/*

 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

#ifndef SHARE_VM_CLASSFILE_SYMBOLTABLE_HPP

#define SHARE_VM_CLASSFILE_SYMBOLTABLE_HPP

#include "memory/allocation.inline.hpp"

#include "oops/symbol.hpp"

#include "utilities/hashtable.hpp"

// The symbol table holds all Symbol*s and corresponding interned strings.

// Symbol*s and literal strings should be canonicalized.

//

// The interned strings are created lazily.

//

// It is implemented as an open hash table with a fixed number of buckets.

//

// %note:

//  - symbolTableEntrys are allocated in blocks to reduce the space overhead.

class BoolObjectClosure;

// Class to hold a newly created or referenced Symbol* temporarily in scope.

// new_symbol() and lookup() will create a Symbol* if not already in the

// symbol table and add to the symbol's reference count.

// probe() and lookup_only() will increment the refcount if symbol is found.

class TempNewSymbol : public StackObj {

  Symbol* _temp;

 public:

  TempNewSymbol() : _temp(NULL) {}

  // Creating or looking up a symbol increments the symbol's reference count

  TempNewSymbol(Symbol *s) : _temp(s) {}

  // Operator= increments reference count.

  void operator=(const TempNewSymbol &s) {

    _temp = s._temp;

    if (_temp !=NULL) _temp->increment_refcount();

  }

  // Decrement reference counter so it can go away if it's unique

  ~TempNewSymbol() { if (_temp != NULL) _temp->decrement_refcount(); }

  // Operators so they can be used like Symbols

  Symbol* operator -> () const                   { return _temp; }

  bool    operator == (Symbol* o) const          { return _temp == o; }

  // Sneaky conversion function

  operator Symbol*()                             { return _temp; }

};

class SymbolTable : public Hashtable<Symbol*> {

  friend class VMStructs;

  friend class ClassFileParser;

private:

  // The symbol table

  static SymbolTable* _the_table;

  // For statistics

  static int symbols_removed;

  static int symbols_counted;

  Symbol* allocate_symbol(const u1* name, int len, TRAPS);   // Assumes no characters larger than 0x7F

  bool allocate_symbols(int names_count, const u1** names, int* lengths, Symbol** syms, TRAPS);

  // Adding elements

  Symbol* basic_add(int index, u1* name, int len,

                      unsigned int hashValue, TRAPS);

  bool basic_add(constantPoolHandle cp, int names_count,

                 const char** names, int* lengths, int* cp_indices,

                 unsigned int* hashValues, TRAPS);

  static void new_symbols(constantPoolHandle cp, int names_count,

                          const char** name, int* lengths,

                          int* cp_indices, unsigned int* hashValues,

                          TRAPS) {

    add(cp, names_count, name, lengths, cp_indices, hashValues, THREAD);

  }

  // Table size

  enum {

    symbol_table_size = 20011

  };

  Symbol* lookup(int index, const char* name, int len, unsigned int hash);

  SymbolTable()

    : Hashtable<Symbol*>(symbol_table_size, sizeof (HashtableEntry<Symbol*>)) {}

  SymbolTable(HashtableBucket* t, int number_of_entries)

    : Hashtable<Symbol*>(symbol_table_size, sizeof (HashtableEntry<Symbol*>), t,

                number_of_entries) {}

public:

  enum {

    symbol_alloc_batch_size = 8

  };

  // The symbol table

  static SymbolTable* the_table() { return _the_table; }

  static void create_table() {

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

    _the_table = new SymbolTable();

  }

  static void create_table(HashtableBucket* t, int length,

                           int number_of_entries) {

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

    assert(length == symbol_table_size * sizeof(HashtableBucket),

           "bad shared symbol size.");

    _the_table = new SymbolTable(t, number_of_entries);

  }

  static Symbol* lookup(const char* name, int len, TRAPS);

  // lookup only, won't add. Also calculate hash.

  static Symbol* lookup_only(const char* name, int len, unsigned int& hash);

  // Only copy to C string to be added if lookup failed.

  static Symbol* lookup(const Symbol* sym, int begin, int end, TRAPS);

  static void release(Symbol* sym);

  // jchar (utf16) version of lookups

  static Symbol* lookup_unicode(const jchar* name, int len, TRAPS);

  static Symbol* lookup_only_unicode(const jchar* name, int len, unsigned int& hash);

  static void add(constantPoolHandle cp, int names_count,

                  const char** names, int* lengths, int* cp_indices,

                  unsigned int* hashValues, TRAPS);

  // Release any dead symbols

  static void unlink();

  // iterate over symbols

  static void symbols_do(SymbolClosure *cl);

  // Symbol creation

  static Symbol* new_symbol(const char* utf8_buffer, int length, TRAPS) {

    assert(utf8_buffer != NULL, "just checking");

    return lookup(utf8_buffer, length, THREAD);

  }

  static Symbol*       new_symbol(const char* name, TRAPS) {

    return new_symbol(name, (int)strlen(name), THREAD);

  }

  static Symbol*       new_symbol(const Symbol* sym, int begin, int end, TRAPS) {

    assert(begin <= end && end <= sym->utf8_length(), "just checking");

    return lookup(sym, begin, end, THREAD);

  }

  // Symbol lookup

  static Symbol* lookup(int index, const char* name, int len, TRAPS);

  // Needed for preloading classes in signatures when compiling.

  // Returns the symbol is already present in symbol table, otherwise

  // NULL.  NO ALLOCATION IS GUARANTEED!

  static Symbol* probe(const char* name, int len) {

    unsigned int ignore_hash;

    return lookup_only(name, len, ignore_hash);

  }

  static Symbol* probe_unicode(const jchar* name, int len) {

    unsigned int ignore_hash;

    return lookup_only_unicode(name, len, ignore_hash);

  }

  // Histogram

  static void print_histogram()     PRODUCT_RETURN;

  static void print()     PRODUCT_RETURN;

  // Debugging

  static void verify();

  // Sharing

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

    the_table()->Hashtable<Symbol*>::copy_buckets(top, end);

  }

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

    the_table()->Hashtable<Symbol*>::copy_table(top, end);

  }

  static void reverse(void* boundary = NULL) {

    the_table()->Hashtable<Symbol*>::reverse(boundary);

  }

};

class StringTable : public Hashtable<oop> {

  friend class VMStructs;

private:

  // The string table

  static StringTable* _the_table;

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

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

                unsigned int hashValue, TRAPS);

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

  StringTable(HashtableBucket* t, int number_of_entries)

public:

  // The string table

  static StringTable* the_table() { return _the_table; }

  static void create_table() {

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

    _the_table = new StringTable();

  }

  static void create_table(HashtableBucket* t, int length,

                           int number_of_entries) {

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

           "bad shared string size.");

    _the_table = new StringTable(t, number_of_entries);

  }

  static int hash_string(jchar* s, int len);

  // GC support

  //   Delete pointers to otherwise-unreachable objects.

  static void unlink(BoolObjectClosure* cl);

  // Invoke "f->do_oop" on the locations of all oops in the table.

  static void oops_do(OopClosure* f);

  // Probing

  static oop lookup(Symbol* symbol);

  // Interning

  static oop intern(Symbol* symbol, TRAPS);

  static oop intern(oop string, TRAPS);

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

  // Debugging

  static void verify();

  // Sharing

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

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

  }

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

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

  }

  static void reverse() {

    the_table()->Hashtable<oop>::reverse();

  }

};

#endif // SHARE_VM_CLASSFILE_SYMBOLTABLE_HPP