Mercurial > hg > truffle
view src/share/vm/classfile/placeholders.cpp @ 4974:ab906cea36f7
First round of minimizing diff vs OpenJDK.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Mon, 27 Feb 2012 15:15:59 +0100 |
parents | 1d1603768966 |
children | d2a62e0f25eb |
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/* * Copyright (c) 2003, 2011, 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. * */ #include "precompiled.hpp" #include "classfile/placeholders.hpp" #include "classfile/systemDictionary.hpp" #include "oops/oop.inline.hpp" #include "runtime/fieldType.hpp" #include "utilities/hashtable.inline.hpp" // Placeholder methods PlaceholderEntry* PlaceholderTable::new_entry(int hash, Symbol* name, oop loader, bool havesupername, Symbol* supername) { PlaceholderEntry* entry = (PlaceholderEntry*)Hashtable<Symbol*>::new_entry(hash, name); // Hashtable with Symbol* literal must increment and decrement refcount. name->increment_refcount(); entry->set_loader(loader); entry->set_havesupername(havesupername); entry->set_supername(supername); entry->set_superThreadQ(NULL); entry->set_loadInstanceThreadQ(NULL); entry->set_defineThreadQ(NULL); entry->set_definer(NULL); entry->set_instanceKlass(NULL); return entry; } void PlaceholderTable::free_entry(PlaceholderEntry* entry) { // decrement Symbol refcount here because Hashtable doesn't. entry->literal()->decrement_refcount(); if (entry->supername() != NULL) entry->supername()->decrement_refcount(); Hashtable<Symbol*>::free_entry(entry); } // Placeholder objects represent classes currently being loaded. // All threads examining the placeholder table must hold the // SystemDictionary_lock, so we don't need special precautions // on store ordering here. void PlaceholderTable::add_entry(int index, unsigned int hash, Symbol* class_name, Handle class_loader, bool havesupername, Symbol* supername){ assert_locked_or_safepoint(SystemDictionary_lock); assert(class_name != NULL, "adding NULL obj"); // Both readers and writers are locked so it's safe to just // create the placeholder and insert it in the list without a membar. PlaceholderEntry* entry = new_entry(hash, class_name, class_loader(), havesupername, supername); add_entry(index, entry); } // Remove a placeholder object. void PlaceholderTable::remove_entry(int index, unsigned int hash, Symbol* class_name, Handle class_loader) { assert_locked_or_safepoint(SystemDictionary_lock); PlaceholderEntry** p = bucket_addr(index); while (*p) { PlaceholderEntry *probe = *p; if (probe->hash() == hash && probe->equals(class_name, class_loader())) { // Delete entry *p = probe->next(); free_entry(probe); return; } p = probe->next_addr(); } } PlaceholderEntry* PlaceholderTable::get_entry(int index, unsigned int hash, Symbol* class_name, Handle class_loader) { assert_locked_or_safepoint(SystemDictionary_lock); oop class_loader_ = class_loader(); for (PlaceholderEntry *place_probe = bucket(index); place_probe != NULL; place_probe = place_probe->next()) { if (place_probe->hash() == hash && place_probe->equals(class_name, class_loader_)) { return place_probe; } } return NULL; } Symbol* PlaceholderTable::find_entry(int index, unsigned int hash, Symbol* class_name, Handle class_loader) { PlaceholderEntry* probe = get_entry(index, hash, class_name, class_loader); return (probe? probe->klassname(): (Symbol*)NULL); } // find_and_add returns probe pointer - old or new // If no entry exists, add a placeholder entry // If entry exists, reuse entry // For both, push SeenThread for classloadAction // if havesupername: this is used for circularity for instanceklass loading PlaceholderEntry* PlaceholderTable::find_and_add(int index, unsigned int hash, Symbol* name, Handle loader, classloadAction action, Symbol* supername, Thread* thread) { PlaceholderEntry* probe = get_entry(index, hash, name, loader); if (probe == NULL) { // Nothing found, add place holder add_entry(index, hash, name, loader, (action == LOAD_SUPER), supername); probe = get_entry(index, hash, name, loader); } else { if (action == LOAD_SUPER) { probe->set_havesupername(true); probe->set_supername(supername); } } if (probe) probe->add_seen_thread(thread, action); return probe; } // placeholder used to track class loading internal states // placeholder existence now for loading superclass/superinterface // superthreadQ tracks class circularity, while loading superclass/superinterface // loadInstanceThreadQ tracks load_instance_class calls // definer() tracks the single thread that owns define token // defineThreadQ tracks waiters on defining thread's results // 1st claimant creates placeholder // find_and_add adds SeenThread entry for appropriate queue // All claimants remove SeenThread after completing action // On removal: if definer and all queues empty, remove entry // Note: you can be in both placeholders and systemDictionary // see parse_stream for redefine classes // Therefore - must always check SD first // Ignores the case where entry is not found void PlaceholderTable::find_and_remove(int index, unsigned int hash, Symbol* name, Handle loader, Thread* thread) { assert_locked_or_safepoint(SystemDictionary_lock); PlaceholderEntry *probe = get_entry(index, hash, name, loader); if (probe != NULL) { // No other threads using this entry if ((probe->superThreadQ() == NULL) && (probe->loadInstanceThreadQ() == NULL) && (probe->defineThreadQ() == NULL) && (probe->definer() == NULL)) { remove_entry(index, hash, name, loader); } } } PlaceholderTable::PlaceholderTable(int table_size) : TwoOopHashtable<Symbol*>(table_size, sizeof(PlaceholderEntry)) { } void PlaceholderTable::oops_do(OopClosure* f) { for (int index = 0; index < table_size(); index++) { for (PlaceholderEntry* probe = bucket(index); probe != NULL; probe = probe->next()) { probe->oops_do(f); } } } void PlaceholderEntry::oops_do(OopClosure* blk) { assert(klassname() != NULL, "should have a non-null klass"); if (_loader != NULL) { blk->do_oop(loader_addr()); } if (_instanceKlass != NULL) { blk->do_oop((oop*)instanceKlass_addr()); } } // do all entries in the placeholder table void PlaceholderTable::entries_do(void f(Symbol*, oop)) { for (int index = 0; index < table_size(); index++) { for (PlaceholderEntry* probe = bucket(index); probe != NULL; probe = probe->next()) { f(probe->klassname(), probe->loader()); } } } #ifndef PRODUCT // Note, doesn't append a cr void PlaceholderEntry::print() const { klassname()->print_value(); if (loader() != NULL) { tty->print(", loader "); loader()->print_value(); } if (supername() != NULL) { tty->print(", supername "); supername()->print_value(); } if (definer() != NULL) { tty->print(", definer "); definer()->print_value(); } if (instanceKlass() != NULL) { tty->print(", instanceKlass "); instanceKlass()->print_value(); } tty->print("\n"); tty->print("loadInstanceThreadQ threads:"); loadInstanceThreadQ()->printActionQ(); tty->print("\n"); tty->print("superThreadQ threads:"); superThreadQ()->printActionQ(); tty->print("\n"); tty->print("defineThreadQ threads:"); defineThreadQ()->printActionQ(); tty->print("\n"); } #endif void PlaceholderEntry::verify() const { guarantee(loader() == NULL || loader()->is_instance(), "checking type of _loader"); guarantee(instanceKlass() == NULL || Klass::cast(instanceKlass())->oop_is_instance(), "checking type of instanceKlass result"); } void PlaceholderTable::verify() { int element_count = 0; for (int pindex = 0; pindex < table_size(); pindex++) { for (PlaceholderEntry* probe = bucket(pindex); probe != NULL; probe = probe->next()) { probe->verify(); element_count++; // both klasses and place holders count } } guarantee(number_of_entries() == element_count, "Verify of system dictionary failed"); } #ifndef PRODUCT void PlaceholderTable::print() { for (int pindex = 0; pindex < table_size(); pindex++) { for (PlaceholderEntry* probe = bucket(pindex); probe != NULL; probe = probe->next()) { if (Verbose) tty->print("%4d: ", pindex); tty->print(" place holder "); probe->print(); tty->cr(); } } } #endif