1 /*
2 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
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 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/altHashing.hpp"
27 #include "classfile/compactHashtable.inline.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/symbolTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "gc/shared/collectedHeap.inline.hpp"
32 #include "gc/shared/gcLocker.hpp"
33 #include "memory/allocation.inline.hpp"
34 #include "memory/filemap.hpp"
35 #include "memory/metaspaceClosure.hpp"
36 #include "memory/resourceArea.hpp"
37 #include "oops/oop.inline.hpp"
38 #include "runtime/atomic.hpp"
39 #include "runtime/mutexLocker.hpp"
40 #include "runtime/safepointVerifiers.hpp"
41 #include "services/diagnosticCommand.hpp"
42 #include "utilities/hashtable.inline.hpp"
43
44 // --------------------------------------------------------------------------
45 // the number of buckets a thread claims
46 const int ClaimChunkSize = 32;
47
48 SymbolTable* SymbolTable::_the_table = NULL;
49 // Static arena for symbols that are not deallocated
50 Arena* SymbolTable::_arena = NULL;
51 bool SymbolTable::_needs_rehashing = false;
52 bool SymbolTable::_lookup_shared_first = false;
53
54 CompactHashtable<Symbol*, char> SymbolTable::_shared_table;
55
56 Symbol* SymbolTable::allocate_symbol(const u1* name, int len, bool c_heap, TRAPS) {
57 assert (len <= Symbol::max_length(), "should be checked by caller");
58
59 Symbol* sym;
60
61 if (DumpSharedSpaces) {
62 c_heap = false;
63 }
64 if (c_heap) {
65 // refcount starts as 1
66 sym = new (len, THREAD) Symbol(name, len, 1);
67 assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted");
68 } else {
69 // Allocate to global arena
70 sym = new (len, arena(), THREAD) Symbol(name, len, PERM_REFCOUNT);
71 }
72 return sym;
73 }
74
75 void SymbolTable::initialize_symbols(int arena_alloc_size) {
76 // Initialize the arena for global symbols, size passed in depends on CDS.
77 if (arena_alloc_size == 0) {
78 _arena = new (mtSymbol) Arena(mtSymbol);
79 } else {
80 _arena = new (mtSymbol) Arena(mtSymbol, arena_alloc_size);
81 }
82 }
83
84 // Call function for all symbols in the symbol table.
85 void SymbolTable::symbols_do(SymbolClosure *cl) {
86 // all symbols from shared table
87 _shared_table.symbols_do(cl);
88
89 // all symbols from the dynamic table
90 const int n = the_table()->table_size();
91 for (int i = 0; i < n; i++) {
92 for (HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
93 p != NULL;
94 p = p->next()) {
95 cl->do_symbol(p->literal_addr());
96 }
97 }
98 }
99
100 void SymbolTable::metaspace_pointers_do(MetaspaceClosure* it) {
101 assert(DumpSharedSpaces, "called only during dump time");
102 const int n = the_table()->table_size();
103 for (int i = 0; i < n; i++) {
104 for (HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
105 p != NULL;
106 p = p->next()) {
107 it->push(p->literal_addr());
108 }
109 }
110 }
111
112 int SymbolTable::_symbols_removed = 0;
113 int SymbolTable::_symbols_counted = 0;
114 volatile int SymbolTable::_parallel_claimed_idx = 0;
115
116 void SymbolTable::buckets_unlink(int start_idx, int end_idx, BucketUnlinkContext* context) {
117 for (int i = start_idx; i < end_idx; ++i) {
118 HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i);
119 HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i);
120 while (entry != NULL) {
121 // Shared entries are normally at the end of the bucket and if we run into
122 // a shared entry, then there is nothing more to remove. However, if we
123 // have rehashed the table, then the shared entries are no longer at the
124 // end of the bucket.
125 if (entry->is_shared() && !use_alternate_hashcode()) {
126 break;
127 }
128 Symbol* s = entry->literal();
129 context->_num_processed++;
130 assert(s != NULL, "just checking");
131 // If reference count is zero, remove.
132 if (s->refcount() == 0) {
133 assert(!entry->is_shared(), "shared entries should be kept live");
134 delete s;
135 *p = entry->next();
136 context->free_entry(entry);
137 } else {
138 p = entry->next_addr();
139 }
140 // get next entry
141 entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p);
142 }
143 }
144 }
145
146 // Remove unreferenced symbols from the symbol table
147 // This is done late during GC.
