aoqi@0: /*
aoqi@0:  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #include "precompiled.hpp"
aoqi@0: #include "classfile/altHashing.hpp"
aoqi@0: #include "classfile/javaClasses.hpp"
aoqi@0: #include "classfile/symbolTable.hpp"
aoqi@0: #include "classfile/systemDictionary.hpp"
aoqi@0: #include "gc_interface/collectedHeap.inline.hpp"
aoqi@0: #include "memory/allocation.inline.hpp"
aoqi@0: #include "memory/filemap.hpp"
aoqi@0: #include "memory/gcLocker.inline.hpp"
aoqi@0: #include "oops/oop.inline.hpp"
aoqi@0: #include "oops/oop.inline2.hpp"
aoqi@0: #include "runtime/mutexLocker.hpp"
aoqi@0: #include "utilities/hashtable.inline.hpp"
aoqi@0: #if INCLUDE_ALL_GCS
stefank@6992: #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
aoqi@0: #include "gc_implementation/g1/g1StringDedup.hpp"
aoqi@0: #endif
aoqi@0: 
aoqi@0: PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
aoqi@0: 
aoqi@0: // --------------------------------------------------------------------------
aoqi@0: 
aoqi@0: // the number of buckets a thread claims
aoqi@0: const int ClaimChunkSize = 32;
aoqi@0: 
aoqi@0: SymbolTable* SymbolTable::_the_table = NULL;
aoqi@0: // Static arena for symbols that are not deallocated
aoqi@0: Arena* SymbolTable::_arena = NULL;
aoqi@0: bool SymbolTable::_needs_rehashing = false;
aoqi@0: 
aoqi@0: Symbol* SymbolTable::allocate_symbol(const u1* name, int len, bool c_heap, TRAPS) {
aoqi@0:   assert (len <= Symbol::max_length(), "should be checked by caller");
aoqi@0: 
aoqi@0:   Symbol* sym;
aoqi@0: 
aoqi@0:   if (DumpSharedSpaces) {
aoqi@0:     // Allocate all symbols to CLD shared metaspace
aoqi@0:     sym = new (len, ClassLoaderData::the_null_class_loader_data(), THREAD) Symbol(name, len, -1);
aoqi@0:   } else if (c_heap) {
aoqi@0:     // refcount starts as 1
aoqi@0:     sym = new (len, THREAD) Symbol(name, len, 1);
aoqi@0:     assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted");
aoqi@0:   } else {
aoqi@0:     // Allocate to global arena
aoqi@0:     sym = new (len, arena(), THREAD) Symbol(name, len, -1);
aoqi@0:   }
aoqi@0:   return sym;
aoqi@0: }
aoqi@0: 
aoqi@0: void SymbolTable::initialize_symbols(int arena_alloc_size) {
aoqi@0:   // Initialize the arena for global symbols, size passed in depends on CDS.
aoqi@0:   if (arena_alloc_size == 0) {
zgu@7074:     _arena = new (mtSymbol) Arena(mtSymbol);
aoqi@0:   } else {
zgu@7074:     _arena = new (mtSymbol) Arena(mtSymbol, arena_alloc_size);
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: // Call function for all symbols in the symbol table.
aoqi@0: void SymbolTable::symbols_do(SymbolClosure *cl) {
aoqi@0:   const int n = the_table()->table_size();
aoqi@0:   for (int i = 0; i < n; i++) {
aoqi@0:     for (HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
aoqi@0:          p != NULL;
aoqi@0:          p = p->next()) {
aoqi@0:       cl->do_symbol(p->literal_addr());
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: int SymbolTable::_symbols_removed = 0;
aoqi@0: int SymbolTable::_symbols_counted = 0;
aoqi@0: volatile int SymbolTable::_parallel_claimed_idx = 0;
aoqi@0: 
aoqi@0: void SymbolTable::buckets_unlink(int start_idx, int end_idx, int* processed, int* removed, size_t* memory_total) {
aoqi@0:   for (int i = start_idx; i < end_idx; ++i) {
aoqi@0:     HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i);
aoqi@0:     HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i);
aoqi@0:     while (entry != NULL) {
aoqi@0:       // Shared entries are normally at the end of the bucket and if we run into
aoqi@0:       // a shared entry, then there is nothing more to remove. However, if we
aoqi@0:       // have rehashed the table, then the shared entries are no longer at the
aoqi@0:       // end of the bucket.
aoqi@0:       if (entry->is_shared() && !use_alternate_hashcode()) {
aoqi@0:         break;
aoqi@0:       }
aoqi@0:       Symbol* s = entry->literal();
aoqi@0:       (*memory_total) += s->size();
aoqi@0:       (*processed)++;
aoqi@0:       assert(s != NULL, "just checking");
aoqi@0:       // If reference count is zero, remove.
aoqi@0:       if (s->refcount() == 0) {
aoqi@0:         assert(!entry->is_shared(), "shared entries should be kept live");
aoqi@0:         delete s;
aoqi@0:         (*removed)++;
aoqi@0:         *p = entry->next();
aoqi@0:         the_table()->free_entry(entry);
aoqi@0:       } else {
aoqi@0:         p = entry->next_addr();
aoqi@0:       }
aoqi@0:       // get next entry
aoqi@0:       entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p);
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: // Remove unreferenced symbols from the symbol table
aoqi@0: // This is done late during GC.
aoqi@0: void SymbolTable::unlink(int* processed, int* removed) {
aoqi@0:   size_t memory_total = 0;
aoqi@0:   buckets_unlink(0, the_table()->table_size(), processed, removed, &memory_total);
aoqi@0:   _symbols_removed += *removed;
aoqi@0:   _symbols_counted += *processed;
aoqi@0:   // Exclude printing for normal PrintGCDetails because people parse
aoqi@0:   // this output.
aoqi@0:   if (PrintGCDetails && Verbose && WizardMode) {
aoqi@0:     gclog_or_tty->print(" [Symbols=%d size=" SIZE_FORMAT "K] ", *processed,
aoqi@0:                         (memory_total*HeapWordSize)/1024);
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void SymbolTable::possibly_parallel_unlink(int* processed, int* removed) {
aoqi@0:   const int limit = the_table()->table_size();
aoqi@0: 
aoqi@0:   size_t memory_total = 0;
aoqi@0: 
aoqi@0:   for (;;) {
aoqi@0:     // Grab next set of buckets to scan
aoqi@0:     int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
aoqi@0:     if (start_idx >= limit) {
aoqi@0:       // End of table
aoqi@0:       break;
aoqi@0:     }
aoqi@0: 
aoqi@0:     int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
aoqi@0:     buckets_unlink(start_idx, end_idx, processed, removed, &memory_total);
aoqi@0:   }
aoqi@0:   Atomic::add(*processed, &_symbols_counted);
aoqi@0:   Atomic::add(*removed, &_symbols_removed);
aoqi@0:   // Exclude printing for normal PrintGCDetails because people parse
aoqi@0:   // this output.
