasicHashtableEntry** p = _buckets[i].entry_addr(); | |
| 168 *p != NULL; | |
| 169 p = (*p)->next_addr()) { | |
| 170 if (*top + entry_size() > end) { | |
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171 report_out_of_shared_space(SharedMiscData); |
| 0 | 172 } |
| 173 *p = (BasicHashtableEntry*)memcpy(*top, *p, entry_size()); | |
| 174 *top += entry_size(); | |
| 175 } | |
| 176 } | |
| 177 *plen = (char*)(*top) - (char*)plen - sizeof(*plen); | |
| 178 | |
| 179 // Set the shared bit. | |
| 180 | |
| 181 for (i = 0; i < _table_size; ++i) { | |
| 182 for (BasicHashtableEntry* p = bucket(i); p != NULL; p = p->next()) { | |
| 183 p->set_shared(); | |
| 184 } | |
| 185 } | |
| 186 } | |
| 187 | |
| 188 | |
| 189 | |
| 190 // Reverse the order of elements in the hash buckets. | |
| 191 | |
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192 template <class T> void Hashtable<T>::reverse(void* boundary) { |
| 0 | 193 |
| 194 for (int i = 0; i < table_size(); ++i) { | |
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195 HashtableEntry<T>* high_list = NULL; |
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196 HashtableEntry<T>* low_list = NULL; |
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197 HashtableEntry<T>* last_low_entry = NULL; |
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198 HashtableEntry<T>* p = bucket(i); |
| 0 | 199 while (p != NULL) { |
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200 HashtableEntry<T>* next = p->next(); |
| 0 | 201 if ((void*)p->literal() >= boundary) { |
| 202 p->set_next(high_list); | |
| 203 high_list = p; | |
| 204 } else { | |
| 205 p->set_next(low_list); | |
| 206 low_list = p; | |
| 207 if (last_low_entry == NULL) { | |
| 208 last_low_entry = p; | |
| 209 } | |
| 210 } | |
| 211 p = next; | |
| 212 } | |
| 213 if (low_list != NULL) { | |
| 214 *bucket_addr(i) = low_list; | |
| 215 last_low_entry->set_next(high_list); | |
| 216 } else { | |
| 217 *bucket_addr(i) = high_list; | |
| 218 } | |
| 219 } | |
| 220 } | |
| 221 | |
| 222 | |
| 223 // Dump the hash table buckets. | |
| 224 | |
| 225 void BasicHashtable::copy_buckets(char** top, char* end) { | |
| 226 intptr_t len = _table_size * sizeof(HashtableBucket); | |
| 227 *(intptr_t*)(*top) = len; | |
| 228 *top += sizeof(intptr_t); | |
| 229 | |
| 230 *(intptr_t*)(*top) = _number_of_entries; | |
| 231 *top += sizeof(intptr_t); | |
| 232 | |
| 233 if (*top + len > end) { | |
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234 report_out_of_shared_space(SharedMiscData); |
| 0 | 235 } |
| 236 _buckets = (HashtableBucket*)memcpy(*top, _buckets, len); | |
| 237 *top += len; | |
| 238 } | |
| 239 | |
| 240 | |
| 241 #ifndef PRODUCT | |
| 242 | |
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243 template <class T> void Hashtable<T>::print() { |
| 0 | 244 ResourceMark rm; |
| 245 | |
| 246 for (int i = 0; i < table_size(); i++) { | |
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247 HashtableEntry<T>* entry = bucket(i); |
| 0 | 248 while(entry != NULL) { |
| 249 tty->print("%d : ", i); | |
| 250 entry->literal()->print(); | |
| 251 tty->cr(); | |
| 252 entry = entry->next(); | |
| 253 } | |
| 254 } | |
| 255 } | |
| 256 | |
| 257 | |
| 258 void BasicHashtable::verify() { | |
| 259 int count = 0; | |
| 260 for (int i = 0; i < table_size(); i++) { | |
| 261 for (BasicHashtableEntry* p = bucket(i); p != NULL; p = p->next()) { | |
| 262 ++count; | |
| 263 } | |
| 264 } | |
| 265 assert(count == number_of_entries(), "number of hashtable entries incorrect"); | |
| 266 } | |
| 267 | |
| 268 | |
| 269 #endif // PRODUCT | |
| 270 | |
| 271 | |
| 272 #ifdef ASSERT | |
| 273 | |
| 274 void BasicHashtable::verify_lookup_length(double load) { | |
| 275 if ((double)_lookup_length / (double)_lookup_count > load * 2.0) { | |
| 276 warning("Performance bug: SystemDictionary lookup_count=%d " | |
| 277 "lookup_length=%d average=%lf load=%f", | |
| 278 _lookup_count, _lookup_length, | |
| 279 (double) _lookup_length / _lookup_count, load); | |
| 280 } | |
| 281 } | |
| 282 | |
| 283 #endif | |
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284 |
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285 // Explicitly instantiate these types |
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286 template class Hashtable<constantPoolOop>; |
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287 template class Hashtable<Symbol*>; |
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288 template class Hashtable<klassOop>; |
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289 template class Hashtable<oop>; |
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290 |