/*

 * Copyright (c) 2001, 2015, 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/g1CollectedHeap.inline.hpp"

#include "gc/g1/g1SATBCardTableModRefBS.hpp"

#include "gc/g1/heapRegion.hpp"

#include "gc/g1/satbMarkQueue.hpp"

#include "gc/shared/memset_with_concurrent_readers.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/atomic.inline.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/orderAccess.inline.hpp"

#include "runtime/thread.inline.hpp"

G1SATBCardTableModRefBS::G1SATBCardTableModRefBS(

  MemRegion whole_heap,

  const BarrierSet::FakeRtti& fake_rtti) :

  CardTableModRefBS(whole_heap, fake_rtti.add_tag(BarrierSet::G1SATBCT))

{ }

void G1SATBCardTableModRefBS::enqueue(oop pre_val) {

  // Nulls should have been already filtered.

  assert(pre_val->is_oop(true), "Error");

  if (!JavaThread::satb_mark_queue_set().is_active()) return;

  Thread* thr = Thread::current();

  if (thr->is_Java_thread()) {

    JavaThread* jt = (JavaThread*)thr;

    jt->satb_mark_queue().enqueue(pre_val);

  } else {

    MutexLockerEx x(Shared_SATB_Q_lock, Mutex::_no_safepoint_check_flag);

    JavaThread::satb_mark_queue_set().shared_satb_queue()->enqueue(pre_val);

  }

}

template <class T> void

G1SATBCardTableModRefBS::write_ref_array_pre_work(T* dst, int count) {

  if (!JavaThread::satb_mark_queue_set().is_active()) return;

  T* elem_ptr = dst;

  for (int i = 0; i < count; i++, elem_ptr++) {

    T heap_oop = oopDesc::load_heap_oop(elem_ptr);

    if (!oopDesc::is_null(heap_oop)) {

      enqueue(oopDesc::decode_heap_oop_not_null(heap_oop));

    }

  }

}

void G1SATBCardTableModRefBS::write_ref_array_pre(oop* dst, int count, bool dest_uninitialized) {

  if (!dest_uninitialized) {

    write_ref_array_pre_work(dst, count);

  }

}

void G1SATBCardTableModRefBS::write_ref_array_pre(narrowOop* dst, int count, bool dest_uninitialized) {

  if (!dest_uninitialized) {

    write_ref_array_pre_work(dst, count);

  }

}

bool G1SATBCardTableModRefBS::mark_card_deferred(size_t card_index) {

  jbyte val = _byte_map[card_index];

  // It's already processed

  if ((val & (clean_card_mask_val() | deferred_card_val())) == deferred_card_val()) {

    return false;

  }

  if  (val == g1_young_gen) {

    // the card is for a young gen region. We don't need to keep track of all pointers into young

    return false;

  }

  // Cached bit can be installed either on a clean card or on a claimed card.

  jbyte new_val = val;

  if (val == clean_card_val()) {

    new_val = (jbyte)deferred_card_val();

  } else {

    if (val & claimed_card_val()) {

      new_val = val | (jbyte)deferred_card_val();

    }

  }

  if (new_val != val) {

    Atomic::cmpxchg(new_val, &_byte_map[card_index], val);

  }

  return true;

}

void G1SATBCardTableModRefBS::g1_mark_as_young(const MemRegion& mr) {

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

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

  memset_with_concurrent_readers(first, g1_young_gen, last - first);

}

#ifndef PRODUCT

void G1SATBCardTableModRefBS::verify_g1_young_region(MemRegion mr) {

  verify_region(mr, g1_young_gen,  true);

}

#endif

void G1SATBCardTableLoggingModRefBSChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {

  // Default value for a clean card on the card table is -1. So we cannot take advantage of the zero_filled parameter.

  MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);

  _card_table->clear(mr);

}

G1SATBCardTableLoggingModRefBS::

G1SATBCardTableLoggingModRefBS(MemRegion whole_heap) :

  G1SATBCardTableModRefBS(whole_heap, BarrierSet::FakeRtti(G1SATBCTLogging)),

  _dcqs(JavaThread::dirty_card_queue_set()),

  _listener()

{

  _listener.set_card_table(this);

}

void G1SATBCardTableLoggingModRefBS::initialize(G1RegionToSpaceMapper* mapper) {

  mapper->set_mapping_changed_listener(&_listener);

  _byte_map_size = mapper->reserved().byte_size();

  _guard_index = cards_required(_whole_heap.word_size()) - 1;

  _last_valid_index = _guard_index - 1;

  HeapWord* low_bound  = _whole_heap.start();

  HeapWord* high_bound = _whole_heap.end();

  _cur_covered_regions = 1;