aoqi@0:   if (PrintGCDetails && Verbose && WizardMode) {
aoqi@0:     gclog_or_tty->print(" [Symbols: scanned=%d removed=%d size=" SIZE_FORMAT "K] ", *processed, *removed,
aoqi@0:                         (memory_total*HeapWordSize)/1024);
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: // Create a new table and using alternate hash code, populate the new table
aoqi@0: // with the existing strings.   Set flag to use the alternate hash code afterwards.
aoqi@0: void SymbolTable::rehash_table() {
aoqi@0:   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
aoqi@0:   // This should never happen with -Xshare:dump but it might in testing mode.
aoqi@0:   if (DumpSharedSpaces) return;
aoqi@0:   // Create a new symbol table
aoqi@0:   SymbolTable* new_table = new SymbolTable();
aoqi@0: 
aoqi@0:   the_table()->move_to(new_table);
aoqi@0: 
aoqi@0:   // Delete the table and buckets (entries are reused in new table).
aoqi@0:   delete _the_table;
aoqi@0:   // Don't check if we need rehashing until the table gets unbalanced again.
aoqi@0:   // Then rehash with a new global seed.
aoqi@0:   _needs_rehashing = false;
aoqi@0:   _the_table = new_table;
aoqi@0: }
aoqi@0: 
aoqi@0: // Lookup a symbol in a bucket.
aoqi@0: 
aoqi@0: Symbol* SymbolTable::lookup(int index, const char* name,
aoqi@0:                               int len, unsigned int hash) {
aoqi@0:   int count = 0;
aoqi@0:   for (HashtableEntry<Symbol*, mtSymbol>* e = bucket(index); e != NULL; e = e->next()) {
aoqi@0:     count++;  // count all entries in this bucket, not just ones with same hash
aoqi@0:     if (e->hash() == hash) {
aoqi@0:       Symbol* sym = e->literal();
aoqi@0:       if (sym->equals(name, len)) {
aoqi@0:         // something is referencing this symbol now.
aoqi@0:         sym->increment_refcount();
aoqi@0:         return sym;
aoqi@0:       }
aoqi@0:     }
aoqi@0:   }
aoqi@0:   // If the bucket size is too deep check if this hash code is insufficient.
mgerdin@7207:   if (count >= rehash_count && !needs_rehashing()) {
aoqi@0:     _needs_rehashing = check_rehash_table(count);
aoqi@0:   }
aoqi@0:   return NULL;
aoqi@0: }
aoqi@0: 
aoqi@0: // Pick hashing algorithm.
aoqi@0: unsigned int SymbolTable::hash_symbol(const char* s, int len) {
aoqi@0:   return use_alternate_hashcode() ?
aoqi@0:            AltHashing::murmur3_32(seed(), (const jbyte*)s, len) :
aoqi@0:            java_lang_String::hash_code(s, len);
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: // We take care not to be blocking while holding the
aoqi@0: // SymbolTable_lock. Otherwise, the system might deadlock, since the
aoqi@0: // symboltable is used during compilation (VM_thread) The lock free
aoqi@0: // synchronization is simplified by the fact that we do not delete
aoqi@0: // entries in the symbol table during normal execution (only during
aoqi@0: // safepoints).
aoqi@0: 
aoqi@0: Symbol* SymbolTable::lookup(const char* name, int len, TRAPS) {
aoqi@0:   unsigned int hashValue = hash_symbol(name, len);
aoqi@0:   int index = the_table()->hash_to_index(hashValue);
aoqi@0: 
aoqi@0:   Symbol* s = the_table()->lookup(index, name, len, hashValue);
aoqi@0: 
aoqi@0:   // Found
aoqi@0:   if (s != NULL) return s;
aoqi@0: 
aoqi@0:   // Grab SymbolTable_lock first.
aoqi@0:   MutexLocker ml(SymbolTable_lock, THREAD);
aoqi@0: 
aoqi@0:   // Otherwise, add to symbol to table
aoqi@0:   return the_table()->basic_add(index, (u1*)name, len, hashValue, true, CHECK_NULL);
aoqi@0: }
aoqi@0: 
aoqi@0: Symbol* SymbolTable::lookup(const Symbol* sym, int begin, int end, TRAPS) {
aoqi@0:   char* buffer;
aoqi@0:   int index, len;
aoqi@0:   unsigned int hashValue;
aoqi@0:   char* name;
aoqi@0:   {
aoqi@0:     debug_only(No_Safepoint_Verifier nsv;)
aoqi@0: 
aoqi@0:     name = (char*)sym->base() + begin;
aoqi@0:     len = end - begin;
aoqi@0:     hashValue = hash_symbol(name, len);
aoqi@0:     index = the_table()->hash_to_index(hashValue);
aoqi@0:     Symbol* s = the_table()->lookup(index, name, len, hashValue);
aoqi@0: 
aoqi@0:     // Found
aoqi@0:     if (s != NULL) return s;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Otherwise, add to symbol to table. Copy to a C string first.
aoqi@0:   char stack_buf[128];
aoqi@0:   ResourceMark rm(THREAD);
aoqi@0:   if (len <= 128) {
aoqi@0:     buffer = stack_buf;
aoqi@0:   } else {
aoqi@0:     buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len);
aoqi@0:   }
aoqi@0:   for (int i=0; i<len; i++) {
aoqi@0:     buffer[i] = name[i];
aoqi@0:   }
aoqi@0:   // Make sure there is no safepoint in the code above since name can't move.
aoqi@0:   // We can't include the code in No_Safepoint_Verifier because of the
aoqi@0:   // ResourceMark.
aoqi@0: 
aoqi@0:   // Grab SymbolTable_lock first.
aoqi@0:   MutexLocker ml(SymbolTable_lock, THREAD);
aoqi@0: 
aoqi@0:   return the_table()->basic_add(index, (u1*)buffer, len, hashValue, true, CHECK_NULL);
aoqi@0: }
aoqi@0: 
aoqi@0: Symbol* SymbolTable::lookup_only(const char* name, int len,
aoqi@0:                                    unsigned int& hash) {
aoqi@0:   hash = hash_symbol(name, len);
aoqi@0:   int index = the_table()->hash_to_index(hash);
aoqi@0: 
aoqi@0:   Symbol* s = the_table()->lookup(index, name, len, hash);
aoqi@0:   return s;
aoqi@0: }
aoqi@0: 
aoqi@0: // Look up the address of the literal in the SymbolTable for this Symbol*
aoqi@0: // Do not create any new symbols
aoqi@0: // Do not increment the reference count to keep this alive
aoqi@0: Symbol** SymbolTable::lookup_symbol_addr(Symbol* sym){
aoqi@0:   unsigned int hash = hash_symbol((char*)sym->bytes(), sym->utf8_length());
aoqi@0:   int index = the_table()->hash_to_index(hash);
aoqi@0: 
aoqi@0:   for (HashtableEntry<Symbol*, mtSymbol>* e = the_table()->bucket(index); e != NULL; e = e->next()) {
aoqi@0:     if (e->hash() == hash) {
aoqi@0:       Symbol* literal_sym = e->literal();
aoqi@0:       if (sym == literal_sym) {
aoqi@0:         return e->literal_addr();
aoqi@0:       }
aoqi@0:     }
aoqi@0:   }
aoqi@0:   return NULL;
aoqi@0: }
aoqi@0: 
aoqi@0: // Suggestion: Push unicode-based lookup all the way into the hashing
aoqi@0: // and probing logic, so there is no need for convert_to_utf8 until
aoqi@0: // an actual new Symbol* is created.
