Quellcode-Bibliothek

^© Kompilation durch diese Firma

[Weder Korrektheit noch Funktionsfähigkeit der Software werden zugesichert.]

Datei: dictionary.cpp Sprache: C

/*
* Copyright (c) 2003, 2022, 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/dictionary.hpp"
#include "classfile/javaClasses.hpp"
#include "classfile/protectionDomainCache.hpp"
#include "classfile/systemDictionary.hpp"
#include "classfile/vmSymbols.hpp"
#include "logging/log.hpp"
#include "logging/logStream.hpp"
#include "memory/iterator.hpp"
#include "memory/metaspaceClosure.hpp"
#include "memory/resourceArea.hpp"
#include "memory/universe.hpp"
#include "oops/klass.inline.hpp"
#include "oops/method.hpp"
#include "oops/oop.inline.hpp"
#include "oops/oopHandle.inline.hpp"
#include "runtime/arguments.hpp"
#include "runtime/handles.inline.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/safepointVerifiers.hpp"
#include "utilities/concurrentHashTable.inline.hpp"
#include "utilities/growableArray.hpp"
#include "utilities/tableStatistics.hpp"

// 2^24 is max size, like StringTable.
const size_t END_SIZE = 24;
// If a chain gets to 100 something might be wrong
const size_t REHASH_LEN = 100;

Dictionary::Dictionary(ClassLoaderData* loader_data, size_t table_size)
  : _number_of_entries(0), _loader_data(loader_data) {

  size_t start_size_log_2 = MAX2(ceil_log2(table_size), (size_t)2); // 2 is minimum size even though some dictionaries only have one entry
  size_t current_size = ((size_t)1) << start_size_log_2;
  log_info(class, loader, data)("Dictionary start size: " SIZE_FORMAT " (" SIZE_FORMAT ")",
                                current_size, start_size_log_2);
  _table = new ConcurrentTable(start_size_log_2, END_SIZE, REHASH_LEN);
}

Dictionary::~Dictionary() {
  // This deletes the table and all the nodes, by calling free_node in Config.
  delete _table;
}

uintx Dictionary::Config::get_hash(Value const& value, bool* is_dead) {
  return value->instance_klass()->name()->identity_hash();
}

void* Dictionary::Config::allocate_node(void* context, size_t size, Value const& value) {
  return AllocateHeap(size, mtClass);
}

void Dictionary::Config::free_node(void* context, void* memory, Value const& value) {
  delete value; // Call DictionaryEntry destructor
  FreeHeap(memory);
}

DictionaryEntry::DictionaryEntry(InstanceKlass* klass) : _instance_klass(klass) {
  release_set_pd_set(nullptr);
}

DictionaryEntry::~DictionaryEntry() {
  // avoid recursion when deleting linked list
  // pd_set is accessed during a safepoint.
  // This doesn't require a lock because nothing is reading this
  // entry anymore.  The ClassLoader is dead.
  while (pd_set_acquire() != NULL) {
    ProtectionDomainEntry* to_delete = pd_set_acquire();
    release_set_pd_set(to_delete->next_acquire());
    delete to_delete;
  }
}

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

int Dictionary::table_size() const {
  return 1 << _table->get_size_log2(Thread::current());
}

bool Dictionary::check_if_needs_resize() {
  return ((_number_of_entries > (_resize_load_trigger * table_size())) &&
         !_table->is_max_size_reached());
}

bool DictionaryEntry::is_valid_protection_domain(Handle protection_domain) {

  return protection_domain() == NULL || !java_lang_System::allow_security_manager()
        ? true
        : contains_protection_domain(protection_domain());
}

// Reading the pd_set on each DictionaryEntry is lock free and cannot safepoint.
// Adding and deleting entries is under the SystemDictionary_lock
// Deleting unloaded entries on ClassLoaderData for dictionaries that are not unloaded
// is a three step process:
//     moving the entries to a separate list, handshake to wait for
//     readers to complete (see NSV here), and then actually deleting the entries.
// Deleting entries is done by the ServiceThread when triggered by class unloading.

