/*

 * Copyright 2000-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

// This kind of "BarrierSet" allows a "CollectedHeap" to detect and

// enumerate ref fields that have been modified (since the last

// enumeration.)

# include "incls/_precompiled.incl"

# include "incls/_cardTableModRefBS.cpp.incl"

size_t CardTableModRefBS::cards_required(size_t covered_words)

{

  // Add one for a guard card, used to detect errors.

  const size_t words = align_size_up(covered_words, card_size_in_words);

  return words / card_size_in_words + 1;

}

size_t CardTableModRefBS::compute_byte_map_size()

{

  assert(_guard_index == cards_required(_whole_heap.word_size()) - 1,

                                        "unitialized, check declaration order");

  assert(_page_size != 0, "unitialized, check declaration order");

  const size_t granularity = os::vm_allocation_granularity();

  return align_size_up(_guard_index + 1, MAX2(_page_size, granularity));

}

CardTableModRefBS::CardTableModRefBS(MemRegion whole_heap,

                                     int max_covered_regions):

  ModRefBarrierSet(max_covered_regions),

  _whole_heap(whole_heap),

  _guard_index(cards_required(whole_heap.word_size()) - 1),

  _last_valid_index(_guard_index - 1),

  _page_size(os::vm_page_size()),

  _byte_map_size(compute_byte_map_size())

{

  _kind = BarrierSet::CardTableModRef;

  HeapWord* low_bound  = _whole_heap.start();

  HeapWord* high_bound = _whole_heap.end();

  assert((uintptr_t(low_bound)  & (card_size - 1))  == 0, "heap must start at card boundary");

  assert((uintptr_t(high_bound) & (card_size - 1))  == 0, "heap must end at card boundary");

  assert(card_size <= 512, "card_size must be less than 512"); // why?

  _covered   = new MemRegion[max_covered_regions];

  _committed = new MemRegion[max_covered_regions];

  if (_covered == NULL || _committed == NULL)

    vm_exit_during_initialization("couldn't alloc card table covered region set.");

  int i;

  for (i = 0; i < max_covered_regions; i++) {

    _covered[i].set_word_size(0);

    _committed[i].set_word_size(0);

  }

  _cur_covered_regions = 0;

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

    MAX2(_page_size, (size_t) os::vm_allocation_granularity());

  ReservedSpace heap_rs(_byte_map_size, rs_align, false);

  os::trace_page_sizes("card table", _guard_index + 1, _guard_index + 1,

                       _page_size, heap_rs.base(), heap_rs.size());

  if (!heap_rs.is_reserved()) {

    vm_exit_during_initialization("Could not reserve enough space for the "

                                  "card marking array");

  }

  // The assember store_check code will do an unsigned shift of the oop,

  // then add it to byte_map_base, i.e.

  //

  //   _byte_map = byte_map_base + (uintptr_t(low_bound) >> card_shift)

  _byte_map = (jbyte*) heap_rs.base();

  byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);

  assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");

  assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");

  jbyte* guard_card = &_byte_map[_guard_index];

  uintptr_t guard_page = align_size_down((uintptr_t)guard_card, _page_size);

  _guard_region = MemRegion((HeapWord*)guard_page, _page_size);

  if (!os::commit_memory((char*)guard_page, _page_size, _page_size)) {

    // Do better than this for Merlin

    vm_exit_out_of_memory(_page_size, "card table last card");

  }

  *guard_card = last_card;

   _lowest_non_clean =

    NEW_C_HEAP_ARRAY(CardArr, max_covered_regions);

  _lowest_non_clean_chunk_size =

    NEW_C_HEAP_ARRAY(size_t, max_covered_regions);

  _lowest_non_clean_base_chunk_index =

    NEW_C_HEAP_ARRAY(uintptr_t, max_covered_regions);

