diff -r fd16c54261b3 -r 489c9b5090e2 hotspot/src/share/vm/classfile/symbolTable.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/classfile/symbolTable.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,484 @@
+/*
+ * Copyright 1997-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+# include "incls/_precompiled.incl"
+# include "incls/_symbolTable.cpp.incl"
+
+// --------------------------------------------------------------------------
+
+SymbolTable* SymbolTable::_the_table = NULL;
+
+// Lookup a symbol in a bucket.
+
+symbolOop SymbolTable::lookup(int index, const char* name,
+                              int len, unsigned int hash) {
+  for (HashtableEntry* e = bucket(index); e != NULL; e = e->next()) {
+    if (e->hash() == hash) {
+      symbolOop sym = symbolOop(e->literal());
+      if (sym->equals(name, len)) {
+        return sym;
+      }
+    }
+  }
+  return NULL;
+}
+
+
+// We take care not to be blocking while holding the
+// SymbolTable_lock. Otherwise, the system might deadlock, since the
+// symboltable is used during compilation (VM_thread) The lock free
+// synchronization is simplified by the fact that we do not delete
+// entries in the symbol table during normal execution (only during
+// safepoints).
+
+symbolOop SymbolTable::lookup(const char* name, int len, TRAPS) {
+  unsigned int hashValue = hash_symbol(name, len);
+  int index = the_table()->hash_to_index(hashValue);
+
+  symbolOop s = the_table()->lookup(index, name, len, hashValue);
+
+  // Found
+  if (s != NULL) return s;
+
+  // Otherwise, add to symbol to table
+  return the_table()->basic_add(index, (u1*)name, len, hashValue, CHECK_NULL);
+}
+
+symbolOop SymbolTable::lookup(symbolHandle sym, int begin, int end, TRAPS) {
+  char* buffer;
+  int index, len;
+  unsigned int hashValue;
+  char* name;
+  {
+    debug_only(No_Safepoint_Verifier nsv;)
+
+    name = (char*)sym->base() + begin;
+    len = end - begin;
+    hashValue = hash_symbol(name, len);
+    index = the_table()->hash_to_index(hashValue);
+    symbolOop s = the_table()->lookup(index, name, len, hashValue);
+
+    // Found
+    if (s != NULL) return s;
+  }
+
+  // Otherwise, add to symbol to table. Copy to a C string first.
+  char stack_buf[128];
+  ResourceMark rm(THREAD);
+  if (len <= 128) {
+    buffer = stack_buf;
+  } else {
+    buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len);
+  }
+  for (int i=0; i<len; i++) {
+    buffer[i] = name[i];
+  }
+  // Make sure there is no safepoint in the code above since name can't move.
+  // We can't include the code in No_Safepoint_Verifier because of the
+  // ResourceMark.
+
+  return the_table()->basic_add(index, (u1*)buffer, len, hashValue, CHECK_NULL);
+}
+
+symbolOop SymbolTable::lookup_only(const char* name, int len,
+                                   unsigned int& hash) {
+  hash = hash_symbol(name, len);
+  int index = the_table()->hash_to_index(hash);
+
+  return the_table()->lookup(index, name, len, hash);
+}
+
+void SymbolTable::add(constantPoolHandle cp, int names_count,
+                      const char** names, int* lengths, int* cp_indices,
+                      unsigned int* hashValues, TRAPS) {
+  SymbolTable* table = the_table();
+  bool added = table->basic_add(cp, names_count, names, lengths,
+                                cp_indices, hashValues, CHECK);
+  if (!added) {
+    // do it the hard way
+    for (int i=0; i<names_count; i++) {
+      int index = table->hash_to_index(hashValues[i]);
+      symbolOop sym = table->basic_add(index, (u1*)names[i], lengths[i],
+                                       hashValues[i], CHECK);
+      cp->symbol_at_put(cp_indices[i], sym);
+    }
+  }
+}
+
+// Needed for preloading classes in signatures when compiling.
+
+symbolOop SymbolTable::probe(const char* name, int len) {
+  unsigned int hashValue = hash_symbol(name, len);
+  int index = the_table()->hash_to_index(hashValue);
+  return the_table()->lookup(index, name, len, hashValue);
+}
+
+
+symbolOop SymbolTable::basic_add(int index, u1 *name, int len,
+                                 unsigned int hashValue, TRAPS) {
+  assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(),
+         "proposed name of symbol must be stable");
+
+  // We assume that lookup() has been called already, that it failed,
+  // and symbol was not found.  We create the symbol here.
