/*

 * Copyright (c) 2001, 2019, 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/g1BlockOffsetTable.inline.hpp"

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

#include "gc/g1/g1ConcurrentRefine.hpp"

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

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

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

#include "memory/allocation.hpp"

#include "memory/padded.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.hpp"

#include "utilities/bitMap.inline.hpp"

#include "utilities/debug.hpp"

#include "utilities/formatBuffer.hpp"

#include "utilities/globalDefinitions.hpp"

#include "utilities/growableArray.hpp"

const char* HeapRegionRemSet::_state_strings[] =  {"Untracked", "Updating", "Complete"};

const char* HeapRegionRemSet::_short_state_strings[] =  {"UNTRA", "UPDAT", "CMPLT"};

PerRegionTable* PerRegionTable::alloc(HeapRegion* hr) {

  PerRegionTable* fl = _free_list;

  while (fl != NULL) {

    PerRegionTable* nxt = fl->next();

    PerRegionTable* res = Atomic::cmpxchg(nxt, &_free_list, fl);

    if (res == fl) {

      fl->init(hr, true);

      return fl;

    } else {

      fl = _free_list;

    }

  }

  assert(fl == NULL, "Loop condition.");

  return new PerRegionTable(hr);

}

PerRegionTable* volatile PerRegionTable::_free_list = NULL;

size_t OtherRegionsTable::_max_fine_entries = 0;

size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;

size_t OtherRegionsTable::_fine_eviction_stride = 0;

size_t OtherRegionsTable::_fine_eviction_sample_size = 0;

OtherRegionsTable::OtherRegionsTable(Mutex* m) :

  _g1h(G1CollectedHeap::heap()),

  _m(m),

  _coarse_map(G1CollectedHeap::heap()->max_regions(), mtGC),

  _n_coarse_entries(0),

  _fine_grain_regions(NULL),

  _n_fine_entries(0),

  _first_all_fine_prts(NULL),

  _last_all_fine_prts(NULL),

  _fine_eviction_start(0),

  _sparse_table()

{

  typedef PerRegionTable* PerRegionTablePtr;

  if (_max_fine_entries == 0) {

    assert(_mod_max_fine_entries_mask == 0, "Both or none.");

    size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);

    _max_fine_entries = (size_t)1 << max_entries_log;

    _mod_max_fine_entries_mask = _max_fine_entries - 1;

    assert(_fine_eviction_sample_size == 0

           && _fine_eviction_stride == 0, "All init at same time.");

    _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);

    _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;

  }

  _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,

                        mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);

  if (_fine_grain_regions == NULL) {

    vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,

                          "Failed to allocate _fine_grain_entries.");

  }

  for (size_t i = 0; i < _max_fine_entries; i++) {

    _fine_grain_regions[i] = NULL;

  }

}

void OtherRegionsTable::link_to_all(PerRegionTable* prt) {

  // We always append to the beginning of the list for convenience;

  // the order of entries in this list does not matter.

  if (_first_all_fine_prts != NULL) {

    assert(_first_all_fine_prts->prev() == NULL, "invariant");

    _first_all_fine_prts->set_prev(prt);

    prt->set_next(_first_all_fine_prts);

  } else {

    // this is the first element we insert. Adjust the "last" pointer

    _last_all_fine_prts = prt;

    assert(prt->next() == NULL, "just checking");

  }

  // the new element is always the first element without a predecessor

  prt->set_prev(NULL);

  _first_all_fine_prts = prt;

  assert(prt->prev() == NULL, "just checking");

  assert(_first_all_fine_prts == prt, "just checking");

  assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||

         (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),

         "just checking");

  assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,

         "just checking");

  assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,

         "just checking");

}

void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {

  if (prt->prev() != NULL) {

    assert(_first_all_fine_prts != prt, "just checking");

    prt->prev()->set_next(prt->next());

    // removing the last element in the list?

    if (_last_all_fine_prts == prt) {

      _last_all_fine_prts = prt->prev();

    }

  } else {

    assert(_first_all_fine_prts == prt, "just checking");

    _first_all_fine_prts = prt->next();

    // list is empty now?

    if (_first_all_fine_prts == NULL) {

      _last_all_fine_prts = NULL;

    }

  }

  if (prt->next() != NULL) {

    prt->next()->set_prev(prt->prev());

  }

  prt->set_next(NULL);

  prt->set_prev(NULL);

  assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||

         (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),

         "just checking");

  assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,

         "just checking");

  assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,

         "just checking");

}

CardIdx_t OtherRegionsTable::card_within_region(OopOrNarrowOopStar within_region, HeapRegion* hr) {

  assert(hr->is_in_reserved(within_region),

         "HeapWord " PTR_FORMAT " is outside of region %u [" PTR_FORMAT ", " PTR_FORMAT ")",

         p2i(within_region), hr->hrm_index(), p2i(hr->bottom()), p2i(hr->end()));

  CardIdx_t result = (CardIdx_t)(pointer_delta((HeapWord*)within_region, hr->bottom()) >> (CardTable::card_shift - LogHeapWordSize));

  return result;

}

void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {

  // Note that this may be a continued H region.