bool DictionaryEntry::contains_protection_domain(oop protection_domain) const {
  assert(Thread::current()->is_Java_thread() || SafepointSynchronize::is_at_safepoint(),
         "can only be called by a JavaThread or at safepoint");
  // This cannot safepoint while reading the protection domain set.
  NoSafepointVerifier nsv;
#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_acquire();
                                current != NULL;
                                current = current->next_acquire()) {
      if (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 (protection_domain == instance_klass()->protection_domain()) {
    // Succeeds trivially
    return true;
  }

  for (ProtectionDomainEntry* current = pd_set_acquire();
                              current != NULL;
                              current = current->next_acquire()) {
    if (current->object_no_keepalive() == protection_domain) {
      return true;
    }
  }
  return false;
}

void DictionaryEntry::add_protection_domain(ClassLoaderData* loader_data, Handle protection_domain) {
  assert_lock_strong(SystemDictionary_lock);
  if (!contains_protection_domain(protection_domain())) {
    WeakHandle obj = ProtectionDomainCacheTable::add_if_absent(protection_domain);
    // Additions and deletions hold the SystemDictionary_lock, readers are lock-free
    ProtectionDomainEntry* new_head = new ProtectionDomainEntry(obj, _pd_set);
    release_set_pd_set(new_head);
  }
  LogTarget(Trace, protectiondomain) lt;
  if (lt.is_enabled()) {
    ResourceMark rm;
    LogStream ls(lt);
    ls.print("adding protection domain for class %s", instance_klass()->name()->as_C_string());
    ls.print(" class loader: ");
    loader_data->class_loader()->print_value_on(&ls);
    ls.print(" protection domain: ");
    protection_domain->print_value_on(&ls);
    ls.print(" ");
    print_count(&ls);
    ls.cr();
  }
}

//   Just the classes from defining class loaders
void Dictionary::classes_do(void f(InstanceKlass*)) {
  auto doit = [&] (DictionaryEntry** value) {
    InstanceKlass* k = (*value)->instance_klass();
    if (loader_data() == k->class_loader_data()) {
      f(k);
    }
    return true;
  };

  _table->do_scan(Thread::current(), doit);
}

// All classes, and their class loaders, including initiating class loaders
void Dictionary::all_entries_do(KlassClosure* closure) {
  auto all_doit = [&] (DictionaryEntry** value) {
    InstanceKlass* k = (*value)->instance_klass();
    closure->do_klass(k);
    return true;
  };

  _table->do_scan(Thread::current(), all_doit);
}

// Used to scan and relocate the classes during CDS archive dump.
void Dictionary::classes_do(MetaspaceClosure* it) {
  Arguments::assert_is_dumping_archive();

  auto push = [&] (DictionaryEntry** value) {
    InstanceKlass** k = (*value)->instance_klass_addr();
    it->push(k);
    return true;
  };
  _table->do_scan(Thread::current(), push);
}

class DictionaryLookup : StackObj {
private:
  Symbol* _name;
public:
  DictionaryLookup(Symbol* name) : _name(name) { }
  uintx get_hash() const {
    return _name->identity_hash();
  }
  bool equals(DictionaryEntry** value, bool* is_dead) {
    DictionaryEntry *entry = *value;
    *is_dead = false;
    return (entry->instance_klass()->name() == _name);
  }
};

// Add a loaded class to the dictionary.
void Dictionary::add_klass(JavaThread* current, Symbol* class_name,
                           InstanceKlass* obj) {
  assert_locked_or_safepoint(SystemDictionary_lock); // doesn't matter now
  assert(obj != NULL, "adding NULL obj");
  assert(obj->name() == class_name, "sanity check on name");

  DictionaryEntry* entry = new DictionaryEntry(obj);
  DictionaryLookup lookup(class_name);
  bool needs_rehashing, clean_hint;
  bool created = _table->insert(current, lookup, entry, &needs_rehashing, &clean_hint);
  assert(created, "should be because we have a lock");
  assert (!needs_rehashing, "should never need rehashing");
  assert(!clean_hint, "no class should be unloaded");
  _number_of_entries++;  // still locked
  // This table can be resized while another thread is reading it.
  if (check_if_needs_resize()) {
    _table->grow(current);

    // It would be nice to have a JFR event here, add some logging.
    LogTarget(Info, class, loader, data) lt;
    if (lt.is_enabled()) {
      ResourceMark rm;
      LogStream ls(<);
      ls.print("Dictionary resized to %d entries %d for ", table_size(), _number_of_entries);
      loader_data()->print_value_on(&ls);
    }
  }
}