aoqi@0: Symbol* SymbolTable::lookup_unicode(const jchar* name, int utf16_length, TRAPS) {
aoqi@0:   int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
aoqi@0:   char stack_buf[128];
aoqi@0:   if (utf8_length < (int) sizeof(stack_buf)) {
aoqi@0:     char* chars = stack_buf;
aoqi@0:     UNICODE::convert_to_utf8(name, utf16_length, chars);
aoqi@0:     return lookup(chars, utf8_length, THREAD);
aoqi@0:   } else {
aoqi@0:     ResourceMark rm(THREAD);
aoqi@0:     char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
aoqi@0:     UNICODE::convert_to_utf8(name, utf16_length, chars);
aoqi@0:     return lookup(chars, utf8_length, THREAD);
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: Symbol* SymbolTable::lookup_only_unicode(const jchar* name, int utf16_length,
aoqi@0:                                            unsigned int& hash) {
aoqi@0:   int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length);
aoqi@0:   char stack_buf[128];
aoqi@0:   if (utf8_length < (int) sizeof(stack_buf)) {
aoqi@0:     char* chars = stack_buf;
aoqi@0:     UNICODE::convert_to_utf8(name, utf16_length, chars);
aoqi@0:     return lookup_only(chars, utf8_length, hash);
aoqi@0:   } else {
aoqi@0:     ResourceMark rm;
aoqi@0:     char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1);;
aoqi@0:     UNICODE::convert_to_utf8(name, utf16_length, chars);
aoqi@0:     return lookup_only(chars, utf8_length, hash);
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void SymbolTable::add(ClassLoaderData* loader_data, constantPoolHandle cp,
aoqi@0:                       int names_count,
aoqi@0:                       const char** names, int* lengths, int* cp_indices,
aoqi@0:                       unsigned int* hashValues, TRAPS) {
aoqi@0:   // Grab SymbolTable_lock first.
aoqi@0:   MutexLocker ml(SymbolTable_lock, THREAD);
aoqi@0: 
aoqi@0:   SymbolTable* table = the_table();
aoqi@0:   bool added = table->basic_add(loader_data, cp, names_count, names, lengths,
aoqi@0:                                 cp_indices, hashValues, CHECK);
aoqi@0:   if (!added) {
aoqi@0:     // do it the hard way
aoqi@0:     for (int i=0; i<names_count; i++) {
aoqi@0:       int index = table->hash_to_index(hashValues[i]);
aoqi@0:       bool c_heap = !loader_data->is_the_null_class_loader_data();
aoqi@0:       Symbol* sym = table->basic_add(index, (u1*)names[i], lengths[i], hashValues[i], c_heap, CHECK);
aoqi@0:       cp->symbol_at_put(cp_indices[i], sym);
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: Symbol* SymbolTable::new_permanent_symbol(const char* name, TRAPS) {
aoqi@0:   unsigned int hash;
aoqi@0:   Symbol* result = SymbolTable::lookup_only((char*)name, (int)strlen(name), hash);
aoqi@0:   if (result != NULL) {
aoqi@0:     return result;
aoqi@0:   }
aoqi@0:   // Grab SymbolTable_lock first.
aoqi@0:   MutexLocker ml(SymbolTable_lock, THREAD);
aoqi@0: 
aoqi@0:   SymbolTable* table = the_table();
aoqi@0:   int index = table->hash_to_index(hash);
aoqi@0:   return table->basic_add(index, (u1*)name, (int)strlen(name), hash, false, THREAD);
aoqi@0: }
aoqi@0: 
aoqi@0: Symbol* SymbolTable::basic_add(int index_arg, u1 *name, int len,
aoqi@0:                                unsigned int hashValue_arg, bool c_heap, TRAPS) {
aoqi@0:   assert(!Universe::heap()->is_in_reserved(name),
aoqi@0:          "proposed name of symbol must be stable");
aoqi@0: 
aoqi@0:   // Don't allow symbols to be created which cannot fit in a Symbol*.
aoqi@0:   if (len > Symbol::max_length()) {
aoqi@0:     THROW_MSG_0(vmSymbols::java_lang_InternalError(),
aoqi@0:                 "name is too long to represent");
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Cannot hit a safepoint in this function because the "this" pointer can move.
aoqi@0:   No_Safepoint_Verifier nsv;
aoqi@0: 
aoqi@0:   // Check if the symbol table has been rehashed, if so, need to recalculate
aoqi@0:   // the hash value and index.
aoqi@0:   unsigned int hashValue;
aoqi@0:   int index;
aoqi@0:   if (use_alternate_hashcode()) {
aoqi@0:     hashValue = hash_symbol((const char*)name, len);
aoqi@0:     index = hash_to_index(hashValue);
aoqi@0:   } else {
aoqi@0:     hashValue = hashValue_arg;
aoqi@0:     index = index_arg;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Since look-up was done lock-free, we need to check if another
aoqi@0:   // thread beat us in the race to insert the symbol.
aoqi@0:   Symbol* test = lookup(index, (char*)name, len, hashValue);
aoqi@0:   if (test != NULL) {
aoqi@0:     // A race occurred and another thread introduced the symbol.
aoqi@0:     assert(test->refcount() != 0, "lookup should have incremented the count");
aoqi@0:     return test;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Create a new symbol.
aoqi@0:   Symbol* sym = allocate_symbol(name, len, c_heap, CHECK_NULL);
aoqi@0:   assert(sym->equals((char*)name, len), "symbol must be properly initialized");
aoqi@0: 
aoqi@0:   HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym);
aoqi@0:   add_entry(index, entry);
aoqi@0:   return sym;
aoqi@0: }
aoqi@0: 
aoqi@0: // This version of basic_add adds symbols in batch from the constant pool
aoqi@0: // parsing.
aoqi@0: bool SymbolTable::basic_add(ClassLoaderData* loader_data, constantPoolHandle cp,
aoqi@0:                             int names_count,
aoqi@0:                             const char** names, int* lengths,
aoqi@0:                             int* cp_indices, unsigned int* hashValues,
aoqi@0:                             TRAPS) {
aoqi@0: 
aoqi@0:   // Check symbol names are not too long.  If any are too long, don't add any.
