src/share/vm/classfile/symbolTable.cpp

*** 37,51 ****
  #include "utilities/hashtable.inline.hpp"
  #if INCLUDE_ALL_GCS
  #include "gc_implementation/g1/g1StringDedup.hpp"
  #endif
  
- // --------------------------------------------------------------------------
- 
- // the number of buckets a thread claims
- const int ClaimChunkSize = 32;
- 
  SymbolTable* SymbolTable::_the_table = NULL;
  // Static arena for symbols that are not deallocated
  Arena* SymbolTable::_arena = NULL;
  bool SymbolTable::_needs_rehashing = false;
  
--- 37,46 ----
*** 585,1079 ****
        tty->cr();
      }
    }
  }
  #endif // PRODUCT
- 
- // --------------------------------------------------------------------------
- 
- #ifdef ASSERT
- class StableMemoryChecker : public StackObj {
-   enum { _bufsize = wordSize*4 };
- 
-   address _region;
-   jint    _size;
-   u1      _save_buf[_bufsize];
- 
-   int sample(u1* save_buf) {
-     if (_size <= _bufsize) {
-       memcpy(save_buf, _region, _size);
-       return _size;
-     } else {
-       // copy head and tail
-       memcpy(&save_buf[0],          _region,                      _bufsize/2);
-       memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2);
-       return (_bufsize/2)*2;
-     }
-   }
- 
-  public:
-   StableMemoryChecker(const void* region, jint size) {
-     _region = (address) region;
-     _size   = size;
-     sample(_save_buf);
-   }
- 
-   bool verify() {
-     u1 check_buf[sizeof(_save_buf)];
-     int check_size = sample(check_buf);
-     return (0 == memcmp(_save_buf, check_buf, check_size));
-   }
- 
-   void set_region(const void* region) { _region = (address) region; }
- };
- #endif
- 
- 
- // --------------------------------------------------------------------------
- StringTable* StringTable::_the_table = NULL;
- 
- bool StringTable::_needs_rehashing = false;
- 
- volatile int StringTable::_parallel_claimed_idx = 0;
- 
- // Pick hashing algorithm
- unsigned int StringTable::hash_string(const jchar* s, int len) {
-   return use_alternate_hashcode() ? AltHashing::murmur3_32(seed(), s, len) :
-                                     java_lang_String::hash_code(s, len);
- }
- 
- oop StringTable::lookup(int index, jchar* name,
-                         int len, unsigned int hash) {
-   int count = 0;
-   for (HashtableEntry<oop, mtSymbol>* l = bucket(index); l != NULL; l = l->next()) {
-     count++;
-     if (l->hash() == hash) {
-       if (java_lang_String::equals(l->literal(), name, len)) {
-         return l->literal();
-       }
-     }
-   }
-   // If the bucket size is too deep check if this hash code is insufficient.
-   if (count >= BasicHashtable<mtSymbol>::rehash_count && !needs_rehashing()) {
-     _needs_rehashing = check_rehash_table(count);
-   }
-   return NULL;
- }
- 
- 
- oop StringTable::basic_add(int index_arg, Handle string, jchar* name,
-                            int len, unsigned int hashValue_arg, TRAPS) {
- 
-   assert(java_lang_String::equals(string(), name, len),
-          "string must be properly initialized");
-   // Cannot hit a safepoint in this function because the "this" pointer can move.
-   No_Safepoint_Verifier nsv;
- 
-   // Check if the symbol table has been rehashed, if so, need to recalculate
-   // the hash value and index before second lookup.
-   unsigned int hashValue;
-   int index;
-   if (use_alternate_hashcode()) {
-     hashValue = hash_string(name, len);
-     index = hash_to_index(hashValue);
-   } else {
-     hashValue = hashValue_arg;
-     index = index_arg;
-   }
- 
-   // Since look-up was done lock-free, we need to check if another
-   // thread beat us in the race to insert the symbol.
