/*

 * Copyright (c) 1997, 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.

 *

 */

#include "precompiled.hpp"

#include "compiler/compileBroker.hpp"

#include "gc/serial/markSweep.inline.hpp"

#include "gc/shared/collectedHeap.inline.hpp"

#include "gc/shared/gcTimer.hpp"

#include "gc/shared/gcTrace.hpp"

#include "memory/iterator.inline.hpp"

#include "memory/universe.hpp"

#include "oops/access.inline.hpp"

#include "oops/compressedOops.inline.hpp"

#include "oops/instanceClassLoaderKlass.inline.hpp"

#include "oops/instanceKlass.inline.hpp"

#include "oops/instanceMirrorKlass.inline.hpp"

#include "oops/instanceRefKlass.inline.hpp"

#include "oops/methodData.hpp"

#include "oops/objArrayKlass.inline.hpp"

#include "oops/oop.inline.hpp"

#include "oops/typeArrayOop.inline.hpp"

#include "utilities/macros.hpp"

#include "utilities/stack.inline.hpp"

uint                    MarkSweep::_total_invocations = 0;

Stack<oop, mtGC>              MarkSweep::_marking_stack;

Stack<ObjArrayTask, mtGC>     MarkSweep::_objarray_stack;

Stack<oop, mtGC>              MarkSweep::_preserved_oop_stack;

Stack<markWord, mtGC>         MarkSweep::_preserved_mark_stack;

size_t                  MarkSweep::_preserved_count = 0;

size_t                  MarkSweep::_preserved_count_max = 0;

PreservedMark*          MarkSweep::_preserved_marks = NULL;

ReferenceProcessor*     MarkSweep::_ref_processor   = NULL;

STWGCTimer*             MarkSweep::_gc_timer        = NULL;

SerialOldTracer*        MarkSweep::_gc_tracer       = NULL;

MarkSweep::FollowRootClosure  MarkSweep::follow_root_closure;

MarkAndPushClosure MarkSweep::mark_and_push_closure;

CLDToOopClosure    MarkSweep::follow_cld_closure(&mark_and_push_closure, ClassLoaderData::_claim_strong);

CLDToOopClosure    MarkSweep::adjust_cld_closure(&adjust_pointer_closure, ClassLoaderData::_claim_strong);

template <class T> inline void MarkSweep::KeepAliveClosure::do_oop_work(T* p) {

  mark_and_push(p);

}

void MarkSweep::push_objarray(oop obj, size_t index) {

  ObjArrayTask task(obj, index);

  assert(task.is_valid(), "bad ObjArrayTask");

  _objarray_stack.push(task);

}

inline void MarkSweep::follow_array(objArrayOop array) {

  MarkSweep::follow_klass(array->klass());

  // Don't push empty arrays to avoid unnecessary work.

  if (array->length() > 0) {

    MarkSweep::push_objarray(array, 0);

  }

}

inline void MarkSweep::follow_object(oop obj) {

  assert(obj->is_gc_marked(), "should be marked");

  if (obj->is_objArray()) {

    // Handle object arrays explicitly to allow them to

    // be split into chunks if needed.

    MarkSweep::follow_array((objArrayOop)obj);

  } else {

    obj->oop_iterate(&mark_and_push_closure);

  }

}

void MarkSweep::follow_array_chunk(objArrayOop array, int index) {

  const int len = array->length();

  const int beg_index = index;

  assert(beg_index < len || len == 0, "index too large");

  const int stride = MIN2(len - beg_index, (int) ObjArrayMarkingStride);

  const int end_index = beg_index + stride;

  array->oop_iterate_range(&mark_and_push_closure, beg_index, end_index);

  if (end_index < len) {

    MarkSweep::push_objarray(array, end_index); // Push the continuation.