aoqi@0:   for (int i = 0; i< names_count; i++) {
aoqi@0:     if (lengths[i] > Symbol::max_length()) {
aoqi@0:       THROW_MSG_0(vmSymbols::java_lang_InternalError(),
aoqi@0:                   "name is too long to represent");
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Cannot hit a safepoint in this function because the "this" pointer can move.
aoqi@0:   No_Safepoint_Verifier nsv;
aoqi@0: 
aoqi@0:   for (int i=0; i<names_count; i++) {
aoqi@0:     // Check if the symbol table has been rehashed, if so, need to recalculate
aoqi@0:     // the hash value.
aoqi@0:     unsigned int hashValue;
aoqi@0:     if (use_alternate_hashcode()) {
aoqi@0:       hashValue = hash_symbol(names[i], lengths[i]);
aoqi@0:     } else {
aoqi@0:       hashValue = hashValues[i];
aoqi@0:     }
aoqi@0:     // Since look-up was done lock-free, we need to check if another
aoqi@0:     // thread beat us in the race to insert the symbol.
aoqi@0:     int index = hash_to_index(hashValue);
aoqi@0:     Symbol* test = lookup(index, names[i], lengths[i], hashValue);
aoqi@0:     if (test != NULL) {
aoqi@0:       // A race occurred and another thread introduced the symbol, this one
aoqi@0:       // will be dropped and collected. Use test instead.
aoqi@0:       cp->symbol_at_put(cp_indices[i], test);
aoqi@0:       assert(test->refcount() != 0, "lookup should have incremented the count");
aoqi@0:     } else {
aoqi@0:       // Create a new symbol.  The null class loader is never unloaded so these
aoqi@0:       // are allocated specially in a permanent arena.
aoqi@0:       bool c_heap = !loader_data->is_the_null_class_loader_data();
aoqi@0:       Symbol* sym = allocate_symbol((const u1*)names[i], lengths[i], c_heap, CHECK_(false));
aoqi@0:       assert(sym->equals(names[i], lengths[i]), "symbol must be properly initialized");  // why wouldn't it be???
aoqi@0:       HashtableEntry<Symbol*, mtSymbol>* entry = new_entry(hashValue, sym);
aoqi@0:       add_entry(index, entry);
aoqi@0:       cp->symbol_at_put(cp_indices[i], sym);
aoqi@0:     }
aoqi@0:   }
aoqi@0:   return true;
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: void SymbolTable::verify() {
aoqi@0:   for (int i = 0; i < the_table()->table_size(); ++i) {
aoqi@0:     HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
aoqi@0:     for ( ; p != NULL; p = p->next()) {
aoqi@0:       Symbol* s = (Symbol*)(p->literal());
aoqi@0:       guarantee(s != NULL, "symbol is NULL");
aoqi@0:       unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length());
aoqi@0:       guarantee(p->hash() == h, "broken hash in symbol table entry");
aoqi@0:       guarantee(the_table()->hash_to_index(h) == i,
aoqi@0:                 "wrong index in symbol table");
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void SymbolTable::dump(outputStream* st) {
aoqi@0:   the_table()->dump_table(st, "SymbolTable");
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: //---------------------------------------------------------------------------
aoqi@0: // Non-product code
aoqi@0: 
aoqi@0: #ifndef PRODUCT
aoqi@0: 
aoqi@0: void SymbolTable::print_histogram() {
aoqi@0:   MutexLocker ml(SymbolTable_lock);
aoqi@0:   const int results_length = 100;
aoqi@0:   int results[results_length];
aoqi@0:   int i,j;
aoqi@0: 
aoqi@0:   // initialize results to zero
aoqi@0:   for (j = 0; j < results_length; j++) {
aoqi@0:     results[j] = 0;
aoqi@0:   }
aoqi@0: 
aoqi@0:   int total = 0;
aoqi@0:   int max_symbols = 0;
aoqi@0:   int out_of_range = 0;
aoqi@0:   int memory_total = 0;
aoqi@0:   int count = 0;
aoqi@0:   for (i = 0; i < the_table()->table_size(); i++) {
aoqi@0:     HashtableEntry<Symbol*, mtSymbol>* p = the_table()->bucket(i);
aoqi@0:     for ( ; p != NULL; p = p->next()) {
aoqi@0:       memory_total += p->literal()->size();
aoqi@0:       count++;
aoqi@0:       int counter = p->literal()->utf8_length();
aoqi@0:       total += counter;
aoqi@0:       if (counter < results_length) {
aoqi@0:         results[counter]++;
aoqi@0:       } else {
aoqi@0:         out_of_range++;
aoqi@0:       }
aoqi@0:       max_symbols = MAX2(max_symbols, counter);
aoqi@0:     }
aoqi@0:   }
aoqi@0:   tty->print_cr("Symbol Table:");
aoqi@0:   tty->print_cr("Total number of symbols  %5d", count);
aoqi@0:   tty->print_cr("Total size in memory     %5dK",
aoqi@0:           (memory_total*HeapWordSize)/1024);
aoqi@0:   tty->print_cr("Total counted            %5d", _symbols_counted);
aoqi@0:   tty->print_cr("Total removed            %5d", _symbols_removed);
aoqi@0:   if (_symbols_counted > 0) {
aoqi@0:     tty->print_cr("Percent removed          %3.2f",
aoqi@0:           ((float)_symbols_removed/(float)_symbols_counted)* 100);
aoqi@0:   }
aoqi@0:   tty->print_cr("Reference counts         %5d", Symbol::_total_count);
aoqi@0:   tty->print_cr("Symbol arena size        %5d used %5d",
aoqi@0:                  arena()->size_in_bytes(), arena()->used());
aoqi@0:   tty->print_cr("Histogram of symbol length:");
aoqi@0:   tty->print_cr("%8s %5d", "Total  ", total);
aoqi@0:   tty->print_cr("%8s %5d", "Maximum", max_symbols);
aoqi@0:   tty->print_cr("%8s %3.2f", "Average",
aoqi@0:           ((float) total / (float) the_table()->table_size()));
aoqi@0:   tty->print_cr("%s", "Histogram:");
aoqi@0:   tty->print_cr(" %s %29s", "Length", "Number chains that length");
aoqi@0:   for (i = 0; i < results_length; i++) {
aoqi@0:     if (results[i] > 0) {
aoqi@0:       tty->print_cr("%6d %10d", i, results[i]);
aoqi@0:     }
aoqi@0:   }
aoqi@0:   if (Verbose) {
aoqi@0:     int line_length = 70;
aoqi@0:     tty->print_cr("%s %30s", " Length", "Number chains that length");
aoqi@0:     for (i = 0; i < results_length; i++) {