  _last_LNC_resizing_collection =

    NEW_C_HEAP_ARRAY(int, max_covered_regions);

  if (_lowest_non_clean == NULL

      || _lowest_non_clean_chunk_size == NULL

      || _lowest_non_clean_base_chunk_index == NULL

      || _last_LNC_resizing_collection == NULL)

    vm_exit_during_initialization("couldn't allocate an LNC array.");

  for (i = 0; i < max_covered_regions; i++) {

    _lowest_non_clean[i] = NULL;

    _lowest_non_clean_chunk_size[i] = 0;

    _last_LNC_resizing_collection[i] = -1;

  }

  if (TraceCardTableModRefBS) {

    gclog_or_tty->print_cr("CardTableModRefBS::CardTableModRefBS: ");

    gclog_or_tty->print_cr("  "

                  "  &_byte_map[0]: " INTPTR_FORMAT

                  "  &_byte_map[_last_valid_index]: " INTPTR_FORMAT,

                  &_byte_map[0],

                  &_byte_map[_last_valid_index]);

    gclog_or_tty->print_cr("  "

                  "  byte_map_base: " INTPTR_FORMAT,

                  byte_map_base);

  }

}

int CardTableModRefBS::find_covering_region_by_base(HeapWord* base) {

  int i;

  for (i = 0; i < _cur_covered_regions; i++) {

    if (_covered[i].start() == base) return i;

    if (_covered[i].start() > base) break;

  }

  // If we didn't find it, create a new one.

  assert(_cur_covered_regions < _max_covered_regions,

         "too many covered regions");

  // Move the ones above up, to maintain sorted order.

  for (int j = _cur_covered_regions; j > i; j--) {

    _covered[j] = _covered[j-1];

    _committed[j] = _committed[j-1];

  }

  int res = i;

  _cur_covered_regions++;

  _covered[res].set_start(base);

  _covered[res].set_word_size(0);

  jbyte* ct_start = byte_for(base);

  uintptr_t ct_start_aligned = align_size_down((uintptr_t)ct_start, _page_size);

  _committed[res].set_start((HeapWord*)ct_start_aligned);

  _committed[res].set_word_size(0);

  return res;

}

int CardTableModRefBS::find_covering_region_containing(HeapWord* addr) {

  for (int i = 0; i < _cur_covered_regions; i++) {

    if (_covered[i].contains(addr)) {

      return i;

    }

  }

  assert(0, "address outside of heap?");

  return -1;

}

HeapWord* CardTableModRefBS::largest_prev_committed_end(int ind) const {

  HeapWord* max_end = NULL;

  for (int j = 0; j < ind; j++) {

    HeapWord* this_end = _committed[j].end();

    if (this_end > max_end) max_end = this_end;

  }

  return max_end;

}

MemRegion CardTableModRefBS::committed_unique_to_self(int self,

                                                      MemRegion mr) const {

  MemRegion result = mr;

  for (int r = 0; r < _cur_covered_regions; r += 1) {

    if (r != self) {

      result = result.minus(_committed[r]);

    }

  }

  // Never include the guard page.

  result = result.minus(_guard_region);

  return result;

}

void CardTableModRefBS::resize_covered_region(MemRegion new_region) {

  // We don't change the start of a region, only the end.

  assert(_whole_heap.contains(new_region),

           "attempt to cover area not in reserved area");

  debug_only(verify_guard();)

  // collided is true if the expansion would push into another committed region

  debug_only(bool collided = false;)

  int const ind = find_covering_region_by_base(new_region.start());

  MemRegion const old_region = _covered[ind];

  assert(old_region.start() == new_region.start(), "just checking");

  if (new_region.word_size() != old_region.word_size()) {

    // Commit new or uncommit old pages, if necessary.

    MemRegion cur_committed = _committed[ind];

    // Extend the end of this _commited region

    // to cover the end of any lower _committed regions.

    // This forms overlapping regions, but never interior regions.

