/*

 * Copyright (c) 2003, 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

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 */

#include "precompiled.hpp"

#include "classfile/classLoaderData.inline.hpp"

#include "classfile/dictionary.inline.hpp"

#include "classfile/protectionDomainCache.hpp"

#include "classfile/systemDictionary.hpp"

#include "logging/log.hpp"

#include "logging/logStream.hpp"

#include "memory/iterator.hpp"

#include "memory/metaspaceClosure.hpp"

#include "memory/resourceArea.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.hpp"

#include "runtime/orderAccess.hpp"

#include "runtime/safepointVerifiers.hpp"

#include "utilities/hashtable.inline.hpp"

// Optimization: if any dictionary needs resizing, we set this flag,

// so that we dont't have to walk all dictionaries to check if any actually

// needs resizing, which is costly to do at Safepoint.

bool Dictionary::_some_dictionary_needs_resizing = false;

Dictionary::Dictionary(ClassLoaderData* loader_data, int table_size, bool resizable)

  : Hashtable<InstanceKlass*, mtClass>(table_size, (int)sizeof(DictionaryEntry)),

    _resizable(resizable), _needs_resizing(false), _loader_data(loader_data) {

};

Dictionary::Dictionary(ClassLoaderData* loader_data,

                       int table_size, HashtableBucket<mtClass>* t,

                       int number_of_entries, bool resizable)

  : Hashtable<InstanceKlass*, mtClass>(table_size, (int)sizeof(DictionaryEntry), t, number_of_entries),

    _resizable(resizable), _needs_resizing(false), _loader_data(loader_data) {

};

Dictionary::~Dictionary() {

  DictionaryEntry* probe = NULL;

  for (int index = 0; index < table_size(); index++) {

    for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {

      probe = *p;

      *p = probe->next();

      free_entry(probe);

    }

  }

  assert(number_of_entries() == 0, "should have removed all entries");

  assert(new_entry_free_list() == NULL, "entry present on Dictionary's free list");

}

DictionaryEntry* Dictionary::new_entry(unsigned int hash, InstanceKlass* klass) {

  DictionaryEntry* entry = (DictionaryEntry*)Hashtable<InstanceKlass*, mtClass>::allocate_new_entry(hash, klass);

  entry->set_pd_set(NULL);

  assert(klass->is_instance_klass(), "Must be");

  return entry;

}

void Dictionary::free_entry(DictionaryEntry* entry) {

  // avoid recursion when deleting linked list

  // pd_set is accessed during a safepoint.

  while (entry->pd_set() != NULL) {

    ProtectionDomainEntry* to_delete = entry->pd_set();

    entry->set_pd_set(to_delete->next());

    delete to_delete;

  }

  // Unlink from the Hashtable prior to freeing

  unlink_entry(entry);

  FREE_C_HEAP_ARRAY(char, entry);

}

const int _resize_load_trigger = 5;       // load factor that will trigger the resize

const double _resize_factor    = 2.0;     // by how much we will resize using current number of entries

const int _resize_max_size     = 40423;   // the max dictionary size allowed

const int _primelist[] = {107, 1009, 2017, 4049, 5051, 10103, 20201, _resize_max_size};

const int _prime_array_size = sizeof(_primelist)/sizeof(int);

// Calculate next "good" dictionary size based on requested count

static int calculate_dictionary_size(int requested) {

  int newsize = _primelist[0];

  int index = 0;

  for (newsize = _primelist[index]; index < (_prime_array_size - 1);

       newsize = _primelist[++index]) {

    if (requested <= newsize) {

      break;

    }

  }

  return newsize;

}

bool Dictionary::does_any_dictionary_needs_resizing() {

  return Dictionary::_some_dictionary_needs_resizing;

}

void Dictionary::check_if_needs_resize() {

  if (_resizable == true) {

    if (number_of_entries() > (_resize_load_trigger*table_size())) {

      _needs_resizing = true;

      Dictionary::_some_dictionary_needs_resizing = true;

