/*

 * Copyright (c) 2001, 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

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 */

#include "precompiled.hpp"

#include "code/nmethod.hpp"

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

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

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

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

#include "gc_implementation/g1/heapRegionRemSet.hpp"

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

#include "gc_implementation/shared/liveRange.hpp"

#include "memory/genOopClosures.inline.hpp"

#include "memory/iterator.hpp"

#include "memory/space.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.inline.hpp"

#include "runtime/orderAccess.inline.hpp"

PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

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, ExtendedOopClosure* cl,

                                 CardTableModRefBS::PrecisionStyle precision,

                                 FilterKind fk) :

  DirtyCardToOopClosure(hr, cl, precision, NULL),

  _hr(hr), _fk(fk), _g1(g1) { }

FilterOutOfRegionClosure::FilterOutOfRegionClosure(HeapRegion* r,

                                                   OopClosure* oc) :

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

template<class ClosureType>

HeapWord* walk_mem_region_loop(ClosureType* cl, G1CollectedHeap* g1h,

                               HeapRegion* hr,

                               HeapWord* cur, HeapWord* top) {

  oop cur_oop = oop(cur);

  size_t 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, hr)) {

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

      // non-memRegion version of oop_iterate below.

      cur_oop->oop_iterate(cl);

    }

    cur = next_obj;

    cur_oop = oop(cur);

    oop_size = hr->block_size(cur);

    next_obj = cur + oop_size;

  }

  return cur;

}

void HeapRegionDCTOC::walk_mem_region(MemRegion mr,

                                      HeapWord* bottom,

                                      HeapWord* top) {

  G1CollectedHeap* g1h = _g1;

  size_t oop_size;

  ExtendedOopClosure* cl2 = NULL;

  FilterIntoCSClosure intoCSFilt(this, g1h, _cl);

  FilterOutOfRegionClosure outOfRegionFilt(_hr, _cl);

  switch (_fk) {

  case NoFilterKind:          cl2 = _cl; break;

  case IntoCSFilterKind:      cl2 = &intoCSFilt; break;

  case OutOfRegionFilterKind: cl2 = &outOfRegionFilt; break;

  default:                    ShouldNotReachHere();

  }

  // 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(bottom), _hr)) {

    oop_size = oop(bottom)->oop_iterate(cl2, mr);

  } else {

    oop_size = _hr->block_size(bottom);

  }

  bottom += oop_size;

  if (bottom < top) {

    // We replicate the loop below for several kinds of possible filters.

    switch (_fk) {

    case NoFilterKind:

      bottom = walk_mem_region_loop(_cl, g1h, _hr, bottom, top);

      break;

    case IntoCSFilterKind: {

      FilterIntoCSClosure filt(this, g1h, _cl);

      bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);

      break;

    }

    case OutOfRegionFilterKind: {

      FilterOutOfRegionClosure filt(_hr, _cl);

      bottom = walk_mem_region_loop(&filt, g1h, _hr, bottom, top);

      break;

    }

    default:

      ShouldNotReachHere();

    }

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

    if (!g1h->is_obj_dead(oop(bottom), _hr)) {

      oop(bottom)->oop_iterate(cl2, mr);

    }

  }

}

// Minimum region size; we won't go lower than that.

// We might want to decrease this in the future, to deal with small

// heaps a bit more efficiently.

#define MIN_REGION_SIZE  (      1024 * 1024 )

// Maximum region size; we don't go higher than that. There's a good

// reason for having an upper bound. We don't want regions to get too

// large, otherwise cleanup's effectiveness would decrease as there

// will be fewer opportunities to find totally empty regions after

// marking.

#define MAX_REGION_SIZE  ( 32 * 1024 * 1024 )

// The automatic region size calculation will try to have around this

// many regions in the heap (based on the min heap size).