    HeapWord* const max_prev_end = largest_prev_committed_end(ind);

    if (max_prev_end > cur_committed.end()) {

      cur_committed.set_end(max_prev_end);

    }

    // Align the end up to a page size (starts are already aligned).

    jbyte* const new_end = byte_after(new_region.last());

    HeapWord* new_end_aligned =

      (HeapWord*) align_size_up((uintptr_t)new_end, _page_size);

    assert(new_end_aligned >= (HeapWord*) new_end,

           "align up, but less");

    // Check the other regions (excludes "ind") to ensure that

    // the new_end_aligned does not intrude onto the committed

    // space of another region.

    int ri = 0;

    for (ri = 0; ri < _cur_covered_regions; ri++) {

      if (ri != ind) {

        if (_committed[ri].contains(new_end_aligned)) {

          // The prior check included in the assert

          // (new_end_aligned >= _committed[ri].start())

          // is redundant with the "contains" test.

          // Any region containing the new end

          // should start at or beyond the region found (ind)

          // for the new end (committed regions are not expected to

          // be proper subsets of other committed regions).

          assert(_committed[ri].start() >= _committed[ind].start(),

                 "New end of committed region is inconsistent");

          new_end_aligned = _committed[ri].start();

          // new_end_aligned can be equal to the start of its

          // committed region (i.e., of "ind") if a second

          // region following "ind" also start at the same location

          // as "ind".

          assert(new_end_aligned >= _committed[ind].start(),

            "New end of committed region is before start");

          debug_only(collided = true;)

          // Should only collide with 1 region

          break;

        }

      }

    }

#ifdef ASSERT

    for (++ri; ri < _cur_covered_regions; ri++) {

      assert(!_committed[ri].contains(new_end_aligned),

        "New end of committed region is in a second committed region");

    }

#endif

    // The guard page is always committed and should not be committed over.

    HeapWord* const new_end_for_commit = MIN2(new_end_aligned,

                                              _guard_region.start());

    if (new_end_for_commit > cur_committed.end()) {

      // Must commit new pages.

      MemRegion const new_committed =

        MemRegion(cur_committed.end(), new_end_for_commit);

      assert(!new_committed.is_empty(), "Region should not be empty here");

      if (!os::commit_memory((char*)new_committed.start(),

                             new_committed.byte_size(), _page_size)) {

        // Do better than this for Merlin

        vm_exit_out_of_memory(new_committed.byte_size(),

                "card table expansion");

      }

    // Use new_end_aligned (as opposed to new_end_for_commit) because

    // the cur_committed region may include the guard region.

    } else if (new_end_aligned < cur_committed.end()) {

      // Must uncommit pages.

      MemRegion const uncommit_region =

        committed_unique_to_self(ind, MemRegion(new_end_aligned,

                                                cur_committed.end()));

      if (!uncommit_region.is_empty()) {

        if (!os::uncommit_memory((char*)uncommit_region.start(),

                                 uncommit_region.byte_size())) {

          assert(false, "Card table contraction failed");

          // The call failed so don't change the end of the

          // committed region.  This is better than taking the

          // VM down.

          new_end_aligned = _committed[ind].end();

        }

      }

    }

    // In any case, we can reset the end of the current committed entry.

    _committed[ind].set_end(new_end_aligned);

    // The default of 0 is not necessarily clean cards.

    jbyte* entry;

    if (old_region.last() < _whole_heap.start()) {

      entry = byte_for(_whole_heap.start());

    } else {

      entry = byte_after(old_region.last());

    }

    assert(index_for(new_region.last()) <  _guard_index,

      "The guard card will be overwritten");

    // This line commented out cleans the newly expanded region and

    // not the aligned up expanded region.

    // jbyte* const end = byte_after(new_region.last());

    jbyte* const end = (jbyte*) new_end_for_commit;

    assert((end >= byte_after(new_region.last())) || collided,

      "Expect to be beyond new region unless impacting another region");

    // do nothing if we resized downward.

