/*

 * Copyright (c) 2001, 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

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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/g1HeapRegionTraceType.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/g1/heapRegionTracer.hpp"

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

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

#include "logging/log.hpp"

#include "memory/iterator.hpp"

#include "memory/resourceArea.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.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) { }

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;

  log_info(gc, heap)("Heap region size: " SIZE_FORMAT "M", GrainBytes / M);

  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;

  if (G1HeapRegionSize != GrainBytes) {

    FLAG_SET_ERGO(size_t, G1HeapRegionSize, GrainBytes);

  }

}

void HeapRegion::reset_after_compaction() {

  G1ContiguousSpace::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 keep_remset, 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 (!keep_remset) {

    if (locked) {

      rem_set()->clear_locked();

    } else {

      rem_set()->clear();

    }

  }

  zero_marked_bytes();

  init_top_at_mark_start();

  _gc_time_stamp = G1CollectedHeap::heap()->get_gc_time_stamp();

  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();

  G1Policy* 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_free() {

  report_region_type_change(G1HeapRegionTraceType::Free);

  _type.set_free();

}

void HeapRegion::set_eden() {

  report_region_type_change(G1HeapRegionTraceType::Eden);

  _type.set_eden();

}

void HeapRegion::set_eden_pre_gc() {

  report_region_type_change(G1HeapRegionTraceType::Eden);

  _type.set_eden_pre_gc();

}

void HeapRegion::set_survivor() {

  report_region_type_change(G1HeapRegionTraceType::Survivor);

  _type.set_survivor();

}

void HeapRegion::set_old() {

  report_region_type_change(G1HeapRegionTraceType::Old);

  _type.set_old();

}

void HeapRegion::set_archive() {

  report_region_type_change(G1HeapRegionTraceType::Archive);

  _type.set_archive();

}

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

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

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

  report_region_type_change(G1HeapRegionTraceType::StartsHumongous);

  _type.set_starts_humongous();

  _humongous_start_region = this;

  _bot_part.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");

  report_region_type_change(G1HeapRegionTraceType::ContinuesHumongous);

  _type.set_continues_humongous();

  _humongous_start_region = first_hr;

  _bot_part.set_object_can_span(true);

}

void HeapRegion::clear_humongous() {

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

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

  _humongous_start_region = NULL;

  _bot_part.set_object_can_span(false);

}

HeapRegion::HeapRegion(uint hrm_index,

                       G1BlockOffsetTable* bot,

                       MemRegion mr) :

    G1ContiguousSpace(bot),

    _hrm_index(hrm_index),

    _allocation_context(AllocationContext::system()),

    _humongous_start_region(NULL),

    _evacuation_failed(false),

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

    _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)

{

  _rem_set = new HeapRegionRemSet(bot, this);

  initialize(mr);

}

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

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

  G1ContiguousSpace::initialize(mr, clear_space, mangle_space);

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

  set_top(bottom());

  record_timestamp();

}

void HeapRegion::report_region_type_change(G1HeapRegionTraceType::Type to) {

  HeapRegionTracer::send_region_type_change(_hrm_index,

                                            get_trace_type(),

                                            to,

                                            (uintptr_t)bottom(),

                                            used(),

                                            (uint)allocation_context());

}

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(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;

}

// 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;

  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

          log_error(gc, verify)("Object " PTR_FORMAT " in region [" PTR_FORMAT ", " PTR_FORMAT ") is above top " PTR_FORMAT,

                               p2i(obj), p2i(_hr->bottom()), p2i(_hr->end()), p2i(_hr->top()));

          _failures = true;

          return;

        }

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

        _has_oops_in_region = true;

      }

    }

  }

public:

  VerifyStrongCodeRootOopClosure(const HeapRegion* hr):

    _hr(hr), _failures(false), _has_oops_in_region(false) {}

  void do_oop(narrowOop* p) { do_oop_work(p); }

  void do_oop(oop* p)       { do_oop_work(p); }

  bool failures()           { return _failures; }

  bool has_oops_in_region() { return _has_oops_in_region; }

};

class VerifyStrongCodeRootCodeBlobClosure: public CodeBlobClosure {

  const HeapRegion* _hr;

  bool _failures;

public:

  VerifyStrongCodeRootCodeBlobClosure(const HeapRegion* hr) :

    _hr(hr), _failures(false) {}

  void do_code_blob(CodeBlob* cb) {

    nmethod* nm = (cb == NULL) ? NULL : cb->as_compiled_method()->as_nmethod_or_null();

    if (nm != NULL) {

      // Verify that the nemthod is live

      if (!nm->is_alive()) {

        log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has dead nmethod " PTR_FORMAT " in its strong code roots",

                              p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));

        _failures = true;

      } else {

        VerifyStrongCodeRootOopClosure oop_cl(_hr);

        nm->oops_do(&oop_cl);

        if (!oop_cl.has_oops_in_region()) {

          log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has nmethod " PTR_FORMAT " in its strong code roots with no pointers into region",

                                p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));

          _failures = true;

        } else if (oop_cl.failures()) {

          log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] has other failures for nmethod " PTR_FORMAT,

                                p2i(_hr->bottom()), p2i(_hr->end()), p2i(nm));

          _failures = true;

        }

      }

    }

  }

  bool failures()       { return _failures; }

};

void HeapRegion::verify_strong_code_roots(VerifyOption vo, bool* failures) const {

  if (!G1VerifyHeapRegionCodeRoots) {

    // We're not verifying code roots.

    return;

  }

  if (vo == VerifyOption_G1UseMarkWord) {

    // Marking verification during a full GC is performed after class

    // unloading, code cache unloading, etc so the strong code roots

    // attached to each heap region are in an inconsistent state. They won't

    // be consistent until the strong code roots are rebuilt after the

    // actual GC. Skip verifying the strong code roots in this particular

    // time.

    assert(VerifyDuringGC, "only way to get here");

    return;

  }

  HeapRegionRemSet* hrrs = rem_set();

  size_t strong_code_roots_length = hrrs->strong_code_roots_list_length();

  // if this region is empty then there should be no entries

  // on its strong code root list

  if (is_empty()) {

    if (strong_code_roots_length > 0) {

      log_error(gc, verify)("region [" PTR_FORMAT "," PTR_FORMAT "] is empty but has " SIZE_FORMAT " code root entries",

                            p2i(bottom()), p2i(end()), strong_code_roots_length);

      *failures = true;

    }

    return;

  }

  if (is_continues_humongous()) {

    if (strong_code_roots_length > 0) {

      log_error(gc, verify)("region " HR_FORMAT " is a continuation of a humongous region but has " SIZE_FORMAT " code root entries",

                            HR_FORMAT_PARAMS(this), strong_code_roots_length);

      *failures = true;

    }

    return;

  }

  VerifyStrongCodeRootCodeBlobClosure cb_cl(this);

  strong_code_roots_do(&cb_cl);