  }

}

void MarkSweep::follow_stack() {

  do {

    while (!_marking_stack.is_empty()) {

      oop obj = _marking_stack.pop();

      assert (obj->is_gc_marked(), "p must be marked");

      follow_object(obj);

    }

    // Process ObjArrays one at a time to avoid marking stack bloat.

    if (!_objarray_stack.is_empty()) {

      ObjArrayTask task = _objarray_stack.pop();

      follow_array_chunk(objArrayOop(task.obj()), task.index());

    }

  } while (!_marking_stack.is_empty() || !_objarray_stack.is_empty());

}

MarkSweep::FollowStackClosure MarkSweep::follow_stack_closure;

void MarkSweep::FollowStackClosure::do_void() { follow_stack(); }

template <class T> inline void MarkSweep::follow_root(T* p) {

  assert(!Universe::heap()->is_in(p),

         "roots shouldn't be things within the heap");

  T heap_oop = RawAccess<>::oop_load(p);

  if (!CompressedOops::is_null(heap_oop)) {

    oop obj = CompressedOops::decode_not_null(heap_oop);

    if (!obj->mark_raw().is_marked()) {

      mark_object(obj);

      follow_object(obj);

    }

  }

  follow_stack();

}

void MarkSweep::FollowRootClosure::do_oop(oop* p)       { follow_root(p); }

void MarkSweep::FollowRootClosure::do_oop(narrowOop* p) { follow_root(p); }

void PreservedMark::adjust_pointer() {

  MarkSweep::adjust_pointer(&_obj);

}

void PreservedMark::restore() {

  _obj->set_mark_raw(_mark);

}

// We preserve the mark which should be replaced at the end and the location

// that it will go.  Note that the object that this markWord belongs to isn't

// currently at that address but it will be after phase4

void MarkSweep::preserve_mark(oop obj, markWord mark) {

  // We try to store preserved marks in the to space of the new generation since

  // this is storage which should be available.  Most of the time this should be

  // sufficient space for the marks we need to preserve but if it isn't we fall

  // back to using Stacks to keep track of the overflow.

  if (_preserved_count < _preserved_count_max) {

    _preserved_marks[_preserved_count++].init(obj, mark);

  } else {

    _preserved_mark_stack.push(mark);

    _preserved_oop_stack.push(obj);

  }

}

void MarkSweep::set_ref_processor(ReferenceProcessor* rp) {

  _ref_processor = rp;

  mark_and_push_closure.set_ref_discoverer(_ref_processor);

}

AdjustPointerClosure MarkSweep::adjust_pointer_closure;

void MarkSweep::adjust_marks() {

  assert( _preserved_oop_stack.size() == _preserved_mark_stack.size(),

         "inconsistent preserved oop stacks");

  // adjust the oops we saved earlier

  for (size_t i = 0; i < _preserved_count; i++) {

    _preserved_marks[i].adjust_pointer();

  }

  // deal with the overflow stack

  StackIterator<oop, mtGC> iter(_preserved_oop_stack);

  while (!iter.is_empty()) {

    oop* p = iter.next_addr();

    adjust_pointer(p);

  }

}

void MarkSweep::restore_marks() {

  assert(_preserved_oop_stack.size() == _preserved_mark_stack.size(),

         "inconsistent preserved oop stacks");

  log_trace(gc)("Restoring " SIZE_FORMAT " marks", _preserved_count + _preserved_oop_stack.size());

  // restore the marks we saved earlier

  for (size_t i = 0; i < _preserved_count; i++) {

    _preserved_marks[i].restore();

  }

  // deal with the overflow

  while (!_preserved_oop_stack.is_empty()) {

    oop obj       = _preserved_oop_stack.pop();

    markWord mark = _preserved_mark_stack.pop();

    obj->set_mark_raw(mark);

  }

}

MarkSweep::IsAliveClosure   MarkSweep::is_alive;

bool MarkSweep::IsAliveClosure::do_object_b(oop p) { return p->is_gc_marked(); }

MarkSweep::KeepAliveClosure MarkSweep::keep_alive;

void MarkSweep::KeepAliveClosure::do_oop(oop* p)       { MarkSweep::KeepAliveClosure::do_oop_work(p); }

void MarkSweep::KeepAliveClosure::do_oop(narrowOop* p) { MarkSweep::KeepAliveClosure::do_oop_work(p); }

void MarkSweep::initialize() {

  MarkSweep::_gc_timer = new (ResourceObj::C_HEAP, mtGC) STWGCTimer();

  MarkSweep::_gc_tracer = new (ResourceObj::C_HEAP, mtGC) SerialOldTracer();

}