Mon, 16 Jul 2012 19:50:52 -0700
Merge
duke@435 | 1 | /* |
coleenp@3682 | 2 | * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved. |
duke@435 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
duke@435 | 4 | * |
duke@435 | 5 | * This code is free software; you can redistribute it and/or modify it |
duke@435 | 6 | * under the terms of the GNU General Public License version 2 only, as |
duke@435 | 7 | * published by the Free Software Foundation. |
duke@435 | 8 | * |
duke@435 | 9 | * This code is distributed in the hope that it will be useful, but WITHOUT |
duke@435 | 10 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
duke@435 | 11 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
duke@435 | 12 | * version 2 for more details (a copy is included in the LICENSE file that |
duke@435 | 13 | * accompanied this code). |
duke@435 | 14 | * |
duke@435 | 15 | * You should have received a copy of the GNU General Public License version |
duke@435 | 16 | * 2 along with this work; if not, write to the Free Software Foundation, |
duke@435 | 17 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
duke@435 | 18 | * |
trims@1907 | 19 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
trims@1907 | 20 | * or visit www.oracle.com if you need additional information or have any |
trims@1907 | 21 | * questions. |
duke@435 | 22 | * |
duke@435 | 23 | */ |
duke@435 | 24 | |
stefank@2314 | 25 | #include "precompiled.hpp" |
coleenp@3865 | 26 | #include "classfile/altHashing.hpp" |
stefank@2314 | 27 | #include "classfile/javaClasses.hpp" |
stefank@2314 | 28 | #include "classfile/symbolTable.hpp" |
stefank@2314 | 29 | #include "classfile/systemDictionary.hpp" |
stefank@2314 | 30 | #include "gc_interface/collectedHeap.inline.hpp" |
coleenp@3682 | 31 | #include "memory/allocation.inline.hpp" |
stefank@2314 | 32 | #include "memory/filemap.hpp" |
stefank@2314 | 33 | #include "memory/gcLocker.inline.hpp" |
stefank@2314 | 34 | #include "oops/oop.inline.hpp" |
stefank@2314 | 35 | #include "oops/oop.inline2.hpp" |
stefank@2314 | 36 | #include "runtime/mutexLocker.hpp" |
stefank@2314 | 37 | #include "utilities/hashtable.inline.hpp" |
coleenp@3865 | 38 | #include "utilities/numberSeq.hpp" |
duke@435 | 39 | |
duke@435 | 40 | // -------------------------------------------------------------------------- |
duke@435 | 41 | |
duke@435 | 42 | SymbolTable* SymbolTable::_the_table = NULL; |
coleenp@3682 | 43 | // Static arena for symbols that are not deallocated |
coleenp@3682 | 44 | Arena* SymbolTable::_arena = NULL; |
coleenp@3865 | 45 | bool SymbolTable::_needs_rehashing = false; |
duke@435 | 46 | |
coleenp@3682 | 47 | Symbol* SymbolTable::allocate_symbol(const u1* name, int len, bool c_heap, TRAPS) { |
coleenp@3875 | 48 | assert (len <= Symbol::max_length(), "should be checked by caller"); |
coleenp@3875 | 49 | |
coleenp@3682 | 50 | Symbol* sym; |
coleenp@3682 | 51 | // Allocate symbols in the C heap when dumping shared spaces in case there |
coleenp@3682 | 52 | // are temporary symbols we can remove. |
coleenp@3682 | 53 | if (c_heap || DumpSharedSpaces) { |
coleenp@3682 | 54 | // refcount starts as 1 |
coleenp@3682 | 55 | sym = new (len, THREAD) Symbol(name, len, 1); |
coleenp@3682 | 56 | } else { |
coleenp@3682 | 57 | sym = new (len, arena(), THREAD) Symbol(name, len, -1); |
coleenp@3682 | 58 | } |
coleenp@2497 | 59 | assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted"); |
coleenp@2497 | 60 | return sym; |
coleenp@2497 | 61 | } |
coleenp@2497 | 62 | |
coleenp@3682 | 63 | void SymbolTable::initialize_symbols(int arena_alloc_size) { |
coleenp@3682 | 64 | // Initialize the arena for global symbols, size passed in depends on CDS. |
coleenp@3682 | 65 | if (arena_alloc_size == 0) { |
zgu@3900 | 66 | _arena = new (mtSymbol) Arena(); |
coleenp@3682 | 67 | } else { |
zgu@3900 | 68 | _arena = new (mtSymbol) Arena(arena_alloc_size); |
coleenp@2497 | 69 | } |
coleenp@2497 | 70 | } |
coleenp@2497 | 71 | |
coleenp@2497 | 72 | // Call function for all symbols in the symbol table. |
coleenp@2497 | 73 | void SymbolTable::symbols_do(SymbolClosure *cl) { |
coleenp@2497 | 74 | const int n = the_table()->table_size(); |
coleenp@2497 | 75 | for (int i = 0; i < n; i++) { |
zgu@3900 | 76 | for (HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i); |
coleenp@2497 | 77 | p != NULL; |
coleenp@2497 | 78 | p = p->next()) { |
coleenp@2497 | 79 | cl->do_symbol(p->literal_addr()); |
coleenp@2497 | 80 | } |
coleenp@2497 | 81 | } |
coleenp@2497 | 82 | } |
coleenp@2497 | 83 | |
coleenp@2497 | 84 | int SymbolTable::symbols_removed = 0; |
coleenp@2497 | 85 | int SymbolTable::symbols_counted = 0; |
coleenp@2497 | 86 | |
coleenp@2497 | 87 | // Remove unreferenced symbols from the symbol table |
coleenp@3682 | 88 | // This is done late during GC. |
coleenp@2497 | 89 | void SymbolTable::unlink() { |
coleenp@2497 | 90 | int removed = 0; |
coleenp@2497 | 91 | int total = 0; |
coleenp@2618 | 92 | size_t memory_total = 0; |
coleenp@2497 | 93 | for (int i = 0; i < the_table()->table_size(); ++i) { |
zgu@3900 | 94 | HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i); |
zgu@3900 | 95 | HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i); |
coleenp@3875 | 96 | while (entry != NULL) { |
coleenp@3875 | 97 | // Shared entries are normally at the end of the bucket and if we run into |
coleenp@3875 | 98 | // a shared entry, then there is nothing more to remove. However, if we |
coleenp@3875 | 99 | // have rehashed the table, then the shared entries are no longer at the |
