/*

 * Copyright (c) 2005, 2018, 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/parallel/parMarkBitMap.inline.hpp"

#include "gc/parallel/psCompactionManager.inline.hpp"

#include "gc/parallel/psParallelCompact.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.hpp"

#include "runtime/os.hpp"

#include "services/memTracker.hpp"

#include "utilities/align.hpp"

#include "utilities/bitMap.inline.hpp"

bool

ParMarkBitMap::initialize(MemRegion covered_region)

{

  const idx_t bits = bits_required(covered_region);

  // The bits will be divided evenly between two bitmaps; each of them should be

  // an integral number of words.

  assert(bits % (BitsPerWord * 2) == 0, "region size unaligned");

  const size_t words = bits / BitsPerWord;

  const size_t raw_bytes = words * sizeof(idx_t);

  const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);

  const size_t granularity = os::vm_allocation_granularity();

  _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));

  const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :

    MAX2(page_sz, granularity);

  ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);

  os::trace_page_sizes("Mark Bitmap", raw_bytes, raw_bytes, page_sz,

                       rs.base(), rs.size());

  MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);

  _virtual_space = new PSVirtualSpace(rs, page_sz);

  if (_virtual_space != NULL && _virtual_space->expand_by(_reserved_byte_size)) {

    _region_start = covered_region.start();

    _region_size = covered_region.word_size();

    BitMap::bm_word_t* map = (BitMap::bm_word_t*)_virtual_space->reserved_low_addr();

    _beg_bits = BitMapView(map,             bits / 2);

    _end_bits = BitMapView(map + words / 2, bits / 2);

    return true;

  }

  _region_start = 0;

  _region_size = 0;

  if (_virtual_space != NULL) {

    delete _virtual_space;

    _virtual_space = NULL;

    // Release memory reserved in the space.

    rs.release();

  }

  return false;

}

#ifdef ASSERT

extern size_t mark_bitmap_count;

extern size_t mark_bitmap_size;

#endif  // #ifdef ASSERT

bool

ParMarkBitMap::mark_obj(HeapWord* addr, size_t size)

{

  const idx_t beg_bit = addr_to_bit(addr);

  if (_beg_bits.par_set_bit(beg_bit)) {

    const idx_t end_bit = addr_to_bit(addr + size - 1);

    bool end_bit_ok = _end_bits.par_set_bit(end_bit);

    assert(end_bit_ok, "concurrency problem");

    DEBUG_ONLY(Atomic::inc(&mark_bitmap_count));

    return true;

  }

  return false;

}

inline bool

ParMarkBitMap::is_live_words_in_range_in_cache(ParCompactionManager* cm, HeapWord* beg_addr) const {

  return cm->last_query_begin() == beg_addr;

}

inline void

ParMarkBitMap::update_live_words_in_range_cache(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj, size_t result) const {

  cm->set_last_query_begin(beg_addr);

  cm->set_last_query_object(end_obj);

  cm->set_last_query_return(result);

}

size_t

ParMarkBitMap::live_words_in_range_helper(HeapWord* beg_addr, oop end_obj) const

{

  assert(beg_addr <= (HeapWord*)end_obj, "bad range");

  assert(is_marked(end_obj), "end_obj must be live");

  idx_t live_bits = 0;

  // The bitmap routines require the right boundary to be word-aligned.

  const idx_t end_bit = addr_to_bit((HeapWord*)end_obj);

  const idx_t range_end = BitMap::word_align_up(end_bit);

  idx_t beg_bit = find_obj_beg(addr_to_bit(beg_addr), range_end);

  while (beg_bit < end_bit) {

    idx_t tmp_end = find_obj_end(beg_bit, range_end);

    assert(tmp_end < end_bit, "missing end bit");

    live_bits += tmp_end - beg_bit + 1;

    beg_bit = find_obj_beg(tmp_end + 1, range_end);

  }

  return bits_to_words(live_bits);

}

size_t

ParMarkBitMap::live_words_in_range_use_cache(ParCompactionManager* cm, HeapWord* beg_addr, oop end_oop) const

{

  HeapWord* last_beg = cm->last_query_begin();

  HeapWord* last_obj = (HeapWord*)cm->last_query_object();

  HeapWord* end_obj  = (HeapWord*)end_oop;

  size_t last_ret = cm->last_query_return();

  if (end_obj > last_obj) {

    last_ret = last_ret + live_words_in_range_helper(last_obj, end_oop);

    last_obj = end_obj;

  } else if (end_obj < last_obj) {

    // The cached value is for an object that is to the left (lower address) of the current

    // end_obj. Calculate back from that cached value.

    if (pointer_delta(end_obj, beg_addr) > pointer_delta(last_obj, end_obj)) {

      last_ret = last_ret - live_words_in_range_helper(end_obj, (oop)last_obj);