// 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
// the table is read here, so the caller will not see the new entry.
// The entry may be accessed by the VM thread in verification.
DictionaryEntry* Dictionary::get_entry(Thread* current,
                                       Symbol* class_name) {
  DictionaryLookup lookup(class_name);
  DictionaryEntry* result = nullptr;
  auto get = [&] (DictionaryEntry** value) {
    // function called if value is found so is never null
    result = (*value);
  };
  bool needs_rehashing = false;
  _table->get(current, lookup, get, &needs_rehashing);
  assert (!needs_rehashing, "should never need rehashing");
  return result;
}

InstanceKlass* Dictionary::find(Thread* current, Symbol* name,
                                Handle protection_domain) {
  NoSafepointVerifier nsv;

  DictionaryEntry* entry = get_entry(current, name);
  if (entry != NULL && entry->is_valid_protection_domain(protection_domain)) {
    return entry->instance_klass();
  } else {
    return NULL;
  }
}

InstanceKlass* Dictionary::find_class(Thread* current,
                                      Symbol* name) {
  assert_locked_or_safepoint(SystemDictionary_lock);
  DictionaryEntry* entry = get_entry(current, name);
  return (entry != NULL) ? entry->instance_klass() : NULL;
}

void Dictionary::add_protection_domain(JavaThread* current,
                                       InstanceKlass* klass,
                                       Handle protection_domain) {
  assert(java_lang_System::allow_security_manager(), "only needed if security manager allowed");
  Symbol*  klass_name = klass->name();
  DictionaryEntry* entry = get_entry(current, 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(loader_data(), 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");
}

inline bool Dictionary::is_valid_protection_domain(JavaThread* current,
                                            Symbol* name,
                                            Handle protection_domain) {
  DictionaryEntry* entry = get_entry(current, name);
  return entry->is_valid_protection_domain(protection_domain);
}

void Dictionary::validate_protection_domain(InstanceKlass* klass,
                                            Handle class_loader,
                                            Handle protection_domain,
                                            TRAPS) {

  assert(class_loader() != NULL, "Should not call this");
  assert(protection_domain() != NULL, "Should not call this");

  if (!java_lang_System::allow_security_manager() ||
      is_valid_protection_domain(THREAD, klass->name(), protection_domain)) {
    return;
  }

  // We only have to call checkPackageAccess if there's a security manager installed.
  if (java_lang_System::has_security_manager()) {

    // This handle and the class_loader handle passed in keeps this class from
    // being unloaded through several GC points.
    // The class_loader handle passed in is the initiating loader.
    Handle mirror(THREAD, klass->java_mirror());

    // Now we have to call back to java to check if the initating class has access
    InstanceKlass* system_loader = vmClasses::ClassLoader_klass();
    JavaValue result(T_VOID);
    JavaCalls::call_special(&result,
                           class_loader,
                           system_loader,
                           vmSymbols::checkPackageAccess_name(),
                           vmSymbols::class_protectiondomain_signature(),
                           mirror,
                           protection_domain,
                           THREAD);

    LogTarget(Debug, protectiondomain) lt;
    if (lt.is_enabled()) {
      ResourceMark rm(THREAD);
      // Print out trace information
      LogStream ls(lt);
      ls.print_cr("Checking package access");
      ls.print("class loader: ");
      class_loader()->print_value_on(&ls);
      ls.print(" protection domain: ");
      protection_domain()->print_value_on(&ls);
      ls.print(" loading: "); klass->print_value_on(&ls);
      if (HAS_PENDING_EXCEPTION) {
        ls.print_cr(" DENIED !!!!!!!!!!!!!!!!!!!!!");
      } else {
        ls.print_cr(" granted");
      }
    }

    if (HAS_PENDING_EXCEPTION) return;
  }

  // If no exception has been thrown, we have validated the protection domain
  // Insert the protection domain of the initiating class into the set.
  // We still have to add the protection_domain to the dictionary in case a new
  // security manager is installed later. Calls to load the same class with class loader
  // and protection domain are expected to succeed.
  {
    MutexLocker mu(THREAD, SystemDictionary_lock);
    add_protection_domain(THREAD, klass,
                          protection_domain);
  }
}

