/*

 * Copyright (c) 2014, 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_implementation/g1/g1CollectedHeap.inline.hpp"

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

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

#include "oops/oop.inline.hpp"

#include "oops/oop.pcgc.inline.hpp"

#include "runtime/prefetch.inline.hpp"

G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp)

  : _g1h(g1h),

    _refs(g1h->task_queue(queue_num)),

    _dcq(&g1h->dirty_card_queue_set()),

    _ct_bs(g1h->g1_barrier_set()),

    _g1_rem(g1h->g1_rem_set()),

    _hash_seed(17), _queue_num(queue_num),

    _term_attempts(0),

    _surviving_alloc_buffer(g1h->desired_plab_sz(GCAllocForSurvived)),

    _tenured_alloc_buffer(g1h->desired_plab_sz(GCAllocForTenured)),

    _age_table(false), _scanner(g1h, rp),

    _strong_roots_time(0), _term_time(0),

    _alloc_buffer_waste(0), _undo_waste(0) {

  _scanner.set_par_scan_thread_state(this);

  // 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

  uint real_length = 1 + _g1h->g1_policy()->young_cset_region_length();

  uint 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, (size_t) real_length * sizeof(size_t));

  _alloc_buffers[GCAllocForSurvived] = &_surviving_alloc_buffer;

  _alloc_buffers[GCAllocForTenured]  = &_tenured_alloc_buffer;

  _start = os::elapsedTime();

}

G1ParScanThreadState::~G1ParScanThreadState() {

  retire_alloc_buffers();

  FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC);

}

void

G1ParScanThreadState::print_termination_stats_hdr(outputStream* const st)

{

  st->print_raw_cr("GC Termination Stats");

  st->print_raw_cr("     elapsed  --strong roots-- -------termination-------"

                   " ------waste (KiB)------");

  st->print_raw_cr("thr     ms        ms      %        ms      %    attempts"

                   "  total   alloc    undo");

  st->print_raw_cr("--- --------- --------- ------ --------- ------ --------"

                   " ------- ------- -------");

}

void

G1ParScanThreadState::print_termination_stats(int i,

                                              outputStream* const st) const

{

  const double elapsed_ms = elapsed_time() * 1000.0;

  const double s_roots_ms = strong_roots_time() * 1000.0;

  const double term_ms    = term_time() * 1000.0;

  st->print_cr("%3d %9.2f %9.2f %6.2f "

               "%9.2f %6.2f " SIZE_FORMAT_W(8) " "

               SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),

               i, elapsed_ms, s_roots_ms, s_roots_ms * 100 / elapsed_ms,

               term_ms, term_ms * 100 / elapsed_ms, term_attempts(),

               (alloc_buffer_waste() + undo_waste()) * HeapWordSize / K,

               alloc_buffer_waste() * HeapWordSize / K,

               undo_waste() * HeapWordSize / K);

}

#ifdef ASSERT

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

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

  assert(UseCompressedOops, "sanity");

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

  oop p = oopDesc::load_decode_heap_oop(ref);

  assert(_g1h->is_in_g1_reserved(p),

         err_msg("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->obj_in_cs(p),

           err_msg("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),

           err_msg("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() {

  assert(_evac_failure_cl != NULL, "not set");

  StarTask ref;

  do {

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

    while (_refs->pop_overflow(ref)) {

      dispatch_reference(ref);

    }

    while (_refs->pop_local(ref)) {

      dispatch_reference(ref);

    }

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

}

oop G1ParScanThreadState::copy_to_survivor_space(oop const old) {

  size_t word_sz = old->size();

  HeapRegion* from_region = _g1h->heap_region_containing_raw(old);

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

  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" );

  G1CollectorPolicy* g1p = _g1h->g1_policy();

  markOop m = old->mark();

  int age = m->has_displaced_mark_helper() ? m->displaced_mark_helper()->age()

                                           : m->age();

  GCAllocPurpose alloc_purpose = g1p->evacuation_destination(from_region, age,

                                                             word_sz);

  HeapWord* obj_ptr = allocate(alloc_purpose, word_sz);

#ifndef PRODUCT

  // Should this evacuation fail?

  if (_g1h->evacuation_should_fail()) {

    if (obj_ptr != NULL) {

      undo_allocation(alloc_purpose, obj_ptr, word_sz);

      obj_ptr = NULL;