    }

  }

}

bool Dictionary::resize_if_needed() {

  int desired_size = 0;

  if (_needs_resizing == true) {

    desired_size = calculate_dictionary_size((int)(_resize_factor*number_of_entries()));

    if (desired_size >= _resize_max_size) {

      desired_size = _resize_max_size;

      // We have reached the limit, turn resizing off

      _resizable = false;

    }

    if ((desired_size != 0) && (desired_size != table_size())) {

      if (!resize(desired_size)) {

        // Something went wrong, turn resizing off

        _resizable = false;

      }

    }

  }

  _needs_resizing = false;

  Dictionary::_some_dictionary_needs_resizing = false;

  return (desired_size != 0);

}

bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {

#ifdef ASSERT

  if (oopDesc::equals(protection_domain, instance_klass()->protection_domain())) {

    // Ensure this doesn't show up in the pd_set (invariant)

    bool in_pd_set = false;

    for (ProtectionDomainEntry* current = pd_set_acquire();

                                current != NULL;

                                current = current->next()) {

      if (oopDesc::equals(current->object_no_keepalive(), protection_domain)) {

        in_pd_set = true;

        break;

      }

    }

    if (in_pd_set) {

      assert(false, "A klass's protection domain should not show up "

                    "in its sys. dict. PD set");

    }

  }

#endif /* ASSERT */

  if (oopDesc::equals(protection_domain, instance_klass()->protection_domain())) {

    // Succeeds trivially

    return true;

  }

  for (ProtectionDomainEntry* current = pd_set_acquire();

                              current != NULL;

                              current = current->next()) {

    if (oopDesc::equals(current->object_no_keepalive(), protection_domain)) return true;

  }

  return false;

}

void DictionaryEntry::add_protection_domain(Dictionary* dict, Handle protection_domain) {

  assert_locked_or_safepoint(SystemDictionary_lock);

  if (!contains_protection_domain(protection_domain())) {

    ProtectionDomainCacheEntry* entry = SystemDictionary::cache_get(protection_domain);

    ProtectionDomainEntry* new_head =

                new ProtectionDomainEntry(entry, pd_set());

    // Warning: Preserve store ordering.  The SystemDictionary is read

    //          without locks.  The new ProtectionDomainEntry must be

    //          complete before other threads can be allowed to see it

    //          via a store to _pd_set.

    release_set_pd_set(new_head);

  }

  LogTarget(Trace, protectiondomain) lt;

  if (lt.is_enabled()) {

    LogStream ls(lt);

    print_count(&ls);

  }

}

// During class loading we may have cached a protection domain that has

// since been unreferenced, so this entry should be cleared.

void Dictionary::clean_cached_protection_domains(DictionaryEntry* probe) {

  assert_locked_or_safepoint(SystemDictionary_lock);

  ProtectionDomainEntry* current = probe->pd_set();

  ProtectionDomainEntry* prev = NULL;

  while (current != NULL) {

    if (current->object_no_keepalive() == NULL) {

      LogTarget(Debug, protectiondomain) lt;

      if (lt.is_enabled()) {

        ResourceMark rm;

        // Print out trace information

        LogStream ls(lt);

        ls.print_cr("PD in set is not alive:");

        ls.print("class loader: "); loader_data()->class_loader()->print_value_on(&ls);

        ls.print(" loading: "); probe->instance_klass()->print_value_on(&ls);

        ls.cr();

      }

      if (probe->pd_set() == current) {

        probe->set_pd_set(current->next());

      } else {

        assert(prev != NULL, "should be set by alive entry");

        prev->set_next(current->next());

      }

      ProtectionDomainEntry* to_delete = current;

      current = current->next();

      delete to_delete;

    } else {

      prev = current;

      current = current->next();

    }

  }

}

void Dictionary::do_unloading() {

  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");

  // The NULL class loader doesn't initiate loading classes from other class loaders

  if (loader_data() == ClassLoaderData::the_null_class_loader_data()) {

    return;

  }

  // Remove unloaded entries and classes from this dictionary

  DictionaryEntry* probe = NULL;

  for (int index = 0; index < table_size(); index++) {

    for (DictionaryEntry** p = bucket_addr(index); *p != NULL; ) {

      probe = *p;

