annotate hotspot/src/share/vm/utilities/hashtable.cpp @ 13097:c146b608d91f

7178670: runtime/7158800/BadUtf8.java fails in SymbolTable::rehash_table Summary: Cannot delete _buckets and HashtableEntries in shared space (CDS) Reviewed-by: acorn, kvn, dlong, dcubed, kamg
author coleenp
date Mon, 25 Jun 2012 21:33:35 -0400
parents 673ea6efaf18
children be27e1b6a4b9
rev   line source
duke@1 1 /*
coleenp@13087 2 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
duke@1 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@1 4 *
duke@1 5 * This code is free software; you can redistribute it and/or modify it
duke@1 6 * under the terms of the GNU General Public License version 2 only, as
duke@1 7 * published by the Free Software Foundation.
duke@1 8 *
duke@1 9 * This code is distributed in the hope that it will be useful, but WITHOUT
duke@1 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@1 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@1 12 * version 2 for more details (a copy is included in the LICENSE file that
duke@1 13 * accompanied this code).
duke@1 14 *
duke@1 15 * You should have received a copy of the GNU General Public License version
duke@1 16 * 2 along with this work; if not, write to the Free Software Foundation,
duke@1 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@1 18 *
trims@5547 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@5547 20 * or visit www.oracle.com if you need additional information or have any
trims@5547 21 * questions.
duke@1 22 *
duke@1 23 */
duke@1 24
stefank@7397 25 #include "precompiled.hpp"
stefank@7397 26 #include "memory/allocation.inline.hpp"
coleenp@13097 27 #include "memory/filemap.hpp"
stefank@7397 28 #include "memory/resourceArea.hpp"
stefank@7397 29 #include "oops/oop.inline.hpp"
stefank@7397 30 #include "runtime/safepoint.hpp"
stefank@7397 31 #include "utilities/dtrace.hpp"
stefank@7397 32 #include "utilities/hashtable.hpp"
stefank@7397 33 #include "utilities/hashtable.inline.hpp"
duke@1 34
coleenp@8076 35
dcubed@10739 36 #ifndef USDT2
duke@1 37 HS_DTRACE_PROBE_DECL4(hs_private, hashtable__new_entry,
coleenp@8076 38 void*, unsigned int, void*, void*);
dcubed@10739 39 #endif /* !USDT2 */
duke@1 40
duke@1 41 // This is a generic hashtable, designed to be used for the symbol
duke@1 42 // and string tables.
duke@1 43 //
duke@1 44 // It is implemented as an open hash table with a fixed number of buckets.
duke@1 45 //
duke@1 46 // %note:
duke@1 47 // - HashtableEntrys are allocated in blocks to reduce the space overhead.
duke@1 48
duke@1 49 BasicHashtableEntry* BasicHashtable::new_entry(unsigned int hashValue) {
duke@1 50 BasicHashtableEntry* entry;
duke@1 51
duke@1 52 if (_free_list) {
duke@1 53 entry = _free_list;
duke@1 54 _free_list = _free_list->next();
duke@1 55 } else {
jrose@1551 56 if (_first_free_entry + _entry_size >= _end_block) {
jrose@1551 57 int block_size = MIN2(512, MAX2((int)_table_size / 2, (int)_number_of_entries));
duke@1 58 int len = _entry_size * block_size;
jrose@1551 59 len = 1 << log2_intptr(len); // round down to power of 2
jrose@1551 60 assert(len >= _entry_size, "");
duke@1 61 _first_free_entry = NEW_C_HEAP_ARRAY(char, len);
duke@1 62 _end_block = _first_free_entry + len;
duke@1 63 }
duke@1 64 entry = (BasicHashtableEntry*)_first_free_entry;
duke@1 65 _first_free_entry += _entry_size;
duke@1 66 }
duke@1 67
jrose@1551 68 assert(_entry_size % HeapWordSize == 0, "");
duke@1 69 entry->set_hash(hashValue);
duke@1 70 return entry;
duke@1 71 }
duke@1 72
duke@1 73
coleenp@8076 74 template <class T> HashtableEntry<T>* Hashtable<T>::new_entry(unsigned int hashValue, T obj) {
coleenp@8076 75 HashtableEntry<T>* entry;
duke@1 76