  _covered[0] = _whole_heap;

  _byte_map = (jbyte*) mapper->reserved().start();

  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");

  if (TraceCardTableModRefBS) {

    gclog_or_tty->print_cr("G1SATBCardTableModRefBS::G1SATBCardTableModRefBS: ");

    gclog_or_tty->print_cr("  "

                  "  &_byte_map[0]: " INTPTR_FORMAT

                  "  &_byte_map[_last_valid_index]: " INTPTR_FORMAT,

                  p2i(&_byte_map[0]),

                  p2i(&_byte_map[_last_valid_index]));

    gclog_or_tty->print_cr("  "

                  "  byte_map_base: " INTPTR_FORMAT,

                  p2i(byte_map_base));

  }

}

void

G1SATBCardTableLoggingModRefBS::write_ref_field_work(void* field,

                                                     oop new_val,

                                                     bool release) {

  volatile jbyte* byte = byte_for(field);

  if (*byte == g1_young_gen) {

    return;

  }

  OrderAccess::storeload();

  if (*byte != dirty_card) {

    *byte = dirty_card;

    Thread* thr = Thread::current();

    if (thr->is_Java_thread()) {

      JavaThread* jt = (JavaThread*)thr;

      jt->dirty_card_queue().enqueue(byte);

    } else {

      MutexLockerEx x(Shared_DirtyCardQ_lock,

                      Mutex::_no_safepoint_check_flag);

      _dcqs.shared_dirty_card_queue()->enqueue(byte);

    }

  }

}

void

G1SATBCardTableLoggingModRefBS::invalidate(MemRegion mr, bool whole_heap) {

  volatile jbyte* byte = byte_for(mr.start());

  jbyte* last_byte = byte_for(mr.last());

  Thread* thr = Thread::current();

  if (whole_heap) {

    while (byte <= last_byte) {

      *byte = dirty_card;

      byte++;

    }

  } else {

    // skip all consecutive young cards

    for (; byte <= last_byte && *byte == g1_young_gen; byte++);

    if (byte <= last_byte) {

      OrderAccess::storeload();

      // Enqueue if necessary.

      if (thr->is_Java_thread()) {

        JavaThread* jt = (JavaThread*)thr;

        for (; byte <= last_byte; byte++) {

          if (*byte == g1_young_gen) {

            continue;

          }

          if (*byte != dirty_card) {

            *byte = dirty_card;

            jt->dirty_card_queue().enqueue(byte);

          }

        }

      } else {

        MutexLockerEx x(Shared_DirtyCardQ_lock,

                        Mutex::_no_safepoint_check_flag);

        for (; byte <= last_byte; byte++) {

          if (*byte == g1_young_gen) {

            continue;

          }

          if (*byte != dirty_card) {

            *byte = dirty_card;

            _dcqs.shared_dirty_card_queue()->enqueue(byte);

          }

        }

      }

    }

  }

}

void G1SATBCardTableModRefBS::write_ref_nmethod_post(oop* dst, nmethod* nm) {

  oop obj = oopDesc::load_heap_oop(dst);

  if (obj != NULL) {

    G1CollectedHeap* g1h = G1CollectedHeap::heap();

    HeapRegion* hr = g1h->heap_region_containing(obj);

    hr->add_strong_code_root(nm);

  }

}

class G1EnsureLastRefToRegion : public OopClosure {

  G1CollectedHeap* _g1h;

  HeapRegion* _hr;

  oop* _dst;

  bool _value;

public:

  G1EnsureLastRefToRegion(G1CollectedHeap* g1h, HeapRegion* hr, oop* dst) :

    _g1h(g1h), _hr(hr), _dst(dst), _value(true) {}

  void do_oop(oop* p) {

    if (_value && p != _dst) {

      oop obj = oopDesc::load_heap_oop(p);

      if (obj != NULL) {

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

        if (hr == _hr) {

          // Another reference to the same region.

          _value = false;

        }

      }

    }

  }

  void do_oop(narrowOop* p) { ShouldNotReachHere(); }

  bool value() const        { return _value;  }

};

void G1SATBCardTableModRefBS::write_ref_nmethod_pre(oop* dst, nmethod* nm) {

  oop obj = oopDesc::load_heap_oop(dst);

  if (obj != NULL) {

    G1CollectedHeap* g1h = G1CollectedHeap::heap();

    HeapRegion* hr = g1h->heap_region_containing(obj);

    G1EnsureLastRefToRegion ensure_last_ref(g1h, hr, dst);

    nm->oops_do(&ensure_last_ref);

    if (ensure_last_ref.value()) {

      // Last reference to this region, remove the nmethod from the rset.

      hr->remove_strong_code_root(nm);

    }

  }

}