aoqi@0:       if (results[i] > 0) {
aoqi@0:         tty->print("%4d", i);
aoqi@0:         for (j = 0; (j < results[i]) && (j < line_length);  j++) {
aoqi@0:           tty->print("%1s", "*");
aoqi@0:         }
aoqi@0:         if (j == line_length) {
aoqi@0:           tty->print("%1s", "+");
aoqi@0:         }
aoqi@0:         tty->cr();
aoqi@0:       }
aoqi@0:     }
aoqi@0:   }
aoqi@0:   tty->print_cr(" %s %d: %d\n", "Number chains longer than",
aoqi@0:                     results_length, out_of_range);
aoqi@0: }
aoqi@0: 
aoqi@0: void SymbolTable::print() {
aoqi@0:   for (int i = 0; i < the_table()->table_size(); ++i) {
aoqi@0:     HashtableEntry<Symbol*, mtSymbol>** p = the_table()->bucket_addr(i);
aoqi@0:     HashtableEntry<Symbol*, mtSymbol>* entry = the_table()->bucket(i);
aoqi@0:     if (entry != NULL) {
aoqi@0:       while (entry != NULL) {
aoqi@0:         tty->print(PTR_FORMAT " ", entry->literal());
aoqi@0:         entry->literal()->print();
aoqi@0:         tty->print(" %d", entry->literal()->refcount());
aoqi@0:         p = entry->next_addr();
aoqi@0:         entry = (HashtableEntry<Symbol*, mtSymbol>*)HashtableEntry<Symbol*, mtSymbol>::make_ptr(*p);
aoqi@0:       }
aoqi@0:       tty->cr();
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: #endif // PRODUCT
aoqi@0: 
aoqi@0: // --------------------------------------------------------------------------
aoqi@0: 
aoqi@0: #ifdef ASSERT
aoqi@0: class StableMemoryChecker : public StackObj {
aoqi@0:   enum { _bufsize = wordSize*4 };
aoqi@0: 
aoqi@0:   address _region;
aoqi@0:   jint    _size;
aoqi@0:   u1      _save_buf[_bufsize];
aoqi@0: 
aoqi@0:   int sample(u1* save_buf) {
aoqi@0:     if (_size <= _bufsize) {
aoqi@0:       memcpy(save_buf, _region, _size);
aoqi@0:       return _size;
aoqi@0:     } else {
aoqi@0:       // copy head and tail
aoqi@0:       memcpy(&save_buf[0],          _region,                      _bufsize/2);
aoqi@0:       memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2);
aoqi@0:       return (_bufsize/2)*2;
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:  public:
aoqi@0:   StableMemoryChecker(const void* region, jint size) {
aoqi@0:     _region = (address) region;
aoqi@0:     _size   = size;
aoqi@0:     sample(_save_buf);
aoqi@0:   }
aoqi@0: 
aoqi@0:   bool verify() {
aoqi@0:     u1 check_buf[sizeof(_save_buf)];
aoqi@0:     int check_size = sample(check_buf);
aoqi@0:     return (0 == memcmp(_save_buf, check_buf, check_size));
aoqi@0:   }
aoqi@0: 
aoqi@0:   void set_region(const void* region) { _region = (address) region; }
aoqi@0: };
aoqi@0: #endif
aoqi@0: 
aoqi@0: 
aoqi@0: // --------------------------------------------------------------------------
aoqi@0: StringTable* StringTable::_the_table = NULL;
aoqi@0: 
aoqi@0: bool StringTable::_needs_rehashing = false;
aoqi@0: 
aoqi@0: volatile int StringTable::_parallel_claimed_idx = 0;
aoqi@0: 
aoqi@0: // Pick hashing algorithm
aoqi@0: unsigned int StringTable::hash_string(const jchar* s, int len) {
aoqi@0:   return use_alternate_hashcode() ? AltHashing::murmur3_32(seed(), s, len) :
aoqi@0:                                     java_lang_String::hash_code(s, len);
aoqi@0: }
aoqi@0: 
aoqi@0: oop StringTable::lookup(int index, jchar* name,
aoqi@0:                         int len, unsigned int hash) {
aoqi@0:   int count = 0;
aoqi@0:   for (HashtableEntry<oop, mtSymbol>* l = bucket(index); l != NULL; l = l->next()) {
aoqi@0:     count++;
aoqi@0:     if (l->hash() == hash) {
aoqi@0:       if (java_lang_String::equals(l->literal(), name, len)) {
aoqi@0:         return l->literal();
aoqi@0:       }
aoqi@0:     }
aoqi@0:   }
aoqi@0:   // If the bucket size is too deep check if this hash code is insufficient.
mgerdin@7207:   if (count >= rehash_count && !needs_rehashing()) {
aoqi@0:     _needs_rehashing = check_rehash_table(count);
aoqi@0:   }
aoqi@0:   return NULL;
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: oop StringTable::basic_add(int index_arg, Handle string, jchar* name,
aoqi@0:                            int len, unsigned int hashValue_arg, TRAPS) {
aoqi@0: 
aoqi@0:   assert(java_lang_String::equals(string(), name, len),
aoqi@0:          "string must be properly initialized");
aoqi@0:   // Cannot hit a safepoint in this function because the "this" pointer can move.
aoqi@0:   No_Safepoint_Verifier nsv;
aoqi@0: 
aoqi@0:   // Check if the symbol table has been rehashed, if so, need to recalculate
aoqi@0:   // the hash value and index before second lookup.
aoqi@0:   unsigned int hashValue;
aoqi@0:   int index;
aoqi@0:   if (use_alternate_hashcode()) {
aoqi@0:     hashValue = hash_string(name, len);
aoqi@0:     index = hash_to_index(hashValue);
aoqi@0:   } else {
aoqi@0:     hashValue = hashValue_arg;
aoqi@0:     index = index_arg;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Since look-up was done lock-free, we need to check if another
aoqi@0:   // thread beat us in the race to insert the symbol.
aoqi@0: 
aoqi@0:   oop test = lookup(index, name, len, hashValue); // calls lookup(u1*, int)
aoqi@0:   if (test != NULL) {
aoqi@0:     // Entry already added
aoqi@0:     return test;
aoqi@0:   }
aoqi@0: 
aoqi@0:   HashtableEntry<oop, mtSymbol>* entry = new_entry(hashValue, string());
aoqi@0:   add_entry(index, entry);
aoqi@0:   return string();
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: oop StringTable::lookup(Symbol* symbol) {
aoqi@0:   ResourceMark rm;
aoqi@0:   int length;
aoqi@0:   jchar* chars = symbol->as_unicode(length);
aoqi@0:   return lookup(chars, length);
aoqi@0: }
aoqi@0: 
stefank@6992: // Tell the GC that this string was looked up in the StringTable.
