/*

 * Copyright (c) 2017, 2019, 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/classLoaderDataGraph.hpp"

#include "classfile/dictionary.hpp"

#include "classfile/protectionDomainCache.hpp"

#include "classfile/systemDictionary.hpp"

#include "logging/log.hpp"

#include "logging/logStream.hpp"

#include "memory/iterator.hpp"

#include "memory/resourceArea.hpp"

#include "oops/oop.inline.hpp"

#include "oops/weakHandle.inline.hpp"

#include "utilities/hashtable.inline.hpp"

unsigned int ProtectionDomainCacheTable::compute_hash(Handle protection_domain) {

  // Identity hash can safepoint, so keep protection domain in a Handle.

  return (unsigned int)(protection_domain->identity_hash());

}

int ProtectionDomainCacheTable::index_for(Handle protection_domain) {

  return hash_to_index(compute_hash(protection_domain));

}

ProtectionDomainCacheTable::ProtectionDomainCacheTable(int table_size)

  : Hashtable<WeakHandle<vm_class_loader_data>, mtClass>(table_size, sizeof(ProtectionDomainCacheEntry))

{   _dead_entries = false;

    _total_oops_removed = 0;

}

void ProtectionDomainCacheTable::trigger_cleanup() {

  MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);

  _dead_entries = true;

  Service_lock->notify_all();

}

class CleanProtectionDomainEntries : public CLDClosure {

  void do_cld(ClassLoaderData* data) {

    Dictionary* dictionary = data->dictionary();

    if (dictionary != NULL) {

      dictionary->clean_cached_protection_domains();

    }

  }

};

void ProtectionDomainCacheTable::unlink() {

  {

    // First clean cached pd lists in loaded CLDs

    // It's unlikely, but some loaded classes in a dictionary might

    // point to a protection_domain that has been unloaded.

    // The dictionary pd_set points at entries in the ProtectionDomainCacheTable.

    MutexLocker ml(ClassLoaderDataGraph_lock);

    MutexLocker mldict(SystemDictionary_lock);  // need both.

    CleanProtectionDomainEntries clean;

    ClassLoaderDataGraph::loaded_cld_do(&clean);

  }

  MutexLocker ml(SystemDictionary_lock);

  int oops_removed = 0;

  for (int i = 0; i < table_size(); ++i) {

    ProtectionDomainCacheEntry** p = bucket_addr(i);

    ProtectionDomainCacheEntry* entry = bucket(i);

    while (entry != NULL) {

      oop pd = entry->object_no_keepalive();

      if (pd != NULL) {

        p = entry->next_addr();

      } else {

        oops_removed++;

        LogTarget(Debug, protectiondomain, table) lt;

        if (lt.is_enabled()) {

          LogStream ls(lt);

          ls.print_cr("protection domain unlinked at %d", i);

        }

        entry->literal().release();

        *p = entry->next();

        free_entry(entry);

      }

      entry = *p;

    }

  }

  _total_oops_removed += oops_removed;

  _dead_entries = false;

}

void ProtectionDomainCacheTable::print_on(outputStream* st) const {

  assert_locked_or_safepoint(SystemDictionary_lock);

  st->print_cr("Protection domain cache table (table_size=%d, classes=%d)",

               table_size(), number_of_entries());

  for (int index = 0; index < table_size(); index++) {

    for (ProtectionDomainCacheEntry* probe = bucket(index);

                                     probe != NULL;

                                     probe = probe->next()) {

      st->print_cr("%4d: protection_domain: " PTR_FORMAT, index, p2i(probe->object_no_keepalive()));

    }

  }

}

void ProtectionDomainCacheTable::verify() {

  verify_table<ProtectionDomainCacheEntry>("Protection Domain Table");

}

oop ProtectionDomainCacheEntry::object() {

  return literal().resolve();

}

oop ProtectionDomainEntry::object() {

  return _pd_cache->object();

}

// The object_no_keepalive() call peeks at the phantomly reachable oop without

// keeping it alive. This is okay to do in the VM thread state if it is not

// leaked out to become strongly reachable.

oop ProtectionDomainCacheEntry::object_no_keepalive() {

  return literal().peek();

}

oop ProtectionDomainEntry::object_no_keepalive() {

  return _pd_cache->object_no_keepalive();

}

void ProtectionDomainCacheEntry::verify() {

  guarantee(object_no_keepalive() == NULL || oopDesc::is_oop(object_no_keepalive()), "must be an oop");

}

ProtectionDomainCacheEntry* ProtectionDomainCacheTable::get(Handle protection_domain) {

  unsigned int hash = compute_hash(protection_domain);

  int index = hash_to_index(hash);

  ProtectionDomainCacheEntry* entry = find_entry(index, protection_domain);

  if (entry == NULL) {

    entry = add_entry(index, hash, protection_domain);

  }

  // keep entry alive

  (void)entry->object();

  return entry;

}

ProtectionDomainCacheEntry* ProtectionDomainCacheTable::find_entry(int index, Handle protection_domain) {

  assert_locked_or_safepoint(SystemDictionary_lock);

  for (ProtectionDomainCacheEntry* e = bucket(index); e != NULL; e = e->next()) {

      return e;

    }

  }

  return NULL;

}

ProtectionDomainCacheEntry* ProtectionDomainCacheTable::add_entry(int index, unsigned int hash, Handle protection_domain) {

  assert_locked_or_safepoint(SystemDictionary_lock);

  assert(index == index_for(protection_domain), "incorrect index?");

  assert(find_entry(index, protection_domain) == NULL, "no double entry");

  LogTarget(Debug, protectiondomain, table) lt;

  if (lt.is_enabled()) {

    LogStream ls(lt);

    ls.print("protection domain added ");

    protection_domain->print_value_on(&ls);

    ls.cr();

  }

  WeakHandle<vm_class_loader_data> w = WeakHandle<vm_class_loader_data>::create(protection_domain);

  ProtectionDomainCacheEntry* p = new_entry(hash, w);

  Hashtable<WeakHandle<vm_class_loader_data>, mtClass>::add_entry(index, p);

  return p;

}