/*

 * 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/g1BufferNodeList.hpp"

#include "gc/g1/g1CardTableEntryClosure.hpp"

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

#include "gc/g1/g1DirtyCardQueue.hpp"

#include "gc/g1/g1FreeIdSet.hpp"

#include "gc/g1/g1RedirtyCardsQueue.hpp"

#include "gc/g1/g1RemSet.hpp"

#include "gc/g1/g1ThreadLocalData.hpp"

#include "gc/g1/heapRegionRemSet.hpp"

#include "gc/shared/suspendibleThreadSet.hpp"

#include "gc/shared/workgroup.hpp"

#include "runtime/atomic.hpp"

#include "runtime/flags/flagSetting.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/os.hpp"

#include "runtime/safepoint.hpp"

#include "runtime/thread.inline.hpp"

#include "runtime/threadSMR.hpp"

G1DirtyCardQueue::G1DirtyCardQueue(G1DirtyCardQueueSet* qset) :

  // Dirty card queues are always active, so we create them with their

  // active field set to true.

  PtrQueue(qset, true /* active */)

{ }

G1DirtyCardQueue::~G1DirtyCardQueue() {

  flush();

}

void G1DirtyCardQueue::handle_completed_buffer() {

  assert(_buf != NULL, "precondition");

  BufferNode* node = BufferNode::make_node_from_buffer(_buf, index());

  G1DirtyCardQueueSet* dcqs = dirty_card_qset();

  if (dcqs->process_or_enqueue_completed_buffer(node)) {

    reset();                    // Buffer fully processed, reset index.

  } else {

    allocate_buffer();          // Buffer enqueued, get a new one.

  }

}

// Assumed to be zero by concurrent threads.

static uint par_ids_start() { return 0; }

G1DirtyCardQueueSet::G1DirtyCardQueueSet(Monitor* cbl_mon,

                                         BufferNode::Allocator* allocator) :

  PtrQueueSet(allocator),

  _cbl_mon(cbl_mon),

  _completed_buffers_head(NULL),

  _completed_buffers_tail(NULL),

  _num_cards(0),

  _process_cards_threshold(ProcessCardsThresholdNever),

  _process_completed_buffers(false),

  _max_cards(MaxCardsUnlimited),

  _max_cards_padding(0),

  _free_ids(par_ids_start(), num_par_ids()),

  _mutator_refined_cards_counters(NEW_C_HEAP_ARRAY(size_t, num_par_ids(), mtGC))

{

  ::memset(_mutator_refined_cards_counters, 0, num_par_ids() * sizeof(size_t));

  _all_active = true;

}

G1DirtyCardQueueSet::~G1DirtyCardQueueSet() {

  abandon_completed_buffers();

  FREE_C_HEAP_ARRAY(size_t, _mutator_refined_cards_counters);

}

// Determines how many mutator threads can process the buffers in parallel.

uint G1DirtyCardQueueSet::num_par_ids() {

  return (uint)os::initial_active_processor_count();

}

size_t G1DirtyCardQueueSet::total_mutator_refined_cards() const {

  size_t sum = 0;

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

    sum += _mutator_refined_cards_counters[i];

  }

  return sum;

}

void G1DirtyCardQueueSet::handle_zero_index_for_thread(Thread* t) {

  G1ThreadLocalData::dirty_card_queue(t).handle_zero_index();

}

void G1DirtyCardQueueSet::enqueue_completed_buffer(BufferNode* cbn) {

  MonitorLocker ml(_cbl_mon, Mutex::_no_safepoint_check_flag);

  cbn->set_next(NULL);

  if (_completed_buffers_tail == NULL) {

    assert(_completed_buffers_head == NULL, "Well-formedness");

    _completed_buffers_head = cbn;

    _completed_buffers_tail = cbn;

  } else {

    _completed_buffers_tail->set_next(cbn);

    _completed_buffers_tail = cbn;

  }

  _num_cards += buffer_size() - cbn->index();

  if (!process_completed_buffers() &&

      (num_cards() > process_cards_threshold())) {

    set_process_completed_buffers(true);

    ml.notify_all();

