/*+
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 * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.+
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.+
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 *+
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 * This code is free software; you can redistribute it and/or modify it+
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 * under the terms of the GNU General Public License version 2 only, as+
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 * published by the Free Software Foundation.+
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 *+
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 * This code is distributed in the hope that it will be useful, but WITHOUT+
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or+
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License+
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 * version 2 for more details (a copy is included in the LICENSE file that+
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 * accompanied this code).+
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 *+
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 * You should have received a copy of the GNU General Public License version+
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 * 2 along with this work; if not, write to the Free Software Foundation,+
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.+
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 *+
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA+
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 * or visit www.oracle.com if you need additional information or have any+
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 * questions.+
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 *+
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 */+
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+
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#include "precompiled.hpp"+
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#include "classfile/placeholders.hpp"+
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#include "classfile/systemDictionary.hpp"+
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#include "oops/oop.inline.hpp"+
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#include "runtime/fieldType.hpp"+
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#include "utilities/hashtable.inline.hpp"+
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+
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// Placeholder methods+
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+
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PlaceholderEntry* PlaceholderTable::new_entry(int hash, Symbol* name,+
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                                              ClassLoaderData* loader_data,+
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                                              bool havesupername,+
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                                              Symbol* supername) {+
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  PlaceholderEntry* entry = (PlaceholderEntry*)Hashtable<Symbol*, mtClass>::new_entry(hash, name);+
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  // Hashtable with Symbol* literal must increment and decrement refcount.+
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  name->increment_refcount();+
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  entry->set_loader_data(loader_data);+
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  entry->set_havesupername(havesupername);+
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  entry->set_supername(supername);+
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  entry->set_superThreadQ(NULL);+
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  entry->set_loadInstanceThreadQ(NULL);+
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  entry->set_defineThreadQ(NULL);+
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  entry->set_definer(NULL);+
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  entry->set_instance_klass(NULL);+
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  return entry;+
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}+
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+
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void PlaceholderTable::free_entry(PlaceholderEntry* entry) {+
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  // decrement Symbol refcount here because Hashtable doesn't.+
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  entry->literal()->decrement_refcount();+
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  if (entry->supername() != NULL) entry->supername()->decrement_refcount();+
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  Hashtable<Symbol*, mtClass>::free_entry(entry);+
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}+
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+
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+
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// Placeholder objects represent classes currently being loaded.+
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// All threads examining the placeholder table must hold the+
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// SystemDictionary_lock, so we don't need special precautions+
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// on store ordering here.+
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void PlaceholderTable::add_entry(int index, unsigned int hash,+
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                                 Symbol* class_name, ClassLoaderData* loader_data,+
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                                 bool havesupername, Symbol* supername){+
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  assert_locked_or_safepoint(SystemDictionary_lock);+
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  assert(class_name != NULL, "adding NULL obj");+
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+
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  // Both readers and writers are locked so it's safe to just+
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  // create the placeholder and insert it in the list without a membar.+
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  PlaceholderEntry* entry = new_entry(hash, class_name, loader_data, havesupername, supername);+
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  add_entry(index, entry);+
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}+
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+
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+
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// Remove a placeholder object.+
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void PlaceholderTable::remove_entry(int index, unsigned int hash,+
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                                    Symbol* class_name,+
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                                    ClassLoaderData* loader_data) {+
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  assert_locked_or_safepoint(SystemDictionary_lock);+
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  PlaceholderEntry** p = bucket_addr(index);+
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  while (*p) {+
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    PlaceholderEntry *probe = *p;+
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    if (probe->hash() == hash && probe->equals(class_name, loader_data)) {+
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      // Delete entry+
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      *p = probe->next();+
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      free_entry(probe);+
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      return;+
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    }+
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    p = probe->next_addr();+
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  }+
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}+
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+
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PlaceholderEntry* PlaceholderTable::get_entry(int index, unsigned int hash,+
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                                       Symbol* class_name,+
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                                       ClassLoaderData* loader_data) {+
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  assert_locked_or_safepoint(SystemDictionary_lock);+
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+
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  for (PlaceholderEntry *place_probe = bucket(index);+
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                         place_probe != NULL;+
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                         place_probe = place_probe->next()) {+
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    if (place_probe->hash() == hash &&+
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        place_probe->equals(class_name, loader_data)) {+
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      return place_probe;+
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    }+
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  }+
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  return NULL;+
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}+
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+
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Symbol* PlaceholderTable::find_entry(int index, unsigned int hash,+
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                                       Symbol* class_name,+
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                                       ClassLoaderData* loader_data) {+
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  PlaceholderEntry* probe = get_entry(index, hash, class_name, loader_data);+
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  return (probe? probe->klassname(): (Symbol*)NULL);+
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}+
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+
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  // find_and_add returns probe pointer - old or new+
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  // If no entry exists, add a placeholder entry+
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  // If entry exists, reuse entry+
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  // For both, push SeenThread for classloadAction+