    }

  }

#endif // !PRODUCT

  if (obj_ptr == NULL) {

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

    // installed a forwarding pointer.

    return _g1h->handle_evacuation_failure_par(this, old);

  }

  oop obj = oop(obj_ptr);

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

  Prefetch::write(obj_ptr, PrefetchCopyIntervalInBytes);

  oop forward_ptr = old->forward_to_atomic(obj);

  if (forward_ptr == NULL) {

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

    // alloc_purpose is just a hint to allocate() above, recheck the type of region

    // we actually allocated from and update alloc_purpose accordingly

    HeapRegion* to_region = _g1h->heap_region_containing_raw(obj_ptr);

    alloc_purpose = to_region->is_young() ? GCAllocForSurvived : GCAllocForTenured;

    if (g1p->track_object_age(alloc_purpose)) {

      // We could simply do obj->incr_age(). However, this causes a

      // performance issue. obj->incr_age() will first check whether

      // the object has a displaced mark by checking its mark word;

      // getting the mark word from the new location of the object

      // stalls. So, given that we already have the mark word and we

      // are about to install it anyway, it's better to increase the

      // age on the mark word, when the object does not have a

      // displaced mark word. We're not expecting many objects to have

      // a displaced marked word, so that case is not optimized

      // further (it could be...) and we simply call obj->incr_age().

      if (m->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(m);

        obj->incr_age();

      } else {

        m = m->incr_age();

        obj->set_mark(m);

      }

      age_table()->add(obj, word_sz);

    } else {

      obj->set_mark(m);

    }

    if (G1StringDedup::is_enabled()) {

      G1StringDedup::enqueue_from_evacuation(from_region->is_young(),

                                             to_region->is_young(),

                                             queue_num(),

                                             obj);

    }

    size_t* surv_young_words = surviving_young_words();

    surv_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 {

      // No point in using the slower heap_region_containing() method,

      // given that we know obj is in the heap.

      _scanner.set_region(_g1h->heap_region_containing_raw(obj));

      obj->oop_iterate_backwards(&_scanner);

    }

  } else {

    undo_allocation(alloc_purpose, obj_ptr, word_sz);

    obj = forward_ptr;

  }

  return obj;

}

HeapWord* G1ParScanThreadState::allocate_slow(GCAllocPurpose purpose, size_t word_sz) {

  HeapWord* obj = NULL;

  size_t gclab_word_size = _g1h->desired_plab_sz(purpose);

  if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) {

    G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose);

    add_to_alloc_buffer_waste(alloc_buf->words_remaining());

    alloc_buf->retire(false /* end_of_gc */, false /* retain */);

    HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size);

    if (buf == NULL) {

      return NULL; // Let caller handle allocation failure.

    }

    // Otherwise.

    alloc_buf->set_word_size(gclab_word_size);

    alloc_buf->set_buf(buf);

    obj = alloc_buf->allocate(word_sz);

    assert(obj != NULL, "buffer was definitely big enough...");

  } else {

    obj = _g1h->par_allocate_during_gc(purpose, word_sz);

  }

  return obj;

}

void G1ParScanThreadState::undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) {

  if (alloc_buffer(purpose)->contains(obj)) {

    assert(alloc_buffer(purpose)->contains(obj + word_sz - 1),

           "should contain whole object");

    alloc_buffer(purpose)->undo_allocation(obj, word_sz);

  } else {

    CollectedHeap::fill_with_object(obj, word_sz);

    add_to_undo_waste(word_sz);

  }

}

HeapWord* G1ParScanThreadState::allocate(GCAllocPurpose purpose, size_t word_sz) {

  HeapWord* obj = NULL;

  if (purpose == GCAllocForSurvived) {

    obj = alloc_buffer(GCAllocForSurvived)->allocate_aligned(word_sz, SurvivorAlignmentInBytes);

  } else {

    obj = alloc_buffer(GCAllocForTenured)->allocate(word_sz);

  }

  if (obj != NULL) {

    return obj;

  }

  return allocate_slow(purpose, word_sz);

}

void G1ParScanThreadState::retire_alloc_buffers() {

  for (int ap = 0; ap < GCAllocPurposeCount; ++ap) {

    size_t waste = _alloc_buffers[ap]->words_remaining();

    add_to_alloc_buffer_waste(waste);

    _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap),

                                               true /* end_of_gc */,

                                               false /* retain */);

  }

}