coleenp@3875 | 100 | // end of the bucket. |
coleenp@3875 | 101 | if (entry->is_shared() && !use_alternate_hashcode()) { |
coleenp@2497 | 102 | break; |
coleenp@2497 | 103 | } |
coleenp@2497 | 104 | Symbol* s = entry->literal(); |
coleenp@2497 | 105 | memory_total += s->object_size(); |
coleenp@2497 | 106 | total++; |
coleenp@2497 | 107 | assert(s != NULL, "just checking"); |
coleenp@2497 | 108 | // If reference count is zero, remove. |
coleenp@2497 | 109 | if (s->refcount() == 0) { |
coleenp@3875 | 110 | assert(!entry->is_shared(), "shared entries should be kept live"); |
coleenp@2497 | 111 | delete s; |
coleenp@2497 | 112 | removed++; |
coleenp@2497 | 113 | *p = entry->next(); |
coleenp@2497 | 114 | the_table()->free_entry(entry); |
coleenp@2497 | 115 | } else { |
coleenp@2497 | 116 | p = entry->next_addr(); |
coleenp@2497 | 117 | } |
coleenp@3875 | 118 | // get next entry |
zgu@3900 | 119 | entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p); |
coleenp@2497 | 120 | } |
coleenp@2497 | 121 | } |
coleenp@2497 | 122 | symbols_removed += removed; |
coleenp@2497 | 123 | symbols_counted += total; |
coleenp@2618 | 124 | // Exclude printing for normal PrintGCDetails because people parse |
coleenp@2618 | 125 | // this output. |
coleenp@2618 | 126 | if (PrintGCDetails && Verbose && WizardMode) { |
coleenp@2618 | 127 | gclog_or_tty->print(" [Symbols=%d size=" SIZE_FORMAT "K] ", total, |
coleenp@2497 | 128 | (memory_total*HeapWordSize)/1024); |
coleenp@2497 | 129 | } |
coleenp@2497 | 130 | } |
coleenp@2497 | 131 | |
coleenp@3865 | 132 | // Create a new table and using alternate hash code, populate the new table |
coleenp@3865 | 133 | // with the existing strings. Set flag to use the alternate hash code afterwards. |
coleenp@3865 | 134 | void SymbolTable::rehash_table() { |
coleenp@3865 | 135 | assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); |
coleenp@3875 | 136 | // This should never happen with -Xshare:dump but it might in testing mode. |
coleenp@3875 | 137 | if (DumpSharedSpaces) return; |
coleenp@3865 | 138 | // Create a new symbol table |
coleenp@3865 | 139 | SymbolTable* new_table = new SymbolTable(); |
coleenp@3865 | 140 | |
coleenp@3865 | 141 | the_table()->move_to(new_table); |
coleenp@3865 | 142 | |
coleenp@3865 | 143 | // Delete the table and buckets (entries are reused in new table). |
coleenp@3865 | 144 | delete _the_table; |
coleenp@3865 | 145 | // Don't check if we need rehashing until the table gets unbalanced again. |
coleenp@3865 | 146 | // Then rehash with a new global seed. |
coleenp@3865 | 147 | _needs_rehashing = false; |
coleenp@3865 | 148 | _the_table = new_table; |
coleenp@3865 | 149 | } |
coleenp@2497 | 150 | |
duke@435 | 151 | // Lookup a symbol in a bucket. |
duke@435 | 152 | |
coleenp@2497 | 153 | Symbol* SymbolTable::lookup(int index, const char* name, |
duke@435 | 154 | int len, unsigned int hash) { |
coleenp@3865 | 155 | int count = 0; |
zgu@3900 | 156 | for (HashtableEntry<Symbol*, mtSymbol>* e = bucket(index); e != NULL; e = e->next()) { |
coleenp@3865 | 157 | count++; // count all entries in this bucket, not just ones with same hash |
duke@435 | 158 | if (e->hash() == hash) { |
coleenp@2497 | 159 | Symbol* sym = e->literal(); |
duke@435 | 160 | if (sym->equals(name, len)) { |
coleenp@2497 | 161 | // something is referencing this symbol now. |
coleenp@2497 | 162 | sym->increment_refcount(); |
duke@435 | 163 | return sym; |
duke@435 | 164 | } |
duke@435 | 165 | } |
duke@435 | 166 | } |
coleenp@3865 | 167 | // If the bucket size is too deep check if this hash code is insufficient. |
zgu@3900 | 168 | if (count >= BasicHashtable<mtSymbol>::rehash_count && !needs_rehashing()) { |
coleenp@3865 | 169 | _needs_rehashing = check_rehash_table(count); |
coleenp@3865 | 170 | } |
duke@435 | 171 | return NULL; |
duke@435 | 172 | } |
duke@435 | 173 | |
coleenp@3875 | 174 | // Pick hashing algorithm. |
coleenp@3875 | 175 | unsigned int SymbolTable::hash_symbol(const char* s, int len) { |
coleenp@3865 | 176 | return use_alternate_hashcode() ? |
coleenp@3865 | 177 | AltHashing::murmur3_32(seed(), (const jbyte*)s, len) : |
coleenp@3875 | 178 | java_lang_String::to_hash(s, len); |
coleenp@3865 | 179 | } |
coleenp@3865 | 180 | |
duke@435 | 181 | |
duke@435 | 182 | // We take care not to be blocking while holding the |
duke@435 | 183 | // SymbolTable_lock. Otherwise, the system might deadlock, since the |
duke@435 | 184 | // symboltable is used during compilation (VM_thread) The lock free |
duke@435 | 185 | // synchronization is simplified by the fact that we do not delete |
duke@435 | 186 | // entries in the symbol table during normal execution (only during |
duke@435 | 187 | // safepoints). |
duke@435 | 188 | |
coleenp@2497 | 189 | Symbol* SymbolTable::lookup(const char* name, int len, TRAPS) { |
duke@435 | 190 | unsigned int hashValue = hash_symbol(name, len); |
duke@435 | 191 | int index = the_table()->hash_to_index(hashValue); |
duke@435 | 192 | |
coleenp@2497 | 193 | Symbol* s = the_table()->lookup(index, name, len, hashValue); |
duke@435 | 194 | |
duke@435 | 195 | // Found |
duke@435 | 196 | if (s != NULL) return s; |
duke@435 | 197 | |
coleenp@3875 | 198 | // Grab SymbolTable_lock first. |
coleenp@3875 | 199 | MutexLocker ml(SymbolTable_lock, THREAD); |
coleenp@3875 | 200 | |
duke@435 | 201 | // Otherwise, add to symbol to table |
coleenp@3682 | 202 | return the_table()->basic_add(index, (u1*)name, len, hashValue, true, CHECK_NULL); |
duke@435 | 203 | } |
duke@435 | 204 | |