+  symbolKlass* sk  = (symbolKlass*) Universe::symbolKlassObj()->klass_part();
+  symbolOop s_oop = sk->allocate_symbol(name, len, CHECK_NULL);
+  symbolHandle sym (THREAD, s_oop);
+
+  // Allocation must be done before grapping the SymbolTable_lock lock
+  MutexLocker ml(SymbolTable_lock, THREAD);
+
+  assert(sym->equals((char*)name, len), "symbol must be properly initialized");
+
+  // Since look-up was done lock-free, we need to check if another
+  // thread beat us in the race to insert the symbol.
+
+  symbolOop test = lookup(index, (char*)name, len, hashValue);
+  if (test != NULL) {
+    // A race occured and another thread introduced the symbol, this one
+    // will be dropped and collected.
+    return test;
+  }
+
+  HashtableEntry* entry = new_entry(hashValue, sym());
+  add_entry(index, entry);
+  return sym();
+}
+
+bool SymbolTable::basic_add(constantPoolHandle cp, int names_count,
+                            const char** names, int* lengths,
+                            int* cp_indices, unsigned int* hashValues,
+                            TRAPS) {
+  symbolKlass* sk  = (symbolKlass*) Universe::symbolKlassObj()->klass_part();
+  symbolOop sym_oops[symbol_alloc_batch_size];
+  bool allocated = sk->allocate_symbols(names_count, names, lengths,
+                                        sym_oops, CHECK_false);
+  if (!allocated) {
+    return false;
+  }
+  symbolHandle syms[symbol_alloc_batch_size];
+  int i;
+  for (i=0; i<names_count; i++) {
+    syms[i] = symbolHandle(THREAD, sym_oops[i]);
+  }
+
+  // Allocation must be done before grabbing the SymbolTable_lock lock
+  MutexLocker ml(SymbolTable_lock, THREAD);
+
+  for (i=0; i<names_count; i++) {
+    assert(syms[i]->equals(names[i], lengths[i]), "symbol must be properly initialized");
+    // Since look-up was done lock-free, we need to check if another
+    // thread beat us in the race to insert the symbol.
+    int index = hash_to_index(hashValues[i]);
+    symbolOop test = lookup(index, names[i], lengths[i], hashValues[i]);
+    if (test != NULL) {
+      // A race occured and another thread introduced the symbol, this one
+      // will be dropped and collected. Use test instead.
+      cp->symbol_at_put(cp_indices[i], test);
+    } else {
+      symbolOop sym = syms[i]();
+      HashtableEntry* entry = new_entry(hashValues[i], sym);
+      add_entry(index, entry);
+      cp->symbol_at_put(cp_indices[i], sym);
+    }
+  }
+
+  return true;
+}
+
+
+void SymbolTable::verify() {
+  for (int i = 0; i < the_table()->table_size(); ++i) {
+    HashtableEntry* p = the_table()->bucket(i);
+    for ( ; p != NULL; p = p->next()) {
+      symbolOop s = symbolOop(p->literal());
+      guarantee(s != NULL, "symbol is NULL");
+      s->verify();
+      guarantee(s->is_perm(), "symbol not in permspace");
+      unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length());
+      guarantee(p->hash() == h, "broken hash in symbol table entry");
+      guarantee(the_table()->hash_to_index(h) == i,
+                "wrong index in symbol table");
+    }
+  }
+}
+
+
+//---------------------------------------------------------------------------
+// Non-product code
+
+#ifndef PRODUCT
+
+void SymbolTable::print_histogram() {
+  MutexLocker ml(SymbolTable_lock);
+  const int results_length = 100;
+  int results[results_length];
+  int i,j;
+
+  // initialize results to zero
+  for (j = 0; j < results_length; j++) {
+    results[j] = 0;
+  }
+
+  int total = 0;
+  int max_symbols = 0;
+  int out_of_range = 0;
+  for (i = 0; i < the_table()->table_size(); i++) {
+    HashtableEntry* p = the_table()->bucket(i);
+    for ( ; p != NULL; p = p->next()) {
+      int counter = symbolOop(p->literal())->utf8_length();
+      total += counter;
+      if (counter < results_length) {
+        results[counter]++;
+      } else {
+        out_of_range++;
+      }
+      max_symbols = MAX2(max_symbols, counter);
+    }
+  }
+  tty->print_cr("Symbol Table:");
+  tty->print_cr("%8s %5d", "Total  ", total);
+  tty->print_cr("%8s %5d", "Maximum", max_symbols);
+  tty->print_cr("%8s %3.2f", "Average",
+          ((float) total / (float) the_table()->table_size()));
+  tty->print_cr("%s", "Histogram:");
+  tty->print_cr(" %s %29s", "Length", "Number chains that length");
+  for (i = 0; i < results_length; i++) {
+    if (results[i] > 0) {
+      tty->print_cr("%6d %10d", i, results[i]);
+    }
+  }
+  int line_length = 70;
+  tty->print_cr("%s %30s", " Length", "Number chains that length");
+  for (i = 0; i < results_length; i++) {
+    if (results[i] > 0) {
+      tty->print("%4d", i);
+      for (j = 0; (j < results[i]) && (j < line_length);  j++) {
+        tty->print("%1s", "*");
+      }
+      if (j == line_length) {
+        tty->print("%1s", "+");
+      }
+      tty->cr();
+    }
+  }
+  tty->print_cr(" %s %d: %d\n", "Number chains longer than",
+                    results_length, out_of_range);
+}
+
+#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
+
+
+// --------------------------------------------------------------------------
+
+
+// Compute the hash value for a java.lang.String object which would
+// contain the characters passed in. This hash value is used for at
+// least two purposes.