#define TARGET_REGION_NUMBER          2048

size_t HeapRegion::max_region_size() {

  return (size_t)MAX_REGION_SIZE;

}

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

  uintx 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 / TARGET_REGION_NUMBER,

                       (uintx) MIN_REGION_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 = ((uintx)1 << region_size_log);

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

  if (region_size < MIN_REGION_SIZE) {

    region_size = MIN_REGION_SIZE;

  } else if (region_size > MAX_REGION_SIZE) {

    region_size = MAX_REGION_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 = (size_t)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_type == NotHumongous,

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

  assert(_humongous_start_region == NULL,

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

  assert(_end == _orig_end,

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

  _in_collection_set = false;

  set_young_index_in_cset(-1);

  uninstall_surv_rate_group();

  set_young_type(NotYoung);

  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();

    }

    _claimed = InitialClaimValue;

  }

  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 =

                   (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_startsHumongous(HeapWord* new_top, HeapWord* new_end) {

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

  assert(end() == _orig_end,

         "Should be normal before the humongous object allocation");

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

  assert(bottom() <= new_top && new_top <= new_end, "pre-condition");

  _humongous_type = StartsHumongous;

  _humongous_start_region = this;

  set_end(new_end);

  _offsets.set_for_starts_humongous(new_top);

}

void HeapRegion::set_continuesHumongous(HeapRegion* first_hr) {

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

  assert(end() == _orig_end,

         "Should be normal before the humongous object allocation");

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

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

  _humongous_type = ContinuesHumongous;

  _humongous_start_region = first_hr;

}

void HeapRegion::set_notHumongous() {

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

  if (startsHumongous()) {

    assert(top() <= end(), "pre-condition");

    set_end(_orig_end);

    if (top() > end()) {

      // at least one "continues humongous" region after it

      set_top(end());

    }

  } else {

    // continues humongous

    assert(end() == _orig_end, "sanity");

  }

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

  _humongous_type = NotHumongous;

  _humongous_start_region = NULL;

}

bool HeapRegion::claimHeapRegion(jint claimValue) {

  jint current = _claimed;

  if (current != claimValue) {

    jint res = Atomic::cmpxchg(claimValue, &_claimed, current);

    if (res == current) {

      return true;

    }

  }

  return false;

}

HeapWord* HeapRegion::next_block_start_careful(HeapWord* addr) {

  HeapWord* low = addr;

  HeapWord* high = end();

  while (low < high) {

    size_t diff = pointer_delta(high, low);

    // Must add one below to bias toward the high amount.  Otherwise, if

  // "high" were at the desired value, and "low" were one less, we

    // would not converge on "high".  This is not symmetric, because

    // we set "high" to a block start, which might be the right one,

    // which we don't do for "low".

    HeapWord* middle = low + (diff+1)/2;

    if (middle == high) return high;

    HeapWord* mid_bs = block_start_careful(middle);

    if (mid_bs < addr) {

      low = middle;

    } else {

      high = mid_bs;

    }

  }

  assert(low == high && low >= addr, "Didn't work.");

  return low;

}

#ifdef _MSC_VER // the use of 'this' below gets a warning, make it go away

#pragma warning( disable:4355 ) // 'this' : used in base member initializer list

#endif // _MSC_VER

HeapRegion::HeapRegion(uint hrs_index,

                       G1BlockOffsetSharedArray* sharedOffsetArray,

                       MemRegion mr) :

    G1OffsetTableContigSpace(sharedOffsetArray, mr),

    _hrs_index(hrs_index),

    _humongous_type(NotHumongous), _humongous_start_region(NULL),

    _in_collection_set(false),

    _next_in_special_set(NULL), _orig_end(NULL),

    _claimed(InitialClaimValue), _evacuation_failed(false),

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

    _young_type(NotYoung), _next_young_region(NULL),

    _next_dirty_cards_region(NULL), _next(NULL), _prev(NULL), _pending_removal(false),

#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);

  _orig_end = mr.end();

  // Note that initialize() will set the start of the unmarked area of the

  // region.

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

  set_top(bottom());

  record_top_and_timestamp();

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

}

CompactibleSpace* HeapRegion::next_compaction_space() const {

  // We're not using an iterator given that it will wrap around when

  // it reaches the last region and this is not what we want here.

  G1CollectedHeap* g1h = G1CollectedHeap::heap();

  uint index = hrs_index() + 1;

  while (index < g1h->n_regions()) {

    HeapRegion* hr = g1h->region_at(index);

    if (!hr->isHumongous()) {

      return hr;

    }

    index += 1;

  }

  return NULL;

}

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(0 <= marked_bytes && marked_bytes <= used(),

         err_msg("marked: "SIZE_FORMAT" used: "SIZE_FORMAT,

                 marked_bytes, used()));

  _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 "saved_mark" of the region.

  if (g1h->is_gc_active()) {

    mr = mr.intersection(used_region_at_save_marks());

  } 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).