/*

 * 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/g1Arguments.hpp"

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

#include "gc/g1/g1ConcurrentRefine.hpp"

#include "gc/g1/heapRegion.hpp"

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

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

#include "gc/g1/heterogeneousHeapRegionManager.hpp"

#include "memory/allocation.hpp"

#include "utilities/bitMap.inline.hpp"

class MasterFreeRegionListChecker : public HeapRegionSetChecker {

public:

  void check_mt_safety() {

    // Master Free List MT safety protocol:

    // (a) If we're at a safepoint, operations on the master free list

    // should be invoked by either the VM thread (which will serialize

    // them) or by the GC workers while holding the

    // FreeList_lock.

    // (b) If we're not at a safepoint, operations on the master free

    // list should be invoked while holding the Heap_lock.

    if (SafepointSynchronize::is_at_safepoint()) {

      guarantee(Thread::current()->is_VM_thread() ||

                FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint");

    } else {

      guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint");

    }

  }

  bool is_correct_type(HeapRegion* hr) { return hr->is_free(); }

  const char* get_description() { return "Free Regions"; }

};

HeapRegionManager::HeapRegionManager() :

  _bot_mapper(NULL),

  _cardtable_mapper(NULL),

  _card_counts_mapper(NULL),

  _available_map(mtGC),

  _num_committed(0),

  _allocated_heapregions_length(0),

  _regions(), _heap_mapper(NULL),

  _prev_bitmap_mapper(NULL),

  _next_bitmap_mapper(NULL),

  _free_list("Free list", new MasterFreeRegionListChecker())

{ }

HeapRegionManager* HeapRegionManager::create_manager(G1CollectedHeap* heap) {

  if (G1Arguments::is_heterogeneous_heap()) {

    return new HeterogeneousHeapRegionManager((uint)(G1Arguments::heap_max_size_bytes() / HeapRegion::GrainBytes) /*heap size as num of regions*/);

  }

  return new HeapRegionManager();

}

void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage,

                               G1RegionToSpaceMapper* prev_bitmap,

                               G1RegionToSpaceMapper* next_bitmap,

                               G1RegionToSpaceMapper* bot,

                               G1RegionToSpaceMapper* cardtable,

                               G1RegionToSpaceMapper* card_counts) {

  _allocated_heapregions_length = 0;

  _heap_mapper = heap_storage;

  _prev_bitmap_mapper = prev_bitmap;

  _next_bitmap_mapper = next_bitmap;

  _bot_mapper = bot;

  _cardtable_mapper = cardtable;

  _card_counts_mapper = card_counts;

  MemRegion reserved = heap_storage->reserved();

  _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes);

  _available_map.initialize(_regions.length());

}

bool HeapRegionManager::is_available(uint region) const {

  return _available_map.at(region);

}

#ifdef ASSERT

bool HeapRegionManager::is_free(HeapRegion* hr) const {

  return _free_list.contains(hr);

}

#endif

HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) {

  G1CollectedHeap* g1h = G1CollectedHeap::heap();

  HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index);

  MemRegion mr(bottom, bottom + HeapRegion::GrainWords);

  assert(reserved().contains(mr), "invariant");

  return g1h->new_heap_region(hrm_index, mr);

}

void HeapRegionManager::commit_regions(uint index, size_t num_regions, WorkGang* pretouch_gang) {

  guarantee(num_regions > 0, "Must commit more than zero regions");

  guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");

  _num_committed += (uint)num_regions;

  _heap_mapper->commit_regions(index, num_regions, pretouch_gang);

  // Also commit auxiliary data

  _prev_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);

  _next_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);

  _bot_mapper->commit_regions(index, num_regions, pretouch_gang);

  _cardtable_mapper->commit_regions(index, num_regions, pretouch_gang);

  _card_counts_mapper->commit_regions(index, num_regions, pretouch_gang);

}

void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) {

  guarantee(num_regions >= 1, "Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start);

  guarantee(_num_committed >= num_regions, "pre-condition");

  // Print before uncommitting.

  if (G1CollectedHeap::heap()->hr_printer()->is_active()) {

    for (uint i = start; i < start + num_regions; i++) {

      HeapRegion* hr = at(i);

      G1CollectedHeap::heap()->hr_printer()->uncommit(hr);