stefank@6992: static void ensure_string_alive(oop string) {
stefank@6992:   // A lookup in the StringTable could return an object that was previously
stefank@6992:   // considered dead. The SATB part of G1 needs to get notified about this
stefank@6992:   // potential resurrection, otherwise the marking might not find the object.
stefank@6992: #if INCLUDE_ALL_GCS
stefank@6992:   if (UseG1GC && string != NULL) {
stefank@6992:     G1SATBCardTableModRefBS::enqueue(string);
stefank@6992:   }
stefank@6992: #endif
stefank@6992: }
aoqi@0: 
aoqi@0: oop StringTable::lookup(jchar* name, int len) {
aoqi@0:   unsigned int hash = hash_string(name, len);
aoqi@0:   int index = the_table()->hash_to_index(hash);
stefank@6992:   oop string = the_table()->lookup(index, name, len, hash);
stefank@6992: 
stefank@6992:   ensure_string_alive(string);
stefank@6992: 
stefank@6992:   return string;
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: oop StringTable::intern(Handle string_or_null, jchar* name,
aoqi@0:                         int len, TRAPS) {
aoqi@0:   unsigned int hashValue = hash_string(name, len);
aoqi@0:   int index = the_table()->hash_to_index(hashValue);
aoqi@0:   oop found_string = the_table()->lookup(index, name, len, hashValue);
aoqi@0: 
aoqi@0:   // Found
stefank@6992:   if (found_string != NULL) {
stefank@6992:     ensure_string_alive(found_string);
stefank@6992:     return found_string;
stefank@6992:   }
aoqi@0: 
aoqi@0:   debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
aoqi@0:   assert(!Universe::heap()->is_in_reserved(name),
aoqi@0:          "proposed name of symbol must be stable");
aoqi@0: 
aoqi@0:   Handle string;
aoqi@0:   // try to reuse the string if possible
aoqi@0:   if (!string_or_null.is_null()) {
aoqi@0:     string = string_or_null;
aoqi@0:   } else {
aoqi@0:     string = java_lang_String::create_from_unicode(name, len, CHECK_NULL);
aoqi@0:   }
aoqi@0: 
aoqi@0: #if INCLUDE_ALL_GCS
aoqi@0:   if (G1StringDedup::is_enabled()) {
aoqi@0:     // Deduplicate the string before it is interned. Note that we should never
aoqi@0:     // deduplicate a string after it has been interned. Doing so will counteract
aoqi@0:     // compiler optimizations done on e.g. interned string literals.
aoqi@0:     G1StringDedup::deduplicate(string());
aoqi@0:   }
aoqi@0: #endif
aoqi@0: 
aoqi@0:   // Grab the StringTable_lock before getting the_table() because it could
aoqi@0:   // change at safepoint.
stefank@6992:   oop added_or_found;
stefank@6992:   {
stefank@6992:     MutexLocker ml(StringTable_lock, THREAD);
stefank@6992:     // Otherwise, add to symbol to table
stefank@6992:     added_or_found = the_table()->basic_add(index, string, name, len,
stefank@6992:                                   hashValue, CHECK_NULL);
stefank@6992:   }
aoqi@0: 
stefank@6992:   ensure_string_alive(added_or_found);
stefank@6992: 
stefank@6992:   return added_or_found;
aoqi@0: }
aoqi@0: 
aoqi@0: oop StringTable::intern(Symbol* symbol, TRAPS) {
aoqi@0:   if (symbol == NULL) return NULL;
aoqi@0:   ResourceMark rm(THREAD);
aoqi@0:   int length;
aoqi@0:   jchar* chars = symbol->as_unicode(length);
aoqi@0:   Handle string;
aoqi@0:   oop result = intern(string, chars, length, CHECK_NULL);
aoqi@0:   return result;
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: oop StringTable::intern(oop string, TRAPS)
aoqi@0: {
aoqi@0:   if (string == NULL) return NULL;
aoqi@0:   ResourceMark rm(THREAD);
aoqi@0:   int length;
aoqi@0:   Handle h_string (THREAD, string);
aoqi@0:   jchar* chars = java_lang_String::as_unicode_string(string, length, CHECK_NULL);
aoqi@0:   oop result = intern(h_string, chars, length, CHECK_NULL);
aoqi@0:   return result;
aoqi@0: }
aoqi@0: 
aoqi@0: 
aoqi@0: oop StringTable::intern(const char* utf8_string, TRAPS) {
aoqi@0:   if (utf8_string == NULL) return NULL;
aoqi@0:   ResourceMark rm(THREAD);
aoqi@0:   int length = UTF8::unicode_length(utf8_string);
aoqi@0:   jchar* chars = NEW_RESOURCE_ARRAY(jchar, length);
aoqi@0:   UTF8::convert_to_unicode(utf8_string, chars, length);
aoqi@0:   Handle string;
aoqi@0:   oop result = intern(string, chars, length, CHECK_NULL);
aoqi@0:   return result;
aoqi@0: }
aoqi@0: 
aoqi@0: void StringTable::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
aoqi@0:   buckets_unlink_or_oops_do(is_alive, f, 0, the_table()->table_size(), processed, removed);
aoqi@0: }
aoqi@0: 
aoqi@0: void StringTable::possibly_parallel_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int* processed, int* removed) {
aoqi@0:   // Readers of the table are unlocked, so we should only be removing
aoqi@0:   // entries at a safepoint.