- 
-   oop test = lookup(index, name, len, hashValue); // calls lookup(u1*, int)
-   if (test != NULL) {
-     // Entry already added
-     return test;
-   }
- 
-   HashtableEntry<oop, mtSymbol>* entry = new_entry(hashValue, string());
-   add_entry(index, entry);
-   return string();
- }
- 
- 
- oop StringTable::lookup(Symbol* symbol) {
-   ResourceMark rm;
-   int length;
-   jchar* chars = symbol->as_unicode(length);
-   return lookup(chars, length);
- }
- 
- 
- oop StringTable::lookup(jchar* name, int len) {
-   unsigned int hash = hash_string(name, len);
-   int index = the_table()->hash_to_index(hash);
-   return the_table()->lookup(index, name, len, hash);
- }
- 
- 
- oop StringTable::intern(Handle string_or_null, jchar* name,
-                         int len, TRAPS) {
-   unsigned int hashValue = hash_string(name, len);
-   int index = the_table()->hash_to_index(hashValue);
-   oop found_string = the_table()->lookup(index, name, len, hashValue);
- 
-   // Found
-   if (found_string != NULL) return found_string;
- 
-   debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
-   assert(!Universe::heap()->is_in_reserved(name),
-          "proposed name of symbol must be stable");
- 
-   Handle string;
-   // try to reuse the string if possible
-   if (!string_or_null.is_null()) {
-     string = string_or_null;
-   } else {
-     string = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
-   }
- 
- #if INCLUDE_ALL_GCS
-   if (G1StringDedup::is_enabled()) {
-     // Deduplicate the string before it is interned. Note that we should never
-     // deduplicate a string after it has been interned. Doing so will counteract
-     // compiler optimizations done on e.g. interned string literals.
-     G1StringDedup::deduplicate(string());
-   }
- #endif
- 
-   // Grab the StringTable_lock before getting the_table() because it could
-   // change at safepoint.
-   MutexLocker ml(StringTable_lock, THREAD);
- 
-   // Otherwise, add to symbol to table
-   return the_table()->basic_add(index, string, name, len,
-                                 hashValue, CHECK_NULL);
- }
- 
- oop StringTable::intern(Symbol* symbol, TRAPS) {
-   if (symbol == NULL) return NULL;
-   ResourceMark rm(THREAD);
-   int length;
-   jchar* chars = symbol->as_unicode(length);
-   Handle string;
-   oop result = intern(string, chars, length, CHECK_NULL);
-   return result;
- }
- 
- 
- oop StringTable::intern(oop string, TRAPS)
- {
-   if (string == NULL) return NULL;
-   ResourceMark rm(THREAD);
-   int length;
-   Handle h_string (THREAD, string);
-   jchar* chars = java_lang_String::as_unicode_string(string, length, CHECK_NULL);
-   oop result = intern(h_string, chars, length, CHECK_NULL);
-   return result;
- }
- 
- 
- oop StringTable::intern(const char* utf8_string, TRAPS) {
-   if (utf8_string == NULL) return NULL;
-   ResourceMark rm(THREAD);
-   int length = UTF8::unicode_length(utf8_string);
-   jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
-   UTF8::convert_to_unicode(utf8_string, chars, length);
-   Handle string;
-   oop result = intern(string, chars, length, CHECK_NULL);
-   return result;
- }
- 
- void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
-   buckets_unlink_or_oops_do(is_alive, f, 0, the_table()->table_size(), processed, removed);
- }
- 
- void StringTable::possibly_parallel_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
-   // Readers of the table are unlocked, so we should only be removing
-   // entries at a safepoint.
-   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
-   const int limit = the_table()->table_size();
- 
-   for (;;) {
-     // Grab next set of buckets to scan
-     int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
-     if (start_idx >= limit) {
-       // End of table
-       break;
-     }
- 
-     int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
-     buckets_unlink_or_oops_do(is_alive, f, start_idx, end_idx, processed, removed);
-   }
- }
- 
- void StringTable::buckets_oops_do(OopClosure* f, int start_idx, int end_idx) {
-   const int limit = the_table()->table_size();
- 
-   assert(0 <= start_idx && start_idx <= limit,
-          err_msg("start_idx (%d) is out of bounds", start_idx));
-   assert(0 <= end_idx && end_idx <= limit,
-          err_msg("end_idx (%d) is out of bounds", end_idx));
-   assert(start_idx <= end_idx,
-          err_msg("Index ordering: start_idx=%d, end_idx=%d",
-                  start_idx, end_idx));
- 
-   for (int i = start_idx; i < end_idx; i += 1) {
-     HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
-     while (entry != NULL) {
-       assert(!entry->is_shared(), "CDS not used for the StringTable");
- 
-       f->do_oop((oop*)entry->literal_addr());
- 
-       entry = entry->next();
-     }
-   }
- }
- 
- void StringTable::buckets_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int start_idx, int end_idx, int* processed, int* removed) {
-   const int limit = the_table()->table_size();
- 
-   assert(0 <= start_idx && start_idx <= limit,
-          err_msg("start_idx (%d) is out of bounds", start_idx));
-   assert(0 <= end_idx && end_idx <= limit,
-          err_msg("end_idx (%d) is out of bounds", end_idx));
-   assert(start_idx <= end_idx,
-          err_msg("Index ordering: start_idx=%d, end_idx=%d",
-                  start_idx, end_idx));
- 
-   for (int i = start_idx; i < end_idx; ++i) {
-     HashtableEntry<oop, mtSymbol>** p = the_table()->bucket_addr(i);
-     HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
-     while (entry != NULL) {
-       assert(!entry->is_shared(), "CDS not used for the StringTable");
- 
-       if (is_alive->do_object_b(entry->literal())) {
-         if (f != NULL) {
-           f->do_oop((oop*)entry->literal_addr());
-         }
-         p = entry->next_addr();
-       } else {
-         *p = entry->next();
-         the_table()->free_entry(entry);
-         (*removed)++;
-       }
-       (*processed)++;
-       entry = *p;
-     }
-   }
- }
- 
- void StringTable::oops_do(OopClosure* f) {
-   buckets_oops_do(f, 0, the_table()->table_size());
- }
- 
- void StringTable::possibly_parallel_oops_do(OopClosure* f) {
-   const int limit = the_table()->table_size();
- 
-   for (;;) {
-     // Grab next set of buckets to scan
-     int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
-     if (start_idx >= limit) {
-       // End of table
-       break;
-     }
- 
-     int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
-     buckets_oops_do(f, start_idx, end_idx);
-   }
- }
- 
- // This verification is part of Universe::verify() and needs to be quick.
