/*

 * Copyright (c) 2001, 2015, 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

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 */

#include "precompiled.hpp"

#include "code/nmethod.hpp"

#include "gc/g1/g1BlockOffsetTable.inline.hpp"

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

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

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

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

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

#include "gc/g1/heapRegionRemSet.hpp"

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

#include "gc/shared/liveRange.hpp"

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

#include "memory/iterator.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.inline.hpp"

#include "runtime/orderAccess.inline.hpp"

int    HeapRegion::LogOfHRGrainBytes = 0;

int    HeapRegion::LogOfHRGrainWords = 0;

size_t HeapRegion::GrainBytes        = 0;

size_t HeapRegion::GrainWords        = 0;

size_t HeapRegion::CardsPerRegion    = 0;

HeapRegionDCTOC::HeapRegionDCTOC(G1CollectedHeap* g1,

                                 HeapRegion* hr,

                                 G1ParPushHeapRSClosure* cl,

                                 CardTableModRefBS::PrecisionStyle precision) :

  DirtyCardToOopClosure(hr, cl, precision, NULL),

  _hr(hr), _rs_scan(cl), _g1(g1) { }

FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,

                                                   OopClosure* oc) :

  _r_bottom(r->bottom()), _r_end(r->end()), _oc(oc) { }

void HeapRegionDCTOC::walk_mem_region(MemRegion mr,

                                      HeapWord* bottom,

                                      HeapWord* top) {

  G1CollectedHeap* g1h = _g1;

  size_t oop_size;

  HeapWord* cur = bottom;

  // Start filtering what we add to the remembered set. If the object is

  // not considered dead, either because it is marked (in the mark bitmap)

  // or it was allocated after marking finished, then we add it. Otherwise

  // we can safely ignore the object.

  if (!g1h->is_obj_dead(oop(cur))) {

    oop_size = oop(cur)->oop_iterate_size(_rs_scan, mr);

  } else {

    oop_size = _hr->block_size(cur);

  }

  cur += oop_size;

  if (cur < top) {

    oop cur_oop = oop(cur);

    oop_size = _hr->block_size(cur);

    HeapWord* next_obj = cur + oop_size;

    while (next_obj < top) {

      // Keep filtering the remembered set.

      if (!g1h->is_obj_dead(cur_oop)) {

        // Bottom lies entirely below top, so we can call the

        // non-memRegion version of oop_iterate below.

        cur_oop->oop_iterate(_rs_scan);

      }

      cur = next_obj;

      cur_oop = oop(cur);

      oop_size = _hr->block_size(cur);

      next_obj = cur + oop_size;

    }

    // Last object. Need to do dead-obj filtering here too.

    if (!g1h->is_obj_dead(oop(cur))) {

      oop(cur)->oop_iterate(_rs_scan, mr);

    }

  }

}

size_t HeapRegion::max_region_size() {

  return HeapRegionBounds::max_size();

}

size_t HeapRegion::min_region_size_in_words() {

  return HeapRegionBounds::min_size() >> LogHeapWordSize;

}

void HeapRegion::setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size) {

  size_t region_size = G1HeapRegionSize;

  if (FLAG_IS_DEFAULT(G1HeapRegionSize)) {

    size_t average_heap_size = (initial_heap_size + max_heap_size) / 2;

    region_size = MAX2(average_heap_size / HeapRegionBounds::target_number(),

                       HeapRegionBounds::min_size());

  }

  int region_size_log = log2_long((jlong) region_size);

  // Recalculate the region size to make sure it's a power of

  // 2. This means that region_size is the largest power of 2 that's

  // <= what we've calculated so far.

  region_size = ((size_t)1 << region_size_log);

  // Now make sure that we don't go over or under our limits.

  if (region_size < HeapRegionBounds::min_size()) {

    region_size = HeapRegionBounds::min_size();

  } else if (region_size > HeapRegionBounds::max_size()) {

    region_size = HeapRegionBounds::max_size();

  }

  // And recalculate the log.

  region_size_log = log2_long((jlong) region_size);

  // Now, set up the globals.

  guarantee(LogOfHRGrainBytes == 0, "we should only set it once");

  LogOfHRGrainBytes = region_size_log;

  guarantee(LogOfHRGrainWords == 0, "we should only set it once");

  LogOfHRGrainWords = LogOfHRGrainBytes - LogHeapWordSize;

  guarantee(GrainBytes == 0, "we should only set it once");

  // The cast to int is safe, given that we've bounded region_size by

  // MIN_REGION_SIZE and MAX_REGION_SIZE.

