/*

 * Copyright (c) 2018, 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.

 *

 */

#ifndef SHARE_VM_CLASSFILE_CLASSLOADERDATAGRAPH_HPP

#define SHARE_VM_CLASSFILE_CLASSLOADERDATAGRAPH_HPP

#include "classfile/classLoaderData.hpp"

#include "memory/allocation.hpp"

#include "utilities/growableArray.hpp"

#include "utilities/macros.hpp"

// GC root for walking class loader data created

class ClassLoaderDataGraph : public AllStatic {

  friend class ClassLoaderData;

  friend class ClassLoaderDataGraphMetaspaceIterator;

  friend class ClassLoaderDataGraphKlassIteratorAtomic;

  friend class ClassLoaderDataGraphKlassIteratorStatic;

  friend class ClassLoaderDataGraphIterator;

  friend class VMStructs;

 private:

  // All CLDs (except the null CLD) can be reached by walking _head->_next->...

  static ClassLoaderData* _head;

  static ClassLoaderData* _unloading;

  // CMS support.

  static ClassLoaderData* _saved_head;

  static ClassLoaderData* _saved_unloading;

  static bool _should_purge;

  // Set if there's anything to purge in the deallocate lists or previous versions

  // during a safepoint after class unloading in a full GC.

  static bool _should_clean_deallocate_lists;

  static bool _safepoint_cleanup_needed;

  // OOM has been seen in metaspace allocation. Used to prevent some

  // allocations until class unloading

  static bool _metaspace_oom;

  static volatile size_t  _num_instance_classes;

  static volatile size_t  _num_array_classes;

  static ClassLoaderData* add_to_graph(Handle class_loader, bool is_unsafe_anonymous);

  static ClassLoaderData* add(Handle class_loader, bool is_unsafe_anonymous);

 public:

  static ClassLoaderData* find_or_create(Handle class_loader);

  static void clean_module_and_package_info();

  static void purge();

  static void clear_claimed_marks();

  // Iteration through CLDG inside a safepoint; GC support

  static void cld_do(CLDClosure* cl);

  static void cld_unloading_do(CLDClosure* cl);

  static void roots_cld_do(CLDClosure* strong, CLDClosure* weak);

  static void always_strong_cld_do(CLDClosure* cl);

  // klass do

  // Walking classes through the ClassLoaderDataGraph include array classes.  It also includes

  // classes that are allocated but not loaded, classes that have errors, and scratch classes

  // for redefinition.  These classes are removed during the next class unloading.

  // Walking the ClassLoaderDataGraph also includes unsafe anonymous classes.

  static void classes_do(KlassClosure* klass_closure);

  static void classes_do(void f(Klass* const));

  static void methods_do(void f(Method*));

  static void modules_do(void f(ModuleEntry*));

  static void modules_unloading_do(void f(ModuleEntry*));

  static void packages_do(void f(PackageEntry*));

  static void packages_unloading_do(void f(PackageEntry*));

  static void loaded_classes_do(KlassClosure* klass_closure);

  static void unlocked_loaded_classes_do(KlassClosure* klass_closure);

  static void classes_unloading_do(void f(Klass* const));

  static bool do_unloading(bool do_cleaning);

  // Expose state to avoid logging overhead in safepoint cleanup tasks.

  static inline bool should_clean_metaspaces_and_reset();

  static void set_should_clean_deallocate_lists() { _should_clean_deallocate_lists = true; }

  static void clean_deallocate_lists(bool purge_previous_versions);

  static void walk_metadata_and_clean_metaspaces();

  // dictionary do

  // Iterate over all klasses in dictionary, but

  // just the classes from defining class loaders.

  static void dictionary_classes_do(void f(InstanceKlass*));

  // Added for initialize_itable_for_klass to handle exceptions.

  static void dictionary_classes_do(void f(InstanceKlass*, TRAPS), TRAPS);

  // VM_CounterDecay iteration support

  static InstanceKlass* try_get_next_class();

  static void adjust_saved_class(ClassLoaderData* cld);

  static void adjust_saved_class(Klass* klass);

  static void verify_dictionary();

  static void print_dictionary(outputStream* st);

  static void print_dictionary_statistics(outputStream* st);

  // CMS support.

  static void remember_new_clds(bool remember) { _saved_head = (remember ? _head : NULL); }

  static GrowableArray<ClassLoaderData*>* new_clds();

  static void set_should_purge(bool b) { _should_purge = b; }

  static void purge_if_needed() {

    // Only purge the CLDG for CMS if concurrent sweep is complete.

    if (_should_purge) {

      purge();

      // reset for next time.

      set_should_purge(false);

    }

  }

  static int resize_if_needed();

  static bool has_metaspace_oom()           { return _metaspace_oom; }

  static void set_metaspace_oom(bool value) { _metaspace_oom = value; }

  static void print_on(outputStream * const out) PRODUCT_RETURN;

  static void print() { print_on(tty); }

  static void verify();

  // instance and array class counters

  static inline size_t num_instance_classes();

  static inline size_t num_array_classes();

  static inline void inc_instance_classes(size_t count);

  static inline void dec_instance_classes(size_t count);

  static inline void inc_array_classes(size_t count);

  static inline void dec_array_classes(size_t count);

#ifndef PRODUCT

  static bool contains_loader_data(ClassLoaderData* loader_data);

#endif

  // Check if ClassLoaderData is part of the ClassLoaderDataGraph (not unloaded)

  // Usage without lock only allowed during error reporting.

  static bool is_valid(ClassLoaderData* loader_data);

};

class LockedClassesDo : public KlassClosure {

  typedef void (*classes_do_func_t)(Klass*);

  classes_do_func_t _function;

public:

  LockedClassesDo();  // For callers who provide their own do_klass

  LockedClassesDo(classes_do_func_t function);

  ~LockedClassesDo();

  void do_klass(Klass* k) {

    (*_function)(k);

  }

};

// An iterator that distributes Klasses to parallel worker threads.

class ClassLoaderDataGraphKlassIteratorAtomic : public StackObj {

 Klass* volatile _next_klass;

 public:

  ClassLoaderDataGraphKlassIteratorAtomic();

  Klass* next_klass();

 private:

  static Klass* next_klass_in_cldg(Klass* klass);

};

class ClassLoaderDataGraphMetaspaceIterator : public StackObj {

  ClassLoaderData* _data;

 public:

  ClassLoaderDataGraphMetaspaceIterator();

  ~ClassLoaderDataGraphMetaspaceIterator();

  bool repeat() { return _data != NULL; }

  ClassLoaderMetaspace* get_next();

};

#endif // SHARE_VM_CLASSFILE_CLASSLOADERDATAGRAPH_HPP