- // See StringTable::verify_and_compare() below for exhaustive verification.
- void StringTable::verify() {
-   for (int i = 0; i < the_table()->table_size(); ++i) {
-     HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i);
-     for ( ; p != NULL; p = p->next()) {
-       oop s = p->literal();
-       guarantee(s != NULL, "interned string is NULL");
-       unsigned int h = java_lang_String::hash_string(s);
-       guarantee(p->hash() == h, "broken hash in string table entry");
-       guarantee(the_table()->hash_to_index(h) == i,
-                 "wrong index in string table");
-     }
-   }
- }
- 
- void StringTable::dump(outputStream* st) {
-   the_table()->dump_table(st, "StringTable");
- }
- 
- StringTable::VerifyRetTypes StringTable::compare_entries(
-                                       int bkt1, int e_cnt1,
-                                       HashtableEntry<oop, mtSymbol>* e_ptr1,
-                                       int bkt2, int e_cnt2,
-                                       HashtableEntry<oop, mtSymbol>* e_ptr2) {
-   // These entries are sanity checked by verify_and_compare_entries()
-   // before this function is called.
-   oop str1 = e_ptr1->literal();
-   oop str2 = e_ptr2->literal();
- 
-   if (str1 == str2) {
-     tty->print_cr("ERROR: identical oop values (0x" PTR_FORMAT ") "
-                   "in entry @ bucket[%d][%d] and entry @ bucket[%d][%d]",
-                   (void *)str1, bkt1, e_cnt1, bkt2, e_cnt2);
-     return _verify_fail_continue;
-   }
- 
-   if (java_lang_String::equals(str1, str2)) {
-     tty->print_cr("ERROR: identical String values in entry @ "
-                   "bucket[%d][%d] and entry @ bucket[%d][%d]",
-                   bkt1, e_cnt1, bkt2, e_cnt2);
-     return _verify_fail_continue;
-   }
- 
-   return _verify_pass;
- }
- 
- StringTable::VerifyRetTypes StringTable::verify_entry(int bkt, int e_cnt,
-                                       HashtableEntry<oop, mtSymbol>* e_ptr,
-                                       StringTable::VerifyMesgModes mesg_mode) {
- 
-   VerifyRetTypes ret = _verify_pass;  // be optimistic
- 
-   oop str = e_ptr->literal();
-   if (str == NULL) {
-     if (mesg_mode == _verify_with_mesgs) {
-       tty->print_cr("ERROR: NULL oop value in entry @ bucket[%d][%d]", bkt,
-                     e_cnt);
-     }
-     // NULL oop means no more verifications are possible
-     return _verify_fail_done;
-   }
- 
-   if (str->klass() != SystemDictionary::String_klass()) {
-     if (mesg_mode == _verify_with_mesgs) {
-       tty->print_cr("ERROR: oop is not a String in entry @ bucket[%d][%d]",
-                     bkt, e_cnt);
-     }
-     // not a String means no more verifications are possible
-     return _verify_fail_done;
-   }
- 
-   unsigned int h = java_lang_String::hash_string(str);
-   if (e_ptr->hash() != h) {
-     if (mesg_mode == _verify_with_mesgs) {
-       tty->print_cr("ERROR: broken hash value in entry @ bucket[%d][%d], "
-                     "bkt_hash=%d, str_hash=%d", bkt, e_cnt, e_ptr->hash(), h);
-     }
-     ret = _verify_fail_continue;
-   }
- 
-   if (the_table()->hash_to_index(h) != bkt) {
-     if (mesg_mode == _verify_with_mesgs) {
-       tty->print_cr("ERROR: wrong index value for entry @ bucket[%d][%d], "
-                     "str_hash=%d, hash_to_index=%d", bkt, e_cnt, h,
-                     the_table()->hash_to_index(h));
-     }
-     ret = _verify_fail_continue;
-   }
- 
-   return ret;
- }
- 
- // See StringTable::verify() above for the quick verification that is
- // part of Universe::verify(). This verification is exhaustive and
- // reports on every issue that is found. StringTable::verify() only
- // reports on the first issue that is found.