coleenp@2497 | 205 | Symbol* SymbolTable::lookup(const Symbol* sym, int begin, int end, TRAPS) { |
duke@435 | 206 | char* buffer; |
duke@435 | 207 | int index, len; |
duke@435 | 208 | unsigned int hashValue; |
duke@435 | 209 | char* name; |
duke@435 | 210 | { |
duke@435 | 211 | debug_only(No_Safepoint_Verifier nsv;) |
duke@435 | 212 | |
duke@435 | 213 | name = (char*)sym->base() + begin; |
duke@435 | 214 | len = end - begin; |
duke@435 | 215 | hashValue = hash_symbol(name, len); |
duke@435 | 216 | index = the_table()->hash_to_index(hashValue); |
coleenp@2497 | 217 | Symbol* s = the_table()->lookup(index, name, len, hashValue); |
duke@435 | 218 | |
duke@435 | 219 | // Found |
duke@435 | 220 | if (s != NULL) return s; |
duke@435 | 221 | } |
duke@435 | 222 | |
duke@435 | 223 | // Otherwise, add to symbol to table. Copy to a C string first. |
duke@435 | 224 | char stack_buf[128]; |
duke@435 | 225 | ResourceMark rm(THREAD); |
duke@435 | 226 | if (len <= 128) { |
duke@435 | 227 | buffer = stack_buf; |
duke@435 | 228 | } else { |
duke@435 | 229 | buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len); |
duke@435 | 230 | } |
duke@435 | 231 | for (int i=0; i<len; i++) { |
duke@435 | 232 | buffer[i] = name[i]; |
duke@435 | 233 | } |
duke@435 | 234 | // Make sure there is no safepoint in the code above since name can't move. |
duke@435 | 235 | // We can't include the code in No_Safepoint_Verifier because of the |
duke@435 | 236 | // ResourceMark. |
duke@435 | 237 | |
coleenp@3875 | 238 | // Grab SymbolTable_lock first. |
coleenp@3875 | 239 | MutexLocker ml(SymbolTable_lock, THREAD); |
coleenp@3875 | 240 | |
coleenp@3682 | 241 | return the_table()->basic_add(index, (u1*)buffer, len, hashValue, true, CHECK_NULL); |
duke@435 | 242 | } |
duke@435 | 243 | |
coleenp@2497 | 244 | Symbol* SymbolTable::lookup_only(const char* name, int len, |
duke@435 | 245 | unsigned int& hash) { |
duke@435 | 246 | hash = hash_symbol(name, len); |
duke@435 | 247 | int index = the_table()->hash_to_index(hash); |
duke@435 | 248 | |
coleenp@2497 | 249 | Symbol* s = the_table()->lookup(index, name, len, hash); |
coleenp@2497 | 250 | return s; |
duke@435 | 251 | } |
duke@435 | 252 | |
phh@3427 | 253 | // Look up the address of the literal in the SymbolTable for this Symbol* |
phh@3427 | 254 | // Do not create any new symbols |
phh@3427 | 255 | // Do not increment the reference count to keep this alive |
phh@3427 | 256 | Symbol** SymbolTable::lookup_symbol_addr(Symbol* sym){ |
phh@3427 | 257 | unsigned int hash = hash_symbol((char*)sym->bytes(), sym->utf8_length()); |
phh@3427 | 258 | int index = the_table()->hash_to_index(hash); |
phh@3427 | 259 | |
zgu@3900 | 260 | for (HashtableEntry<Symbol*, mtSymbol>* e = the_table()->bucket(index); e != NULL; e = e->next()) { |
phh@3427 | 261 | if (e->hash() == hash) { |
phh@3427 | 262 | Symbol* literal_sym = e->literal(); |
phh@3427 | 263 | if (sym == literal_sym) { |
phh@3427 | 264 | return e->literal_addr(); |
phh@3427 | 265 | } |
phh@3427 | 266 | } |
phh@3427 | 267 | } |
phh@3427 | 268 | return NULL; |
phh@3427 | 269 | } |
phh@3427 | 270 | |
jrose@1100 | 271 | // Suggestion: Push unicode-based lookup all the way into the hashing |
jrose@1100 | 272 | // and probing logic, so there is no need for convert_to_utf8 until |
coleenp@2497 | 273 | // an actual new Symbol* is created. |
coleenp@2497 | 274 | Symbol* SymbolTable::lookup_unicode(const jchar* name, int utf16_length, TRAPS) { |
jrose@1100 | 275 | int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length); |
jrose@1100 | 276 | char stack_buf[128]; |
jrose@1100 | 277 | if (utf8_length < (int) sizeof(stack_buf)) { |
jrose@1100 | 278 | char* chars = stack_buf; |
jrose@1100 | 279 | UNICODE::convert_to_utf8(name, utf16_length, chars); |
jrose@1100 | 280 | return lookup(chars, utf8_length, THREAD); |
jrose@1100 | 281 | } else { |
jrose@1100 | 282 | ResourceMark rm(THREAD); |
jrose@1100 | 283 | char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);; |
jrose@1100 | 284 | UNICODE::convert_to_utf8(name, utf16_length, chars); |
jrose@1100 | 285 | return lookup(chars, utf8_length, THREAD); |
jrose@1100 | 286 | } |
jrose@1100 | 287 | } |
jrose@1100 | 288 | |
coleenp@2497 | 289 | Symbol* SymbolTable::lookup_only_unicode(const jchar* name, int utf16_length, |
jrose@1100 | 290 | unsigned int& hash) { |
jrose@1100 | 291 | int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length); |
jrose@1100 | 292 | char stack_buf[128]; |
jrose@1100 | 293 | if (utf8_length < (int) sizeof(stack_buf)) { |
jrose@1100 | 294 | char* chars = stack_buf; |
jrose@1100 | 295 | UNICODE::convert_to_utf8(name, utf16_length, chars); |
jrose@1100 | 296 | return lookup_only(chars, utf8_length, hash); |
jrose@1100 | 297 | } else { |
jrose@1100 | 298 | ResourceMark rm; |
jrose@1100 | 299 | char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);; |
jrose@1100 | 300 | UNICODE::convert_to_utf8(name, utf16_length, chars); |
jrose@1100 | 301 | return lookup_only(chars, utf8_length, hash); |
jrose@1100 | 302 | } |
jrose@1100 | 303 | } |
jrose@1100 | 304 | |
coleenp@3682 | 305 | void SymbolTable::add(Handle class_loader, constantPoolHandle cp, |
coleenp@3682 | 306 | int names_count, |
duke@435 | 307 | const char** names, int* lengths, int* cp_indices, |
duke@435 | 308 | unsigned int* hashValues, TRAPS) { |
coleenp@3875 | 309 | // Grab SymbolTable_lock first. |
coleenp@3875 | 310 | MutexLocker ml(SymbolTable_lock, THREAD); |
coleenp@3875 | 311 | |
duke@435 | 312 | SymbolTable* table = the_table(); |
