/*

 * Copyright (c) 2014, 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 "gc/g1/g1Allocator.inline.hpp"

#include "gc/g1/g1CollectedHeap.inline.hpp"

#include "gc/g1/g1CollectionSet.hpp"

#include "gc/g1/g1OopClosures.inline.hpp"

#include "gc/g1/g1ParScanThreadState.inline.hpp"

#include "gc/g1/g1RootClosures.hpp"

#include "gc/g1/g1StringDedup.hpp"

#include "gc/g1/g1Trace.hpp"

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

#include "memory/allocation.inline.hpp"

#include "oops/access.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/prefetch.inline.hpp"

G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h,

                                           G1RedirtyCardsQueueSet* rdcqs,

                                           uint worker_id,

                                           size_t young_cset_length,

                                           size_t optional_cset_length)

  : _g1h(g1h),

    _refs(g1h->task_queue(worker_id)),

    _rdcq(rdcqs),

    _ct(g1h->card_table()),

    _closures(NULL),

    _plab_allocator(NULL),

    _age_table(false),

    _tenuring_threshold(g1h->policy()->tenuring_threshold()),

    _scanner(g1h, this),

    _worker_id(worker_id),

    _last_enqueued_card(SIZE_MAX),

    _stack_trim_upper_threshold(GCDrainStackTargetSize * 2 + 1),

    _stack_trim_lower_threshold(GCDrainStackTargetSize),

    _trim_ticks(),

    _old_gen_is_full(false),

    _num_optional_regions(optional_cset_length)

{

  // We allocate number of young gen regions in the collection set plus one

  // entries, since entry 0 keeps track of surviving bytes for non-young regions.

  // We also add a few elements at the beginning and at the end in

  // an attempt to eliminate cache contention

  size_t real_length = young_cset_length + 1;

  size_t array_length = PADDING_ELEM_NUM + real_length + PADDING_ELEM_NUM;

  _surviving_young_words_base = NEW_C_HEAP_ARRAY(size_t, array_length, mtGC);

  _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;

  memset(_surviving_young_words, 0, real_length * sizeof(size_t));

  _plab_allocator = new G1PLABAllocator(_g1h->allocator());

  // The dest for Young is used when the objects are aged enough to

  // need to be moved to the next space.

  _dest[G1HeapRegionAttr::Young] = G1HeapRegionAttr::Old;

  _dest[G1HeapRegionAttr::Old]   = G1HeapRegionAttr::Old;

  _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);

  _oops_into_optional_regions = new G1OopStarChunkedList[_num_optional_regions];

}

// Pass locally gathered statistics to global state.

void G1ParScanThreadState::flush(size_t* surviving_young_words) {

  _rdcq.flush();

  // Update allocation statistics.

  _plab_allocator->flush_and_retire_stats();

  _g1h->policy()->record_age_table(&_age_table);

  uint length = _g1h->collection_set()->young_region_length() + 1;

  for (uint i = 0; i < length; i++) {

    surviving_young_words[i] += _surviving_young_words[i];

  }

}

G1ParScanThreadState::~G1ParScanThreadState() {

  delete _plab_allocator;

  delete _closures;

  FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);

  delete[] _oops_into_optional_regions;

}

size_t G1ParScanThreadState::lab_waste_words() const {

  return _plab_allocator->waste();

}

size_t G1ParScanThreadState::lab_undo_waste_words() const {

  return _plab_allocator->undo_waste();

}

#ifdef ASSERT

bool G1ParScanThreadState::verify_ref(narrowOop* ref) const {

  assert(ref != NULL, "invariant");

  assert(UseCompressedOops, "sanity");

  assert(!has_partial_array_mask(ref), "ref=" PTR_FORMAT, p2i(ref));

  oop p = RawAccess<>::oop_load(ref);

  assert(_g1h->is_in_g1_reserved(p),

         "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));

  return true;

}

bool G1ParScanThreadState::verify_ref(oop* ref) const {

  assert(ref != NULL, "invariant");

  if (has_partial_array_mask(ref)) {

    // Must be in the collection set--it's already been copied.

    oop p = clear_partial_array_mask(ref);

    assert(_g1h->is_in_cset(p),

           "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));

  } else {

    oop p = RawAccess<>::oop_load(ref);

    assert(_g1h->is_in_g1_reserved(p),

           "ref=" PTR_FORMAT " p=" PTR_FORMAT, p2i(ref), p2i(p));

  }

  return true;

}

bool G1ParScanThreadState::verify_task(StarTask ref) const {

  if (ref.is_narrow()) {

    return verify_ref((narrowOop*) ref);

  } else {

    return verify_ref((oop*) ref);

  }

}

#endif // ASSERT

void G1ParScanThreadState::trim_queue() {

  StarTask ref;

  do {

    // Fully drain the queue.

    trim_queue_to_threshold(0);

  } while (!_refs->is_empty());

}

                                                      size_t word_sz,

  assert(dest->is_in_cset_or_humongous(), "Unexpected dest: %s region attr", dest->get_type_str());

  // Right now we only have two types of regions (young / old) so

  // let's keep the logic here simple. We can generalize it when necessary.

  if (dest->is_young()) {

    bool plab_refill_in_old_failed = false;

    HeapWord* const obj_ptr = _plab_allocator->allocate(G1HeapRegionAttr::Old,

                                                        word_sz,

    // Make sure that we won't attempt to copy any other objects out

    // of a survivor region (given that apparently we cannot allocate

    // any new ones) to avoid coming into this slow path again and again.