  }

  verify_num_cards();

}

BufferNode* G1DirtyCardQueueSet::get_completed_buffer(size_t stop_at) {

  MutexLocker x(_cbl_mon, Mutex::_no_safepoint_check_flag);

  if (num_cards() <= stop_at) {

    return NULL;

  }

  assert(num_cards() > 0, "invariant");

  assert(_completed_buffers_head != NULL, "invariant");

  assert(_completed_buffers_tail != NULL, "invariant");

  BufferNode* bn = _completed_buffers_head;

  _num_cards -= buffer_size() - bn->index();

  _completed_buffers_head = bn->next();

  if (_completed_buffers_head == NULL) {

    assert(num_cards() == 0, "invariant");

    _completed_buffers_tail = NULL;

    set_process_completed_buffers(false);

  }

  verify_num_cards();

  bn->set_next(NULL);

  return bn;

}

#ifdef ASSERT

void G1DirtyCardQueueSet::verify_num_cards() const {

  size_t actual = 0;

  BufferNode* cur = _completed_buffers_head;

  while (cur != NULL) {

    actual += buffer_size() - cur->index();

    cur = cur->next();

  }

  assert(actual == _num_cards,

         "Num entries in completed buffers should be " SIZE_FORMAT " but are " SIZE_FORMAT,

         _num_cards, actual);

}

#endif

void G1DirtyCardQueueSet::abandon_completed_buffers() {

  BufferNode* buffers_to_delete = NULL;

  {

    MutexLocker x(_cbl_mon, Mutex::_no_safepoint_check_flag);

    buffers_to_delete = _completed_buffers_head;

    _completed_buffers_head = NULL;

    _completed_buffers_tail = NULL;

    _num_cards = 0;

    set_process_completed_buffers(false);

  }

  while (buffers_to_delete != NULL) {

    BufferNode* bn = buffers_to_delete;

    buffers_to_delete = bn->next();

    bn->set_next(NULL);

    deallocate_buffer(bn);

  }

}

void G1DirtyCardQueueSet::notify_if_necessary() {

  MonitorLocker ml(_cbl_mon, Mutex::_no_safepoint_check_flag);

  if (num_cards() > process_cards_threshold()) {

    set_process_completed_buffers(true);

    ml.notify_all();

  }

}

// Merge lists of buffers. Notify the processing threads.

// The source queue is emptied as a result. The queues

// must share the monitor.

void G1DirtyCardQueueSet::merge_bufferlists(G1RedirtyCardsQueueSet* src) {

  assert(allocator() == src->allocator(), "precondition");

  const G1BufferNodeList from = src->take_all_completed_buffers();

  if (from._head == NULL) return;

  MutexLocker x(_cbl_mon, Mutex::_no_safepoint_check_flag);

  if (_completed_buffers_tail == NULL) {

    assert(_completed_buffers_head == NULL, "Well-formedness");

    _completed_buffers_head = from._head;

    _completed_buffers_tail = from._tail;

  } else {

    assert(_completed_buffers_head != NULL, "Well formedness");

    _completed_buffers_tail->set_next(from._head);

    _completed_buffers_tail = from._tail;

  }

  _num_cards += from._entry_count;

  assert(_completed_buffers_head == NULL && _completed_buffers_tail == NULL ||

         _completed_buffers_head != NULL && _completed_buffers_tail != NULL,

         "Sanity");

  verify_num_cards();

}

G1BufferNodeList G1DirtyCardQueueSet::take_all_completed_buffers() {

  MutexLocker x(_cbl_mon, Mutex::_no_safepoint_check_flag);

  G1BufferNodeList result(_completed_buffers_head, _completed_buffers_tail, _num_cards);

  _completed_buffers_head = NULL;

  _completed_buffers_tail = NULL;

  _num_cards = 0;

  return result;