aoqi@0:   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
aoqi@0:   const int limit = the_table()->table_size();
aoqi@0: 
aoqi@0:   for (;;) {
aoqi@0:     // Grab next set of buckets to scan
aoqi@0:     int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
aoqi@0:     if (start_idx >= limit) {
aoqi@0:       // End of table
aoqi@0:       break;
aoqi@0:     }
aoqi@0: 
aoqi@0:     int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
aoqi@0:     buckets_unlink_or_oops_do(is_alive, f, start_idx, end_idx, processed, removed);
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void StringTable::buckets_oops_do(OopClosure* f, int start_idx, int end_idx) {
aoqi@0:   const int limit = the_table()->table_size();
aoqi@0: 
aoqi@0:   assert(0 <= start_idx && start_idx <= limit,
aoqi@0:          err_msg("start_idx (" INT32_FORMAT ") is out of bounds", start_idx));
aoqi@0:   assert(0 <= end_idx && end_idx <= limit,
aoqi@0:          err_msg("end_idx (" INT32_FORMAT ") is out of bounds", end_idx));
aoqi@0:   assert(start_idx <= end_idx,
aoqi@0:          err_msg("Index ordering: start_idx=" INT32_FORMAT", end_idx=" INT32_FORMAT,
aoqi@0:                  start_idx, end_idx));
aoqi@0: 
aoqi@0:   for (int i = start_idx; i < end_idx; i += 1) {
aoqi@0:     HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
aoqi@0:     while (entry != NULL) {
aoqi@0:       assert(!entry->is_shared(), "CDS not used for the StringTable");
aoqi@0: 
aoqi@0:       f->do_oop((oop*)entry->literal_addr());
aoqi@0: 
aoqi@0:       entry = entry->next();
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void StringTable::buckets_unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f, int start_idx, int end_idx, int* processed, int* removed) {
aoqi@0:   const int limit = the_table()->table_size();
aoqi@0: 
aoqi@0:   assert(0 <= start_idx && start_idx <= limit,
aoqi@0:          err_msg("start_idx (" INT32_FORMAT ") is out of bounds", start_idx));
aoqi@0:   assert(0 <= end_idx && end_idx <= limit,
aoqi@0:          err_msg("end_idx (" INT32_FORMAT ") is out of bounds", end_idx));
aoqi@0:   assert(start_idx <= end_idx,
aoqi@0:          err_msg("Index ordering: start_idx=" INT32_FORMAT", end_idx=" INT32_FORMAT,
aoqi@0:                  start_idx, end_idx));
aoqi@0: 
aoqi@0:   for (int i = start_idx; i < end_idx; ++i) {
aoqi@0:     HashtableEntry<oop, mtSymbol>** p = the_table()->bucket_addr(i);
aoqi@0:     HashtableEntry<oop, mtSymbol>* entry = the_table()->bucket(i);
aoqi@0:     while (entry != NULL) {
aoqi@0:       assert(!entry->is_shared(), "CDS not used for the StringTable");
aoqi@0: 
aoqi@0:       if (is_alive->do_object_b(entry->literal())) {
aoqi@0:         if (f != NULL) {
aoqi@0:           f->do_oop((oop*)entry->literal_addr());
aoqi@0:         }
aoqi@0:         p = entry->next_addr();
aoqi@0:       } else {
aoqi@0:         *p = entry->next();
aoqi@0:         the_table()->free_entry(entry);
aoqi@0:         (*removed)++;
aoqi@0:       }
aoqi@0:       (*processed)++;
aoqi@0:       entry = *p;
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void StringTable::oops_do(OopClosure* f) {
aoqi@0:   buckets_oops_do(f, 0, the_table()->table_size());
aoqi@0: }
aoqi@0: 
aoqi@0: void StringTable::possibly_parallel_oops_do(OopClosure* f) {
aoqi@0:   const int limit = the_table()->table_size();
aoqi@0: 
aoqi@0:   for (;;) {
aoqi@0:     // Grab next set of buckets to scan
aoqi@0:     int start_idx = Atomic::add(ClaimChunkSize, &_parallel_claimed_idx) - ClaimChunkSize;
aoqi@0:     if (start_idx >= limit) {
aoqi@0:       // End of table
aoqi@0:       break;
aoqi@0:     }
aoqi@0: 
aoqi@0:     int end_idx = MIN2(limit, start_idx + ClaimChunkSize);
aoqi@0:     buckets_oops_do(f, start_idx, end_idx);
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: // This verification is part of Universe::verify() and needs to be quick.
aoqi@0: // See StringTable::verify_and_compare() below for exhaustive verification.
aoqi@0: void StringTable::verify() {
aoqi@0:   for (int i = 0; i < the_table()->table_size(); ++i) {
aoqi@0:     HashtableEntry<oop, mtSymbol>* p = the_table()->bucket(i);
aoqi@0:     for ( ; p != NULL; p = p->next()) {
aoqi@0:       oop s = p->literal();
aoqi@0:       guarantee(s != NULL, "interned string is NULL");
aoqi@0:       unsigned int h = java_lang_String::hash_string(s);
aoqi@0:       guarantee(p->hash() == h, "broken hash in string table entry");
aoqi@0:       guarantee(the_table()->hash_to_index(h) == i,
aoqi@0:                 "wrong index in string table");
aoqi@0:     }
aoqi@0:   }
aoqi@0: }
aoqi@0: 
aoqi@0: void StringTable::dump(outputStream* st) {
aoqi@0:   the_table()->dump_table(st, "StringTable");
aoqi@0: }
aoqi@0: 
aoqi@0: StringTable::VerifyRetTypes StringTable::compare_entries(
aoqi@0:                                       int bkt1, int e_cnt1,
aoqi@0:                                       HashtableEntry<oop, mtSymbol>* e_ptr1,
aoqi@0:                                       int bkt2, int e_cnt2,
aoqi@0:                                       HashtableEntry<oop, mtSymbol>* e_ptr2) {
aoqi@0:   // These entries are sanity checked by verify_and_compare_entries()
aoqi@0:   // before this function is called.
aoqi@0:   oop str1 = e_ptr1->literal();
aoqi@0:   oop str2 = e_ptr2->literal();
aoqi@0: 
aoqi@0:   if (str1 == str2) {
aoqi@0:     tty->print_cr("ERROR: identical oop values (0x" PTR_FORMAT ") "
aoqi@0:                   "in entry @ bucket[%d][%d] and entry @ bucket[%d][%d]",
aoqi@0:                   (void *)str1, bkt1, e_cnt1, bkt2, e_cnt2);
aoqi@0:     return _verify_fail_continue;
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (java_lang_String::equals(str1, str2)) {
aoqi@0:     tty->print_cr("ERROR: identical String values in entry @ "
aoqi@0:                   "bucket[%d][%d] and entry @ bucket[%d][%d]",
aoqi@0:                   bkt1, e_cnt1, bkt2, e_cnt2);
aoqi@0:     return _verify_fail_continue;
aoqi@0:   }
aoqi@0: 
aoqi@0:   return _verify_pass;
aoqi@0: }
aoqi@0: 
aoqi@0: StringTable::VerifyRetTypes StringTable::verify_entry(int bkt, int e_cnt,
aoqi@0:                                       HashtableEntry<oop, mtSymbol>* e_ptr,
aoqi@0:                                       StringTable::VerifyMesgModes mesg_mode) {
aoqi@0: 
aoqi@0:   VerifyRetTypes ret = _verify_pass;  // be optimistic
aoqi@0: 
aoqi@0:   oop str = e_ptr->literal();
aoqi@0:   if (str == NULL) {
aoqi@0:     if (mesg_mode == _verify_with_mesgs) {
aoqi@0:       tty->print_cr("ERROR: NULL oop value in entry @ bucket[%d][%d]", bkt,
aoqi@0:                     e_cnt);
aoqi@0:     }
aoqi@0:     // NULL oop means no more verifications are possible
aoqi@0:     return _verify_fail_done;
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (str->klass() != SystemDictionary::String_klass()) {
aoqi@0:     if (mesg_mode == _verify_with_mesgs) {
aoqi@0:       tty->print_cr("ERROR: oop is not a String in entry @ bucket[%d][%d]",
aoqi@0:                     bkt, e_cnt);
aoqi@0:     }
aoqi@0:     // not a String means no more verifications are possible
aoqi@0:     return _verify_fail_done;
aoqi@0:   }
aoqi@0: 
aoqi@0:   unsigned int h = java_lang_String::hash_string(str);
aoqi@0:   if (e_ptr->hash() != h) {
aoqi@0:     if (mesg_mode == _verify_with_mesgs) {
aoqi@0:       tty->print_cr("ERROR: broken hash value in entry @ bucket[%d][%d], "
aoqi@0:                     "bkt_hash=%d, str_hash=%d", bkt, e_cnt, e_ptr->hash(), h);
aoqi@0:     }
aoqi@0:     ret = _verify_fail_continue;
aoqi@0:   }
aoqi@0: 
aoqi@0:   if (the_table()->hash_to_index(h) != bkt) {
aoqi@0:     if (mesg_mode == _verify_with_mesgs) {
aoqi@0:       tty->print_cr("ERROR: wrong index value for entry @ bucket[%d][%d], "
aoqi@0:                     "str_hash=%d, hash_to_index=%d", bkt, e_cnt, h,
aoqi@0:                     the_table()->hash_to_index(h));
aoqi@0:     }
aoqi@0:     ret = _verify_fail_continue;
aoqi@0:   }
aoqi@0: 
aoqi@0:   return ret;
aoqi@0: }
aoqi@0: 
aoqi@0: // See StringTable::verify() above for the quick verification that is
aoqi@0: // part of Universe::verify(). This verification is exhaustive and
aoqi@0: // reports on every issue that is found. StringTable::verify() only
aoqi@0: // reports on the first issue that is found.