    // Only consider failed PLAB refill here: failed inline allocations are

    // typically large, so not indicative of remaining space.

    if (previous_plab_refill_failed) {

      _tenuring_threshold = 0;

    }

    if (obj_ptr != NULL) {

      dest->set_old();

    } else {

      // We just failed to allocate in old gen. The same idea as explained above

      // for making survivor gen unavailable for allocation applies for old gen.

      _old_gen_is_full = plab_refill_in_old_failed;

    }

    return obj_ptr;

  } else {

    _old_gen_is_full = previous_plab_refill_failed;

    assert(dest->is_old(), "Unexpected dest region attr: %s", dest->get_type_str());

    // no other space to try.

    return NULL;

  }

}

G1HeapRegionAttr G1ParScanThreadState::next_region_attr(G1HeapRegionAttr const region_attr, markWord const m, uint& age) {

  if (region_attr.is_young()) {

    age = !m.has_displaced_mark_helper() ? m.age()

                                         : m.displaced_mark_helper().age();

    if (age < _tenuring_threshold) {

      return region_attr;

    }

  }

  return dest(region_attr);

}

void G1ParScanThreadState::report_promotion_event(G1HeapRegionAttr const dest_attr,

                                                  oop const old, size_t word_sz, uint age,

  if (alloc_buf->contains(obj_ptr)) {

    _g1h->_gc_tracer_stw->report_promotion_in_new_plab_event(old->klass(), word_sz * HeapWordSize, age,

                                                             dest_attr.type() == G1HeapRegionAttr::Old,

                                                             alloc_buf->word_sz() * HeapWordSize);

  } else {

    _g1h->_gc_tracer_stw->report_promotion_outside_plab_event(old->klass(), word_sz * HeapWordSize, age,

                                                              dest_attr.type() == G1HeapRegionAttr::Old);

  }

}

oop G1ParScanThreadState::copy_to_survivor_space(G1HeapRegionAttr const region_attr,

                                                 oop const old,

                                                 markWord const old_mark) {

  const size_t word_sz = old->size();

  uint age = 0;

  G1HeapRegionAttr dest_attr = next_region_attr(region_attr, old_mark, age);

  // The second clause is to prevent premature evacuation failure in case there

  // is still space in survivor, but old gen is full.

  if (_old_gen_is_full && dest_attr.is_old()) {

    return handle_evacuation_failure_par(old, old_mark);

  }

  // PLAB allocations should succeed most of the time, so we'll

  // normally check against NULL once and that's it.

  if (obj_ptr == NULL) {

    bool plab_refill_failed = false;

    if (obj_ptr == NULL) {

      if (obj_ptr == NULL) {

        // This will either forward-to-self, or detect that someone else has

        // installed a forwarding pointer.

        return handle_evacuation_failure_par(old, old_mark);

      }

    }

    if (_g1h->_gc_tracer_stw->should_report_promotion_events()) {

      // The events are checked individually as part of the actual commit

    }

  }

  assert(obj_ptr != NULL, "when we get here, allocation should have succeeded");

  assert(_g1h->is_in_reserved(obj_ptr), "Allocated memory should be in the heap");

#ifndef PRODUCT

  // Should this evacuation fail?

  if (_g1h->evacuation_should_fail()) {

    // Doing this after all the allocation attempts also tests the

    // undo_allocation() method too.

    return handle_evacuation_failure_par(old, old_mark);

  }

#endif // !PRODUCT

  // We're going to allocate linearly, so might as well prefetch ahead.

  Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);

  const oop obj = oop(obj_ptr);

  const oop forward_ptr = old->forward_to_atomic(obj, old_mark, memory_order_relaxed);

  if (forward_ptr == NULL) {

    Copy::aligned_disjoint_words((HeapWord*) old, obj_ptr, word_sz);

    const uint young_index = from_region->young_index_in_cset();

    assert((from_region->is_young() && young_index >  0) ||

           (!from_region->is_young() && young_index == 0), "invariant" );

    if (dest_attr.is_young()) {

      if (age < markWord::max_age) {

        age++;

      }

      if (old_mark.has_displaced_mark_helper()) {

        // In this case, we have to install the mark word first,

        // otherwise obj looks to be forwarded (the old mark word,

        // which contains the forward pointer, was copied)

        obj->set_mark_raw(old_mark);

        markWord new_mark = old_mark.displaced_mark_helper().set_age(age);

        old_mark.set_displaced_mark_helper(new_mark);

      } else {

        obj->set_mark_raw(old_mark.set_age(age));

      }

      _age_table.add(age, word_sz);