148 void SymbolTable::unlink(int* processed, int* removed) {
149 BucketUnlinkContext context;
150 buckets_unlink(0, the_table()->table_size(), &context);
151 _the_table->bulk_free_entries(&context);
152 *processed = context._num_processed;
153 *removed = context._num_removed;
154
155 _symbols_removed = context._num_removed;
156 _symbols_counted = context._num_processed;
157 }
158
159 void SymbolTable::possibly_parallel_unlink(int* processed, int* removed) {
160 const int limit = the_table()->table_size();
161
162 BucketUnlinkContext context;
163 for (;;) {
164 // Grab next set of buckets to scan
165 int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
166 if (start_idx >= limit) {
167 // End of table
168 break;
169 }
170
171 int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
172 buckets_unlink(start_idx, end_idx, &context);
173 }
174
175 _the_table->bulk_free_entries(&context);
176 *processed = context._num_processed;
177 *removed = context._num_removed;
178
179 Atomic::add(context._num_processed, &_symbols_counted);
180 Atomic::add(context._num_removed, &_symbols_removed);
181 }
182
183 // Create a new table and using alternate hash code, populate the new table
184 // with the existing strings. Set flag to use the alternate hash code afterwards.
185 void SymbolTable::rehash_table() {
186 if (DumpSharedSpaces) {
187 tty->print_cr("Warning: rehash_table should not be called while dumping archive");
188 return;
189 }
190
191 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
192 // This should never happen with -Xshare:dump but it might in testing mode.
193 if (DumpSharedSpaces) return;
194 // Create a new symbol table
195 SymbolTable* new_table = new SymbolTable();
196
197 the_table()->move_to(new_table);
198
199 // Delete the table and buckets (entries are reused in new table).
200 delete _the_table;
201 // Don't check if we need rehashing until the table gets unbalanced again.
202 // Then rehash with a new global seed.
203 _needs_rehashing = false;
204 _the_table = new_table;
205 }
206
207 // Lookup a symbol in a bucket.
208
209 Symbol* SymbolTable::lookup_dynamic(int index, const char* name,
210 int len, unsigned int hash) {
211 int count = 0;
212 for (HashtableEntry<Symbol*, mtSymbol>* e = bucket(index); e != NULL; e = e->next()) {
213 count++; // count all entries in this bucket, not just ones with same hash
214 if (e->hash() == hash) {
215 Symbol* sym = e->literal();
216 if (sym->equals(name, len)) {
217 // something is referencing this symbol now.
218 sym->increment_refcount();
219 return sym;
220 }
221 }
222 }
223 // If the bucket size is too deep check if this hash code is insufficient.
224 if (count >= rehash_count && !needs_rehashing()) {
225 _needs_rehashing = check_rehash_table(count);
226 }
227 return NULL;
228 }
229
230 Symbol* SymbolTable::lookup_shared(const char* name,
231 int len, unsigned int hash) {
232 if (use_alternate_hashcode()) {
233 // hash_code parameter may use alternate hashing algorithm but the shared table
234 // always uses the same original hash code.
235 hash = hash_shared_symbol(name, len);
236 }
237 return _shared_table.lookup(name, hash, len);
238 }
239
240 Symbol* SymbolTable::lookup(int index, const char* name,
241 int len, unsigned int hash) {
242 Symbol* sym;
243 if (_lookup_shared_first) {
244 sym = lookup_shared(name, len, hash);
245 if (sym != NULL) {
246 return sym;
247 }
248 _lookup_shared_first = false;
249 return lookup_dynamic(index, name, len, hash);
250 } else {
251 sym = lookup_dynamic(index, name, len, hash);
252 if (sym != NULL) {
253 return sym;
254 }
255 sym = lookup_shared(name, len, hash);
256 if (sym != NULL) {
257 _lookup_shared_first = true;
258 }
259 return sym;
260 }
261 }
262
263 u4 SymbolTable::encode_shared(Symbol* sym) {
264 assert(DumpSharedSpaces, "called only during dump time");
265 uintx base_address = uintx(MetaspaceShared::shared_rs()->base());
266 uintx offset = uintx(sym) - base_address;
267 assert(offset < 0x7fffffff, "sanity");
268 return u4(offset);
269 }
270
271 Symbol* SymbolTable::decode_shared(u4 offset) {
272 assert(!DumpSharedSpaces, "called only during runtime");
273 uintx base_address = _shared_table.base_address();
274 Symbol* sym = (Symbol*)(base_address + offset);
275
276 #ifndef PRODUCT
277 const char* s = (const char*)sym->bytes();
278 int len = sym->utf8_length();
279 unsigned int hash = hash_symbol(s, len);
280 assert(sym == lookup_shared(s, len, hash), "must be shared symbol");
281 #endif
282
283 return sym;
284 }
285
286 // Pick hashing algorithm.