// 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(GrowableArray<ProtectionDomainEntry*>* delete_list) {
  assert(Thread::current()->is_Java_thread(), "only called by JavaThread");
  assert_lock_strong(SystemDictionary_lock);
  assert(!loader_data()->has_class_mirror_holder(), "cld should have a ClassLoader holder not a Class holder");

  if (loader_data()->is_the_null_class_loader_data()) {
    // Classes in the boot loader are not loaded with protection domains
    return;
  }

  auto clean_entries = [&] (DictionaryEntry** value) {
      DictionaryEntry* probe = *value;
      Klass* e = probe->instance_klass();

      ProtectionDomainEntry* current = probe->pd_set_acquire();
      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_acquire() == current) {
            probe->release_set_pd_set(current->next_acquire());
          } else {
            assert(prev != NULL, "should be set by alive entry");
            prev->release_set_next(current->next_acquire());
          }
          // Mark current for deletion but in the meantime it can still be
          // traversed.
          delete_list->push(current);
          current = current->next_acquire();
        } else {
          prev = current;
          current = current->next_acquire();
        }
      }
      return true;
  };

  _table->do_scan(Thread::current(), clean_entries);
}

void DictionaryEntry::verify_protection_domain_set() {
  assert(SafepointSynchronize::is_at_safepoint(), "must only be called as safepoint");
  for (ProtectionDomainEntry* current = pd_set_acquire(); // accessed at a safepoint
                              current != NULL;
                              current = current->next_acquire()) {
    guarantee(oopDesc::is_oop_or_null(current->object_no_keepalive()), "Invalid oop");
  }
}

void DictionaryEntry::print_count(outputStream *st) {
  assert_locked_or_safepoint(SystemDictionary_lock);
  int count = 0;
  for (ProtectionDomainEntry* current = pd_set_acquire();
                              current != NULL;
                              current = current->next_acquire()) {
    count++;
  }
  st->print("pd set count = #%d", count);
}

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

void Dictionary::print_size(outputStream* st) const {
  st->print_cr("Java dictionary (table_size=%d, classes=%d)",
               table_size(), _number_of_entries);
}

void Dictionary::print_on(outputStream* st) const {
  ResourceMark rm;

  assert(loader_data() != NULL, "loader data should not be null");
  assert(!loader_data()->has_class_mirror_holder(), "cld should have a ClassLoader holder not a Class holder");
  print_size(st);
  st->print_cr("^ indicates that initiating loader is different from defining loader");

  auto printer = [&] (DictionaryEntry** entry) {
    DictionaryEntry* probe = *entry;
    Klass* e = probe->instance_klass();
    bool is_defining_class =
       (_loader_data == e->class_loader_data());
    st->print(" %s%s", is_defining_class ? " " : "^", e->external_name());
    ClassLoaderData* cld = e->class_loader_data();
    if (!_loader_data->is_the_null_class_loader_data()) {
      // Class loader output for the dictionary for the null class loader data is
      // redundant and obvious.
      st->print(", ");
      cld->print_value_on(st);
      st->print(", ");
      probe->print_count(st);
    }
    st->cr();
    return true;
  };

  if (SafepointSynchronize::is_at_safepoint()) {
    _table->do_safepoint_scan(printer);
  } else {
    _table->do_scan(Thread::current(), printer);
  }
  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
  // bootstrap loader
  guarantee(cld != NULL &&
            (cld->is_the_null_class_loader_data() || cld->class_loader_no_keepalive()->is_instance()),
            "checking type of class_loader");

  auto verifier = [&] (DictionaryEntry** val) {
    (*val)->verify();
    return true;
  };

  _table->do_safepoint_scan(verifier);
}

void Dictionary::print_table_statistics(outputStream* st, const char* table_name) {
  static TableStatistics ts;
  auto sz = [&] (DictionaryEntry** val) {
    return sizeof(**val);
  };
  ts = _table->statistics_get(Thread::current(), sz, ts);
  ts.print(st, table_name);
}

¤ Dauer der Verarbeitung: 0.4 Sekunden (vorverarbeitet) ¤

Download des Quellennavigators
Download des sprechenden Kalenders
in der Quellcodebibliothek suchen

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.