#ifdef ASSERT

    for (int ri = 0; ri < _cur_covered_regions; ri++) {

      if (ri != ind) {

        // The end of the new committed region should not

        // be in any existing region unless it matches

        // the start of the next region.

        assert(!_committed[ri].contains(end) ||

               (_committed[ri].start() == (HeapWord*) end),

               "Overlapping committed regions");

      }

    }

#endif

    if (entry < end) {

      memset(entry, clean_card, pointer_delta(end, entry, sizeof(jbyte)));

    }

  }

  // In any case, the covered size changes.

  _covered[ind].set_word_size(new_region.word_size());

  if (TraceCardTableModRefBS) {

    gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: ");

    gclog_or_tty->print_cr("  "

                  "  _covered[%d].start(): " INTPTR_FORMAT

                  "  _covered[%d].last(): " INTPTR_FORMAT,

                  ind, _covered[ind].start(),

                  ind, _covered[ind].last());

    gclog_or_tty->print_cr("  "

                  "  _committed[%d].start(): " INTPTR_FORMAT

                  "  _committed[%d].last(): " INTPTR_FORMAT,

                  ind, _committed[ind].start(),

                  ind, _committed[ind].last());

    gclog_or_tty->print_cr("  "

                  "  byte_for(start): " INTPTR_FORMAT

                  "  byte_for(last): " INTPTR_FORMAT,

                  byte_for(_covered[ind].start()),

                  byte_for(_covered[ind].last()));

    gclog_or_tty->print_cr("  "

                  "  addr_for(start): " INTPTR_FORMAT

                  "  addr_for(last): " INTPTR_FORMAT,

                  addr_for((jbyte*) _committed[ind].start()),

                  addr_for((jbyte*) _committed[ind].last()));

  }

  debug_only(verify_guard();)

}

// Note that these versions are precise!  The scanning code has to handle the

// fact that the write barrier may be either precise or imprecise.

void CardTableModRefBS::write_ref_field_work(void* field, oop newVal) {

  inline_write_ref_field(field, newVal);

}

bool CardTableModRefBS::claim_card(size_t card_index) {

  jbyte val = _byte_map[card_index];

  if (val != claimed_card_val()) {

    jbyte res = Atomic::cmpxchg((jbyte) claimed_card_val(), &_byte_map[card_index], val);

    if (res == val)

      return true;

    else return false;

  }

  return false;

}

void CardTableModRefBS::non_clean_card_iterate(Space* sp,

                                               MemRegion mr,

                                               DirtyCardToOopClosure* dcto_cl,

                                               MemRegionClosure* cl,

                                               bool clear) {

  if (!mr.is_empty()) {

    int n_threads = SharedHeap::heap()->n_par_threads();

    if (n_threads > 0) {

#ifndef SERIALGC

      par_non_clean_card_iterate_work(sp, mr, dcto_cl, cl, clear, n_threads);

#else  // SERIALGC

      fatal("Parallel gc not supported here.");

#endif // SERIALGC

    } else {

      non_clean_card_iterate_work(mr, cl, clear);

    }

  }

}

// NOTE: For this to work correctly, it is important that

// we look for non-clean cards below (so as to catch those

// marked precleaned), rather than look explicitly for dirty

// cards (and miss those marked precleaned). In that sense,

// the name precleaned is currently somewhat of a misnomer.

void CardTableModRefBS::non_clean_card_iterate_work(MemRegion mr,

                                                    MemRegionClosure* cl,

                                                    bool clear) {

  // Figure out whether we have to worry about parallelism.

  bool is_par = (SharedHeap::heap()->n_par_threads() > 1);

  for (int i = 0; i < _cur_covered_regions; i++) {

    MemRegion mri = mr.intersection(_covered[i]);

    if (mri.word_size() > 0) {

      jbyte* cur_entry = byte_for(mri.last());

      jbyte* limit = byte_for(mri.start());

      while (cur_entry >= limit) {

        jbyte* next_entry = cur_entry - 1;

        if (*cur_entry != clean_card) {

          size_t non_clean_cards = 1;

          // Should the next card be included in this range of dirty cards.

          while (next_entry >= limit && *next_entry != clean_card) {

            non_clean_cards++;

            cur_entry = next_entry;

            next_entry--;

          }

          // The memory region may not be on a card boundary.  So that

          // objects beyond the end of the region are not processed, make

          // cur_cards precise with regard to the end of the memory region.