coleenp@8076 77 entry = (HashtableEntry<T>*)BasicHashtable::new_entry(hashValue);
coleenp@8076 78 entry->set_literal(obj);
dcubed@10739 79 #ifndef USDT2
duke@1 80 HS_DTRACE_PROBE4(hs_private, hashtable__new_entry,
duke@1 81 this, hashValue, obj, entry);
dcubed@10739 82 #else /* USDT2 */
dcubed@10739 83 HS_PRIVATE_HASHTABLE_NEW_ENTRY(
dcubed@10739 84 this, hashValue, (uintptr_t) obj, entry);
dcubed@10739 85 #endif /* USDT2 */
duke@1 86 return entry;
duke@1 87 }
duke@1 88
duke@1 89
coleenp@13087 90 // Check to see if the hashtable is unbalanced. The caller set a flag to
coleenp@13087 91 // rehash at the next safepoint. If this bucket is 60 times greater than the
coleenp@13087 92 // expected average bucket length, it's an unbalanced hashtable.
coleenp@13087 93 // This is somewhat an arbitrary heuristic but if one bucket gets to
coleenp@13087 94 // rehash_count which is currently 100, there's probably something wrong.
coleenp@13087 95
coleenp@13087 96 bool BasicHashtable::check_rehash_table(int count) {
coleenp@13087 97 assert(table_size() != 0, "underflow");
coleenp@13087 98 if (count > (((double)number_of_entries()/(double)table_size())*rehash_multiple)) {
coleenp@13087 99 // Set a flag for the next safepoint, which should be at some guaranteed
coleenp@13087 100 // safepoint interval.
coleenp@13087 101 return true;
coleenp@13087 102 }
coleenp@13087 103 return false;
coleenp@13087 104 }
coleenp@13087 105
coleenp@13087 106 // Create a new table and using alternate hash code, populate the new table
coleenp@13087 107 // with the existing elements. This can be used to change the hash code
coleenp@13087 108 // and could in the future change the size of the table.
coleenp@13087 109
coleenp@13087 110 template <class T> void Hashtable<T>::move_to(Hashtable<T>* new_table) {
coleenp@13087 111 int saved_entry_count = number_of_entries();
coleenp@13087 112
coleenp@13087 113 // Iterate through the table and create a new entry for the new table
coleenp@13087 114 for (int i = 0; i < new_table->table_size(); ++i) {
coleenp@13087 115 for (HashtableEntry<T>* p = bucket(i); p != NULL; ) {
coleenp@13087 116 HashtableEntry<T>* next = p->next();
coleenp@13087 117 T string = p->literal();
coleenp@13087 118 // Use alternate hashing algorithm on the symbol in the first table
coleenp@13087 119 unsigned int hashValue = new_hash(string);
coleenp@13087 120 // Get a new index relative to the new table (can also change size)
coleenp@13087 121 int index = new_table->hash_to_index(hashValue);
coleenp@13087 122 p->set_hash(hashValue);
coleenp@13097 123 // Keep the shared bit in the Hashtable entry to indicate that this entry
coleenp@13097 124 // can't be deleted. The shared bit is the LSB in the _next field so
coleenp@13097 125 // walking the hashtable past these entries requires
coleenp@13097 126 // BasicHashtableEntry::make_ptr() call.
coleenp@13097 127 bool keep_shared = p->is_shared();
coleenp@13087 128 unlink_entry(p);
coleenp@13087 129 new_table->add_entry(index, p);
coleenp@13097 130 if (keep_shared) {
coleenp@13097 131 p->set_shared();
coleenp@13097 132 }
coleenp@13087 133 p = next;
coleenp@13087 134 }
coleenp@13087 135 }
coleenp@13087 136 // give the new table the free list as well
coleenp@13087 137 new_table->copy_freelist(this);
coleenp@13087 138 assert(new_table->number_of_entries() == saved_entry_count, "lost entry on dictionary copy?");
coleenp@13087 139
coleenp@13087 140 // Destroy memory used by the buckets in the hashtable. The memory
coleenp@13087 141 // for the elements has been used in a new table and is not
coleenp@13087 142 // destroyed. The memory reuse will benefit resizing the SystemDictionary
coleenp@13087 143 // to avoid a memory allocation spike at safepoint.