      InstanceKlass* ik = probe->instance_klass();

      ClassLoaderData* k_def_class_loader_data = ik->class_loader_data();

      // If the klass that this loader initiated is dead,

      // (determined by checking the defining class loader)

      // remove this entry.

      if (k_def_class_loader_data->is_unloading()) {

        assert(k_def_class_loader_data != loader_data(),

               "cannot have live defining loader and unreachable klass");

        *p = probe->next();

        free_entry(probe);

        continue;

      }

      // Clean pd_set

      clean_cached_protection_domains(probe);

      p = probe->next_addr();

    }

  }

}

//   Just the classes from defining class loaders

void Dictionary::classes_do(void f(InstanceKlass*)) {

  for (int index = 0; index < table_size(); index++) {

    for (DictionaryEntry* probe = bucket(index);

                          probe != NULL;

                          probe = probe->next()) {

      InstanceKlass* k = probe->instance_klass();

      if (loader_data() == k->class_loader_data()) {

        f(k);

      }

    }

  }

}

// Added for initialize_itable_for_klass to handle exceptions

//   Just the classes from defining class loaders

void Dictionary::classes_do(void f(InstanceKlass*, TRAPS), TRAPS) {

  for (int index = 0; index < table_size(); index++) {

    for (DictionaryEntry* probe = bucket(index);

                          probe != NULL;

                          probe = probe->next()) {

      InstanceKlass* k = probe->instance_klass();

      if (loader_data() == k->class_loader_data()) {

        f(k, CHECK);

      }

    }

  }

}

// All classes, and their class loaders, including initiating class loaders

void Dictionary::all_entries_do(KlassClosure* closure) {

  for (int index = 0; index < table_size(); index++) {

    for (DictionaryEntry* probe = bucket(index);

                          probe != NULL;

                          probe = probe->next()) {

      InstanceKlass* k = probe->instance_klass();

      closure->do_klass(k);

    }

  }

}

// Used to scan and relocate the classes during CDS archive dump.

void Dictionary::classes_do(MetaspaceClosure* it) {

  assert(DumpSharedSpaces, "dump-time only");

  for (int index = 0; index < table_size(); index++) {

    for (DictionaryEntry* probe = bucket(index);

                          probe != NULL;

                          probe = probe->next()) {

      it->push(probe->klass_addr());

    }

  }

}

// Add a loaded class to the dictionary.

// Readers of the SystemDictionary aren't always locked, so _buckets

// is volatile. The store of the next field in the constructor is

// also cast to volatile;  we do this to ensure store order is maintained

// by the compilers.

void Dictionary::add_klass(unsigned int hash, Symbol* class_name,

                           InstanceKlass* obj) {

  assert_locked_or_safepoint(SystemDictionary_lock);

  assert(obj != NULL, "adding NULL obj");

  assert(obj->name() == class_name, "sanity check on name");

  DictionaryEntry* entry = new_entry(hash, obj);

  int index = hash_to_index(hash);

  add_entry(index, entry);

  check_if_needs_resize();

}

// This routine does not lock the dictionary.

//

// Since readers don't hold a lock, we must make sure that system

// dictionary entries are only removed at a safepoint (when only one

// thread is running), and are added to in a safe way (all links must

// be updated in an MT-safe manner).

//

// Callers should be aware that an entry could be added just after

// _buckets[index] is read here, so the caller will not see the new entry.

DictionaryEntry* Dictionary::get_entry(int index, unsigned int hash,

                                       Symbol* class_name) {

  for (DictionaryEntry* entry = bucket(index);

                        entry != NULL;

                        entry = entry->next()) {

    if (entry->hash() == hash && entry->equals(class_name)) {

      return entry;

    }

  }

  return NULL;

}

InstanceKlass* Dictionary::find(unsigned int hash, Symbol* name,

                                Handle protection_domain) {

  NoSafepointVerifier nsv;

  int index = hash_to_index(hash);

  DictionaryEntry* entry = get_entry(index, hash, name);

  if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {

    return entry->instance_klass();

  } else {

    return NULL;