    }

  }

  _num_committed -= (uint)num_regions;

  _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);

  _heap_mapper->uncommit_regions(start, num_regions);

  // Also uncommit auxiliary data

  _prev_bitmap_mapper->uncommit_regions(start, num_regions);

  _next_bitmap_mapper->uncommit_regions(start, num_regions);

  _bot_mapper->uncommit_regions(start, num_regions);

  _cardtable_mapper->uncommit_regions(start, num_regions);

  _card_counts_mapper->uncommit_regions(start, num_regions);

}

void HeapRegionManager::make_regions_available(uint start, uint num_regions, WorkGang* pretouch_gang) {

  guarantee(num_regions > 0, "No point in calling this for zero regions");

  commit_regions(start, num_regions, pretouch_gang);

  for (uint i = start; i < start + num_regions; i++) {

    if (_regions.get_by_index(i) == NULL) {

      HeapRegion* new_hr = new_heap_region(i);

      OrderAccess::storestore();

      _regions.set_by_index(i, new_hr);

      _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);

    }

  }

  _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);

  for (uint i = start; i < start + num_regions; i++) {

    assert(is_available(i), "Just made region %u available but is apparently not.", i);

    HeapRegion* hr = at(i);

    if (G1CollectedHeap::heap()->hr_printer()->is_active()) {

      G1CollectedHeap::heap()->hr_printer()->commit(hr);

    }

    HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i);

    MemRegion mr(bottom, bottom + HeapRegion::GrainWords);

    hr->initialize(mr);

    insert_into_free_list(at(i));

  }

}

MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const {

  size_t used_sz =

    _prev_bitmap_mapper->committed_size() +

    _next_bitmap_mapper->committed_size() +

    _bot_mapper->committed_size() +

    _cardtable_mapper->committed_size() +

    _card_counts_mapper->committed_size();

  size_t committed_sz =

    _prev_bitmap_mapper->reserved_size() +

    _next_bitmap_mapper->reserved_size() +

    _bot_mapper->reserved_size() +

    _cardtable_mapper->reserved_size() +

    _card_counts_mapper->reserved_size();

  return MemoryUsage(0, used_sz, committed_sz, committed_sz);

}

uint HeapRegionManager::expand_by(uint num_regions, WorkGang* pretouch_workers) {

  return expand_at(0, num_regions, pretouch_workers);

}

uint HeapRegionManager::expand_at(uint start, uint num_regions, WorkGang* pretouch_workers) {

  if (num_regions == 0) {

    return 0;

  }

  uint cur = start;

  uint idx_last_found = 0;

  uint num_last_found = 0;

  uint expanded = 0;

  while (expanded < num_regions &&

         (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {

    uint to_expand = MIN2(num_regions - expanded, num_last_found);

    make_regions_available(idx_last_found, to_expand, pretouch_workers);

    expanded += to_expand;

    cur = idx_last_found + num_last_found + 1;

  }

  verify_optional();

  return expanded;

}

uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) {

  uint found = 0;

  size_t length_found = 0;

  uint cur = 0;

  while (length_found < num && cur < max_length()) {

    HeapRegion* hr = _regions.get_by_index(cur);

    if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {

      // This region is a potential candidate for allocation into.

      length_found++;

    } else {

      // This region is not a candidate. The next region is the next possible one.

      found = cur + 1;

      length_found = 0;

    }

    cur++;

  }

  if (length_found == num) {

    for (uint i = found; i < (found + num); i++) {

      HeapRegion* hr = _regions.get_by_index(i);

      // sanity check

      guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),

                "Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT

                " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr));

    }

    return found;

  } else {

    return G1_NO_HRM_INDEX;

  }

}

HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {

  guarantee(r != NULL, "Start region must be a valid region");

  guarantee(is_available(r->hrm_index()), "Trying to iterate starting from region %u which is not in the heap", r->hrm_index());

  for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {

    HeapRegion* hr = _regions.get_by_index(i);

    if (is_available(i)) {

      return hr;

    }

  }

  return NULL;

}

void HeapRegionManager::iterate(HeapRegionClosure* blk) const {

  uint len = max_length();

  for (uint i = 0; i < len; i++) {

    if (!is_available(i)) {

      continue;