+//
+// (a) As the hash value used by the StringTable for bucket selection
+//     and comparison (stored in the HashtableEntry structures).  This
+//     is used in the String.intern() method.
+//
+// (b) As the hash value used by the String object itself, in
+//     String.hashCode().  This value is normally calculate in Java code
+//     in the String.hashCode method(), but is precomputed for String
+//     objects in the shared archive file.
+//
+//     For this reason, THIS ALGORITHM MUST MATCH String.hashCode().
+
+int StringTable::hash_string(jchar* s, int len) {
+  unsigned h = 0;
+  while (len-- > 0) {
+    h = 31*h + (unsigned) *s;
+    s++;
+  }
+  return h;
+}
+
+
+StringTable* StringTable::_the_table = NULL;
+
+oop StringTable::lookup(int index, jchar* name,
+                        int len, unsigned int hash) {
+  for (HashtableEntry* l = bucket(index); l != NULL; l = l->next()) {
+    if (l->hash() == hash) {
+      if (java_lang_String::equals(l->literal(), name, len)) {
+        return l->literal();
+      }
+    }
+  }
+  return NULL;
+}
+
+
+oop StringTable::basic_add(int index, Handle string_or_null, jchar* name,
+                           int len, unsigned int hashValue, TRAPS) {
+  debug_only(StableMemoryChecker smc(name, len * sizeof(name[0])));
+  assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(),
+         "proposed name of symbol must be stable");
+
+  Handle string;
+  // try to reuse the string if possible
+  if (!string_or_null.is_null() && string_or_null()->is_perm()) {
+    string = string_or_null;
+  } else {
+    string = java_lang_String::create_tenured_from_unicode(name, len, CHECK_NULL);
+  }
+
+  // Allocation must be done before grapping the SymbolTable_lock lock
+  MutexLocker ml(StringTable_lock, THREAD);
+
+  assert(java_lang_String::equals(string(), name, len),
+         "string must be properly initialized");
+
+  // 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* entry = new_entry(hashValue, string());
+  add_entry(index, entry);
+  return string();
+}
+
+
+oop StringTable::lookup(symbolOop symbol) {
+  ResourceMark rm;
+  int length;
+  jchar* chars = symbol->as_unicode(length);
+  unsigned int hashValue = hash_string(chars, length);
+  int index = the_table()->hash_to_index(hashValue);
+  return the_table()->lookup(index, chars, length, hashValue);
+}
+
+
+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 string = the_table()->lookup(index, name, len, hashValue);
+
+  // Found
+  if (string != NULL) return string;
+
+  // Otherwise, add to symbol to table
+  return the_table()->basic_add(index, string_or_null, name, len,
+                                hashValue, CHECK_NULL);
+}
+
+oop StringTable::intern(symbolOop 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);
+  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::verify() {
+  for (int i = 0; i < the_table()->table_size(); ++i) {
+    HashtableEntry* p = the_table()->bucket(i);
+    for ( ; p != NULL; p = p->next()) {
+      oop s = p->literal();
+      guarantee(s != NULL, "interned string is NULL");
+      guarantee(s->is_perm(), "interned string not in permspace");
+
+      int length;
+      jchar* chars = java_lang_String::as_unicode_string(s, length);
+      unsigned int h = hash_string(chars, length);
+      guarantee(p->hash() == h, "broken hash in string table entry");
+      guarantee(the_table()->hash_to_index(h) == i,
+                "wrong index in string table");
+    }
+  }
+}