    } else {

      obj->set_mark_raw(old_mark);

    }

    if (G1StringDedup::is_enabled()) {

      const bool is_from_young = region_attr.is_young();

      const bool is_to_young = dest_attr.is_young();

      assert(is_from_young == from_region->is_young(),

             "sanity");

      assert(is_to_young == _g1h->heap_region_containing(obj)->is_young(),

             "sanity");

      G1StringDedup::enqueue_from_evacuation(is_from_young,

                                             is_to_young,

                                             _worker_id,

                                             obj);

    }

    _surviving_young_words[young_index] += word_sz;

    if (obj->is_objArray() && arrayOop(obj)->length() >= ParGCArrayScanChunk) {

      // We keep track of the next start index in the length field of

      // the to-space object. The actual length can be found in the

      // length field of the from-space object.

      arrayOop(obj)->set_length(0);

      oop* old_p = set_partial_array_mask(old);

      do_oop_partial_array(old_p);

    } else {

      G1ScanInYoungSetter x(&_scanner, dest_attr.is_young());

      obj->oop_iterate_backwards(&_scanner);

    }

    return obj;

  } else {

    return forward_ptr;

  }

}

G1ParScanThreadState* G1ParScanThreadStateSet::state_for_worker(uint worker_id) {

  assert(worker_id < _n_workers, "out of bounds access");

  if (_states[worker_id] == NULL) {

    _states[worker_id] =

      new G1ParScanThreadState(_g1h, _rdcqs, worker_id, _young_cset_length, _optional_cset_length);

  }

  return _states[worker_id];

}

const size_t* G1ParScanThreadStateSet::surviving_young_words() const {

  assert(_flushed, "thread local state from the per thread states should have been flushed");

  return _surviving_young_words_total;

}

void G1ParScanThreadStateSet::flush() {

  assert(!_flushed, "thread local state from the per thread states should be flushed once");

  for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {

    G1ParScanThreadState* pss = _states[worker_index];

    if (pss == NULL) {

      continue;

    }

    pss->flush(_surviving_young_words_total);

    delete pss;

    _states[worker_index] = NULL;

  }

  _flushed = true;

}

void G1ParScanThreadStateSet::record_unused_optional_region(HeapRegion* hr) {

  for (uint worker_index = 0; worker_index < _n_workers; ++worker_index) {

    G1ParScanThreadState* pss = _states[worker_index];

    if (pss == NULL) {

      continue;

    }

    size_t used_memory = pss->oops_into_optional_region(hr)->used_memory();

    _g1h->phase_times()->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanHR, worker_index, used_memory, G1GCPhaseTimes::ScanHRUsedMemory);

  }

}

oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markWord m) {

  assert(_g1h->is_in_cset(old), "Object " PTR_FORMAT " should be in the CSet", p2i(old));

  oop forward_ptr = old->forward_to_atomic(old, m, memory_order_relaxed);

  if (forward_ptr == NULL) {

    // Forward-to-self succeeded. We are the "owner" of the object.

    HeapRegion* r = _g1h->heap_region_containing(old);

    if (!r->evacuation_failed()) {

      r->set_evacuation_failed(true);

     _g1h->hr_printer()->evac_failure(r);

    }

    _g1h->preserve_mark_during_evac_failure(_worker_id, old, m);

    G1ScanInYoungSetter x(&_scanner, r->is_young());

    old->oop_iterate_backwards(&_scanner);

    return old;

  } else {

    // Forward-to-self failed. Either someone else managed to allocate

    // space for this object (old != forward_ptr) or they beat us in

    // self-forwarding it (old == forward_ptr).

    assert(old == forward_ptr || !_g1h->is_in_cset(forward_ptr),

           "Object " PTR_FORMAT " forwarded to: " PTR_FORMAT " "

           "should not be in the CSet",

           p2i(old), p2i(forward_ptr));

    return forward_ptr;

  }

}

G1ParScanThreadStateSet::G1ParScanThreadStateSet(G1CollectedHeap* g1h,

                                                 G1RedirtyCardsQueueSet* rdcqs,

                                                 uint n_workers,

                                                 size_t young_cset_length,

                                                 size_t optional_cset_length) :

    _g1h(g1h),

    _rdcqs(rdcqs),

    _states(NEW_C_HEAP_ARRAY(G1ParScanThreadState*, n_workers, mtGC)),

    _surviving_young_words_total(NEW_C_HEAP_ARRAY(size_t, young_cset_length + 1, mtGC)),

    _young_cset_length(young_cset_length),

    _optional_cset_length(optional_cset_length),

    _n_workers(n_workers),

    _flushed(false) {

  for (uint i = 0; i < n_workers; ++i) {

    _states[i] = NULL;

  }

  memset(_surviving_young_words_total, 0, (young_cset_length + 1) * sizeof(size_t));

}

G1ParScanThreadStateSet::~G1ParScanThreadStateSet() {

  assert(_flushed, "thread local state from the per thread states should have been flushed");

  FREE_C_HEAP_ARRAY(G1ParScanThreadState*, _states);

  FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_total);

}