287 unsigned int SymbolTable::hash_symbol(const char* s, int len) {
288 return use_alternate_hashcode() ?
289 AltHashing::murmur3_32(seed(), (const jbyte*)s, len) :
290 java_lang_String::hash_code((const jbyte*)s, len);
291 }
292
293 unsigned int SymbolTable::hash_shared_symbol(const char* s, int len) {
294 return java_lang_String::hash_code((const jbyte*)s, len);
295 }
296
297
298 // We take care not to be blocking while holding the
299 // SymbolTable_lock. Otherwise, the system might deadlock, since the
300 // symboltable is used during compilation (VM_thread) The lock free
301 // synchronization is simplified by the fact that we do not delete
302 // entries in the symbol table during normal execution (only during
303 // safepoints).
304
305 Symbol* SymbolTable::lookup(const char* name, int len, TRAPS) {
306 unsigned int hashValue = hash_symbol(name, len);
307 int index = the_table()->hash_to_index(hashValue);
308
309 Symbol* s = the_table()->lookup(index, name, len, hashValue);
310
311 // Found
312 if (s != NULL) return s;
313
314 // Grab SymbolTable_lock first.
315 MutexLocker ml(SymbolTable_lock, THREAD);
316
317 // Otherwise, add to symbol to table
318 return the_table()->basic_add(index, (u1*)name, len, hashValue, true, THREAD);
319 }
320
321 Symbol* SymbolTable::lookup(const Symbol* sym, int begin, int end, TRAPS) {
322 char* buffer;
323 int index, len;
324 unsigned int hashValue;
325 char* name;
326 {
327 debug_only(NoSafepointVerifier nsv;)
328
329 name = (char*)sym->base() + begin;
330 len = end - begin;
331 hashValue = hash_symbol(name, len);
332 index = the_table()->hash_to_index(hashValue);
333 Symbol* s = the_table()->lookup(index, name, len, hashValue);
334
335 // Found
336 if (s != NULL) return s;
337 }
338
339 // Otherwise, add to symbol to table. Copy to a C string first.
340 char stack_buf[128];
341 ResourceMark rm(THREAD);
342 if (len <= 128) {
343 buffer = stack_buf;
344 } else {
345 buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len);
346 }
347 for (int i=0; i<len; i++) {
348 buffer[i] = name[i];
349 }
350 // Make sure there is no safepoint in the code above since name can't move.
351 // We can't include the code in NoSafepointVerifier because of the
352 // ResourceMark.
353
354 // Grab SymbolTable_lock first.
355 MutexLocker ml(SymbolTable_lock, THREAD);
356
357 return the_table()->basic_add(index, (u1*)buffer, len, hashValue, true, THREAD);
358 }
359
360 Symbol* SymbolTable::lookup_only(const char* name, int len,
361 unsigned int& hash) {
362 hash = hash_symbol(name, len);
363 int index = the_table()->hash_to_index(hash);
364
365 Symbol* s = the_table()->lookup(index, name, len, hash);
366 return s;
367 }
368
369 // Look up the address of the literal in the SymbolTable for this Symbol*
370 // Do not create any new symbols
371 // Do not increment the reference count to keep this alive
372 Symbol** SymbolTable::lookup_symbol_addr(Symbol* sym){
373 unsigned int hash = hash_symbol((char*)sym->bytes(), sym->utf8_length());
374 int index = the_table()->hash_to_index(hash);
375
376 for (HashtableEntry<Symbol*, mtSymbol>* e = the_table()->bucket(index); e != NULL; e = e->next()) {
377 if (e->hash() == hash) {
378 Symbol* literal_sym = e->literal();
379 if (sym == literal_sym) {
380 return e->literal_addr();
381 }
382 }
383 }
384 return NULL;
385 }
386
387 // Suggestion: Push unicode-based lookup all the way into the hashing
388 // and probing logic, so there is no need for convert_to_utf8 until
389 // an actual new Symbol* is created.