  }

}

InstanceKlass* Dictionary::find_class(int index, unsigned int hash,

                                      Symbol* name) {

  assert_locked_or_safepoint(SystemDictionary_lock);

  assert (index == index_for(name), "incorrect index?");

  DictionaryEntry* entry = get_entry(index, hash, name);

  return (entry != NULL) ? entry->instance_klass() : NULL;

}

void Dictionary::add_protection_domain(int index, unsigned int hash,

                                       InstanceKlass* klass,

                                       Handle protection_domain,

                                       TRAPS) {

  Symbol*  klass_name = klass->name();

  DictionaryEntry* entry = get_entry(index, hash, klass_name);

  assert(entry != NULL,"entry must be present, we just created it");

  assert(protection_domain() != NULL,

         "real protection domain should be present");

  entry->add_protection_domain(this, protection_domain);

#ifdef ASSERT

  assert(loader_data() != ClassLoaderData::the_null_class_loader_data(), "doesn't make sense");

#endif

  assert(entry->contains_protection_domain(protection_domain()),

         "now protection domain should be present");

}

bool Dictionary::is_valid_protection_domain(unsigned int hash,

                                            Symbol* name,

                                            Handle protection_domain) {

  int index = hash_to_index(hash);

  DictionaryEntry* entry = get_entry(index, hash, name);

  return entry->is_valid_protection_domain(protection_domain);

}

SymbolPropertyTable::SymbolPropertyTable(int table_size)

  : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry))

{

}

SymbolPropertyTable::SymbolPropertyTable(int table_size, HashtableBucket<mtSymbol>* t,

                                         int number_of_entries)

  : Hashtable<Symbol*, mtSymbol>(table_size, sizeof(SymbolPropertyEntry), t, number_of_entries)

{

}

SymbolPropertyEntry* SymbolPropertyTable::find_entry(int index, unsigned int hash,

                                                     Symbol* sym,

                                                     intptr_t sym_mode) {

  assert(index == index_for(sym, sym_mode), "incorrect index?");

  for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {

    if (p->hash() == hash && p->symbol() == sym && p->symbol_mode() == sym_mode) {

      return p;

    }

  }

  return NULL;

}

SymbolPropertyEntry* SymbolPropertyTable::add_entry(int index, unsigned int hash,

                                                    Symbol* sym, intptr_t sym_mode) {

  assert_locked_or_safepoint(SystemDictionary_lock);

  assert(index == index_for(sym, sym_mode), "incorrect index?");

  assert(find_entry(index, hash, sym, sym_mode) == NULL, "no double entry");

  SymbolPropertyEntry* p = new_entry(hash, sym, sym_mode);

  Hashtable<Symbol*, mtSymbol>::add_entry(index, p);

  return p;

}

void SymbolPropertyTable::oops_do(OopClosure* f) {

  for (int index = 0; index < table_size(); index++) {

    for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {

      if (p->method_type() != NULL) {

        f->do_oop(p->method_type_addr());

      }

    }

  }

}

void SymbolPropertyTable::methods_do(void f(Method*)) {

  for (int index = 0; index < table_size(); index++) {

    for (SymbolPropertyEntry* p = bucket(index); p != NULL; p = p->next()) {

      Method* prop = p->method();

      if (prop != NULL) {

        f((Method*)prop);

      }

    }

  }

}

// ----------------------------------------------------------------------------

void Dictionary::print_on(outputStream* st) const {

  ResourceMark rm;

  assert(loader_data() != NULL, "loader data should not be null");

  st->print_cr("Java dictionary (table_size=%d, classes=%d, resizable=%s)",

               table_size(), number_of_entries(), BOOL_TO_STR(_resizable));

  st->print_cr("^ indicates that initiating loader is different from defining loader");

  for (int index = 0; index < table_size(); index++) {

    for (DictionaryEntry* probe = bucket(index);

                          probe != NULL;

                          probe = probe->next()) {

      Klass* e = probe->instance_klass();

      bool is_defining_class =

         (loader_data() == e->class_loader_data());

      st->print("%4d: %s%s", index, is_defining_class ? " " : "^", e->external_name());

      ClassLoaderData* cld = e->class_loader_data();