          MemRegion cur_cards(addr_for(cur_entry),

                              non_clean_cards * card_size_in_words);

          MemRegion dirty_region = cur_cards.intersection(mri);

          if (clear) {

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

              // Clean the dirty cards (but leave the other non-clean

              // alone.)  If parallel, do the cleaning atomically.

              jbyte cur_entry_val = cur_entry[i];

              if (card_is_dirty_wrt_gen_iter(cur_entry_val)) {

                if (is_par) {

                  jbyte res = Atomic::cmpxchg(clean_card, &cur_entry[i], cur_entry_val);

                  assert(res != clean_card,

                         "Dirty card mysteriously cleaned");

                } else {

                  cur_entry[i] = clean_card;

                }

              }

            }

          }

          cl->do_MemRegion(dirty_region);

        }

        cur_entry = next_entry;

      }

    }

  }

}

void CardTableModRefBS::mod_oop_in_space_iterate(Space* sp,

                                                 OopClosure* cl,

                                                 bool clear,

                                                 bool before_save_marks) {

  // Note that dcto_cl is resource-allocated, so there is no

  // corresponding "delete".

  DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision());

  MemRegion used_mr;

  if (before_save_marks) {

    used_mr = sp->used_region_at_save_marks();

  } else {

    used_mr = sp->used_region();

  }

  non_clean_card_iterate(sp, used_mr, dcto_cl, dcto_cl, clear);

}

void CardTableModRefBS::dirty_MemRegion(MemRegion mr) {

  jbyte* cur  = byte_for(mr.start());

  jbyte* last = byte_after(mr.last());

  while (cur < last) {

    *cur = dirty_card;

    cur++;

  }

}

void CardTableModRefBS::invalidate(MemRegion mr, bool whole_heap) {

  for (int i = 0; i < _cur_covered_regions; i++) {

    MemRegion mri = mr.intersection(_covered[i]);

    if (!mri.is_empty()) dirty_MemRegion(mri);

  }

}

void CardTableModRefBS::clear_MemRegion(MemRegion mr) {

  // Be conservative: only clean cards entirely contained within the

  // region.

  jbyte* cur;

  if (mr.start() == _whole_heap.start()) {

    cur = byte_for(mr.start());

  } else {

    assert(mr.start() > _whole_heap.start(), "mr is not covered.");

    cur = byte_after(mr.start() - 1);

  }

  jbyte* last = byte_after(mr.last());

  memset(cur, clean_card, pointer_delta(last, cur, sizeof(jbyte)));

}

void CardTableModRefBS::clear(MemRegion mr) {

  for (int i = 0; i < _cur_covered_regions; i++) {

    MemRegion mri = mr.intersection(_covered[i]);

    if (!mri.is_empty()) clear_MemRegion(mri);

  }

}

void CardTableModRefBS::dirty(MemRegion mr) {

  jbyte* first = byte_for(mr.start());

  jbyte* last  = byte_after(mr.last());

  memset(first, dirty_card, last-first);

}

// NOTES:

// (1) Unlike mod_oop_in_space_iterate() above, dirty_card_iterate()

//     iterates over dirty cards ranges in increasing address order.

void CardTableModRefBS::dirty_card_iterate(MemRegion mr,

                                           MemRegionClosure* cl) {

  for (int i = 0; i < _cur_covered_regions; i++) {

    MemRegion mri = mr.intersection(_covered[i]);

    if (!mri.is_empty()) {

      jbyte *cur_entry, *next_entry, *limit;

      for (cur_entry = byte_for(mri.start()), limit = byte_for(mri.last());

           cur_entry <= limit;

           cur_entry  = next_entry) {

        next_entry = cur_entry + 1;

        if (*cur_entry == dirty_card) {

          size_t dirty_cards;

          // Accumulate maximal dirty card range, starting at cur_entry