    }

    guarantee(at(i) != NULL, "Tried to access region %u that has a NULL HeapRegion*", i);

    bool res = blk->do_heap_region(at(i));

    if (res) {

      blk->set_incomplete();

      return;

    }

  }

}

uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {

  guarantee(res_idx != NULL, "checking");

  guarantee(start_idx <= (max_length() + 1), "checking");

  uint num_regions = 0;

  uint cur = start_idx;

  while (cur < max_length() && is_available(cur)) {

    cur++;

  }

  if (cur == max_length()) {

    return num_regions;

  }

  *res_idx = cur;

  while (cur < max_length() && !is_available(cur)) {

    cur++;

  }

  num_regions = cur - *res_idx;

#ifdef ASSERT

  for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {

    assert(!is_available(i), "just checking");

  }

  assert(cur == max_length() || num_regions == 0 || is_available(cur),

         "The region at the current position %u must be available or at the end of the heap.", cur);

#endif

  return num_regions;

}

uint HeapRegionManager::find_highest_free(bool* expanded) {

  // Loop downwards from the highest region index, looking for an

  // entry which is either free or not yet committed.  If not yet

  // committed, expand_at that index.

  uint curr = max_length() - 1;

  while (true) {

    HeapRegion *hr = _regions.get_by_index(curr);

    if (hr == NULL || !is_available(curr)) {

      uint res = expand_at(curr, 1, NULL);

      if (res == 1) {

        *expanded = true;

        return curr;

      }

    } else {

      if (hr->is_free()) {

        *expanded = false;

        return curr;

      }

    }

    if (curr == 0) {

      return G1_NO_HRM_INDEX;

    }

    curr--;

  }

}

bool HeapRegionManager::allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers) {

  size_t commits = 0;

  uint start_index = (uint)_regions.get_index_by_address(range.start());

  uint last_index = (uint)_regions.get_index_by_address(range.last());

  // Ensure that each G1 region in the range is free, returning false if not.

  // Commit those that are not yet available, and keep count.

  for (uint curr_index = start_index; curr_index <= last_index; curr_index++) {

    if (!is_available(curr_index)) {

      commits++;

      expand_at(curr_index, 1, pretouch_workers);

    }

    HeapRegion* curr_region  = _regions.get_by_index(curr_index);

    if (!curr_region->is_free()) {

      return false;

    }

  }

  allocate_free_regions_starting_at(start_index, (last_index - start_index) + 1);

  *commit_count = commits;

  return true;

}

void HeapRegionManager::par_iterate(HeapRegionClosure* blk, HeapRegionClaimer* hrclaimer, const uint start_index) const {

  // Every worker will actually look at all regions, skipping over regions that

  // are currently not committed.

  // This also (potentially) iterates over regions newly allocated during GC. This

  // is no problem except for some extra work.

  const uint n_regions = hrclaimer->n_regions();

  for (uint count = 0; count < n_regions; count++) {

    const uint index = (start_index + count) % n_regions;

    assert(index < n_regions, "sanity");

    // Skip over unavailable regions

    if (!is_available(index)) {

      continue;

    }

    HeapRegion* r = _regions.get_by_index(index);

    // We'll ignore regions already claimed.

    // However, if the iteration is specified as concurrent, the values for

    // is_starts_humongous and is_continues_humongous can not be trusted,

    // and we should just blindly iterate over regions regardless of their

    // humongous status.

    if (hrclaimer->is_region_claimed(index)) {

      continue;

    }

    // OK, try to claim it

    if (!hrclaimer->claim_region(index)) {

      continue;

    }

    bool res = blk->do_heap_region(r);

    if (res) {

      return;

    }

  }

}

uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {

  assert(length() > 0, "the region sequence should not be empty");

  assert(length() <= _allocated_heapregions_length, "invariant");

  assert(_allocated_heapregions_length > 0, "we should have at least one region committed");

  assert(num_regions_to_remove < length(), "We should never remove all regions");

  if (num_regions_to_remove == 0) {

    return 0;

  }

  uint removed = 0;

  uint cur = _allocated_heapregions_length - 1;

  uint idx_last_found = 0;

  uint num_last_found = 0;

  while ((removed < num_regions_to_remove) &&

      (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {

    uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);

    shrink_at(idx_last_found + num_last_found - to_remove, to_remove);