coleenp@13087 144 free_buckets();
coleenp@13087 145 }
coleenp@13087 146
coleenp@13097 147 void BasicHashtable::free_buckets() {
coleenp@13097 148 if (NULL != _buckets) {
coleenp@13097 149 // Don't delete the buckets in the shared space. They aren't
coleenp@13097 150 // allocated by os::malloc
coleenp@13097 151 if (!UseSharedSpaces ||
coleenp@13097 152 !FileMapInfo::current_info()->is_in_shared_space(_buckets)) {
coleenp@13097 153 FREE_C_HEAP_ARRAY(HashtableBucket, _buckets);
coleenp@13097 154 }
coleenp@13097 155 _buckets = NULL;
coleenp@13097 156 }
coleenp@13097 157 }
coleenp@13097 158
coleenp@13097 159
duke@1 160 // Reverse the order of elements in the hash buckets.
duke@1 161
duke@1 162 void BasicHashtable::reverse() {
duke@1 163
duke@1 164 for (int i = 0; i < _table_size; ++i) {
duke@1 165 BasicHashtableEntry* new_list = NULL;
duke@1 166 BasicHashtableEntry* p = bucket(i);
duke@1 167 while (p != NULL) {
duke@1 168 BasicHashtableEntry* next = p->next();
duke@1 169 p->set_next(new_list);
duke@1 170 new_list = p;
duke@1 171 p = next;
duke@1 172 }
duke@1 173 *bucket_addr(i) = new_list;
duke@1 174 }
duke@1 175 }
duke@1 176
duke@1 177
duke@1 178 // Copy the table to the shared space.
duke@1 179
duke@1 180 void BasicHashtable::copy_table(char** top, char* end) {
duke@1 181
duke@1 182 // Dump the hash table entries.
duke@1 183
duke@1 184 intptr_t *plen = (intptr_t*)(*top);
duke@1 185 *top += sizeof(*plen);
duke@1 186
duke@1 187 int i;
duke@1 188 for (i = 0; i < _table_size; ++i) {
duke@1 189 for (BasicHashtableEntry** p = _buckets[i].entry_addr();
duke@1 190 *p != NULL;
duke@1 191 p = (*p)->next_addr()) {
duke@1 192 if (*top + entry_size() > end) {
coleenp@8076 193 report_out_of_shared_space(SharedMiscData);
duke@1 194 }
duke@1 195 *p = (BasicHashtableEntry*)memcpy(*top, *p, entry_size());
duke@1 196 *top += entry_size();
duke@1 197 }
duke@1 198 }
duke@1 199 *plen = (char*)(*top) - (char*)plen - sizeof(*plen);
duke@1 200
duke@1 201 // Set the shared bit.
duke@1 202
duke@1 203 for (i = 0; i < _table_size; ++i) {
duke@1 204 for (BasicHashtableEntry* p = bucket(i); p != NULL; p = p->next()) {
duke@1 205 p->set_shared();
duke@1 206 }
duke@1 207 }
duke@1 208 }
duke@1 209
duke@1 210
duke@1 211
duke@1 212 // Reverse the order of elements in the hash buckets.