  HeapRegion* from_hr = _g1h->heap_region_containing(from);

  RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();

  // If the region is already coarsened, return.

  if (_coarse_map.at(from_hrm_ind)) {

    assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));

    return;

  }

  // Otherwise find a per-region table to add it to.

  size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;

  PerRegionTable* prt = find_region_table(ind, from_hr);

  if (prt == NULL) {

    MutexLocker x(_m, Mutex::_no_safepoint_check_flag);

    // Confirm that it's really not there...

    prt = find_region_table(ind, from_hr);

    if (prt == NULL) {

      CardIdx_t card_index = card_within_region(from, from_hr);

      if (_sparse_table.add_card(from_hrm_ind, card_index)) {

        assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));

        return;

      }

      if (_n_fine_entries == _max_fine_entries) {

        prt = delete_region_table();

        // There is no need to clear the links to the 'all' list here:

        // prt will be reused immediately, i.e. remain in the 'all' list.

        prt->init(from_hr, false /* clear_links_to_all_list */);

      } else {

        prt = PerRegionTable::alloc(from_hr);

        link_to_all(prt);

      }

      PerRegionTable* first_prt = _fine_grain_regions[ind];

      prt->set_collision_list_next(first_prt);

      // The assignment into _fine_grain_regions allows the prt to

      // start being used concurrently. In addition to

      // collision_list_next which must be visible (else concurrent

      // parsing of the list, if any, may fail to see other entries),

      // the content of the prt must be visible (else for instance

      // some mark bits may not yet seem cleared or a 'later' update

      // performed by a concurrent thread could be undone when the

      // zeroing becomes visible). This requires store ordering.

      _n_fine_entries++;

      // Transfer from sparse to fine-grain.

      SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);

      assert(sprt_entry != NULL, "There should have been an entry");

      for (int i = 0; i < sprt_entry->num_valid_cards(); i++) {

        CardIdx_t c = sprt_entry->card(i);

        prt->add_card(c);

      }

      // Now we can delete the sparse entry.

      bool res = _sparse_table.delete_entry(from_hrm_ind);

      assert(res, "It should have been there.");

    }

    assert(prt != NULL && prt->hr() == from_hr, "consequence");

  }

  // Note that we can't assert "prt->hr() == from_hr", because of the

  // possibility of concurrent reuse.  But see head comment of

  // OtherRegionsTable for why this is OK.

  assert(prt != NULL, "Inv");

  prt->add_reference(from);

  assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT (%d)", p2i(from), prt->contains_reference(from));

}

PerRegionTable*

OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {

  assert(ind < _max_fine_entries, "Preconditions.");

  PerRegionTable* prt = _fine_grain_regions[ind];

  while (prt != NULL && prt->hr() != hr) {

    prt = prt->collision_list_next();

  }

  // Loop postcondition is the method postcondition.

  return prt;

}

jint OtherRegionsTable::_n_coarsenings = 0;

PerRegionTable* OtherRegionsTable::delete_region_table() {

  assert(_m->owned_by_self(), "Precondition");

  assert(_n_fine_entries == _max_fine_entries, "Precondition");

  PerRegionTable* max = NULL;

  jint max_occ = 0;

  PerRegionTable** max_prev = NULL;

  size_t max_ind;

  size_t i = _fine_eviction_start;

  for (size_t k = 0; k < _fine_eviction_sample_size; k++) {

    size_t ii = i;

    // Make sure we get a non-NULL sample.

    while (_fine_grain_regions[ii] == NULL) {

      ii++;

      if (ii == _max_fine_entries) ii = 0;

      guarantee(ii != i, "We must find one.");

    }

    PerRegionTable** prev = &_fine_grain_regions[ii];

    PerRegionTable* cur = *prev;

    while (cur != NULL) {

      jint cur_occ = cur->occupied();

      if (max == NULL || cur_occ > max_occ) {

        max = cur;

        max_prev = prev;

        max_ind = i;

        max_occ = cur_occ;

      }

      prev = cur->collision_list_next_addr();

      cur = cur->collision_list_next();

    }

    i = i + _fine_eviction_stride;

    if (i >= _n_fine_entries) i = i - _n_fine_entries;

  }

  _fine_eviction_start++;

  if (_fine_eviction_start >= _n_fine_entries) {

    _fine_eviction_start -= _n_fine_entries;

  }

  guarantee(max != NULL, "Since _n_fine_entries > 0");

  guarantee(max_prev != NULL, "Since max != NULL.");

  // Set the corresponding coarse bit.

  size_t max_hrm_index = (size_t) max->hr()->hrm_index();

  if (!_coarse_map.at(max_hrm_index)) {

    _coarse_map.at_put(max_hrm_index, true);

    _n_coarse_entries++;

  }

  // Unsplice.