    } else {

      last_ret = live_words_in_range_helper(beg_addr, end_oop);

    }

    last_obj = end_obj;

  }

  update_live_words_in_range_cache(cm, last_beg, (oop)last_obj, last_ret);

  return last_ret;

}

size_t

ParMarkBitMap::live_words_in_range(ParCompactionManager* cm, HeapWord* beg_addr, oop end_obj) const

{

  // Try to reuse result from ParCompactionManager cache first.

  if (is_live_words_in_range_in_cache(cm, beg_addr)) {

    return live_words_in_range_use_cache(cm, beg_addr, end_obj);

  }

  size_t ret = live_words_in_range_helper(beg_addr, end_obj);

  update_live_words_in_range_cache(cm, beg_addr, end_obj, ret);

  return ret;

}

ParMarkBitMap::IterationStatus

ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,

                       idx_t range_beg, idx_t range_end) const

{

  DEBUG_ONLY(verify_bit(range_beg);)

  DEBUG_ONLY(verify_bit(range_end);)

  assert(range_beg <= range_end, "live range invalid");

  // The bitmap routines require the right boundary to be word-aligned.

  const idx_t search_end = BitMap::word_align_up(range_end);

  idx_t cur_beg = find_obj_beg(range_beg, search_end);

  while (cur_beg < range_end) {

    const idx_t cur_end = find_obj_end(cur_beg, search_end);

    if (cur_end >= range_end) {

      // The obj ends outside the range.

      live_closure->set_source(bit_to_addr(cur_beg));

      return incomplete;

    }

    const size_t size = obj_size(cur_beg, cur_end);

    IterationStatus status = live_closure->do_addr(bit_to_addr(cur_beg), size);

    if (status != incomplete) {

      assert(status == would_overflow || status == full, "sanity");

      return status;

    }

    // Successfully processed the object; look for the next object.

    cur_beg = find_obj_beg(cur_end + 1, search_end);

  }

  live_closure->set_source(bit_to_addr(range_end));

  return complete;

}

ParMarkBitMap::IterationStatus

ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,

                       ParMarkBitMapClosure* dead_closure,

                       idx_t range_beg, idx_t range_end,

                       idx_t dead_range_end) const

{

  DEBUG_ONLY(verify_bit(range_beg);)

  DEBUG_ONLY(verify_bit(range_end);)

  DEBUG_ONLY(verify_bit(dead_range_end);)

  assert(range_beg <= range_end, "live range invalid");

  assert(range_end <= dead_range_end, "dead range invalid");

  // The bitmap routines require the right boundary to be word-aligned.

  const idx_t live_search_end = BitMap::word_align_up(range_end);

  const idx_t dead_search_end = BitMap::word_align_up(dead_range_end);

  idx_t cur_beg = range_beg;

  if (range_beg < range_end && is_unmarked(range_beg)) {

    // The range starts with dead space.  Look for the next object, then fill.

    cur_beg = find_obj_beg(range_beg + 1, dead_search_end);

    const idx_t dead_space_end = MIN2(cur_beg - 1, dead_range_end - 1);

    const size_t size = obj_size(range_beg, dead_space_end);

    dead_closure->do_addr(bit_to_addr(range_beg), size);

  }

  while (cur_beg < range_end) {

    const idx_t cur_end = find_obj_end(cur_beg, live_search_end);

    if (cur_end >= range_end) {

      // The obj ends outside the range.

      live_closure->set_source(bit_to_addr(cur_beg));

      return incomplete;

    }

    const size_t size = obj_size(cur_beg, cur_end);

    IterationStatus status = live_closure->do_addr(bit_to_addr(cur_beg), size);

    if (status != incomplete) {

      assert(status == would_overflow || status == full, "sanity");

      return status;

    }

    // Look for the start of the next object.

    const idx_t dead_space_beg = cur_end + 1;

    cur_beg = find_obj_beg(dead_space_beg, dead_search_end);

    if (cur_beg > dead_space_beg) {

      // Found dead space; compute the size and invoke the dead closure.

      const idx_t dead_space_end = MIN2(cur_beg - 1, dead_range_end - 1);

      const size_t size = obj_size(dead_space_beg, dead_space_end);

      dead_closure->do_addr(bit_to_addr(dead_space_beg), size);

    }

  }

  live_closure->set_source(bit_to_addr(range_end));

  return complete;

}

#ifdef ASSERT

void ParMarkBitMap::verify_clear() const

{

  const idx_t* const beg = (const idx_t*)_virtual_space->committed_low_addr();

  const idx_t* const end = (const idx_t*)_virtual_space->committed_high_addr();

  for (const idx_t* p = beg; p < end; ++p) {

    assert(*p == 0, "bitmap not clear");

  }

}

#endif  // #ifdef ASSERT