coleenp@3682 | 313 | bool added = table->basic_add(class_loader, cp, names_count, names, lengths, |
duke@435 | 314 | cp_indices, hashValues, CHECK); |
duke@435 | 315 | if (!added) { |
duke@435 | 316 | // do it the hard way |
duke@435 | 317 | for (int i=0; i<names_count; i++) { |
duke@435 | 318 | int index = table->hash_to_index(hashValues[i]); |
coleenp@3682 | 319 | bool c_heap = class_loader() != NULL; |
coleenp@3682 | 320 | Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i], hashValues[i], c_heap, CHECK); |
duke@435 | 321 | cp->symbol_at_put(cp_indices[i], sym); |
duke@435 | 322 | } |
duke@435 | 323 | } |
duke@435 | 324 | } |
duke@435 | 325 | |
coleenp@3682 | 326 | Symbol* SymbolTable::new_permanent_symbol(const char* name, TRAPS) { |
coleenp@3682 | 327 | unsigned int hash; |
coleenp@3682 | 328 | Symbol* result = SymbolTable::lookup_only((char*)name, (int)strlen(name), hash); |
coleenp@3682 | 329 | if (result != NULL) { |
coleenp@3682 | 330 | return result; |
coleenp@3682 | 331 | } |
coleenp@3875 | 332 | // Grab SymbolTable_lock first. |
coleenp@3875 | 333 | MutexLocker ml(SymbolTable_lock, THREAD); |
coleenp@3875 | 334 | |
coleenp@3682 | 335 | SymbolTable* table = the_table(); |
coleenp@3682 | 336 | int index = table->hash_to_index(hash); |
coleenp@3682 | 337 | return table->basic_add(index, (u1*)name, (int)strlen(name), hash, false, THREAD); |
coleenp@3682 | 338 | } |
coleenp@3682 | 339 | |
coleenp@3875 | 340 | Symbol* SymbolTable::basic_add(int index_arg, u1 *name, int len, |
coleenp@3865 | 341 | unsigned int hashValue_arg, bool c_heap, TRAPS) { |
duke@435 | 342 | assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(), |
duke@435 | 343 | "proposed name of symbol must be stable"); |
duke@435 | 344 | |
coleenp@3875 | 345 | // Don't allow symbols to be created which cannot fit in a Symbol*. |
coleenp@3875 | 346 | if (len > Symbol::max_length()) { |
coleenp@3875 | 347 | THROW_MSG_0(vmSymbols::java_lang_InternalError(), |
coleenp@3875 | 348 | "name is too long to represent"); |
coleenp@3875 | 349 | } |
coleenp@3875 | 350 | |
coleenp@3875 | 351 | // Cannot hit a safepoint in this function because the "this" pointer can move. |
coleenp@3875 | 352 | No_Safepoint_Verifier nsv; |
duke@435 | 353 | |
coleenp@3865 | 354 | // Check if the symbol table has been rehashed, if so, need to recalculate |
coleenp@3875 | 355 | // the hash value and index. |
coleenp@3875 | 356 | unsigned int hashValue; |
coleenp@3875 | 357 | int index; |
coleenp@3875 | 358 | if (use_alternate_hashcode()) { |
coleenp@3875 | 359 | hashValue = hash_symbol((const char*)name, len); |
coleenp@3875 | 360 | index = hash_to_index(hashValue); |
coleenp@3875 | 361 | } else { |
coleenp@3875 | 362 | hashValue = hashValue_arg; |
coleenp@3875 | 363 | index = index_arg; |
coleenp@3875 | 364 | } |
coleenp@3865 | 365 | |
duke@435 | 366 | // Since look-up was done lock-free, we need to check if another |
duke@435 | 367 | // thread beat us in the race to insert the symbol. |
coleenp@2497 | 368 | Symbol* test = lookup(index, (char*)name, len, hashValue); |
duke@435 | 369 | if (test != NULL) { |
coleenp@3682 | 370 | // A race occurred and another thread introduced the symbol. |
coleenp@2497 | 371 | assert(test->refcount() != 0, "lookup should have incremented the count"); |
duke@435 | 372 | return test; |
duke@435 | 373 | } |
duke@435 | 374 | |
coleenp@3682 | 375 | // Create a new symbol. |
coleenp@3682 | 376 | Symbol* sym = allocate_symbol(name, len, c_heap, CHECK_NULL); |
coleenp@3682 | 377 | assert(sym->equals((char*)name, len), "symbol must be properly initialized"); |
coleenp@3682 | 378 | |
zgu@3900 | 379 | HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym); |
duke@435 | 380 | add_entry(index, entry); |
coleenp@2497 | 381 | return sym; |
duke@435 | 382 | } |
duke@435 | 383 | |
coleenp@3682 | 384 | // This version of basic_add adds symbols in batch from the constant pool |
coleenp@3682 | 385 | // parsing. |
coleenp@3682 | 386 | bool SymbolTable::basic_add(Handle class_loader, constantPoolHandle cp, |
coleenp@3682 | 387 | int names_count, |
duke@435 | 388 | const char** names, int* lengths, |
duke@435 | 389 | int* cp_indices, unsigned int* hashValues, |
duke@435 | 390 | TRAPS) { |
coleenp@3682 | 391 | |
coleenp@3682 | 392 | // Check symbol names are not too long. If any are too long, don't add any. |
coleenp@3682 | 393 | for (int i = 0; i< names_count; i++) { |
coleenp@3682 | 394 | if (lengths[i] > Symbol::max_length()) { |
coleenp@3682 | 395 | THROW_MSG_0(vmSymbols::java_lang_InternalError(), |
coleenp@3682 | 396 | "name is too long to represent"); |
coleenp@3682 | 397 | } |
duke@435 | 398 | } |
duke@435 | 399 | |
coleenp@3875 | 400 | // Cannot hit a safepoint in this function because the "this" pointer can move. |
coleenp@3875 | 401 | No_Safepoint_Verifier nsv; |
duke@435 | 402 | |
coleenp@2497 | 403 | for (int i=0; i<names_count; i++) { |
coleenp@3865 | 404 | // Check if the symbol table has been rehashed, if so, need to recalculate |
coleenp@3865 | 405 | // the hash value. |
coleenp@3875 | 406 | unsigned int hashValue; |
coleenp@3875 | 407 | if (use_alternate_hashcode()) { |
coleenp@3875 | 408 | hashValue = hash_symbol(names[i], lengths[i]); |
coleenp@3875 | 409 | } else { |
coleenp@3875 | 410 | hashValue = hashValues[i]; |
coleenp@3875 | 411 | } |
duke@435 | 412 | // Since look-up was done lock-free, we need to check if another |
duke@435 | 413 | // thread beat us in the race to insert the symbol. |