  GrainBytes = region_size;

  guarantee(GrainWords == 0, "we should only set it once");

  GrainWords = GrainBytes >> LogHeapWordSize;

  guarantee((size_t) 1 << LogOfHRGrainWords == GrainWords, "sanity");

  guarantee(CardsPerRegion == 0, "we should only set it once");

  CardsPerRegion = GrainBytes >> CardTableModRefBS::card_shift;

}

void HeapRegion::reset_after_compaction() {

  G1OffsetTableContigSpace::reset_after_compaction();

  // After a compaction the mark bitmap is invalid, so we must

  // treat all objects as being inside the unmarked area.

  zero_marked_bytes();

  init_top_at_mark_start();

}

void HeapRegion::hr_clear(bool par, bool clear_space, bool locked) {

  assert(_humongous_start_region == NULL,

         "we should have already filtered out humongous regions");

  assert(!in_collection_set(),

         "Should not clear heap region %u in the collection set", hrm_index());

  set_allocation_context(AllocationContext::system());

  set_young_index_in_cset(-1);

  uninstall_surv_rate_group();

  set_free();

  reset_pre_dummy_top();

  if (!par) {

    // If this is parallel, this will be done later.

    HeapRegionRemSet* hrrs = rem_set();

    if (locked) {

      hrrs->clear_locked();

    } else {

      hrrs->clear();

    }

  }

  zero_marked_bytes();

  _offsets.resize(HeapRegion::GrainWords);

  init_top_at_mark_start();

  if (clear_space) clear(SpaceDecorator::Mangle);

}

void HeapRegion::par_clear() {

  assert(used() == 0, "the region should have been already cleared");

  assert(capacity() == HeapRegion::GrainBytes, "should be back to normal");

  HeapRegionRemSet* hrrs = rem_set();

  hrrs->clear();

  CardTableModRefBS* ct_bs =

    barrier_set_cast<CardTableModRefBS>(G1CollectedHeap::heap()->barrier_set());

  ct_bs->clear(MemRegion(bottom(), end()));

}

void HeapRegion::calc_gc_efficiency() {

  // GC efficiency is the ratio of how much space would be

  // reclaimed over how long we predict it would take to reclaim it.

  G1CollectedHeap* g1h = G1CollectedHeap::heap();

  G1CollectorPolicy* g1p = g1h->g1_policy();

  // Retrieve a prediction of the elapsed time for this region for

  // a mixed gc because the region will only be evacuated during a

  // mixed gc.

  double region_elapsed_time_ms =

    g1p->predict_region_elapsed_time_ms(this, false /* for_young_gc */);

  _gc_efficiency = (double) reclaimable_bytes() / region_elapsed_time_ms;

}

void HeapRegion::set_starts_humongous(HeapWord* obj_top, size_t fill_size) {

  assert(!is_humongous(), "sanity / pre-condition");

  assert(top() == bottom(), "should be empty");

  _type.set_starts_humongous();

  _humongous_start_region = this;

  _offsets.set_for_starts_humongous(obj_top, fill_size);

}

void HeapRegion::set_continues_humongous(HeapRegion* first_hr) {

  assert(!is_humongous(), "sanity / pre-condition");

  assert(top() == bottom(), "should be empty");

  assert(first_hr->is_starts_humongous(), "pre-condition");

  _type.set_continues_humongous();

  _humongous_start_region = first_hr;

}

void HeapRegion::clear_humongous() {

  assert(is_humongous(), "pre-condition");

  assert(capacity() == HeapRegion::GrainBytes, "pre-condition");

  _humongous_start_region = NULL;

}

HeapRegion::HeapRegion(uint hrm_index,

                       G1BlockOffsetSharedArray* sharedOffsetArray,

                       MemRegion mr) :

