duke@435: /*
acorn@4425:  * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #include "precompiled.hpp"
stefank@2314: #include "classfile/placeholders.hpp"
stefank@2314: #include "classfile/systemDictionary.hpp"
stefank@2314: #include "oops/oop.inline.hpp"
stefank@2314: #include "runtime/fieldType.hpp"
stefank@2314: #include "utilities/hashtable.inline.hpp"
duke@435: 
duke@435: // Placeholder methods
duke@435: 
coleenp@2497: PlaceholderEntry* PlaceholderTable::new_entry(int hash, Symbol* name,
coleenp@4037:                                               ClassLoaderData* loader_data,
coleenp@4037:                                               bool havesupername,
coleenp@2497:                                               Symbol* supername) {
zgu@3900:   PlaceholderEntry* entry = (PlaceholderEntry*)Hashtable<Symbol*, mtClass>::new_entry(hash, name);
coleenp@2497:   // Hashtable with Symbol* literal must increment and decrement refcount.
coleenp@2497:   name->increment_refcount();
coleenp@4037:   entry->set_loader_data(loader_data);
duke@435:   entry->set_havesupername(havesupername);
duke@435:   entry->set_supername(supername);
duke@435:   entry->set_superThreadQ(NULL);
duke@435:   entry->set_loadInstanceThreadQ(NULL);
duke@435:   entry->set_defineThreadQ(NULL);
duke@435:   entry->set_definer(NULL);
hseigel@4278:   entry->set_instance_klass(NULL);
duke@435:   return entry;
duke@435: }
duke@435: 
coleenp@2497: void PlaceholderTable::free_entry(PlaceholderEntry* entry) {
coleenp@2497:   // decrement Symbol refcount here because Hashtable doesn't.
coleenp@2497:   entry->literal()->decrement_refcount();
coleenp@2497:   if (entry->supername() != NULL) entry->supername()->decrement_refcount();
zgu@3900:   Hashtable<Symbol*, mtClass>::free_entry(entry);
coleenp@2497: }
coleenp@2497: 
duke@435: 
duke@435: // Placeholder objects represent classes currently being loaded.
duke@435: // All threads examining the placeholder table must hold the
duke@435: // SystemDictionary_lock, so we don't need special precautions
duke@435: // on store ordering here.
duke@435: void PlaceholderTable::add_entry(int index, unsigned int hash,
coleenp@4037:                                  Symbol* class_name, ClassLoaderData* loader_data,
coleenp@2497:                                  bool havesupername, Symbol* supername){
duke@435:   assert_locked_or_safepoint(SystemDictionary_lock);
coleenp@2497:   assert(class_name != NULL, "adding NULL obj");
duke@435: 
duke@435:   // Both readers and writers are locked so it's safe to just
duke@435:   // create the placeholder and insert it in the list without a membar.
coleenp@4037:   PlaceholderEntry* entry = new_entry(hash, class_name, loader_data, havesupername, supername);
duke@435:   add_entry(index, entry);
duke@435: }
duke@435: 
duke@435: 
duke@435: // Remove a placeholder object.