coleenp@3865 | 414 | int index = hash_to_index(hashValue); |
coleenp@3865 | 415 | Symbol* test = lookup(index, names[i], lengths[i], hashValue); |
duke@435 | 416 | if (test != NULL) { |
twisti@1040 | 417 | // A race occurred and another thread introduced the symbol, this one |
duke@435 | 418 | // will be dropped and collected. Use test instead. |
duke@435 | 419 | cp->symbol_at_put(cp_indices[i], test); |
coleenp@2497 | 420 | assert(test->refcount() != 0, "lookup should have incremented the count"); |
duke@435 | 421 | } else { |
coleenp@3682 | 422 | // Create a new symbol. The null class loader is never unloaded so these |
coleenp@3682 | 423 | // are allocated specially in a permanent arena. |
coleenp@3682 | 424 | bool c_heap = class_loader() != NULL; |
coleenp@3682 | 425 | Symbol* sym = allocate_symbol((const u1*)names[i], lengths[i], c_heap, CHECK_(false)); |
coleenp@3682 | 426 | assert(sym->equals(names[i], lengths[i]), "symbol must be properly initialized"); // why wouldn't it be??? |
zgu@3900 | 427 | HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym); |
duke@435 | 428 | add_entry(index, entry); |
duke@435 | 429 | cp->symbol_at_put(cp_indices[i], sym); |
duke@435 | 430 | } |
duke@435 | 431 | } |
duke@435 | 432 | return true; |
duke@435 | 433 | } |
duke@435 | 434 | |
duke@435 | 435 | |
duke@435 | 436 | void SymbolTable::verify() { |
duke@435 | 437 | for (int i = 0; i < the_table()->table_size(); ++i) { |
zgu@3900 | 438 | HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i); |
duke@435 | 439 | for ( ; p != NULL; p = p->next()) { |
coleenp@2497 | 440 | Symbol* s = (Symbol*)(p->literal()); |
duke@435 | 441 | guarantee(s != NULL, "symbol is NULL"); |
duke@435 | 442 | unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length()); |
duke@435 | 443 | guarantee(p->hash() == h, "broken hash in symbol table entry"); |
duke@435 | 444 | guarantee(the_table()->hash_to_index(h) == i, |
duke@435 | 445 | "wrong index in symbol table"); |
duke@435 | 446 | } |
duke@435 | 447 | } |
duke@435 | 448 | } |
duke@435 | 449 | |
coleenp@3865 | 450 | void SymbolTable::dump(outputStream* st) { |
coleenp@3865 | 451 | NumberSeq summary; |
coleenp@3865 | 452 | for (int i = 0; i < the_table()->table_size(); ++i) { |
coleenp@3865 | 453 | int count = 0; |
zgu@3900 | 454 | for (HashtableEntry<Symbol*, mtSymbol>* e = the_table()->bucket(i); |
coleenp@3865 | 455 | e != NULL; e = e->next()) { |
coleenp@3865 | 456 | count++; |
coleenp@3865 | 457 | } |
coleenp@3865 | 458 | summary.add((double)count); |
coleenp@3865 | 459 | } |
coleenp@3865 | 460 | st->print_cr("SymbolTable statistics:"); |
coleenp@3865 | 461 | st->print_cr("Number of buckets : %7d", summary.num()); |
coleenp@3865 | 462 | st->print_cr("Average bucket size : %7.0f", summary.avg()); |
coleenp@3865 | 463 | st->print_cr("Variance of bucket size : %7.0f", summary.variance()); |
coleenp@3865 | 464 | st->print_cr("Std. dev. of bucket size: %7.0f", summary.sd()); |
coleenp@3865 | 465 | st->print_cr("Maximum bucket size : %7.0f", summary.maximum()); |
coleenp@3865 | 466 | } |
coleenp@3865 | 467 | |
duke@435 | 468 | |
duke@435 | 469 | //--------------------------------------------------------------------------- |
duke@435 | 470 | // Non-product code |
duke@435 | 471 | |
duke@435 | 472 | #ifndef PRODUCT |
duke@435 | 473 | |
duke@435 | 474 | void SymbolTable::print_histogram() { |
duke@435 | 475 | MutexLocker ml(SymbolTable_lock); |
duke@435 | 476 | const int results_length = 100; |
duke@435 | 477 | int results[results_length]; |
duke@435 | 478 | int i,j; |
duke@435 | 479 | |
duke@435 | 480 | // initialize results to zero |
duke@435 | 481 | for (j = 0; j < results_length; j++) { |
duke@435 | 482 | results[j] = 0; |
duke@435 | 483 | } |
duke@435 | 484 | |
duke@435 | 485 | int total = 0; |
duke@435 | 486 | int max_symbols = 0; |
duke@435 | 487 | int out_of_range = 0; |
coleenp@2497 | 488 | int memory_total = 0; |
coleenp@2497 | 489 | int count = 0; |
duke@435 | 490 | for (i = 0; i < the_table()->table_size(); i++) { |
zgu@3900 | 491 | HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i); |
duke@435 | 492 | for ( ; p != NULL; p = p->next()) { |
coleenp@2497 | 493 | memory_total += p->literal()->object_size(); |
coleenp@2497 | 494 | count++; |
coleenp@2497 | 495 | int counter = p->literal()->utf8_length(); |
duke@435 | 496 | total += counter; |
duke@435 | 497 | if (counter < results_length) { |
duke@435 | 498 | results[counter]++; |
duke@435 | 499 | } else { |
duke@435 | 500 | out_of_range++; |
duke@435 | 501 | } |
duke@435 | 502 | max_symbols = MAX2(max_symbols, counter); |
duke@435 | 503 | } |
duke@435 | 504 | } |
duke@435 | 505 | tty->print_cr("Symbol Table:"); |
coleenp@2497 | 506 | tty->print_cr("Total number of symbols %5d", count); |
coleenp@2497 | 507 | tty->print_cr("Total size in memory %5dK", |
coleenp@2497 | 508 | (memory_total*HeapWordSize)/1024); |
coleenp@2497 | 509 | tty->print_cr("Total counted %5d", symbols_counted); |
coleenp@2497 | 510 | tty->print_cr("Total removed %5d", symbols_removed); |
coleenp@2497 | 511 | if (symbols_counted > 0) { |
coleenp@2497 | 512 | tty->print_cr("Percent removed %3.2f", |
coleenp@2497 | 513 | ((float)symbols_removed/(float)symbols_counted)* 100); |
coleenp@2497 | 514 | } |
coleenp@2497 | 515 | tty->print_cr("Reference counts %5d", Symbol::_total_count); |
coleenp@3682 | 516 | tty->print_cr("Symbol arena size %5d used %5d", |
coleenp@3682 | 517 | arena()->size_in_bytes(), arena()->used()); |
coleenp@2497 | 518 | tty->print_cr("Histogram of symbol length:"); |