390 Symbol* SymbolTable::lookup_unicode(const jchar* name, int utf16_length, TRAPS) {
391 int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
392 char stack_buf[128];
393 if (utf8_length < (int) sizeof(stack_buf)) {
394 char* chars = stack_buf;
395 UNICODE::convert_to_utf8(name, utf16_length, chars);
396 return lookup(chars, utf8_length, THREAD);
397 } else {
398 ResourceMark rm(THREAD);
399 char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
400 UNICODE::convert_to_utf8(name, utf16_length, chars);
401 return lookup(chars, utf8_length, THREAD);
402 }
403 }
404
405 Symbol* SymbolTable::lookup_only_unicode(const jchar* name, int utf16_length,
406 unsigned int& hash) {
407 int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
408 char stack_buf[128];
409 if (utf8_length < (int) sizeof(stack_buf)) {
410 char* chars = stack_buf;
411 UNICODE::convert_to_utf8(name, utf16_length, chars);
412 return lookup_only(chars, utf8_length, hash);
413 } else {
414 ResourceMark rm;
415 char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
416 UNICODE::convert_to_utf8(name, utf16_length, chars);
417 return lookup_only(chars, utf8_length, hash);
418 }
419 }
420
421 void SymbolTable::add(ClassLoaderData* loader_data, const constantPoolHandle& cp,
422 int names_count,
423 const char** names, int* lengths, int* cp_indices,
424 unsigned int* hashValues, TRAPS) {
425 // Grab SymbolTable_lock first.
426 MutexLocker ml(SymbolTable_lock, THREAD);
427
428 SymbolTable* table = the_table();
429 bool added = table->basic_add(loader_data, cp, names_count, names, lengths,
430 cp_indices, hashValues, CHECK);
431 if (!added) {
432 // do it the hard way
433 for (int i=0; i<names_count; i++) {
434 int index = table->hash_to_index(hashValues[i]);
435 bool c_heap = !loader_data->is_the_null_class_loader_data();
436 Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i], hashValues[i], c_heap, CHECK);
437 cp->symbol_at_put(cp_indices[i], sym);
438 }
439 }
440 }
441
442 Symbol* SymbolTable::new_permanent_symbol(const char* name, TRAPS) {
443 unsigned int hash;
444 Symbol* result = SymbolTable::lookup_only((char*)name, (int)strlen(name), hash);
445 if (result != NULL) {
446 return result;
447 }
448 // Grab SymbolTable_lock first.
449 MutexLocker ml(SymbolTable_lock, THREAD);
450
451 SymbolTable* table = the_table();
452 int index = table->hash_to_index(hash);
453 return table->basic_add(index, (u1*)name, (int)strlen(name), hash, false, THREAD);
454 }
455
456 Symbol* SymbolTable::basic_add(int index_arg, u1 *name, int len,
457 unsigned int hashValue_arg, bool c_heap, TRAPS) {
458 assert(!Universe::heap()->is_in_reserved(name),
459 "proposed name of symbol must be stable");
460
461 // Don't allow symbols to be created which cannot fit in a Symbol*.
462 if (len > Symbol::max_length()) {
463 THROW_MSG_0(vmSymbols::java_lang_InternalError(),
464 "name is too long to represent");
465 }
466
467 // Cannot hit a safepoint in this function because the "this" pointer can move.
468 NoSafepointVerifier nsv;
469
470 // Check if the symbol table has been rehashed, if so, need to recalculate
471 // the hash value and index.
472 unsigned int hashValue;
473 int index;
474 if (use_alternate_hashcode()) {
475 hashValue = hash_symbol((const char*)name, len);
476 index = hash_to_index(hashValue);
477 } else {
478 hashValue = hashValue_arg;
479 index = index_arg;
480 }
481
482 // Since look-up was done lock-free, we need to check if another
483 // thread beat us in the race to insert the symbol.
484 Symbol* test = lookup(index, (char*)name, len, hashValue);
485 if (test != NULL) {
486 // A race occurred and another thread introduced the symbol.
487 assert(test->refcount() != 0, "lookup should have incremented the count");
488 return test;
489 }
490
491 // Create a new symbol.
492 Symbol* sym = allocate_symbol(name, len, c_heap, CHECK_NULL);
493 assert(sym->equals((char*)name, len), "symbol must be properly initialized");
494
495 HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym);
496 add_entry(index, entry);
497 return sym;
498 }
499
500 // This version of basic_add adds symbols in batch from the constant pool
501 // parsing.
502 bool SymbolTable::basic_add(ClassLoaderData* loader_data, const constantPoolHandle& cp,
503 int names_count,
504 const char** names, int* lengths,
505 int* cp_indices, unsigned int* hashValues,
506 TRAPS) {
507
508 // Check symbol names are not too long. If any are too long, don't add any.