duke@435: void PlaceholderTable::remove_entry(int index, unsigned int hash,
coleenp@2497:                                     Symbol* class_name,
coleenp@4037:                                     ClassLoaderData* loader_data) {
duke@435:   assert_locked_or_safepoint(SystemDictionary_lock);
duke@435:   PlaceholderEntry** p = bucket_addr(index);
duke@435:   while (*p) {
duke@435:     PlaceholderEntry *probe = *p;
coleenp@4037:     if (probe->hash() == hash && probe->equals(class_name, loader_data)) {
duke@435:       // Delete entry
duke@435:       *p = probe->next();
duke@435:       free_entry(probe);
duke@435:       return;
duke@435:     }
duke@435:     p = probe->next_addr();
duke@435:   }
duke@435: }
duke@435: 
duke@435: PlaceholderEntry* PlaceholderTable::get_entry(int index, unsigned int hash,
coleenp@2497:                                        Symbol* class_name,
coleenp@4037:                                        ClassLoaderData* loader_data) {
duke@435:   assert_locked_or_safepoint(SystemDictionary_lock);
duke@435: 
duke@435:   for (PlaceholderEntry *place_probe = bucket(index);
duke@435:                          place_probe != NULL;
duke@435:                          place_probe = place_probe->next()) {
duke@435:     if (place_probe->hash() == hash &&
coleenp@4037:         place_probe->equals(class_name, loader_data)) {
duke@435:       return place_probe;
duke@435:     }
duke@435:   }
duke@435:   return NULL;
duke@435: }
duke@435: 
coleenp@2497: Symbol* PlaceholderTable::find_entry(int index, unsigned int hash,
coleenp@2497:                                        Symbol* class_name,
coleenp@4037:                                        ClassLoaderData* loader_data) {
coleenp@4037:   PlaceholderEntry* probe = get_entry(index, hash, class_name, loader_data);
coleenp@2497:   return (probe? probe->klassname(): (Symbol*)NULL);
duke@435: }
duke@435: 
duke@435:   // find_and_add returns probe pointer - old or new
duke@435:   // If no entry exists, add a placeholder entry
duke@435:   // If entry exists, reuse entry
duke@435:   // For both, push SeenThread for classloadAction
duke@435:   // if havesupername: this is used for circularity for instanceklass loading
coleenp@4037: PlaceholderEntry* PlaceholderTable::find_and_add(int index, unsigned int hash,
coleenp@4037:                                                  Symbol* name,
coleenp@4037:                                                  ClassLoaderData* loader_data,
coleenp@4037:                                                  classloadAction action,
coleenp@4037:                                                  Symbol* supername,
coleenp@4037:                                                  Thread* thread) {
coleenp@4037:   PlaceholderEntry* probe = get_entry(index, hash, name, loader_data);
duke@435:   if (probe == NULL) {
duke@435:     // Nothing found, add place holder
coleenp@4037:     add_entry(index, hash, name, loader_data, (action == LOAD_SUPER), supername);
coleenp@4037:     probe = get_entry(index, hash, name, loader_data);
duke@435:   } else {
duke@435:     if (action == LOAD_SUPER) {
duke@435:       probe->set_havesupername(true);
coleenp@2497:       probe->set_supername(supername);
duke@435:     }
duke@435:   }
duke@435:   if (probe) probe->add_seen_thread(thread, action);
duke@435:   return probe;
duke@435: }
duke@435: 
duke@435: 
acorn@4425: // placeholder is used to track class loading internal states
duke@435: // placeholder existence now for loading superclass/superinterface
duke@435: // superthreadQ tracks class circularity, while loading superclass/superinterface
duke@435: // loadInstanceThreadQ tracks load_instance_class calls
duke@435: // definer() tracks the single thread that owns define token
duke@435: // defineThreadQ tracks waiters on defining thread's results
duke@435: // 1st claimant creates placeholder
duke@435: // find_and_add adds SeenThread entry for appropriate queue
duke@435: // All claimants remove SeenThread after completing action
duke@435: // On removal: if definer and all queues empty, remove entry
duke@435: // Note: you can be in both placeholders and systemDictionary
duke@435: // Therefore - must always check SD first
duke@435: // Ignores the case where entry is not found
duke@435: void PlaceholderTable::find_and_remove(int index, unsigned int hash,
acorn@4425:                                        Symbol* name, ClassLoaderData* loader_data,
acorn@4425:                                        classloadAction action,
acorn@4425:                                        Thread* thread) {
duke@435:     assert_locked_or_safepoint(SystemDictionary_lock);
coleenp@4037:     PlaceholderEntry *probe = get_entry(index, hash, name, loader_data);
