45 

   255 class StringTable : public Hashtable<oop, mtSymbol> {

   256   friend class VMStructs;

   257 

   258 private:

   259   // The string table

   260   static StringTable* _the_table;

   261 

   262   // Set if one bucket is out of balance due to hash algorithm deficiency

   263   static bool _needs_rehashing;

   264 

   265   // Claimed high water mark for parallel chunked scanning

   266   static volatile int _parallel_claimed_idx;

   267 

   268   static oop intern(Handle string_or_null, jchar* chars, int length, TRAPS);

   269   oop basic_add(int index, Handle string_or_null, jchar* name, int len,

   270                 unsigned int hashValue, TRAPS);

   271 

   272   oop lookup(int index, jchar* chars, int length, unsigned int hashValue);

   273 

   274   // Apply the give oop closure to the entries to the buckets

   275   // in the range [start_idx, end_idx).

   276   static void buckets_oops_do(OopClosure* f, int start_idx, int end_idx);

   277   // Unlink or apply the give oop closure to the entries to the buckets

   278   // in the range [start_idx, end_idx).

   279   static void buckets_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int start_idx, int end_idx, int* processed, int* removed);

   280 

   281   StringTable() : Hashtable<oop, mtSymbol>((int)StringTableSize,

   282                               sizeof (HashtableEntry<oop, mtSymbol>)) {}

   283 

   284   StringTable(HashtableBucket<mtSymbol>* t, int number_of_entries)

   285     : Hashtable<oop, mtSymbol>((int)StringTableSize, sizeof (HashtableEntry<oop, mtSymbol>), t,

   286                      number_of_entries) {}

   287 public:

   288   // The string table

   289   static StringTable* the_table() { return _the_table; }

   290 

   291   // Size of one bucket in the string table.  Used when checking for rollover.

   292   static uint bucket_size() { return sizeof(HashtableBucket<mtSymbol>); }

   293 

   294   static void create_table() {

   295     assert(_the_table == NULL, "One string table allowed.");

   296     _the_table = new StringTable();

   297   }

   298 

   299   // GC support

   300   //   Delete pointers to otherwise-unreachable objects.

   301   static void unlink_or_oops_do(BoolObjectClosure* cl, OopClosure* f) {

   302     int processed = 0;

   303     int removed = 0;

   304     unlink_or_oops_do(cl, f, &processed, &removed);

   305   }

   306   static void unlink(BoolObjectClosure* cl) {

   307     int processed = 0;

   308     int removed = 0;

   309     unlink_or_oops_do(cl, NULL, &processed, &removed);

   310   }

   311   static void unlink_or_oops_do(BoolObjectClosure* cl, OopClosure* f, int* processed, int* removed);

   312   static void unlink(BoolObjectClosure* cl, int* processed, int* removed) {

   313     unlink_or_oops_do(cl, NULL, processed, removed);

   314   }

   315   // Serially invoke "f->do_oop" on the locations of all oops in the table.

   316   static void oops_do(OopClosure* f);

   317 

   318   // Possibly parallel versions of the above

   319   static void possibly_parallel_unlink_or_oops_do(BoolObjectClosure* cl, OopClosure* f, int* processed, int* removed);

   320   static void possibly_parallel_unlink(BoolObjectClosure* cl, int* processed, int* removed) {

   321     possibly_parallel_unlink_or_oops_do(cl, NULL, processed, removed);

   322   }

   323   static void possibly_parallel_oops_do(OopClosure* f);

   324 

   325   // Hashing algorithm, used as the hash value used by the

   326   //     StringTable for bucket selection and comparison (stored in the

   327   //     HashtableEntry structures).  This is used in the String.intern() method.

   328   static unsigned int hash_string(const jchar* s, int len);

   329 

   330   // Internal test.

   331   static void test_alt_hash() PRODUCT_RETURN;

   332 

   333   // Probing

   334   static oop lookup(Symbol* symbol);

   335   static oop lookup(jchar* chars, int length);

   336 

   337   // Interning

   338   static oop intern(Symbol* symbol, TRAPS);

   339   static oop intern(oop string, TRAPS);

   340   static oop intern(const char *utf8_string, TRAPS);

   341 

   342   // Debugging

   343   static void verify();

   344   static void dump(outputStream* st);

   345 

   346   enum VerifyMesgModes {

   347     _verify_quietly    = 0,

   348     _verify_with_mesgs = 1

   349   };

   350 

   351   enum VerifyRetTypes {

   352     _verify_pass          = 0,

   353     _verify_fail_continue = 1,

   354     _verify_fail_done     = 2

   355   };

   356 

   357   static VerifyRetTypes compare_entries(int bkt1, int e_cnt1,

   358                                         HashtableEntry<oop, mtSymbol>* e_ptr1,

   359                                         int bkt2, int e_cnt2,

   360                                         HashtableEntry<oop, mtSymbol>* e_ptr2);

   361   static VerifyRetTypes verify_entry(int bkt, int e_cnt,

   362                                      HashtableEntry<oop, mtSymbol>* e_ptr,

   363                                      VerifyMesgModes mesg_mode);

   364   static int verify_and_compare_entries();

   365 

   366   // Sharing

   367   static void copy_buckets(char** top, char*end) {

   368     the_table()->Hashtable<oop, mtSymbol>::copy_buckets(top, end);

   369   }

   370   static void copy_table(char** top, char*end) {

   371     the_table()->Hashtable<oop, mtSymbol>::copy_table(top, end);

   372   }

   373   static void reverse() {

   374     the_table()->Hashtable<oop, mtSymbol>::reverse();

   375   }

   376 

   377   // Rehash the symbol table if it gets out of balance

   378   static void rehash_table();

   379   static bool needs_rehashing() { return _needs_rehashing; }

   380 

   381   // Parallel chunked scanning

   382   static void clear_parallel_claimed_index() { _parallel_claimed_idx = 0; }

   383   static int parallel_claimed_index() { return _parallel_claimed_idx; }

   384 };