    G1OffsetTableContigSpace(sharedOffsetArray, mr),

    _hrm_index(hrm_index),

    _allocation_context(AllocationContext::system()),

    _humongous_start_region(NULL),

    _next_in_special_set(NULL),

    _evacuation_failed(false),

    _prev_marked_bytes(0), _next_marked_bytes(0), _gc_efficiency(0.0),

    _next_young_region(NULL),

    _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL),

#ifdef ASSERT

    _containing_set(NULL),

#endif // ASSERT

     _young_index_in_cset(-1), _surv_rate_group(NULL), _age_index(-1),

    _rem_set(NULL), _recorded_rs_length(0), _predicted_elapsed_time_ms(0),

    _predicted_bytes_to_copy(0)

{

  _rem_set = new HeapRegionRemSet(sharedOffsetArray, this);

  assert(HeapRegionRemSet::num_par_rem_sets() > 0, "Invariant.");

  initialize(mr);

}

void HeapRegion::initialize(MemRegion mr, bool clear_space, bool mangle_space) {

  assert(_rem_set->is_empty(), "Remembered set must be empty");

  G1OffsetTableContigSpace::initialize(mr, clear_space, mangle_space);

  hr_clear(false /*par*/, false /*clear_space*/);

  set_top(bottom());

  record_timestamp();

}

CompactibleSpace* HeapRegion::next_compaction_space() const {

  return G1CollectedHeap::heap()->next_compaction_region(this);

}

void HeapRegion::note_self_forwarding_removal_start(bool during_initial_mark,

                                                    bool during_conc_mark) {

  // We always recreate the prev marking info and we'll explicitly

  // mark all objects we find to be self-forwarded on the prev

  // bitmap. So all objects need to be below PTAMS.

  _prev_marked_bytes = 0;

  if (during_initial_mark) {

    // During initial-mark, we'll also explicitly mark all objects

    // we find to be self-forwarded on the next bitmap. So all

    // objects need to be below NTAMS.

    _next_top_at_mark_start = top();

    _next_marked_bytes = 0;

  } else if (during_conc_mark) {

    // During concurrent mark, all objects in the CSet (including

    // the ones we find to be self-forwarded) are implicitly live.

    // So all objects need to be above NTAMS.

    _next_top_at_mark_start = bottom();

    _next_marked_bytes = 0;

  }

}

void HeapRegion::note_self_forwarding_removal_end(bool during_initial_mark,

                                                  bool during_conc_mark,

                                                  size_t marked_bytes) {

  assert(marked_bytes <= used(),

         "marked: " SIZE_FORMAT " used: " SIZE_FORMAT, marked_bytes, used());

  _prev_top_at_mark_start = top();

  _prev_marked_bytes = marked_bytes;

}

HeapWord*

HeapRegion::object_iterate_mem_careful(MemRegion mr,

                                                 ObjectClosure* cl) {

  G1CollectedHeap* g1h = G1CollectedHeap::heap();

  // We used to use "block_start_careful" here.  But we're actually happy

  // to update the BOT while we do this...

  HeapWord* cur = block_start(mr.start());

  mr = mr.intersection(used_region());

  if (mr.is_empty()) return NULL;

  // Otherwise, find the obj that extends onto mr.start().

  assert(cur <= mr.start()

         && (oop(cur)->klass_or_null() == NULL ||

             cur + oop(cur)->size() > mr.start()),

         "postcondition of block_start");

  oop obj;

  while (cur < mr.end()) {

    obj = oop(cur);

    if (obj->klass_or_null() == NULL) {

      // Ran into an unparseable point.

      return cur;

    } else if (!g1h->is_obj_dead(obj)) {

      cl->do_object(obj);

    }

    cur += block_size(cur);

  }

  return NULL;

}

HeapWord*

HeapRegion::

oops_on_card_seq_iterate_careful(MemRegion mr,

                                 FilterOutOfRegionClosure* cl,

                                 bool filter_young,

                                 jbyte* card_ptr) {

  // Currently, we should only have to clean the card if filter_young

  // is true and vice versa.

  if (filter_young) {

    assert(card_ptr != NULL, "pre-condition");

  } else {

    assert(card_ptr == NULL, "pre-condition");

  }

  G1CollectedHeap* g1h = G1CollectedHeap::heap();

  // If we're within a stop-world GC, then we might look at a card in a

  // GC alloc region that extends onto a GC LAB, which may not be

  // parseable.  Stop such at the "scan_top" of the region.

  if (g1h->is_gc_active()) {

    mr = mr.intersection(MemRegion(bottom(), scan_top()));

  } else {

    mr = mr.intersection(used_region());

  }

  if (mr.is_empty()) return NULL;

  // Otherwise, find the obj that extends onto mr.start().