- //
- // StringTable::verify_entry() checks:
- // - oop value != NULL (same as verify())
- // - oop value is a String
- // - hash(String) == hash in entry (same as verify())
- // - index for hash == index of entry (same as verify())
- //
- // StringTable::compare_entries() checks:
- // - oops are unique across all entries
- // - String values are unique across all entries
- //
- int StringTable::verify_and_compare_entries() {
-   assert(StringTable_lock->is_locked(), "sanity check");
- 
-   int  fail_cnt = 0;
- 
-   // first, verify all the entries individually:
-   for (int bkt = 0; bkt < the_table()->table_size(); bkt++) {
-     HashtableEntry<oop, mtSymbol>* e_ptr = the_table()->bucket(bkt);
-     for (int e_cnt = 0; e_ptr != NULL; e_ptr = e_ptr->next(), e_cnt++) {
-       VerifyRetTypes ret = verify_entry(bkt, e_cnt, e_ptr, _verify_with_mesgs);
-       if (ret != _verify_pass) {
-         fail_cnt++;
-       }
-     }
-   }
- 
-   // Optimization: if the above check did not find any failures, then
-   // the comparison loop below does not need to call verify_entry()
-   // before calling compare_entries(). If there were failures, then we
-   // have to call verify_entry() to see if the entry can be passed to
-   // compare_entries() safely. When we call verify_entry() in the loop
-   // below, we do so quietly to void duplicate messages and we don't
-   // increment fail_cnt because the failures have already been counted.
-   bool need_entry_verify = (fail_cnt != 0);
- 
-   // second, verify all entries relative to each other:
-   for (int bkt1 = 0; bkt1 < the_table()->table_size(); bkt1++) {
-     HashtableEntry<oop, mtSymbol>* e_ptr1 = the_table()->bucket(bkt1);
-     for (int e_cnt1 = 0; e_ptr1 != NULL; e_ptr1 = e_ptr1->next(), e_cnt1++) {
-       if (need_entry_verify) {
-         VerifyRetTypes ret = verify_entry(bkt1, e_cnt1, e_ptr1,
-                                           _verify_quietly);
-         if (ret == _verify_fail_done) {
-           // cannot use the current entry to compare against other entries
-           continue;
-         }
-       }
- 
-       for (int bkt2 = bkt1; bkt2 < the_table()->table_size(); bkt2++) {
-         HashtableEntry<oop, mtSymbol>* e_ptr2 = the_table()->bucket(bkt2);
-         int e_cnt2;
-         for (e_cnt2 = 0; e_ptr2 != NULL; e_ptr2 = e_ptr2->next(), e_cnt2++) {
-           if (bkt1 == bkt2 && e_cnt2 <= e_cnt1) {
-             // skip the entries up to and including the one that
-             // we're comparing against
-             continue;
-           }
- 
-           if (need_entry_verify) {
-             VerifyRetTypes ret = verify_entry(bkt2, e_cnt2, e_ptr2,
-                                               _verify_quietly);
-             if (ret == _verify_fail_done) {
-               // cannot compare against this entry
-               continue;
-             }
-           }
- 
-           // compare two entries, report and count any failures:
-           if (compare_entries(bkt1, e_cnt1, e_ptr1, bkt2, e_cnt2, e_ptr2)
-               != _verify_pass) {
-             fail_cnt++;
-           }
-         }
-       }
-     }
-   }
-   return fail_cnt;
- }
- 
- // Create a new table and using alternate hash code, populate the new table
- // with the existing strings.   Set flag to use the alternate hash code afterwards.
- void StringTable::rehash_table() {
-   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
-   // This should never happen with -Xshare:dump but it might in testing mode.
-   if (DumpSharedSpaces) return;
-   StringTable* new_table = new StringTable();
- 
-   // Rehash the table
-   the_table()->move_to(new_table);
- 
-   // Delete the table and buckets (entries are reused in new table).
-   delete _the_table;
-   // Don't check if we need rehashing until the table gets unbalanced again.
-   // Then rehash with a new global seed.
-   _needs_rehashing = false;
-   _the_table = new_table;
- }
--- 580,584 ----