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 * 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.

 *

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 */

#ifndef SHARE_CLASSFILE_PROTECTIONDOMAINCACHE_HPP

#define SHARE_CLASSFILE_PROTECTIONDOMAINCACHE_HPP

#include "oops/oop.hpp"

#include "oops/weakHandle.hpp"

#include "memory/iterator.hpp"

#include "utilities/hashtable.hpp"

// This class caches the approved protection domains that can access loaded classes.

// Dictionary entry pd_set point to entries in this hashtable.   Please refer

// to dictionary.hpp pd_set for more information about how protection domain entries

// are used.

// This table is walked during GC, rather than the class loader data graph dictionaries.

class ProtectionDomainCacheEntry : public HashtableEntry<WeakHandle<vm_class_loader_data>, mtClass> {

  friend class VMStructs;

 public:

  oop object();

  oop object_no_keepalive();

  ProtectionDomainCacheEntry* next() {

    return (ProtectionDomainCacheEntry*)HashtableEntry<WeakHandle<vm_class_loader_data>, mtClass>::next();

  }

  ProtectionDomainCacheEntry** next_addr() {

    return (ProtectionDomainCacheEntry**)HashtableEntry<WeakHandle<vm_class_loader_data>, mtClass>::next_addr();

  }

  void verify();

};

// The ProtectionDomainCacheTable contains all protection domain oops. The

// dictionary entries reference its entries instead of having references to oops

// directly.

// This is used to speed up system dictionary iteration: the oops in the

// protection domain are the only ones referring the Java heap. So when there is

// need to update these, instead of going over every entry of the system dictionary,

// we only need to iterate over this set.

// The amount of different protection domains used is typically magnitudes smaller

// than the number of system dictionary entries (loaded classes).

class ProtectionDomainCacheTable : public Hashtable<WeakHandle<vm_class_loader_data>, mtClass> {

  friend class VMStructs;

private:

  ProtectionDomainCacheEntry* bucket(int i) const {

    return (ProtectionDomainCacheEntry*) Hashtable<WeakHandle<vm_class_loader_data>, mtClass>::bucket(i);

  }

  // The following method is not MT-safe and must be done under lock.

  ProtectionDomainCacheEntry** bucket_addr(int i) {

    return (ProtectionDomainCacheEntry**) Hashtable<WeakHandle<vm_class_loader_data>, mtClass>::bucket_addr(i);

  }

  ProtectionDomainCacheEntry* new_entry(unsigned int hash, WeakHandle<vm_class_loader_data> protection_domain) {

    ProtectionDomainCacheEntry* entry = (ProtectionDomainCacheEntry*)

      Hashtable<WeakHandle<vm_class_loader_data>, mtClass>::new_entry(hash, protection_domain);

    return entry;

  }

  static unsigned int compute_hash(Handle protection_domain);

  int index_for(Handle protection_domain);

  ProtectionDomainCacheEntry* add_entry(int index, unsigned int hash, Handle protection_domain);

  ProtectionDomainCacheEntry* find_entry(int index, Handle protection_domain);

  bool _dead_entries;

  int _total_oops_removed;

public:

  ProtectionDomainCacheTable(int table_size);

  ProtectionDomainCacheEntry* get(Handle protection_domain);

  void unlink();

  void print_on(outputStream* st) const;

  void verify();

  bool has_work() { return _dead_entries; }

  void trigger_cleanup();

  int removed_entries_count() { return _total_oops_removed; };

};

class ProtectionDomainEntry :public CHeapObj<mtClass> {

  friend class VMStructs;

 public:

  ProtectionDomainEntry* _next;

  ProtectionDomainCacheEntry* _pd_cache;

  ProtectionDomainEntry(ProtectionDomainCacheEntry* pd_cache, ProtectionDomainEntry* next) {

    _pd_cache = pd_cache;

    _next     = next;

  }

  ProtectionDomainEntry* next() { return _next; }

  void set_next(ProtectionDomainEntry* entry) { _next = entry; }

  oop object();

  oop object_no_keepalive();

};

#endif // SHARE_CLASSFILE_PROTECTIONDOMAINCACHE_HPP