/*

 * 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "gc_implementation/g1/heapRegion.hpp"

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

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

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

#include "gc_implementation/g1/concurrentG1Refine.hpp"

#include "memory/allocation.hpp"

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.resize(_regions.length(), false);

  _available_map.clear();

}

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->allocator()->new_heap_region(hrm_index, g1h->bot_shared(), mr);

}

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

  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);

  // Also commit auxiliary data

  _prev_bitmap_mapper->commit_regions(index, num_regions);

  _next_bitmap_mapper->commit_regions(index, num_regions);

  _bot_mapper->commit_regions(index, num_regions);

  _cardtable_mapper->commit_regions(index, num_regions);

  _card_counts_mapper->commit_regions(index, num_regions);

}

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

  guarantee(num_regions >= 1, err_msg("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->bottom(), hr->end());

    }

  }

  _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) {

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

  commit_regions(start, num_regions);

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

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

      HeapRegion* new_hr = new_heap_region(i);

      _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), err_msg("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->bottom(), hr->end());

    }

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

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

    hr->initialize(mr);

    insert_into_free_list(at(i));

  }

}

uint HeapRegionManager::expand_by(uint num_regions) {

  return expand_at(0, num_regions);

}

uint HeapRegionManager::expand_at(uint start, uint num_regions) {

  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);

    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()),

                err_msg("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()), err_msg("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, err_msg("Tried to access region %u that has a NULL HeapRegion*", i));

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

    if (res) {

      blk->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),

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

#endif

  return num_regions;

}

  const uint start_index = hrclaimer->start_region_for_worker(worker_id);

  // 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(0 <= index && index < n_regions, "sanity");

    // Skip over unavailable regions

    if (!is_available(index)) {

      continue;

    }

    HeapRegion* r = _regions.get_by_index(index);

    // We'll ignore "continues humongous" regions (we'll process them

    // when we come across their corresponding "start humongous"

    // region) and regions already claimed.

      continue;

    }

    // OK, try to claim it

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

      continue;

    }

    // Success!

      // If the region is "starts humongous" we'll iterate over its

      // "continues humongous" first; in fact we'll do them

      // first. The order is important. In one case, calling the

      // closure on the "starts humongous" region might de-allocate

      // and clear all its "continues humongous" regions and, as a

      // result, we might end up processing them twice. So, we'll do

      // them first (note: most closures will ignore them anyway) and

      // then we'll do the "starts humongous" region.

      for (uint ch_index = index + 1; ch_index < index + r->region_num(); ch_index++) {

        HeapRegion* chr = _regions.get_by_index(ch_index);

        assert(chr->is_continues_humongous(), "Must be humongous region");

        assert(chr->humongous_start_region() == r,

               err_msg("Must work on humongous continuation of the original start region "

                       PTR_FORMAT ", but is " PTR_FORMAT, p2i(r), p2i(chr)));

        assert(!hrclaimer->is_region_claimed(ch_index),

               "Must not have been claimed yet because claiming of humongous continuation first claims the start region");

        // There's no need to actually claim the continues humongous region, but we can do it in an assert as an extra precaution.

        assert(hrclaimer->claim_region(ch_index), "We should always be able to claim the continuesHumongous part of the humongous object");

        bool res2 = blk->doHeapRegion(chr);

        if (res2) {

          return;

        }

        // Right now, this holds (i.e., no closure that actually

        // does something with "continues humongous" regions

        // clears them). We might have to weaken it in the future,

        // but let's leave these two asserts here for extra safety.

        assert(chr->is_continues_humongous(), "should still be the case");

        assert(chr->humongous_start_region() == r, "sanity");

      }

    }

    bool res = blk->doHeapRegion(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);

    uncommit_regions(idx_last_found + num_last_found - to_remove, to_remove);

    cur -= num_last_found;

    removed += to_remove;

  }

  verify_optional();

  return removed;

}

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

  guarantee(start_idx < _allocated_heapregions_length, "checking");

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

  uint num_regions_found = 0;

  jlong cur = start_idx;

  while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {

    cur--;

  }

  if (cur == -1) {

    return num_regions_found;

  }

  jlong old_cur = cur;

  // cur indexes the first empty region

  while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {

    cur--;

  }

  *res_idx = cur + 1;

  num_regions_found = old_cur - cur;

#ifdef ASSERT

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

    assert(at(i)->is_empty(), "just checking");

  }

#endif

  return num_regions_found;

}

void HeapRegionManager::verify() {

  guarantee(length() <= _allocated_heapregions_length,

            err_msg("invariant: _length: %u _allocated_length: %u",

                    length(), _allocated_heapregions_length));

  guarantee(_allocated_heapregions_length <= max_length(),

            err_msg("invariant: _allocated_length: %u _max_length: %u",

                    _allocated_heapregions_length, max_length()));

  bool prev_committed = true;

  uint num_committed = 0;

  HeapWord* prev_end = heap_bottom();

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

    if (!is_available(i)) {

      prev_committed = false;

      continue;

    }

    num_committed++;

    HeapRegion* hr = _regions.get_by_index(i);

    guarantee(hr != NULL, err_msg("invariant: i: %u", i));

    guarantee(!prev_committed || hr->bottom() == prev_end,

              err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT,

                      i, HR_FORMAT_PARAMS(hr), p2i(prev_end)));

    guarantee(hr->hrm_index() == i,

              err_msg("invariant: i: %u hrm_index(): %u", i, hr->hrm_index()));

    // Asserts will fire if i is >= _length

    HeapWord* addr = hr->bottom();

    guarantee(addr_to_region(addr) == hr, "sanity");

    // We cannot check whether the region is part of a particular set: at the time

    // this method may be called, we have only completed allocation of the regions,

    // but not put into a region set.

    prev_committed = true;

    if (hr->is_starts_humongous()) {

      prev_end = hr->orig_end();

    } else {

      prev_end = hr->end();

    }

  }

  for (uint i = _allocated_heapregions_length; i < max_length(); i++) {

    guarantee(_regions.get_by_index(i) == NULL, err_msg("invariant i: %u", i));

  }

  guarantee(num_committed == _num_committed, err_msg("Found %u committed regions, but should be %u", num_committed, _num_committed));

  _free_list.verify();

}

#ifndef PRODUCT

void HeapRegionManager::verify_optional() {

  verify();

}

#endif // PRODUCT

HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :

    _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm._allocated_heapregions_length), _claims(NULL) {

  assert(n_workers > 0, "Need at least one worker.");

  _claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);

  memset(_claims, Unclaimed, sizeof(*_claims) * _n_regions);

}

HeapRegionClaimer::~HeapRegionClaimer() {

  if (_claims != NULL) {

    FREE_C_HEAP_ARRAY(uint, _claims, mtGC);

  }

}

uint HeapRegionClaimer::start_region_for_worker(uint worker_id) const {

  assert(worker_id < _n_workers, "Invalid worker_id.");

  return _n_regions * worker_id / _n_workers;

}

bool HeapRegionClaimer::is_region_claimed(uint region_index) const {

  assert(region_index < _n_regions, "Invalid index.");

  return _claims[region_index] == Claimed;

}

bool HeapRegionClaimer::claim_region(uint region_index) {

  assert(region_index < _n_regions, "Invalid index.");

  uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);

  return old_val == Unclaimed;

}