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  // if havesupername: this is used for circularity for instanceklass loading+
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PlaceholderEntry* PlaceholderTable::find_and_add(int index, unsigned int hash,+
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                                                 Symbol* name,+
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                                                 ClassLoaderData* loader_data,+
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                                                 classloadAction action,+
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                                                 Symbol* supername,+
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                                                 Thread* thread) {+
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  PlaceholderEntry* probe = get_entry(index, hash, name, loader_data);+
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  if (probe == NULL) {+
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    // Nothing found, add place holder+
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    add_entry(index, hash, name, loader_data, (action == LOAD_SUPER), supername);+
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    probe = get_entry(index, hash, name, loader_data);+
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  } else {+
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    if (action == LOAD_SUPER) {+
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      probe->set_havesupername(true);+
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      probe->set_supername(supername);+
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    }+
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  }+
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  if (probe) probe->add_seen_thread(thread, action);+
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  return probe;+
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}+
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+
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+
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// placeholder is used to track class loading internal states+
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// placeholder existence now for loading superclass/superinterface+
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// superthreadQ tracks class circularity, while loading superclass/superinterface+
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// loadInstanceThreadQ tracks load_instance_class calls+
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// definer() tracks the single thread that owns define token+
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// defineThreadQ tracks waiters on defining thread's results+
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// 1st claimant creates placeholder+
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// find_and_add adds SeenThread entry for appropriate queue+
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// All claimants remove SeenThread after completing action+
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// On removal: if definer and all queues empty, remove entry+
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// Note: you can be in both placeholders and systemDictionary+
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// Therefore - must always check SD first+
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// Ignores the case where entry is not found+
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void PlaceholderTable::find_and_remove(int index, unsigned int hash,+
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                                       Symbol* name, ClassLoaderData* loader_data,+
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                                       classloadAction action,+
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                                       Thread* thread) {+
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    assert_locked_or_safepoint(SystemDictionary_lock);+
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    PlaceholderEntry *probe = get_entry(index, hash, name, loader_data);+
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    if (probe != NULL) {+
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       probe->remove_seen_thread(thread, action);+
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       // If no other threads using this entry, and this thread is not using this entry for other states+
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       if ((probe->superThreadQ() == NULL) && (probe->loadInstanceThreadQ() == NULL)+
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          && (probe->defineThreadQ() == NULL) && (probe->definer() == NULL)) {+
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         remove_entry(index, hash, name, loader_data);+
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       }+
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    }+
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  }+
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+
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PlaceholderTable::PlaceholderTable(int table_size)+
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    : Hashtable<Symbol*, mtClass>(table_size, sizeof(PlaceholderEntry)) {+
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}+
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+
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void PlaceholderEntry::verify() const {+
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  guarantee(loader_data() != NULL, "Must have been setup.");+
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  guarantee(loader_data()->class_loader() == NULL || loader_data()->class_loader()->is_instance(),+
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            "checking type of _loader");+
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  guarantee(instance_klass() == NULL+
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            || instance_klass()->is_instance_klass(),+
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            "checking type of instance_klass result");+
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}+
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+
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void PlaceholderTable::verify() {+
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  verify_table<PlaceholderEntry>("Placeholder Table");+
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}+
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+
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+
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// Note, doesn't append a cr+
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// Can't call this print_on because HashtableEntry doesn't initialize its vptr+
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// and print_on is a virtual function so the vptr call crashes.+
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void PlaceholderEntry::print_entry(outputStream* st) const {+
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  klassname()->print_value_on(st);+
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  if (loader_data() != NULL) {+
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    st->print(", loader ");+
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    loader_data()->print_value_on(st);+
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  }+
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  if (supername() != NULL) {+
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    st->print(", supername ");+
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    supername()->print_value_on(st);+
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  }+
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  if (definer() != NULL) {+
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    st->print(", definer ");+
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    definer()->print_value_on(st);+
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  }+
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  if (instance_klass() != NULL) {+
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    st->print(", InstanceKlass ");+
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    instance_klass()->print_value_on(st);+
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  }+
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  st->cr();+
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  st->print("loadInstanceThreadQ threads:");+
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  loadInstanceThreadQ()->print_action_queue(st);+
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  st->cr();+
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  st->print("superThreadQ threads:");+
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  superThreadQ()->print_action_queue(st);+
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  st->cr();+
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  st->print("defineThreadQ threads:");+
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  defineThreadQ()->print_action_queue(st);+
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  st->cr();+
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}+
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+
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void PlaceholderTable::print_on(outputStream* st) const {+
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  st->print_cr("Placeholder table (table_size=%d, placeholders=%d)",+
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                table_size(), number_of_entries());+
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  for (int pindex = 0; pindex < table_size(); pindex++) {+
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    for (PlaceholderEntry* probe = bucket(pindex);+
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                           probe != NULL;+
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                           probe = probe->next()) {+
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      st->print("%4d: placeholder ", pindex);+
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      probe->print_entry(st);+
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    }+
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  }+
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}+
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