509 for (int i = 0; i< names_count; i++) {
510 if (lengths[i] > Symbol::max_length()) {
511 THROW_MSG_0(vmSymbols::java_lang_InternalError(),
512 "name is too long to represent");
513 }
514 }
515
516 // Cannot hit a safepoint in this function because the "this" pointer can move.
517 NoSafepointVerifier nsv;
518
519 for (int i=0; i<names_count; i++) {
520 // Check if the symbol table has been rehashed, if so, need to recalculate
521 // the hash value.
522 unsigned int hashValue;
523 if (use_alternate_hashcode()) {
524 hashValue = hash_symbol(names[i], lengths[i]);
525 } else {
526 hashValue = hashValues[i];
527 }
528 // Since look-up was done lock-free, we need to check if another
529 // thread beat us in the race to insert the symbol.
530 int index = hash_to_index(hashValue);
531 Symbol* test = lookup(index, names[i], lengths[i], hashValue);
532 if (test != NULL) {
533 // A race occurred and another thread introduced the symbol, this one
534 // will be dropped and collected. Use test instead.
535 cp->symbol_at_put(cp_indices[i], test);
536 assert(test->refcount() != 0, "lookup should have incremented the count");
537 } else {
538 // Create a new symbol. The null class loader is never unloaded so these
539 // are allocated specially in a permanent arena.
540 bool c_heap = !loader_data->is_the_null_class_loader_data();
541 Symbol* sym = allocate_symbol((const u1*)names[i], lengths[i], c_heap, CHECK_(false));
542 assert(sym->equals(names[i], lengths[i]), "symbol must be properly initialized"); // why wouldn't it be???
543 HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym);
544 add_entry(index, entry);
545 cp->symbol_at_put(cp_indices[i], sym);
546 }
547 }
548 return true;
549 }
550
551
552 void SymbolTable::verify() {
553 for (int i = 0; i < the_table()->table_size(); ++i) {
554 HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
555 for ( ; p != NULL; p = p->next()) {
556 Symbol* s = (Symbol*)(p->literal());
557 guarantee(s != NULL, "symbol is NULL");
558 unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length());
559 guarantee(p->hash() == h, "broken hash in symbol table entry");
560 guarantee(the_table()->hash_to_index(h) == i,
561 "wrong index in symbol table");
562 }
563 }
564 }
565
566 void SymbolTable::dump(outputStream* st, bool verbose) {
567 if (!verbose) {
568 the_table()->print_table_statistics(st, "SymbolTable");
569 } else {
570 st->print_cr("VERSION: 1.0");
571 for (int i = 0; i < the_table()->table_size(); ++i) {
572 HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
573 for ( ; p != NULL; p = p->next()) {
574 Symbol* s = (Symbol*)(p->literal());
575 const char* utf8_string = (const char*)s->bytes();
576 int utf8_length = s->utf8_length();
577 st->print("%d %d: ", utf8_length, s->refcount());
578 HashtableTextDump::put_utf8(st, utf8_string, utf8_length);
579 st->cr();
580 }
581 }
582 }
583 }
584
585 void SymbolTable::write_to_archive() {
586 #if INCLUDE_CDS
587 _shared_table.reset();
588
589 int num_buckets = the_table()->number_of_entries() /
590 SharedSymbolTableBucketSize;
591 CompactSymbolTableWriter writer(num_buckets,
592 &MetaspaceShared::stats()->symbol);
593 for (int i = 0; i < the_table()->table_size(); ++i) {
594 HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
595 for ( ; p != NULL; p = p->next()) {
596 Symbol* s = (Symbol*)(p->literal());
597 unsigned int fixed_hash = hash_shared_symbol((char*)s->bytes(), s->utf8_length());
598 assert(fixed_hash == p->hash(), "must not rehash during dumping");
599 writer.add(fixed_hash, s);
600 }
601 }
602
603 writer.dump(&_shared_table);
604
605 // Verify table is correct
606 Symbol* sym = vmSymbols::java_lang_Object();
607 const char* name = (const char*)sym->bytes();
608 int len = sym->utf8_length();
609 unsigned int hash = hash_symbol(name, len);
610 assert(sym == _shared_table.lookup(name, hash, len), "sanity");
611 #endif
612 }
613
614 void SymbolTable::serialize(SerializeClosure* soc) {
615 #if INCLUDE_CDS