duke@435 | 519 | tty->print_cr("%8s %5d", "Total ", total); |
duke@435 | 520 | tty->print_cr("%8s %5d", "Maximum", max_symbols); |
duke@435 | 521 | tty->print_cr("%8s %3.2f", "Average", |
duke@435 | 522 | ((float) total / (float) the_table()->table_size())); |
duke@435 | 523 | tty->print_cr("%s", "Histogram:"); |
duke@435 | 524 | tty->print_cr(" %s %29s", "Length", "Number chains that length"); |
duke@435 | 525 | for (i = 0; i < results_length; i++) { |
duke@435 | 526 | if (results[i] > 0) { |
duke@435 | 527 | tty->print_cr("%6d %10d", i, results[i]); |
duke@435 | 528 | } |
duke@435 | 529 | } |
coleenp@2497 | 530 | if (Verbose) { |
coleenp@2497 | 531 | int line_length = 70; |
coleenp@2497 | 532 | tty->print_cr("%s %30s", " Length", "Number chains that length"); |
coleenp@2497 | 533 | for (i = 0; i < results_length; i++) { |
coleenp@2497 | 534 | if (results[i] > 0) { |
coleenp@2497 | 535 | tty->print("%4d", i); |
coleenp@2497 | 536 | for (j = 0; (j < results[i]) && (j < line_length); j++) { |
coleenp@2497 | 537 | tty->print("%1s", "*"); |
coleenp@2497 | 538 | } |
coleenp@2497 | 539 | if (j == line_length) { |
coleenp@2497 | 540 | tty->print("%1s", "+"); |
coleenp@2497 | 541 | } |
coleenp@2497 | 542 | tty->cr(); |
duke@435 | 543 | } |
coleenp@2497 | 544 | } |
coleenp@2497 | 545 | } |
coleenp@2497 | 546 | tty->print_cr(" %s %d: %d\n", "Number chains longer than", |
coleenp@2497 | 547 | results_length, out_of_range); |
coleenp@2497 | 548 | } |
coleenp@2497 | 549 | |
coleenp@2497 | 550 | void SymbolTable::print() { |
coleenp@2497 | 551 | for (int i = 0; i < the_table()->table_size(); ++i) { |
zgu@3900 | 552 | HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i); |
zgu@3900 | 553 | HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i); |
coleenp@2497 | 554 | if (entry != NULL) { |
coleenp@2497 | 555 | while (entry != NULL) { |
coleenp@2497 | 556 | tty->print(PTR_FORMAT " ", entry->literal()); |
coleenp@2497 | 557 | entry->literal()->print(); |
coleenp@2497 | 558 | tty->print(" %d", entry->literal()->refcount()); |
coleenp@2497 | 559 | p = entry->next_addr(); |
zgu@3900 | 560 | entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p); |
duke@435 | 561 | } |
duke@435 | 562 | tty->cr(); |
duke@435 | 563 | } |
duke@435 | 564 | } |
duke@435 | 565 | } |
duke@435 | 566 | #endif // PRODUCT |
duke@435 | 567 | |
duke@435 | 568 | // -------------------------------------------------------------------------- |
duke@435 | 569 | |
duke@435 | 570 | #ifdef ASSERT |
duke@435 | 571 | class StableMemoryChecker : public StackObj { |
duke@435 | 572 | enum { _bufsize = wordSize*4 }; |
duke@435 | 573 | |
duke@435 | 574 | address _region; |
duke@435 | 575 | jint _size; |
duke@435 | 576 | u1 _save_buf[_bufsize]; |
duke@435 | 577 | |
duke@435 | 578 | int sample(u1* save_buf) { |
duke@435 | 579 | if (_size <= _bufsize) { |
duke@435 | 580 | memcpy(save_buf, _region, _size); |
duke@435 | 581 | return _size; |
duke@435 | 582 | } else { |
duke@435 | 583 | // copy head and tail |
duke@435 | 584 | memcpy(&save_buf[0], _region, _bufsize/2); |
duke@435 | 585 | memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2); |
duke@435 | 586 | return (_bufsize/2)*2; |
duke@435 | 587 | } |
duke@435 | 588 | } |
duke@435 | 589 | |
duke@435 | 590 | public: |
duke@435 | 591 | StableMemoryChecker(const void* region, jint size) { |
duke@435 | 592 | _region = (address) region; |
duke@435 | 593 | _size = size; |
duke@435 | 594 | sample(_save_buf); |
duke@435 | 595 | } |
duke@435 | 596 | |
duke@435 | 597 | bool verify() { |
duke@435 | 598 | u1 check_buf[sizeof(_save_buf)]; |
duke@435 | 599 | int check_size = sample(check_buf); |
duke@435 | 600 | return (0 == memcmp(_save_buf, check_buf, check_size)); |
duke@435 | 601 | } |
duke@435 | 602 | |
duke@435 | 603 | void set_region(const void* region) { _region = (address) region; } |
duke@435 | 604 | }; |
duke@435 | 605 | #endif |
duke@435 | 606 | |
duke@435 | 607 | |
duke@435 | 608 | // -------------------------------------------------------------------------- |
duke@435 | 609 | StringTable* StringTable::_the_table = NULL; |
duke@435 | 610 | |
coleenp@3865 | 611 | bool StringTable::_needs_rehashing = false; |
coleenp@3865 | 612 | |
coleenp@3865 | 613 | // Pick hashing algorithm |
coleenp@3875 | 614 | unsigned int StringTable::hash_string(const jchar* s, int len) { |
coleenp@3865 | 615 | return use_alternate_hashcode() ? AltHashing::murmur3_32(seed(), s, len) : |
coleenp@3875 | 616 | java_lang_String::to_hash(s, len); |
coleenp@3865 | 617 | } |
coleenp@3865 | 618 | |
duke@435 | 619 | oop StringTable::lookup(int index, jchar* name, |
duke@435 | 620 | int len, unsigned int hash) { |
coleenp@3865 | 621 | int count = 0; |
zgu@3900 | 622 | for (HashtableEntry<oop, mtSymbol>* l = bucket(index); l != NULL; l = l->next()) { |
coleenp@3865 | 623 | count++; |
duke@435 | 624 | if (l->hash() == hash) { |
duke@435 | 625 | if (java_lang_String::equals(l->literal(), name, len)) { |
duke@435 | 626 | return l->literal(); |
duke@435 | 627 | } |
duke@435 | 628 | } |
duke@435 | 629 | } |
coleenp@3865 | 630 | // If the bucket size is too deep check if this hash code is insufficient. |
zgu@3900 | 631 | if (count >= BasicHashtable<mtSymbol>::rehash_count && !needs_rehashing()) { |
coleenp@3865 | 632 | _needs_rehashing = check_rehash_table(count); |
coleenp@3865 | 633 | } |
duke@435 | 634 | return NULL; |
duke@435 | 635 | } |
duke@435 | 636 | |
duke@435 | 637 | |
coleenp@3875 | 638 | oop StringTable::basic_add(int index_arg, Handle string, jchar* name, |