duke@1 213
coleenp@8076 214 template <class T> void Hashtable<T>::reverse(void* boundary) {
duke@1 215
duke@1 216 for (int i = 0; i < table_size(); ++i) {
coleenp@8076 217 HashtableEntry<T>* high_list = NULL;
coleenp@8076 218 HashtableEntry<T>* low_list = NULL;
coleenp@8076 219 HashtableEntry<T>* last_low_entry = NULL;
coleenp@8076 220 HashtableEntry<T>* p = bucket(i);
duke@1 221 while (p != NULL) {
coleenp@8076 222 HashtableEntry<T>* next = p->next();
duke@1 223 if ((void*)p->literal() >= boundary) {
duke@1 224 p->set_next(high_list);
duke@1 225 high_list = p;
duke@1 226 } else {
duke@1 227 p->set_next(low_list);
duke@1 228 low_list = p;
duke@1 229 if (last_low_entry == NULL) {
duke@1 230 last_low_entry = p;
duke@1 231 }
duke@1 232 }
duke@1 233 p = next;
duke@1 234 }
duke@1 235 if (low_list != NULL) {
duke@1 236 *bucket_addr(i) = low_list;
duke@1 237 last_low_entry->set_next(high_list);
duke@1 238 } else {
duke@1 239 *bucket_addr(i) = high_list;
duke@1 240 }
duke@1 241 }
duke@1 242 }
duke@1 243
duke@1 244
duke@1 245 // Dump the hash table buckets.
duke@1 246
duke@1 247 void BasicHashtable::copy_buckets(char** top, char* end) {
duke@1 248 intptr_t len = _table_size * sizeof(HashtableBucket);
duke@1 249 *(intptr_t*)(*top) = len;
duke@1 250 *top += sizeof(intptr_t);
duke@1 251
duke@1 252 *(intptr_t*)(*top) = _number_of_entries;
duke@1 253 *top += sizeof(intptr_t);
duke@1 254
duke@1 255 if (*top + len > end) {
coleenp@8076 256 report_out_of_shared_space(SharedMiscData);
duke@1 257 }
duke@1 258 _buckets = (HashtableBucket*)memcpy(*top, _buckets, len);
duke@1 259 *top += len;
duke@1 260 }
duke@1 261
duke@1 262
duke@1 263 #ifndef PRODUCT
duke@1 264
coleenp@8076 265 template <class T> void Hashtable<T>::print() {
duke@1 266 ResourceMark rm;
duke@1 267
duke@1 268 for (int i = 0; i < table_size(); i++) {
coleenp@8076 269 HashtableEntry<T>* entry = bucket(i);
duke@1 270 while(entry != NULL) {
duke@1 271 tty->print("%d : ", i);
duke@1 272 entry->literal()->print();
duke@1 273 tty->cr();
duke@1 274 entry = entry->next();
duke@1 275 }
duke@1 276 }
duke@1 277 }
duke@1 278
duke@1 279
duke@1 280 void BasicHashtable::verify() {
duke@1 281 int count = 0;
duke@1 282 for (int i = 0; i < table_size(); i++) {
duke@1 283 for (BasicHashtableEntry* p = bucket(i); p != NULL; p = p->next()) {
duke@1 284 ++count;
duke@1 285 }
duke@1 286 }
duke@1 287 assert(count == number_of_entries(), "number of hashtable entries incorrect");
duke@1 288 }
duke@1 289
duke@1 290
duke@1 291 #endif // PRODUCT
duke@1 292
duke@1 293
duke@1 294 #ifdef ASSERT
duke@1 295
duke@1 296 void BasicHashtable::verify_lookup_length(double load) {
duke@1 297 if ((double)_lookup_length / (double)_lookup_count > load * 2.0) {
duke@1 298 warning("Performance bug: SystemDictionary lookup_count=%d "
duke@1 299 "lookup_length=%d average=%lf load=%f",
duke@1 300 _lookup_count, _lookup_length,
duke@1 301 (double) _lookup_length / _lookup_count, load);
duke@1 302 }
duke@1 303 }
duke@1 304
duke@1 305 #endif
coleenp@8076 306
coleenp@8076 307 // Explicitly instantiate these types
coleenp@8076 308 template class Hashtable<constantPoolOop>;
coleenp@8076 309 template class Hashtable<Symbol*>;
coleenp@8076 310 template class Hashtable<klassOop>;
coleenp@8076 311 template class Hashtable<oop>;
coleenp@8076 312