Wed, 11 Jan 2012 17:34:02 -0500
7115199: Add event tracing hooks and Java Flight Recorder infrastructure
Summary: Added a nop tracing infrastructure, JFR makefile changes and other infrastructure used only by JFR.
Reviewed-by: acorn, sspitsyn
Contributed-by: markus.gronlund@oracle.com
1 /*
2 * Copyright (c) 1997, 2011, 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 */
25 #include "precompiled.hpp"
26 #include "classfile/javaClasses.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "gc_interface/collectedHeap.inline.hpp"
30 #include "memory/filemap.hpp"
31 #include "memory/gcLocker.inline.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "oops/oop.inline2.hpp"
34 #include "runtime/mutexLocker.hpp"
35 #include "utilities/hashtable.inline.hpp"
37 // --------------------------------------------------------------------------
39 SymbolTable* SymbolTable::_the_table = NULL;
41 Symbol* SymbolTable::allocate_symbol(const u1* name, int len, TRAPS) {
42 // Don't allow symbols to be created which cannot fit in a Symbol*.
43 if (len > Symbol::max_length()) {
44 THROW_MSG_0(vmSymbols::java_lang_InternalError(),
45 "name is too long to represent");
46 }
47 Symbol* sym = new (len) Symbol(name, len);
48 assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted");
49 return sym;
50 }
52 bool SymbolTable::allocate_symbols(int names_count, const u1** names,
53 int* lengths, Symbol** syms, TRAPS) {
54 for (int i = 0; i< names_count; i++) {
55 if (lengths[i] > Symbol::max_length()) {
56 THROW_MSG_0(vmSymbols::java_lang_InternalError(),
57 "name is too long to represent");
58 }
59 }
61 for (int i = 0; i< names_count; i++) {
62 int len = lengths[i];
63 syms[i] = new (len) Symbol(names[i], len);
64 assert(syms[i] != NULL, "new should call vm_exit_out_of_memory if "
65 "C_HEAP is exhausted");
66 }
67 return true;
68 }
70 // Call function for all symbols in the symbol table.
71 void SymbolTable::symbols_do(SymbolClosure *cl) {
72 const int n = the_table()->table_size();
73 for (int i = 0; i < n; i++) {
74 for (HashtableEntry<Symbol*>* p = the_table()->bucket(i);
75 p != NULL;
76 p = p->next()) {
77 cl->do_symbol(p->literal_addr());
78 }
79 }
80 }
82 int SymbolTable::symbols_removed = 0;
83 int SymbolTable::symbols_counted = 0;
85 // Remove unreferenced symbols from the symbol table
86 // This is done late during GC. This doesn't use the hash table unlink because
87 // it assumes that the literals are oops.
88 void SymbolTable::unlink() {
89 int removed = 0;
90 int total = 0;
91 size_t memory_total = 0;
92 for (int i = 0; i < the_table()->table_size(); ++i) {
93 for (HashtableEntry<Symbol*>** p = the_table()->bucket_addr(i); *p != NULL; ) {
94 HashtableEntry<Symbol*>* entry = *p;
95 if (entry->is_shared()) {
96 break;
97 }
98 Symbol* s = entry->literal();
99 memory_total += s->object_size();
100 total++;
101 assert(s != NULL, "just checking");
102 // If reference count is zero, remove.
103 if (s->refcount() == 0) {
104 delete s;
105 removed++;
106 *p = entry->next();
107 the_table()->free_entry(entry);
108 } else {
109 p = entry->next_addr();
110 }
111 }
112 }
113 symbols_removed += removed;
114 symbols_counted += total;
115 // Exclude printing for normal PrintGCDetails because people parse
116 // this output.
117 if (PrintGCDetails && Verbose && WizardMode) {
118 gclog_or_tty->print(" [Symbols=%d size=" SIZE_FORMAT "K] ", total,
119 (memory_total*HeapWordSize)/1024);
120 }
121 }
124 // Lookup a symbol in a bucket.