coleenp@3865 | 639 | int len, unsigned int hashValue_arg, TRAPS) { |
duke@435 | 640 | |
duke@435 | 641 | assert(java_lang_String::equals(string(), name, len), |
duke@435 | 642 | "string must be properly initialized"); |
coleenp@3875 | 643 | // Cannot hit a safepoint in this function because the "this" pointer can move. |
coleenp@3875 | 644 | No_Safepoint_Verifier nsv; |
duke@435 | 645 | |
coleenp@3865 | 646 | // Check if the symbol table has been rehashed, if so, need to recalculate |
coleenp@3875 | 647 | // the hash value and index before second lookup. |
coleenp@3875 | 648 | unsigned int hashValue; |
coleenp@3875 | 649 | int index; |
coleenp@3875 | 650 | if (use_alternate_hashcode()) { |
coleenp@3875 | 651 | hashValue = hash_string(name, len); |
coleenp@3875 | 652 | index = hash_to_index(hashValue); |
coleenp@3875 | 653 | } else { |
coleenp@3875 | 654 | hashValue = hashValue_arg; |
coleenp@3875 | 655 | index = index_arg; |
coleenp@3875 | 656 | } |
coleenp@3865 | 657 | |
duke@435 | 658 | // Since look-up was done lock-free, we need to check if another |
duke@435 | 659 | // thread beat us in the race to insert the symbol. |
duke@435 | 660 | |
duke@435 | 661 | oop test = lookup(index, name, len, hashValue); // calls lookup(u1*, int) |
duke@435 | 662 | if (test != NULL) { |
duke@435 | 663 | // Entry already added |
duke@435 | 664 | return test; |
duke@435 | 665 | } |
duke@435 | 666 | |
zgu@3900 | 667 | HashtableEntry<oop, mtSymbol>* entry = new_entry(hashValue, string()); |
duke@435 | 668 | add_entry(index, entry); |
duke@435 | 669 | return string(); |
duke@435 | 670 | } |
duke@435 | 671 | |
duke@435 | 672 | |
coleenp@2497 | 673 | oop StringTable::lookup(Symbol* symbol) { |
duke@435 | 674 | ResourceMark rm; |
duke@435 | 675 | int length; |
duke@435 | 676 | jchar* chars = symbol->as_unicode(length); |
coleenp@3865 | 677 | unsigned int hashValue = hash_string(chars, length); |
duke@435 | 678 | int index = the_table()->hash_to_index(hashValue); |
duke@435 | 679 | return the_table()->lookup(index, chars, length, hashValue); |
duke@435 | 680 | } |
duke@435 | 681 | |
duke@435 | 682 | |
duke@435 | 683 | oop StringTable::intern(Handle string_or_null, jchar* name, |
duke@435 | 684 | int len, TRAPS) { |
coleenp@3865 | 685 | unsigned int hashValue = hash_string(name, len); |
duke@435 | 686 | int index = the_table()->hash_to_index(hashValue); |
coleenp@3875 | 687 | oop found_string = the_table()->lookup(index, name, len, hashValue); |
duke@435 | 688 | |
duke@435 | 689 | // Found |
coleenp@3875 | 690 | if (found_string != NULL) return found_string; |
coleenp@3875 | 691 | |
coleenp@3875 | 692 | debug_only(StableMemoryChecker smc(name, len * sizeof(name[0]))); |
coleenp@3875 | 693 | assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(), |
coleenp@3875 | 694 | "proposed name of symbol must be stable"); |
coleenp@3875 | 695 | |
coleenp@3875 | 696 | Handle string; |
coleenp@3875 | 697 | // try to reuse the string if possible |
coleenp@3875 | 698 | if (!string_or_null.is_null() && (!JavaObjectsInPerm || string_or_null()->is_perm())) { |
coleenp@3875 | 699 | string = string_or_null; |
coleenp@3875 | 700 | } else { |
coleenp@3875 | 701 | string = java_lang_String::create_tenured_from_unicode(name, len, CHECK_NULL); |
coleenp@3875 | 702 | } |
coleenp@3875 | 703 | |
coleenp@3875 | 704 | // Grab the StringTable_lock before getting the_table() because it could |
coleenp@3875 | 705 | // change at safepoint. |
coleenp@3875 | 706 | MutexLocker ml(StringTable_lock, THREAD); |
duke@435 | 707 | |
duke@435 | 708 | // Otherwise, add to symbol to table |
coleenp@3875 | 709 | return the_table()->basic_add(index, string, name, len, |
duke@435 | 710 | hashValue, CHECK_NULL); |
duke@435 | 711 | } |
duke@435 | 712 | |
coleenp@2497 | 713 | oop StringTable::intern(Symbol* symbol, TRAPS) { |
duke@435 | 714 | if (symbol == NULL) return NULL; |
duke@435 | 715 | ResourceMark rm(THREAD); |
duke@435 | 716 | int length; |
duke@435 | 717 | jchar* chars = symbol->as_unicode(length); |
duke@435 | 718 | Handle string; |
duke@435 | 719 | oop result = intern(string, chars, length, CHECK_NULL); |
duke@435 | 720 | return result; |
duke@435 | 721 | } |
duke@435 | 722 | |
duke@435 | 723 | |
duke@435 | 724 | oop StringTable::intern(oop string, TRAPS) |
duke@435 | 725 | { |
duke@435 | 726 | if (string == NULL) return NULL; |
duke@435 | 727 | ResourceMark rm(THREAD); |
duke@435 | 728 | int length; |
duke@435 | 729 | Handle h_string (THREAD, string); |
duke@435 | 730 | jchar* chars = java_lang_String::as_unicode_string(string, length); |
duke@435 | 731 | oop result = intern(h_string, chars, length, CHECK_NULL); |
duke@435 | 732 | return result; |
duke@435 | 733 | } |
duke@435 | 734 | |
duke@435 | 735 | |
duke@435 | 736 | oop StringTable::intern(const char* utf8_string, TRAPS) { |
duke@435 | 737 | if (utf8_string == NULL) return NULL; |
duke@435 | 738 | ResourceMark rm(THREAD); |
duke@435 | 739 | int length = UTF8::unicode_length(utf8_string); |
duke@435 | 740 | jchar* chars = NEW_RESOURCE_ARRAY(jchar, length); |
duke@435 | 741 | UTF8::convert_to_unicode(utf8_string, chars, length); |
duke@435 | 742 | Handle string; |
duke@435 | 743 | oop result = intern(string, chars, length, CHECK_NULL); |
duke@435 | 744 | return result; |
duke@435 | 745 | } |
duke@435 | 746 | |
coleenp@2497 | 747 | void StringTable::unlink(BoolObjectClosure* is_alive) { |
coleenp@2497 | 748 | // Readers of the table are unlocked, so we should only be removing |