duke@435:     if (probe != NULL) {
acorn@4425:        probe->remove_seen_thread(thread, action);
acorn@4425:        // If no other threads using this entry, and this thread is not using this entry for other states
duke@435:        if ((probe->superThreadQ() == NULL) && (probe->loadInstanceThreadQ() == NULL)
duke@435:           && (probe->defineThreadQ() == NULL) && (probe->definer() == NULL)) {
coleenp@4037:          remove_entry(index, hash, name, loader_data);
duke@435:        }
duke@435:     }
duke@435:   }
duke@435: 
duke@435: PlaceholderTable::PlaceholderTable(int table_size)
zgu@3900:     : TwoOopHashtable<Symbol*, mtClass>(table_size, sizeof(PlaceholderEntry)) {
duke@435: }
duke@435: 
duke@435: 
coleenp@4037: void PlaceholderTable::classes_do(KlassClosure* f) {
duke@435:   for (int index = 0; index < table_size(); index++) {
duke@435:     for (PlaceholderEntry* probe = bucket(index);
duke@435:                            probe != NULL;
duke@435:                            probe = probe->next()) {
coleenp@4037:       probe->classes_do(f);
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
coleenp@4037: void PlaceholderEntry::classes_do(KlassClosure* closure) {
coleenp@2497:   assert(klassname() != NULL, "should have a non-null klass");
duke@435:   if (_instanceKlass != NULL) {
hseigel@4278:     closure->do_klass(instance_klass());
duke@435:   }
duke@435: }
duke@435: 
duke@435: // do all entries in the placeholder table
coleenp@4037: void PlaceholderTable::entries_do(void f(Symbol*)) {
duke@435:   for (int index = 0; index < table_size(); index++) {
duke@435:     for (PlaceholderEntry* probe = bucket(index);
duke@435:                            probe != NULL;
duke@435:                            probe = probe->next()) {
coleenp@4037:       f(probe->klassname());
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: #ifndef PRODUCT
duke@435: // Note, doesn't append a cr
duke@435: void PlaceholderEntry::print() const {
coleenp@2497:   klassname()->print_value();
coleenp@4037:   if (loader_data() != NULL) {
duke@435:     tty->print(", loader ");
coleenp@4037:     loader_data()->print_value();
duke@435:   }
duke@435:   if (supername() != NULL) {
duke@435:     tty->print(", supername ");
duke@435:     supername()->print_value();
duke@435:   }
duke@435:   if (definer() != NULL) {
duke@435:     tty->print(", definer ");
duke@435:     definer()->print_value();
duke@435:   }
hseigel@4278:   if (instance_klass() != NULL) {
coleenp@4037:     tty->print(", InstanceKlass ");
hseigel@4278:     instance_klass()->print_value();
duke@435:   }
duke@435:   tty->print("\n");
duke@435:   tty->print("loadInstanceThreadQ threads:");
duke@435:   loadInstanceThreadQ()->printActionQ();
duke@435:   tty->print("\n");
duke@435:   tty->print("superThreadQ threads:");
duke@435:   superThreadQ()->printActionQ();
duke@435:   tty->print("\n");
duke@435:   tty->print("defineThreadQ threads:");
duke@435:   defineThreadQ()->printActionQ();
duke@435:   tty->print("\n");
duke@435: }
duke@435: #endif
duke@435: 
duke@435: void PlaceholderEntry::verify() const {
coleenp@4037:   guarantee(loader_data() != NULL, "Must have been setup.");
coleenp@4037:   guarantee(loader_data()->class_loader() == NULL || loader_data()->class_loader()->is_instance(),
duke@435:             "checking type of _loader");
hseigel@4278:   guarantee(instance_klass() == NULL
hseigel@4278:             || instance_klass()->oop_is_instance(),
hseigel@4278:             "checking type of instance_klass result");
duke@435: }
duke@435: 
duke@435: void PlaceholderTable::verify() {
duke@435:   int element_count = 0;
duke@435:   for (int pindex = 0; pindex < table_size(); pindex++) {
duke@435:     for (PlaceholderEntry* probe = bucket(pindex);
duke@435:                            probe != NULL;
duke@435:                            probe = probe->next()) {
duke@435:       probe->verify();
duke@435:       element_count++;  // both klasses and place holders count
duke@435:     }
duke@435:   }
duke@435:   guarantee(number_of_entries() == element_count,
duke@435:             "Verify of system dictionary failed");
duke@435: }
duke@435: 
duke@435: 
duke@435: #ifndef PRODUCT
duke@435: void PlaceholderTable::print() {
duke@435:   for (int pindex = 0; pindex < table_size(); pindex++) {
duke@435:     for (PlaceholderEntry* probe = bucket(pindex);
duke@435:                            probe != NULL;
duke@435:                            probe = probe->next()) {
duke@435:       if (Verbose) tty->print("%4d: ", pindex);
duke@435:       tty->print(" place holder ");
duke@435: 
duke@435:       probe->print();
duke@435:       tty->cr();
duke@435:     }
duke@435:   }
duke@435: }
duke@435: #endif