126 Symbol* SymbolTable::lookup(int index, const char* name,
127 int len, unsigned int hash) {
128 for (HashtableEntry<Symbol*>* e = bucket(index); e != NULL; e = e->next()) {
129 if (e->hash() == hash) {
130 Symbol* sym = e->literal();
131 if (sym->equals(name, len)) {
132 // something is referencing this symbol now.
133 sym->increment_refcount();
134 return sym;
135 }
136 }
137 }
138 return NULL;
139 }
142 // We take care not to be blocking while holding the
143 // SymbolTable_lock. Otherwise, the system might deadlock, since the
144 // symboltable is used during compilation (VM_thread) The lock free
145 // synchronization is simplified by the fact that we do not delete
146 // entries in the symbol table during normal execution (only during
147 // safepoints).
149 Symbol* SymbolTable::lookup(const char* name, int len, TRAPS) {
150 unsigned int hashValue = hash_symbol(name, len);
151 int index = the_table()->hash_to_index(hashValue);
153 Symbol* s = the_table()->lookup(index, name, len, hashValue);
155 // Found
156 if (s != NULL) return s;
158 // Otherwise, add to symbol to table
159 return the_table()->basic_add(index, (u1*)name, len, hashValue, CHECK_NULL);
160 }
162 Symbol* SymbolTable::lookup(const Symbol* sym, int begin, int end, TRAPS) {
163 char* buffer;
164 int index, len;
165 unsigned int hashValue;
166 char* name;
167 {
168 debug_only(No_Safepoint_Verifier nsv;)
170 name = (char*)sym->base() + begin;
171 len = end - begin;
172 hashValue = hash_symbol(name, len);
173 index = the_table()->hash_to_index(hashValue);
174 Symbol* s = the_table()->lookup(index, name, len, hashValue);
176 // Found
177 if (s != NULL) return s;
178 }
180 // Otherwise, add to symbol to table. Copy to a C string first.
181 char stack_buf[128];
182 ResourceMark rm(THREAD);
183 if (len <= 128) {
184 buffer = stack_buf;
185 } else {
186 buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len);
187 }
188 for (int i=0; i<len; i++) {
189 buffer[i] = name[i];
190 }
191 // Make sure there is no safepoint in the code above since name can't move.
192 // We can't include the code in No_Safepoint_Verifier because of the
193 // ResourceMark.
195 return the_table()->basic_add(index, (u1*)buffer, len, hashValue, CHECK_NULL);
196 }
198 Symbol* SymbolTable::lookup_only(const char* name, int len,
199 unsigned int& hash) {
200 hash = hash_symbol(name, len);
201 int index = the_table()->hash_to_index(hash);
203 Symbol* s = the_table()->lookup(index, name, len, hash);
204 return s;
205 }
207 // Look up the address of the literal in the SymbolTable for this Symbol*
208 // Do not create any new symbols
209 // Do not increment the reference count to keep this alive
210 Symbol** SymbolTable::lookup_symbol_addr(Symbol* sym){
211 unsigned int hash = hash_symbol((char*)sym->bytes(), sym->utf8_length());
212 int index = the_table()->hash_to_index(hash);
214 for (HashtableEntry<Symbol*>* e = the_table()->bucket(index); e != NULL; e = e->next()) {
215 if (e->hash() == hash) {
216 Symbol* literal_sym = e->literal();
217 if (sym == literal_sym) {
218 return e->literal_addr();
219 }
220 }
221 }
222 return NULL;
223 }
225 // Suggestion: Push unicode-based lookup all the way into the hashing
226 // and probing logic, so there is no need for convert_to_utf8 until
227 // an actual new Symbol* is created.
