/*

 * Copyright (c) 2014, 2017, 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/shared/gcTrace.hpp"

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

#include "oops/oop.inline.hpp"

#include "runtime/prefetch.inline.hpp"

G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint worker_id, size_t young_cset_length)

  : _g1h(g1h),

    _refs(g1h->task_queue(worker_id)),

    _dcq(&g1h->dirty_card_queue_set()),

    _ct_bs(g1h->g1_barrier_set()),

    _closures(NULL),

    _hash_seed(17),

    _worker_id(worker_id),

    _tenuring_threshold(g1h->g1_policy()->tenuring_threshold()),

    _age_table(false),

    _scanner(g1h, this),

    _old_gen_is_full(false)

{

  // we allocate G1YoungSurvRateNumRegions plus one entries, since

  // we "sacrifice" entry 0 to keep track of surviving bytes for

  // non-young regions (where the age is -1)

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

  // an attempt to eliminate cache contention

  size_t real_length = 1 + young_cset_length;

  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);

  if (_surviving_young_words_base == NULL)

    vm_exit_out_of_memory(array_length * sizeof(size_t), OOM_MALLOC_ERROR,

                          "Not enough space for young surv histo.");

  _surviving_young_words = _surviving_young_words_base + PADDING_ELEM_NUM;

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

  _plab_allocator = G1PLABAllocator::create_allocator(_g1h->allocator());

  _dest[InCSetState::NotInCSet]    = InCSetState::NotInCSet;

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

  // need to be moved to the next space.

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

  _dest[InCSetState::Old]          = InCSetState::Old;

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

}

// Pass locally gathered statistics to global state.

void G1ParScanThreadState::flush(size_t* surviving_young_words) {

  _dcq.flush();

  // Update allocation statistics.

  _plab_allocator->flush_and_retire_stats();

  _g1h->g1_policy()->record_age_table(&_age_table);

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

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

    surviving_young_words[region_index] += _surviving_young_words[region_index];

  }

}

G1ParScanThreadState::~G1ParScanThreadState() {

  delete _plab_allocator;

  delete _closures;

  FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);

}

void G1ParScanThreadState::waste(size_t& wasted, size_t& undo_wasted) {

  _plab_allocator->waste(wasted, undo_wasted);

}

#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 = oopDesc::load_decode_heap_oop(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 = oopDesc::load_decode_heap_oop(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 {

    // Drain the overflow stack first, so other threads can steal.

    while (_refs->pop_overflow(ref)) {

      if (!_refs->try_push_to_taskqueue(ref)) {

        dispatch_reference(ref);

      }

    }

    while (_refs->pop_local(ref)) {

      dispatch_reference(ref);

    }

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

}

HeapWord* G1ParScanThreadState::allocate_in_next_plab(InCSetState const state,

                                                      InCSetState* dest,

                                                      size_t word_sz,

                                                      AllocationContext_t const context,

                                                      bool previous_plab_refill_failed) {

  assert(state.is_in_cset_or_humongous(), "Unexpected state: " CSETSTATE_FORMAT, state.value());

  assert(dest->is_in_cset_or_humongous(), "Unexpected dest: " CSETSTATE_FORMAT, dest->value());

  // 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(InCSetState::Old,

                                                        word_sz,

                                                        context,

                                                        &plab_refill_in_old_failed);

    // 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: " CSETSTATE_FORMAT, dest->value());

    // no other space to try.

    return NULL;

  }

}

InCSetState G1ParScanThreadState::next_state(InCSetState const state, markOop const m, uint& age) {

  if (state.is_young()) {

    age = !m->has_displaced_mark_helper() ? m->age()

                                          : m->displaced_mark_helper()->age();

    if (age < _tenuring_threshold) {

      return state;

    }

  }

  return dest(state);

}

void G1ParScanThreadState::report_promotion_event(InCSetState const dest_state,

                                                  oop const old, size_t word_sz, uint age,

                                                  HeapWord * const obj_ptr,

                                                  const AllocationContext_t context) const {

  G1PLAB* alloc_buf = _plab_allocator->alloc_buffer(dest_state, context);

  if (alloc_buf->contains(obj_ptr)) {

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

                                                             dest_state.value() == InCSetState::Old,

                                                             alloc_buf->word_sz());

  } else {

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

                                                              dest_state.value() == InCSetState::Old);

  }

}

oop G1ParScanThreadState::copy_to_survivor_space(InCSetState const state,

                                                 oop const old,

                                                 markOop const old_mark) {

  const size_t word_sz = old->size();

  HeapRegion* const from_region = _g1h->heap_region_containing(old);

  // +1 to make the -1 indexes valid...

  const int young_index = from_region->young_index_in_cset()+1;

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

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

  const AllocationContext_t context = from_region->allocation_context();

  uint age = 0;

  InCSetState dest_state = next_state(state, 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_state.is_old()) {

    return handle_evacuation_failure_par(old, old_mark);

  }

  HeapWord* obj_ptr = _plab_allocator->plab_allocate(dest_state, word_sz, context);

  // 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;

    obj_ptr = _plab_allocator->allocate_direct_or_new_plab(dest_state, word_sz, context, &plab_refill_failed);

    if (obj_ptr == NULL) {

      obj_ptr = allocate_in_next_plab(state, &dest_state, word_sz, context, plab_refill_failed);

      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

      report_promotion_event(dest_state, old, word_sz, age, obj_ptr, context);

    }

  }

  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.

    _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);

    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);

  if (forward_ptr == NULL) {

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

    if (dest_state.is_young()) {

      if (age < markOopDesc::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(old_mark);

        markOop new_mark = old_mark->displaced_mark_helper()->set_age(age);

        old_mark->set_displaced_mark_helper(new_mark);

      } else {

        obj->set_mark(old_mark->set_age(age));

      }

      _age_table.add(age, word_sz);

    } else {

      obj->set_mark(old_mark);

    }

    if (G1StringDedup::is_enabled()) {

      const bool is_from_young = state.is_young();

      const bool is_to_young = dest_state.is_young();

      assert(is_from_young == _g1h->heap_region_containing(old)->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);

      push_on_queue(old_p);

    } else {

      HeapRegion* const to_region = _g1h->heap_region_containing(obj_ptr);

      _scanner.set_region(to_region);

      obj->oop_iterate_backwards(&_scanner);

    }

    return obj;

  } else {

    _plab_allocator->undo_allocation(dest_state, obj_ptr, word_sz, context);

    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_par_scan_state(worker_id, _young_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;

}

oop G1ParScanThreadState::handle_evacuation_failure_par(oop old, markOop 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);

  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);

    _scanner.set_region(r);

    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;

  }

}