  // The intersection of the incoming mr (for the card) and the

  // allocated part of the region is non-empty. This implies that

  // we have actually allocated into this region. The code in

  // G1CollectedHeap.cpp that allocates a new region sets the

  // is_young tag on the region before allocating. Thus we

  // safely know if this region is young.

  if (is_young() && filter_young) {

    return NULL;

  }

  assert(!is_young(), "check value of filter_young");

  // We can only clean the card here, after we make the decision that

  // the card is not young. And we only clean the card if we have been

  // asked to (i.e., card_ptr != NULL).

  if (card_ptr != NULL) {

    *card_ptr = CardTableModRefBS::clean_card_val();

    // We must complete this write before we do any of the reads below.

    OrderAccess::storeload();

  }

  // Cache the boundaries of the memory region in some const locals

  HeapWord* const start = mr.start();

  HeapWord* const end = mr.end();

  // We used to use "block_start_careful" here.  But we're actually happy

  // to update the BOT while we do this...

  HeapWord* cur = block_start(start);

  assert(cur <= start, "Postcondition");

  oop obj;

  HeapWord* next = cur;

  do {

    cur = next;

    obj = oop(cur);

    if (obj->klass_or_null() == NULL) {

      // Ran into an unparseable point.

      return cur;

    }

    // Otherwise...

    next = cur + block_size(cur);

  } while (next <= start);

  // If we finish the above loop...We have a parseable object that

  // begins on or before the start of the memory region, and ends

  // inside or spans the entire region.

  assert(cur <= start, "Loop postcondition");

  assert(obj->klass_or_null() != NULL, "Loop postcondition");

  do {

    obj = oop(cur);

    assert((cur + block_size(cur)) > (HeapWord*)obj, "Loop invariant");

    if (obj->klass_or_null() == NULL) {

      // Ran into an unparseable point.

      return cur;

    }

    // Advance the current pointer. "obj" still points to the object to iterate.

    cur = cur + block_size(cur);

    if (!g1h->is_obj_dead(obj)) {

      // Non-objArrays are sometimes marked imprecise at the object start. We

      // always need to iterate over them in full.

      // We only iterate over object arrays in full if they are completely contained

      // in the memory region.

      if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {

        obj->oop_iterate(cl);

      } else {

        obj->oop_iterate(cl, mr);

      }

    }

  } while (cur < end);

  return NULL;

}

// Code roots support

void HeapRegion::add_strong_code_root(nmethod* nm) {

  HeapRegionRemSet* hrrs = rem_set();

  hrrs->add_strong_code_root(nm);

}

void HeapRegion::add_strong_code_root_locked(nmethod* nm) {

  assert_locked_or_safepoint(CodeCache_lock);

  HeapRegionRemSet* hrrs = rem_set();

  hrrs->add_strong_code_root_locked(nm);

}

void HeapRegion::remove_strong_code_root(nmethod* nm) {

  HeapRegionRemSet* hrrs = rem_set();

  hrrs->remove_strong_code_root(nm);

}

void HeapRegion::strong_code_roots_do(CodeBlobClosure* blk) const {

  HeapRegionRemSet* hrrs = rem_set();

  hrrs->strong_code_roots_do(blk);

}

class VerifyStrongCodeRootOopClosure: public OopClosure {

  const HeapRegion* _hr;

  nmethod* _nm;

  bool _failures;

  bool _has_oops_in_region;

  template <class T> void do_oop_work(T* p) {

    T heap_oop = oopDesc::load_heap_oop(p);

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

      oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);

      // Note: not all the oops embedded in the nmethod are in the

      // current region. We only look at those which are.

      if (_hr->is_in(obj)) {

        // Object is in the region. Check that its less than top

        if (_hr->top() <= (HeapWord*)obj) {

          // Object is above top

          _failures = true;

          return;

        }

        // Nmethod has at least one oop in the current region

        _has_oops_in_region = true;

      }

    }

  }