  *max_prev = max->collision_list_next();

  Atomic::inc(&_n_coarsenings);

  _n_fine_entries--;

  return max;

}

bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {

  if (limit <= (size_t)G1RSetSparseRegionEntries) {

    return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;

  } else {

    // Current uses of this method may only use values less than G1RSetSparseRegionEntries

    // for the limit. The solution, comparing against occupied() would be too slow

    // at this time.

    Unimplemented();

    return false;

  }

}

bool OtherRegionsTable::is_empty() const {

  return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;

}

size_t OtherRegionsTable::occupied() const {

  size_t sum = occ_fine();

  sum += occ_sparse();

  sum += occ_coarse();

  return sum;

}

size_t OtherRegionsTable::occ_fine() const {

  size_t sum = 0;

  size_t num = 0;

  PerRegionTable * cur = _first_all_fine_prts;

  while (cur != NULL) {

    sum += cur->occupied();

    cur = cur->next();

    num++;

  }

  guarantee(num == _n_fine_entries, "just checking");

  return sum;

}

size_t OtherRegionsTable::occ_coarse() const {

  return (_n_coarse_entries * HeapRegion::CardsPerRegion);

}

size_t OtherRegionsTable::occ_sparse() const {

  return _sparse_table.occupied();

}

size_t OtherRegionsTable::mem_size() const {

  size_t sum = 0;

  // all PRTs are of the same size so it is sufficient to query only one of them.

  if (_first_all_fine_prts != NULL) {

    assert(_last_all_fine_prts != NULL &&

      _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");

    sum += _first_all_fine_prts->mem_size() * _n_fine_entries;

  }

  sum += (sizeof(PerRegionTable*) * _max_fine_entries);

  sum += (_coarse_map.size_in_words() * HeapWordSize);

  sum += (_sparse_table.mem_size());

  sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.

  return sum;

}

size_t OtherRegionsTable::static_mem_size() {

  return G1FromCardCache::static_mem_size();

}

size_t OtherRegionsTable::fl_mem_size() {

  return PerRegionTable::fl_mem_size();

}

void OtherRegionsTable::clear() {

  // if there are no entries, skip this step

  if (_first_all_fine_prts != NULL) {

    guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");

    PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);

    memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));

  } else {

    guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");

  }

  _first_all_fine_prts = _last_all_fine_prts = NULL;

  _sparse_table.clear();

  if (_n_coarse_entries > 0) {

    _coarse_map.clear();

  }

  _n_fine_entries = 0;

  _n_coarse_entries = 0;

}

bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {

  // Cast away const in this case.

  MutexLocker x((Mutex*)_m, Mutex::_no_safepoint_check_flag);

  return contains_reference_locked(from);

}

bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {

  HeapRegion* hr = _g1h->heap_region_containing(from);

  RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();

  // Is this region in the coarse map?

  if (_coarse_map.at(hr_ind)) return true;

  PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,

                                          hr);

  if (prt != NULL) {

    return prt->contains_reference(from);

  } else {

    CardIdx_t card_index = card_within_region(from, hr);

    return _sparse_table.contains_card(hr_ind, card_index);

  }

}

HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,

                                   HeapRegion* hr)

  : _bot(bot),

    _code_roots(),

    _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Mutex::_safepoint_check_never),

    _other_regions(&_m),

    _hr(hr),

    _state(Untracked)

{

}

void HeapRegionRemSet::clear_fcc() {

  G1FromCardCache::clear(_hr->hrm_index());

}

void HeapRegionRemSet::setup_remset_size() {

  const int LOG_M = 20;

  guarantee(HeapRegion::LogOfHRGrainBytes >= LOG_M, "Code assumes the region size >= 1M, but is " SIZE_FORMAT "B", HeapRegion::GrainBytes);

  int region_size_log_mb = HeapRegion::LogOfHRGrainBytes - LOG_M;

  if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {

    G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * ((size_t)1 << (region_size_log_mb + 1));

  }

  if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {

    G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);

  }

  guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");

}

void HeapRegionRemSet::clear(bool only_cardset) {

  MutexLocker x(&_m, Mutex::_no_safepoint_check_flag);

  clear_locked(only_cardset);

}

void HeapRegionRemSet::clear_locked(bool only_cardset) {

  if (!only_cardset) {

    _code_roots.clear();

  }

  clear_fcc();

  _other_regions.clear();

  set_state_empty();

  assert(occupied_locked() == 0, "Should be clear.");

}

// Code roots support

//

// The code root set is protected by two separate locking schemes

// When at safepoint the per-hrrs lock must be held during modifications

// except when doing a full gc.

// When not at safepoint the CodeCache_lock must be held during modifications.

// When concurrent readers access the contains() function

// (during the evacuation phase) no removals are allowed.

void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {

  assert(nm != NULL, "sanity");

  assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),

          "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",

          BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));

  // Optimistic unlocked contains-check

  if (!_code_roots.contains(nm)) {

    MutexLocker ml(&_m, Mutex::_no_safepoint_check_flag);

    add_strong_code_root_locked(nm);

  }

}

void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {

  assert(nm != NULL, "sanity");

  assert((CodeCache_lock->owned_by_self() ||

         (SafepointSynchronize::is_at_safepoint() &&