616 _shared_table.set_type(CompactHashtable<Symbol*, char>::_symbol_table);
617 _shared_table.serialize(soc);
618
619 if (soc->writing()) {
620 // Sanity. Make sure we don't use the shared table at dump time
621 _shared_table.reset();
622 }
623 #endif
624 }
625
626 //---------------------------------------------------------------------------
627 // Non-product code
628
629 #ifndef PRODUCT
630
631 void SymbolTable::print_histogram() {
632 MutexLocker ml(SymbolTable_lock);
633 const int results_length = 100;
634 int counts[results_length];
635 int sizes[results_length];
636 int i,j;
637
638 // initialize results to zero
639 for (j = 0; j < results_length; j++) {
640 counts[j] = 0;
641 sizes[j] = 0;
642 }
643
644 int total_size = 0;
645 int total_count = 0;
646 int total_length = 0;
647 int max_length = 0;
648 int out_of_range_count = 0;
649 int out_of_range_size = 0;
650 for (i = 0; i < the_table()->table_size(); i++) {
651 HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
652 for ( ; p != NULL; p = p->next()) {
653 int size = p->literal()->size();
654 int len = p->literal()->utf8_length();
655 if (len < results_length) {
656 counts[len]++;
657 sizes[len] += size;
658 } else {
659 out_of_range_count++;
660 out_of_range_size += size;
661 }
662 total_count++;
663 total_size += size;
664 total_length += len;
665 max_length = MAX2(max_length, len);
666 }
667 }
668 tty->print_cr("Symbol Table Histogram:");
669 tty->print_cr(" Total number of symbols %7d", total_count);
670 tty->print_cr(" Total size in memory %7dK",
671 (total_size*wordSize)/1024);
672 tty->print_cr(" Total counted %7d", _symbols_counted);
673 tty->print_cr(" Total removed %7d", _symbols_removed);
674 if (_symbols_counted > 0) {
675 tty->print_cr(" Percent removed %3.2f",
676 ((float)_symbols_removed/(float)_symbols_counted)* 100);
677 }
678 tty->print_cr(" Reference counts %7d", Symbol::_total_count);
679 tty->print_cr(" Symbol arena used " SIZE_FORMAT_W(7) "K", arena()->used()/1024);
680 tty->print_cr(" Symbol arena size " SIZE_FORMAT_W(7) "K", arena()->size_in_bytes()/1024);
681 tty->print_cr(" Total symbol length %7d", total_length);
682 tty->print_cr(" Maximum symbol length %7d", max_length);
683 tty->print_cr(" Average symbol length %7.2f", ((float) total_length / (float) total_count));
684 tty->print_cr(" Symbol length histogram:");
685 tty->print_cr(" %6s %10s %10s", "Length", "#Symbols", "Size");
686 for (i = 0; i < results_length; i++) {
687 if (counts[i] > 0) {
688 tty->print_cr(" %6d %10d %10dK", i, counts[i], (sizes[i]*wordSize)/1024);
689 }
690 }
691 tty->print_cr(" >=%6d %10d %10dK\n", results_length,
692 out_of_range_count, (out_of_range_size*wordSize)/1024);
693 }
694
695 void SymbolTable::print() {
696 for (int i = 0; i < the_table()->table_size(); ++i) {
697 HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i);
698 HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i);
699 if (entry != NULL) {
700 while (entry != NULL) {
701 tty->print(PTR_FORMAT " ", p2i(entry->literal()));
702 entry->literal()->print();
703 tty->print(" %d", entry->literal()->refcount());
704 p = entry->next_addr();
705 entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p);
706 }
707 tty->cr();
708 }
709 }
710 }
711 #endif // PRODUCT
712
713
714 // Utility for dumping symbols
715 SymboltableDCmd::SymboltableDCmd(outputStream* output, bool heap) :
716 DCmdWithParser(output, heap),
717 _verbose("-verbose", "Dump the content of each symbol in the table",
718 "BOOLEAN", false, "false") {
719 _dcmdparser.add_dcmd_option(&_verbose);
720 }
721
722 void SymboltableDCmd::execute(DCmdSource source, TRAPS) {
723 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSymbols,
724 _verbose.value());
725 VMThread::execute(&dumper);
726 }
727
728 int SymboltableDCmd::num_arguments() {
729 ResourceMark rm;
730 SymboltableDCmd* dcmd = new SymboltableDCmd(NULL, false);
731 if (dcmd != NULL) {
732 DCmdMark mark(dcmd);
733 return dcmd->_dcmdparser.num_arguments();
734 } else {
735 return 0;
736 }
737 }