/*

 * Copyright (c) 1997, 2018, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#ifndef SHARE_VM_CLASSFILE_STRINGTABLE_HPP

#define SHARE_VM_CLASSFILE_STRINGTABLE_HPP

#include "gc/shared/oopStorage.hpp"

#include "gc/shared/oopStorageParState.hpp"

#include "memory/allocation.hpp"

#include "memory/padded.hpp"

#include "oops/oop.hpp"

#include "oops/weakHandle.hpp"

#include "utilities/concurrentHashTable.hpp"

template <class T, class N> class CompactHashtable;

class CompactStringTableWriter;

class SerializeClosure;

class StringTable;

class StringTableConfig;

typedef ConcurrentHashTable<WeakHandle<vm_string_table_data>,

                            StringTableConfig, mtSymbol> StringTableHash;

class StringTableCreateEntry;

class StringTable : public CHeapObj<mtSymbol>{

  friend class VMStructs;

  friend class Symbol;

  friend class StringTableConfig;

  friend class StringTableCreateEntry;

private:

  void grow(JavaThread* jt);

  void clean_dead_entries(JavaThread* jt);

  // The string table

  static StringTable* _the_table;

  // Shared string table

  static CompactHashtable<oop, char> _shared_table;

  static bool _shared_string_mapped;

  static bool _alt_hash;

private:

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

  StringTableHash* _local_table;

  size_t _current_size;

  volatile bool _has_work;

  volatile bool _needs_rehashing;

  OopStorage* _weak_handles;

  volatile size_t _items;

  DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));

  volatile size_t _uncleaned_items;

  DEFINE_PAD_MINUS_SIZE(2, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));

  double get_load_factor();

  double get_dead_factor();

  void check_concurrent_work();

  void trigger_concurrent_work();

  static void item_removed();

  size_t add_items_to_clean(size_t ndead);

  StringTable();

  static oop intern(Handle string_or_null_h, jchar* name, int len, TRAPS);

  oop do_intern(Handle string_or_null, jchar* name, int len, uintx hash, TRAPS);

  oop do_lookup(jchar* name, int len, uintx hash);

  void concurrent_work(JavaThread* jt);

  void print_table_statistics(outputStream* st, const char* table_name);

  void try_rehash_table();

  bool do_rehash();

 public:

  // The string table

  static StringTable* the_table() { return _the_table; }

  size_t table_size(Thread* thread = NULL);

  static OopStorage* weak_storage() { return the_table()->_weak_handles; }

  static void create_table() {

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

    _the_table = new StringTable();

  }

  static void do_concurrent_work(JavaThread* jt);

  static bool has_work() { return the_table()->_has_work; }

  // GC support

  // Must be called before a parallel walk where strings might die.

  static void reset_dead_counter() {

    the_table()->_uncleaned_items = 0;

  }

  // After the parallel walk this method must be called to trigger

  // cleaning. Note it might trigger a resize instead.

  static void finish_dead_counter() {

    the_table()->check_concurrent_work();

  }

  // If GC uses ParState directly it should add the number of cleared

  // strings to this method.

  static void inc_dead_counter(size_t ndead) {

    the_table()->add_items_to_clean(ndead);

  }

  //   Delete pointers to otherwise-unreachable objects.

  static void unlink(BoolObjectClosure* cl) {

    unlink_or_oops_do(cl);

  }

  static void unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* f = NULL,

                                int* processed = NULL, int* removed = NULL);

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

  static void oops_do(OopClosure* f);

  // Possibly parallel versions of the above

  static void possibly_parallel_unlink(

     OopStorage::ParState<false /* concurrent */, false /* const*/>* par_state_string,

     BoolObjectClosure* cl, int* processed, int* removed);

  static void possibly_parallel_oops_do(

     OopStorage::ParState<false /* concurrent */, false /* const*/>* par_state_string,

     OopClosure* f);

  // Probing

  static oop lookup(Symbol* symbol);

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

  // Interning

  static oop intern(Symbol* symbol, TRAPS);

  static oop intern(oop string, TRAPS);

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

  // Rehash the string table if it gets out of balance

  static void rehash_table();

  static bool needs_rehashing()

    { return StringTable::the_table()->_needs_rehashing; }

  // Sharing

 private:

  oop lookup_shared(jchar* name, int len, unsigned int hash) NOT_CDS_JAVA_HEAP_RETURN_(NULL);

  static void copy_shared_string_table(CompactStringTableWriter* ch_table) NOT_CDS_JAVA_HEAP_RETURN;

 public:

  static oop create_archived_string(oop s, Thread* THREAD) NOT_CDS_JAVA_HEAP_RETURN_(NULL);

  static void set_shared_string_mapped() { _shared_string_mapped = true; }

  static bool shared_string_mapped()     { return _shared_string_mapped; }

  static void shared_oops_do(OopClosure* f) NOT_CDS_JAVA_HEAP_RETURN;

  static void write_to_archive() NOT_CDS_JAVA_HEAP_RETURN;

  static void serialize(SerializeClosure* soc) NOT_CDS_JAVA_HEAP_RETURN;

  // Jcmd

  static void dump(outputStream* st, bool verbose=false);

  // Debugging

  static size_t verify_and_compare_entries();

  static void verify();

};

#endif // SHARE_VM_CLASSFILE_STRINGTABLE_HPP