view hotspot/src/share/vm/classfile/dictionary.cpp @ 46729:c62d2e8b2728

7133093: Improve system dictionary performance Summary: implement one dictionary per ClassLoaderData for faster lookup and removal during class unloading Reviewed-by: iklam, acorn, jiangli
author coleenp
date Fri, 28 Jul 2017 10:48:35 -0400
parents f559541c0daa
children 24ec8a039c90
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/*
 * Copyright (c) 2003, 2017, 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/classLoaderData.inline.hpp"
#include "classfile/sharedClassUtil.hpp"
#include "classfile/dictionary.hpp"
#include "classfile/protectionDomainCache.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/systemDictionaryShared.hpp"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/iterator.hpp"
#include "memory/resourceArea.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/atomic.hpp"
#include "runtime/orderAccess.inline.hpp"
#include "utilities/hashtable.inline.hpp"

size_t Dictionary::entry_size() {
  if (DumpSharedSpaces) {
    return SystemDictionaryShared::dictionary_entry_size();
  } else {
    return sizeof(DictionaryEntry);
  }
}

Dictionary::Dictionary(ClassLoaderData* loader_data, int table_size)
  : _loader_data(loader_data), Hashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size()) {
};


Dictionary::Dictionary(ClassLoaderData* loader_data,
                       int table_size, HashtableBucket<mtClass>* t,
                       int number_of_entries)
  : _loader_data(loader_data), Hashtable<InstanceKlass*, mtClass>(table_size, (int)entry_size(), t, number_of_entries) {
};

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");
  free_buckets();
}

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");
  if (DumpSharedSpaces) {
    SystemDictionaryShared::init_shared_dictionary_entry(klass, entry);
  }
  return entry;
}


void Dictionary::free_entry(DictionaryEntry* entry) {
  // avoid recursion when deleting linked list
  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);
}


bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
#ifdef ASSERT
  if (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;
                                current != NULL;
                                current = current->next()) {
      if (current->protection_domain() == 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 (protection_domain == instance_klass()->protection_domain()) {
    // Succeeds trivially
    return true;
  }

  for (ProtectionDomainEntry* current = _pd_set;
                              current != NULL;
                              current = current->next()) {
    if (current->protection_domain() == 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.
    OrderAccess::release_store_ptr(&_pd_set, new_head);
  }
  LogTarget(Trace, protectiondomain) lt;
  if (lt.is_enabled()) {
    LogStream ls(lt);
    print_count(&ls);
  }
}


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;
      }
      p = probe->next_addr();
    }
  }
}

void Dictionary::remove_classes_in_error_state() {
  assert(DumpSharedSpaces, "supported only when dumping");
  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();
      if (ik->is_in_error_state()) { // purge this entry
        *p = probe->next();
        free_entry(probe);
        ResourceMark rm;
        tty->print_cr("Preload Warning: Removed error class: %s", ik->external_name());
        continue;
      }

      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(void f(InstanceKlass*, ClassLoaderData*)) {
  for (int index = 0; index < table_size(); index++) {
    for (DictionaryEntry* probe = bucket(index);
                          probe != NULL;
                          probe = probe->next()) {
      InstanceKlass* k = probe->instance_klass();
      f(k, loader_data());
    }
  }
}


// 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(int index, 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);
  add_entry(index, entry);
}


// 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)) {
      if (!DumpSharedSpaces || SystemDictionaryShared::is_builtin(entry)) {
        return entry;
      }
    }
  }
  return NULL;
}


InstanceKlass* Dictionary::find(int index, unsigned int hash, Symbol* name,
                                Handle protection_domain) {
  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;
}


// Variant of find_class for shared classes.  No locking required, as
// that table is static.

InstanceKlass* Dictionary::find_shared_class(int index, unsigned int hash,
                                             Symbol* name) {
  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);

  assert(entry->contains_protection_domain(protection_domain()),
         "now protection domain should be present");
}


bool Dictionary::is_valid_protection_domain(int index, unsigned int hash,
                                            Symbol* name,
                                            Handle protection_domain) {
  DictionaryEntry* entry = get_entry(index, hash, name);
  return entry->is_valid_protection_domain(protection_domain);
}


void Dictionary::reorder_dictionary() {

  // Copy all the dictionary entries into a single master list.

  DictionaryEntry* master_list = NULL;
  for (int i = 0; i < table_size(); ++i) {
    DictionaryEntry* p = bucket(i);
    while (p != NULL) {
      DictionaryEntry* tmp;
      tmp = p->next();
      p->set_next(master_list);
      master_list = p;
      p = tmp;
    }
    set_entry(i, NULL);
  }

  // Add the dictionary entries back to the list in the correct buckets.
  while (master_list != NULL) {
    DictionaryEntry* p = master_list;
    master_list = master_list->next();
    p->set_next(NULL);
    Symbol* class_name = p->instance_klass()->name();
    // Since the null class loader data isn't copied to the CDS archive,
    // compute the hash with NULL for loader data.
    unsigned int hash = compute_hash(class_name);
    int index = hash_to_index(hash);
    p->set_hash(hash);
    p->set_next(bucket(index));
    set_entry(index, p);
  }
}


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(bool details) {
  ResourceMark rm;

  assert(loader_data() != NULL, "loader data should not be null");
  if (details) {
    tty->print_cr("Java dictionary (table_size=%d, classes=%d)",
                   table_size(), number_of_entries());
    tty->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());
      if (details) {
        tty->print("%4d: ", index);
      }
      tty->print("%s%s", ((!details) || is_defining_class) ? " " : "^",
                 e->external_name());

      if (details) {
        tty->print(", loader ");
        e->class_loader_data()->print_value();
      }
      tty->cr();
    }
  }
  tty->cr();
}

void DictionaryEntry::verify() {
  Klass* e = instance_klass();
  guarantee(e->is_instance_klass(),
                          "Verify of dictionary failed");
  e->verify();
  verify_protection_domain_set();
}

void Dictionary::verify() {
  guarantee(number_of_entries() >= 0, "Verify of dictionary failed");

  ClassLoaderData* cld = loader_data();
  // class loader must be present;  a null class loader is the
  // boostrap loader
  guarantee(cld != NULL || DumpSharedSpaces ||
            cld->class_loader() == NULL ||
            cld->class_loader()->is_instance(),
            "checking type of class_loader");

  ResourceMark rm;
  stringStream tempst;
  tempst.print("System Dictionary for %s", cld->loader_name());
  verify_table<DictionaryEntry>(tempst.as_string());
}