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