228 Symbol* SymbolTable::lookup_unicode(const jchar* name, int utf16_length, TRAPS) {
229 int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
230 char stack_buf[128];
231 if (utf8_length < (int) sizeof(stack_buf)) {
232 char* chars = stack_buf;
233 UNICODE::convert_to_utf8(name, utf16_length, chars);
234 return lookup(chars, utf8_length, THREAD);
235 } else {
236 ResourceMark rm(THREAD);
237 char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
238 UNICODE::convert_to_utf8(name, utf16_length, chars);
239 return lookup(chars, utf8_length, THREAD);
240 }
241 }
243 Symbol* SymbolTable::lookup_only_unicode(const jchar* name, int utf16_length,
244 unsigned int& hash) {
245 int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
246 char stack_buf[128];
247 if (utf8_length < (int) sizeof(stack_buf)) {
248 char* chars = stack_buf;
249 UNICODE::convert_to_utf8(name, utf16_length, chars);
250 return lookup_only(chars, utf8_length, hash);
251 } else {
252 ResourceMark rm;
253 char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
254 UNICODE::convert_to_utf8(name, utf16_length, chars);
255 return lookup_only(chars, utf8_length, hash);
256 }
257 }
259 void SymbolTable::add(constantPoolHandle cp, int names_count,
260 const char** names, int* lengths, int* cp_indices,
261 unsigned int* hashValues, TRAPS) {
262 SymbolTable* table = the_table();
263 bool added = table->basic_add(cp, names_count, names, lengths,
264 cp_indices, hashValues, CHECK);
265 if (!added) {
266 // do it the hard way
267 for (int i=0; i<names_count; i++) {
268 int index = table->hash_to_index(hashValues[i]);
269 Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i],
270 hashValues[i], CHECK);
271 cp->symbol_at_put(cp_indices[i], sym);
272 }
273 }
274 }
276 Symbol* SymbolTable::basic_add(int index, u1 *name, int len,
277 unsigned int hashValue, TRAPS) {
278 assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(),
279 "proposed name of symbol must be stable");
281 // We assume that lookup() has been called already, that it failed,
282 // and symbol was not found. We create the symbol here.
283 Symbol* sym = allocate_symbol(name, len, CHECK_NULL);
285 // Allocation must be done before grabbing the SymbolTable_lock lock
286 MutexLocker ml(SymbolTable_lock, THREAD);
288 assert(sym->equals((char*)name, len), "symbol must be properly initialized");
290 // Since look-up was done lock-free, we need to check if another
291 // thread beat us in the race to insert the symbol.
293 Symbol* test = lookup(index, (char*)name, len, hashValue);
294 if (test != NULL) {
295 // A race occurred and another thread introduced the symbol, this one
296 // will be dropped and collected.
297 delete sym;
298 assert(test->refcount() != 0, "lookup should have incremented the count");
299 return test;
300 }
302 HashtableEntry<Symbol*>* entry = new_entry(hashValue, sym);
303 sym->increment_refcount();
304 add_entry(index, entry);
305 return sym;
306 }
308 bool SymbolTable::basic_add(constantPoolHandle cp, int names_count,
309 const char** names, int* lengths,
310 int* cp_indices, unsigned int* hashValues,
311 TRAPS) {
312 Symbol* syms[symbol_alloc_batch_size];
313 bool allocated = allocate_symbols(names_count, (const u1**)names, lengths,
314 syms, CHECK_false);
315 if (!allocated) {
316 return false;
317 }
319 // Allocation must be done before grabbing the SymbolTable_lock lock
320 MutexLocker ml(SymbolTable_lock, THREAD);
322 for (int i=0; i<names_count; i++) {
323 assert(syms[i]->equals(names[i], lengths[i]), "symbol must be properly initialized");
324 // Since look-up was done lock-free, we need to check if another
325 // thread beat us in the race to insert the symbol.
326 int index = hash_to_index(hashValues[i]);
327 Symbol* test = lookup(index, names[i], lengths[i], hashValues[i]);
328 if (test != NULL) {
329 // A race occurred and another thread introduced the symbol, this one
330 // will be dropped and collected. Use test instead.