aoqi@0: //
aoqi@0: // StringTable::verify_entry() checks:
aoqi@0: // - oop value != NULL (same as verify())
aoqi@0: // - oop value is a String
aoqi@0: // - hash(String) == hash in entry (same as verify())
aoqi@0: // - index for hash == index of entry (same as verify())
aoqi@0: //
aoqi@0: // StringTable::compare_entries() checks:
aoqi@0: // - oops are unique across all entries
aoqi@0: // - String values are unique across all entries
aoqi@0: //
aoqi@0: int StringTable::verify_and_compare_entries() {
aoqi@0:   assert(StringTable_lock->is_locked(), "sanity check");
aoqi@0: 
aoqi@0:   int  fail_cnt = 0;
aoqi@0: 
aoqi@0:   // first, verify all the entries individually:
aoqi@0:   for (int bkt = 0; bkt < the_table()->table_size(); bkt++) {
aoqi@0:     HashtableEntry<oop, mtSymbol>* e_ptr = the_table()->bucket(bkt);
aoqi@0:     for (int e_cnt = 0; e_ptr != NULL; e_ptr = e_ptr->next(), e_cnt++) {
aoqi@0:       VerifyRetTypes ret = verify_entry(bkt, e_cnt, e_ptr, _verify_with_mesgs);
aoqi@0:       if (ret != _verify_pass) {
aoqi@0:         fail_cnt++;
aoqi@0:       }
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Optimization: if the above check did not find any failures, then
aoqi@0:   // the comparison loop below does not need to call verify_entry()
aoqi@0:   // before calling compare_entries(). If there were failures, then we
aoqi@0:   // have to call verify_entry() to see if the entry can be passed to
aoqi@0:   // compare_entries() safely. When we call verify_entry() in the loop
aoqi@0:   // below, we do so quietly to void duplicate messages and we don't
aoqi@0:   // increment fail_cnt because the failures have already been counted.
aoqi@0:   bool need_entry_verify = (fail_cnt != 0);
aoqi@0: 
aoqi@0:   // second, verify all entries relative to each other:
aoqi@0:   for (int bkt1 = 0; bkt1 < the_table()->table_size(); bkt1++) {
aoqi@0:     HashtableEntry<oop, mtSymbol>* e_ptr1 = the_table()->bucket(bkt1);
aoqi@0:     for (int e_cnt1 = 0; e_ptr1 != NULL; e_ptr1 = e_ptr1->next(), e_cnt1++) {
aoqi@0:       if (need_entry_verify) {
aoqi@0:         VerifyRetTypes ret = verify_entry(bkt1, e_cnt1, e_ptr1,
aoqi@0:                                           _verify_quietly);
aoqi@0:         if (ret == _verify_fail_done) {
aoqi@0:           // cannot use the current entry to compare against other entries
aoqi@0:           continue;
aoqi@0:         }
aoqi@0:       }
aoqi@0: 
aoqi@0:       for (int bkt2 = bkt1; bkt2 < the_table()->table_size(); bkt2++) {
aoqi@0:         HashtableEntry<oop, mtSymbol>* e_ptr2 = the_table()->bucket(bkt2);
aoqi@0:         int e_cnt2;
aoqi@0:         for (e_cnt2 = 0; e_ptr2 != NULL; e_ptr2 = e_ptr2->next(), e_cnt2++) {
aoqi@0:           if (bkt1 == bkt2 && e_cnt2 <= e_cnt1) {
aoqi@0:             // skip the entries up to and including the one that
aoqi@0:             // we're comparing against
aoqi@0:             continue;
aoqi@0:           }
aoqi@0: 
aoqi@0:           if (need_entry_verify) {
aoqi@0:             VerifyRetTypes ret = verify_entry(bkt2, e_cnt2, e_ptr2,
aoqi@0:                                               _verify_quietly);
aoqi@0:             if (ret == _verify_fail_done) {
aoqi@0:               // cannot compare against this entry
aoqi@0:               continue;
aoqi@0:             }
aoqi@0:           }
aoqi@0: 
aoqi@0:           // compare two entries, report and count any failures:
aoqi@0:           if (compare_entries(bkt1, e_cnt1, e_ptr1, bkt2, e_cnt2, e_ptr2)
aoqi@0:               != _verify_pass) {
aoqi@0:             fail_cnt++;
aoqi@0:           }
aoqi@0:         }
aoqi@0:       }
aoqi@0:     }
aoqi@0:   }
aoqi@0:   return fail_cnt;
aoqi@0: }
aoqi@0: 
aoqi@0: // Create a new table and using alternate hash code, populate the new table
aoqi@0: // with the existing strings.   Set flag to use the alternate hash code afterwards.
aoqi@0: void StringTable::rehash_table() {
aoqi@0:   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
aoqi@0:   // This should never happen with -Xshare:dump but it might in testing mode.
aoqi@0:   if (DumpSharedSpaces) return;
aoqi@0:   StringTable* new_table = new StringTable();
aoqi@0: 
aoqi@0:   // Rehash the table
aoqi@0:   the_table()->move_to(new_table);
aoqi@0: 
aoqi@0:   // Delete the table and buckets (entries are reused in new table).
aoqi@0:   delete _the_table;
aoqi@0:   // Don't check if we need rehashing until the table gets unbalanced again.
aoqi@0:   // Then rehash with a new global seed.
aoqi@0:   _needs_rehashing = false;
aoqi@0:   _the_table = new_table;
aoqi@0: }