coleenp@2497 | 749 | // entries at a safepoint. |
coleenp@2497 | 750 | assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); |
coleenp@2497 | 751 | for (int i = 0; i < the_table()->table_size(); ++i) { |
zgu@3900 | 752 | HashtableEntry<oop, mtSymbol>** p = the_table()->bucket_addr(i); |
zgu@3900 | 753 | HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i); |
coleenp@3875 | 754 | while (entry != NULL) { |
coleenp@3875 | 755 | // Shared entries are normally at the end of the bucket and if we run into |
coleenp@3875 | 756 | // a shared entry, then there is nothing more to remove. However, if we |
coleenp@3875 | 757 | // have rehashed the table, then the shared entries are no longer at the |
coleenp@3875 | 758 | // end of the bucket. |
coleenp@3875 | 759 | if (entry->is_shared() && !use_alternate_hashcode()) { |
coleenp@2497 | 760 | break; |
coleenp@2497 | 761 | } |
coleenp@2497 | 762 | assert(entry->literal() != NULL, "just checking"); |
coleenp@3875 | 763 | if (entry->is_shared() || is_alive->do_object_b(entry->literal())) { |
coleenp@2497 | 764 | p = entry->next_addr(); |
coleenp@2497 | 765 | } else { |
coleenp@2497 | 766 | *p = entry->next(); |
coleenp@2497 | 767 | the_table()->free_entry(entry); |
coleenp@2497 | 768 | } |
zgu@3900 | 769 | entry = (HashtableEntry<oop, mtSymbol>*)HashtableEntry<oop, mtSymbol>::make_ptr(*p); |
coleenp@2497 | 770 | } |
coleenp@2497 | 771 | } |
coleenp@2497 | 772 | } |
coleenp@2497 | 773 | |
coleenp@2497 | 774 | void StringTable::oops_do(OopClosure* f) { |
coleenp@2497 | 775 | for (int i = 0; i < the_table()->table_size(); ++i) { |
zgu@3900 | 776 | HashtableEntry<oop, mtSymbol>** p = the_table()->bucket_addr(i); |
zgu@3900 | 777 | HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i); |
coleenp@2497 | 778 | while (entry != NULL) { |
coleenp@2497 | 779 | f->do_oop((oop*)entry->literal_addr()); |
coleenp@2497 | 780 | |
coleenp@2497 | 781 | // Did the closure remove the literal from the table? |
coleenp@2497 | 782 | if (entry->literal() == NULL) { |
coleenp@2497 | 783 | assert(!entry->is_shared(), "immutable hashtable entry?"); |
coleenp@2497 | 784 | *p = entry->next(); |
coleenp@2497 | 785 | the_table()->free_entry(entry); |
coleenp@2497 | 786 | } else { |
coleenp@2497 | 787 | p = entry->next_addr(); |
coleenp@2497 | 788 | } |
zgu@3900 | 789 | entry = (HashtableEntry<oop, mtSymbol>*)HashtableEntry<oop, mtSymbol>::make_ptr(*p); |
coleenp@2497 | 790 | } |
coleenp@2497 | 791 | } |
coleenp@2497 | 792 | } |
coleenp@2497 | 793 | |
duke@435 | 794 | void StringTable::verify() { |
duke@435 | 795 | for (int i = 0; i < the_table()->table_size(); ++i) { |
zgu@3900 | 796 | HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i); |
duke@435 | 797 | for ( ; p != NULL; p = p->next()) { |
duke@435 | 798 | oop s = p->literal(); |
duke@435 | 799 | guarantee(s != NULL, "interned string is NULL"); |
jcoomes@2661 | 800 | guarantee(s->is_perm() || !JavaObjectsInPerm, "interned string not in permspace"); |
never@2700 | 801 | unsigned int h = java_lang_String::hash_string(s); |
duke@435 | 802 | guarantee(p->hash() == h, "broken hash in string table entry"); |
duke@435 | 803 | guarantee(the_table()->hash_to_index(h) == i, |
duke@435 | 804 | "wrong index in string table"); |
duke@435 | 805 | } |
duke@435 | 806 | } |
duke@435 | 807 | } |
coleenp@3865 | 808 | |
coleenp@3865 | 809 | void StringTable::dump(outputStream* st) { |
coleenp@3865 | 810 | NumberSeq summary; |
coleenp@3865 | 811 | for (int i = 0; i < the_table()->table_size(); ++i) { |
zgu@3900 | 812 | HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i); |
coleenp@3865 | 813 | int count = 0; |
coleenp@3865 | 814 | for ( ; p != NULL; p = p->next()) { |
coleenp@3865 | 815 | count++; |
coleenp@3865 | 816 | } |
coleenp@3865 | 817 | summary.add((double)count); |
coleenp@3865 | 818 | } |
coleenp@3865 | 819 | st->print_cr("StringTable statistics:"); |
coleenp@3865 | 820 | st->print_cr("Number of buckets : %7d", summary.num()); |
coleenp@3865 | 821 | st->print_cr("Average bucket size : %7.0f", summary.avg()); |
coleenp@3865 | 822 | st->print_cr("Variance of bucket size : %7.0f", summary.variance()); |
coleenp@3865 | 823 | st->print_cr("Std. dev. of bucket size: %7.0f", summary.sd()); |
coleenp@3865 | 824 | st->print_cr("Maximum bucket size : %7.0f", summary.maximum()); |
coleenp@3865 | 825 | } |
coleenp@3865 | 826 | |
coleenp@3865 | 827 | |
coleenp@3865 | 828 | // Create a new table and using alternate hash code, populate the new table |
coleenp@3865 | 829 | // with the existing strings. Set flag to use the alternate hash code afterwards. |
coleenp@3865 | 830 | void StringTable::rehash_table() { |
coleenp@3865 | 831 | assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint"); |
coleenp@3875 | 832 | // This should never happen with -Xshare:dump but it might in testing mode. |
coleenp@3875 | 833 | if (DumpSharedSpaces) return; |
coleenp@3865 | 834 | StringTable* new_table = new StringTable(); |
coleenp@3865 | 835 | |
coleenp@3865 | 836 | // Rehash the table |
coleenp@3865 | 837 | the_table()->move_to(new_table); |
coleenp@3865 | 838 | |
coleenp@3865 | 839 | // Delete the table and buckets (entries are reused in new table). |
coleenp@3865 | 840 | delete _the_table; |
coleenp@3865 | 841 | // Don't check if we need rehashing until the table gets unbalanced again. |
coleenp@3865 | 842 | // Then rehash with a new global seed. |
coleenp@3865 | 843 | _needs_rehashing = false; |
coleenp@3865 | 844 | _the_table = new_table; |
coleenp@3865 | 845 | } |