331 cp->symbol_at_put(cp_indices[i], test);
332 assert(test->refcount() != 0, "lookup should have incremented the count");
333 delete syms[i];
334 } else {
335 Symbol* sym = syms[i];
336 HashtableEntry<Symbol*>* entry = new_entry(hashValues[i], sym);
337 sym->increment_refcount(); // increment refcount in external hashtable
338 add_entry(index, entry);
339 cp->symbol_at_put(cp_indices[i], sym);
340 }
341 }
343 return true;
344 }
347 void SymbolTable::verify() {
348 for (int i = 0; i < the_table()->table_size(); ++i) {
349 HashtableEntry<Symbol*>* p = the_table()->bucket(i);
350 for ( ; p != NULL; p = p->next()) {
351 Symbol* s = (Symbol*)(p->literal());
352 guarantee(s != NULL, "symbol is NULL");
353 unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length());
354 guarantee(p->hash() == h, "broken hash in symbol table entry");
355 guarantee(the_table()->hash_to_index(h) == i,
356 "wrong index in symbol table");
357 }
358 }
359 }
362 //---------------------------------------------------------------------------
363 // Non-product code
365 #ifndef PRODUCT
367 void SymbolTable::print_histogram() {
368 MutexLocker ml(SymbolTable_lock);
369 const int results_length = 100;
370 int results[results_length];
371 int i,j;
373 // initialize results to zero
374 for (j = 0; j < results_length; j++) {
375 results[j] = 0;
376 }
378 int total = 0;
379 int max_symbols = 0;
380 int out_of_range = 0;
381 int memory_total = 0;
382 int count = 0;
383 for (i = 0; i < the_table()->table_size(); i++) {
384 HashtableEntry<Symbol*>* p = the_table()->bucket(i);
385 for ( ; p != NULL; p = p->next()) {
386 memory_total += p->literal()->object_size();
387 count++;
388 int counter = p->literal()->utf8_length();
389 total += counter;
390 if (counter < results_length) {
391 results[counter]++;
392 } else {
393 out_of_range++;
394 }
395 max_symbols = MAX2(max_symbols, counter);
396 }
397 }
398 tty->print_cr("Symbol Table:");
399 tty->print_cr("Total number of symbols %5d", count);
400 tty->print_cr("Total size in memory %5dK",
401 (memory_total*HeapWordSize)/1024);
402 tty->print_cr("Total counted %5d", symbols_counted);
403 tty->print_cr("Total removed %5d", symbols_removed);
404 if (symbols_counted > 0) {
405 tty->print_cr("Percent removed %3.2f",
406 ((float)symbols_removed/(float)symbols_counted)* 100);
407 }
408 tty->print_cr("Reference counts %5d", Symbol::_total_count);
409 tty->print_cr("Histogram of symbol length:");
410 tty->print_cr("%8s %5d", "Total ", total);
411 tty->print_cr("%8s %5d", "Maximum", max_symbols);
412 tty->print_cr("%8s %3.2f", "Average",
413 ((float) total / (float) the_table()->table_size()));
414 tty->print_cr("%s", "Histogram:");
415 tty->print_cr(" %s %29s", "Length", "Number chains that length");
416 for (i = 0; i < results_length; i++) {
417 if (results[i] > 0) {
418 tty->print_cr("%6d %10d", i, results[i]);
419 }
420 }
421 if (Verbose) {
422 int line_length = 70;
423 tty->print_cr("%s %30s", " Length", "Number chains that length");
424 for (i = 0; i < results_length; i++) {
425 if (results[i] > 0) {
426 tty->print("%4d", i);
427 for (j = 0; (j < results[i]) && (j < line_length); j++) {