}

bool G1DirtyCardQueueSet::refine_buffer(BufferNode* node,

                                        uint worker_id,

                                        size_t* total_refined_cards) {

  G1RemSet* rem_set = G1CollectedHeap::heap()->rem_set();

  size_t size = buffer_size();

  void** buffer = BufferNode::make_buffer_from_node(node);

  size_t i = node->index();

  assert(i <= size, "invariant");

  for ( ; (i < size) && !SuspendibleThreadSet::should_yield(); ++i) {

    CardTable::CardValue* cp = static_cast<CardTable::CardValue*>(buffer[i]);

    rem_set->refine_card_concurrently(cp, worker_id);

  }

  *total_refined_cards += (i - node->index());

  node->set_index(i);

  return i == size;

}

#ifndef ASSERT

#define assert_fully_consumed(node, buffer_size)

#else

#define assert_fully_consumed(node, buffer_size)                \

  do {                                                          \

    size_t _afc_index = (node)->index();                        \

    size_t _afc_size = (buffer_size);                           \

    assert(_afc_index == _afc_size,                             \

           "Buffer was not fully consumed as claimed: index: "  \

           SIZE_FORMAT ", size: " SIZE_FORMAT,                  \

            _afc_index, _afc_size);                             \

  } while (0)

#endif // ASSERT

bool G1DirtyCardQueueSet::process_or_enqueue_completed_buffer(BufferNode* node) {

  if (Thread::current()->is_Java_thread()) {

    // If the number of buffers exceeds the limit, make this Java

    // thread do the processing itself.  We don't lock to access

    // buffer count or padding; it is fine to be imprecise here.  The

    // add of padding could overflow, which is treated as unlimited.

    size_t limit = max_cards() + max_cards_padding();

    if ((num_cards() > limit) && (limit >= max_cards())) {

      if (mut_process_buffer(node)) {

        return true;

      }

    }

  }

  enqueue_completed_buffer(node);

  return false;

}

bool G1DirtyCardQueueSet::mut_process_buffer(BufferNode* node) {

  uint worker_id = _free_ids.claim_par_id(); // temporarily claim an id

  uint counter_index = worker_id - par_ids_start();

  size_t* counter = &_mutator_refined_cards_counters[counter_index];

  bool result = refine_buffer(node, worker_id, counter);

  _free_ids.release_par_id(worker_id); // release the id

  if (result) {

    assert_fully_consumed(node, buffer_size());

  }

  return result;

}

bool G1DirtyCardQueueSet::refine_completed_buffer_concurrently(uint worker_id,

                                                               size_t stop_at,

                                                               size_t* total_refined_cards) {

  BufferNode* node = get_completed_buffer(stop_at);

  if (node == NULL) {

    return false;

  } else if (refine_buffer(node, worker_id, total_refined_cards)) {

    assert_fully_consumed(node, buffer_size());

    // Done with fully processed buffer.

    deallocate_buffer(node);

    return true;

  } else {

    // Return partially processed buffer to the queue.

    enqueue_completed_buffer(node);

    return true;

  }

}

void G1DirtyCardQueueSet::abandon_logs() {

  assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");

  abandon_completed_buffers();

  // Since abandon is done only at safepoints, we can safely manipulate

  // these queues.

  struct AbandonThreadLogClosure : public ThreadClosure {

    virtual void do_thread(Thread* t) {

      G1ThreadLocalData::dirty_card_queue(t).reset();

    }

  } closure;

  Threads::threads_do(&closure);

  G1BarrierSet::shared_dirty_card_queue().reset();

}

void G1DirtyCardQueueSet::concatenate_logs() {

  // Iterate over all the threads, if we find a partial log add it to

  // the global list of logs.  Temporarily turn off the limit on the number

  // of outstanding buffers.

  assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");

  size_t old_limit = max_cards();

  set_max_cards(MaxCardsUnlimited);

  struct ConcatenateThreadLogClosure : public ThreadClosure {

    virtual void do_thread(Thread* t) {

      G1DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(t);

      if (!dcq.is_empty()) {

        dcq.flush();

      }

    }

  } closure;

  Threads::threads_do(&closure);

  G1BarrierSet::shared_dirty_card_queue().flush();

  set_max_cards(old_limit);

}