428 tty->print("%1s", "*");
429 }
430 if (j == line_length) {
431 tty->print("%1s", "+");
432 }
433 tty->cr();
434 }
435 }
436 }
437 tty->print_cr(" %s %d: %d\n", "Number chains longer than",
438 results_length, out_of_range);
439 }
441 void SymbolTable::print() {
442 for (int i = 0; i < the_table()->table_size(); ++i) {
443 HashtableEntry<Symbol*>** p = the_table()->bucket_addr(i);
444 HashtableEntry<Symbol*>* entry = the_table()->bucket(i);
445 if (entry != NULL) {
446 while (entry != NULL) {
447 tty->print(PTR_FORMAT " ", entry->literal());
448 entry->literal()->print();
449 tty->print(" %d", entry->literal()->refcount());
450 p = entry->next_addr();
451 entry = (HashtableEntry<Symbol*>*)HashtableEntry<Symbol*>::make_ptr(*p);
452 }
453 tty->cr();
454 }
455 }
456 }
458 #endif // PRODUCT
460 // --------------------------------------------------------------------------
462 #ifdef ASSERT
463 class StableMemoryChecker : public StackObj {
464 enum { _bufsize = wordSize*4 };
466 address _region;
467 jint _size;
468 u1 _save_buf[_bufsize];
470 int sample(u1* save_buf) {
471 if (_size <= _bufsize) {
472 memcpy(save_buf, _region, _size);
473 return _size;
474 } else {
475 // copy head and tail
476 memcpy(&save_buf[0], _region, _bufsize/2);
477 memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2);
478 return (_bufsize/2)*2;
479 }
480 }
482 public:
483 StableMemoryChecker(const void* region, jint size) {
484 _region = (address) region;
485 _size = size;
486 sample(_save_buf);
487 }
489 bool verify() {
490 u1 check_buf[sizeof(_save_buf)];
491 int check_size = sample(check_buf);
492 return (0 == memcmp(_save_buf, check_buf, check_size));
493 }
495 void set_region(const void* region) { _region = (address) region; }
496 };
497 #endif
500 // --------------------------------------------------------------------------
501 StringTable* StringTable::_the_table = NULL;
503 oop StringTable::lookup(int index, jchar* name,
504 int len, unsigned int hash) {
505 for (HashtableEntry<oop>* l = bucket(index); l != NULL; l = l->next()) {
506 if (l->hash() == hash) {
507 if (java_lang_String::equals(l->literal(), name, len)) {
508 return l->literal();
509 }
510 }
511 }
512 return NULL;
513 }
516 oop StringTable::basic_add(int index, Handle string_or_null, jchar* name,
517 int len, unsigned int hashValue, TRAPS) {
518 debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
519 assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(),
520 "proposed name of symbol must be stable");
522 Handle string;
523 // try to reuse the string if possible
524 if (!string_or_null.is_null() && (!JavaObjectsInPerm || string_or_null()->is_perm())) {
525 string = string_or_null;
526 } else {
527 string = java_lang_String::create_tenured_from_unicode(name, len, CHECK_NULL);
528 }
530 // Allocation must be done before grapping the SymbolTable_lock lock
531 MutexLocker ml(StringTable_lock, THREAD);
533 assert(java_lang_String::equals(string(), name, len),
534 "string must be properly initialized");
536 // Since look-up was done lock-free, we need to check if another
537 // thread beat us in the race to insert the symbol.
539 oop test = lookup(index, name, len, hashValue); // calls lookup(u1*, int)
540 if (test != NULL) {
541 // Entry already added
542 return test;
543 }
545 HashtableEntry<oop>* entry = new_entry(hashValue, string());
546 add_entry(index, entry);
547 return string();
548 }
551 oop StringTable::lookup(Symbol* symbol) {
552 ResourceMark rm;
553 int length;
554 jchar* chars = symbol->as_unicode(length);
555 unsigned int hashValue = java_lang_String::hash_string(chars, length);
556 int index = the_table()->hash_to_index(hashValue);
557 return the_table()->lookup(index, chars, length, hashValue);
558 }
561 oop StringTable::intern(Handle string_or_null, jchar* name,
562 int len, TRAPS) {
563 unsigned int hashValue = java_lang_String::hash_string(name, len);
564 int index = the_table()->hash_to_index(hashValue);
565 oop string = the_table()->lookup(index, name, len, hashValue);
567 // Found
568 if (string != NULL) return string;
570 // Otherwise, add to symbol to table
571 return the_table()->basic_add(index, string_or_null, name, len,
572 hashValue, CHECK_NULL);
573 }
575 oop StringTable::intern(Symbol* symbol, TRAPS) {
576 if (symbol == NULL) return NULL;
577 ResourceMark rm(THREAD);
578 int length;
579 jchar* chars = symbol->as_unicode(length);
580 Handle string;
581 oop result = intern(string, chars, length, CHECK_NULL);
582 return result;
583 }
586 oop StringTable::intern(oop string, TRAPS)
587 {
588 if (string == NULL) return NULL;
589 ResourceMark rm(THREAD);
590 int length;
591 Handle h_string (THREAD, string);
592 jchar* chars = java_lang_String::as_unicode_string(string, length);
593 oop result = intern(h_string, chars, length, CHECK_NULL);
594 return result;
595 }
598 oop StringTable::intern(const char* utf8_string, TRAPS) {
599 if (utf8_string == NULL) return NULL;
600 ResourceMark rm(THREAD);
601 int length = UTF8::unicode_length(utf8_string);
602 jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
603 UTF8::convert_to_unicode(utf8_string, chars, length);
604 Handle string;
605 oop result = intern(string, chars, length, CHECK_NULL);
606 return result;
607 }
609 void StringTable::unlink(BoolObjectClosure* is_alive) {
610 // Readers of the table are unlocked, so we should only be removing
611 // entries at a safepoint.
612 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
613 for (int i = 0; i < the_table()->table_size(); ++i) {
614 for (HashtableEntry<oop>** p = the_table()->bucket_addr(i); *p != NULL; ) {
615 HashtableEntry<oop>* entry = *p;
616 if (entry->is_shared()) {
617 break;
618 }
619 assert(entry->literal() != NULL, "just checking");
620 if (is_alive->do_object_b(entry->literal())) {
621 p = entry->next_addr();
622 } else {
623 *p = entry->next();
624 the_table()->free_entry(entry);
625 }
626 }
627 }
628 }
630 void StringTable::oops_do(OopClosure* f) {
631 for (int i = 0; i < the_table()->table_size(); ++i) {
632 HashtableEntry<oop>** p = the_table()->bucket_addr(i);
633 HashtableEntry<oop>* entry = the_table()->bucket(i);
634 while (entry != NULL) {
635 f->do_oop((oop*)entry->literal_addr());
637 // Did the closure remove the literal from the table?
638 if (entry->literal() == NULL) {
639 assert(!entry->is_shared(), "immutable hashtable entry?");
640 *p = entry->next();
641 the_table()->free_entry(entry);
642 } else {
643 p = entry->next_addr();
644 }
645 entry = (HashtableEntry<oop>*)HashtableEntry<oop>::make_ptr(*p);
646 }
647 }
648 }
650 void StringTable::verify() {
651 for (int i = 0; i < the_table()->table_size(); ++i) {
652 HashtableEntry<oop>* p = the_table()->bucket(i);
653 for ( ; p != NULL; p = p->next()) {
654 oop s = p->literal();
655 guarantee(s != NULL, "interned string is NULL");
656 guarantee(s->is_perm() || !JavaObjectsInPerm, "interned string not in permspace");
657 unsigned int h = java_lang_String::hash_string(s);
658 guarantee(p->hash() == h, "broken hash in string table entry");
659 guarantee(the_table()->hash_to_index(h) == i,
660 "wrong index in string table");
661 }
662 }
663 }