/*

 * Copyright (c) 2001, 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/g1/dirtyCardQueue.hpp"

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

#include "runtime/safepoint.hpp"

#include "runtime/thread.inline.hpp"

#include "runtime/threadSMR.hpp"

// Closure used for updating remembered sets and recording references that

// point into the collection set while the mutator is running.

// Assumed to be only executed concurrently with the mutator. Yields via

// SuspendibleThreadSet after every card.

class G1RefineCardConcurrentlyClosure: public CardTableEntryClosure {

public:

  bool do_card_ptr(jbyte* card_ptr, uint worker_i) {

    G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);

    if (SuspendibleThreadSet::should_yield()) {

      // Caller will actually yield.

      return false;

    }

    // Otherwise, we finished successfully; return true.

    return true;

  }

};

// Represents a set of free small integer ids.

class FreeIdSet : public CHeapObj<mtGC> {

  enum {

    end_of_list = UINT_MAX,

    claimed = UINT_MAX - 1

  };

  uint _size;

  Monitor* _mon;

  uint* _ids;

  uint _hd;

  uint _waiters;

  uint _claimed;

public:

  FreeIdSet(uint size, Monitor* mon);

  ~FreeIdSet();

  // Returns an unclaimed parallel id (waiting for one to be released if

  // necessary).

  uint claim_par_id();

  void release_par_id(uint id);

};

FreeIdSet::FreeIdSet(uint size, Monitor* mon) :

  _size(size), _mon(mon), _hd(0), _waiters(0), _claimed(0)

{

  guarantee(size != 0, "must be");

  _ids = NEW_C_HEAP_ARRAY(uint, size, mtGC);

  for (uint i = 0; i < size - 1; i++) {

    _ids[i] = i+1;

  }

  _ids[size-1] = end_of_list; // end of list.

}

FreeIdSet::~FreeIdSet() {

  FREE_C_HEAP_ARRAY(uint, _ids);

}

uint FreeIdSet::claim_par_id() {

  MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);

  while (_hd == end_of_list) {

    _waiters++;

    _mon->wait(Mutex::_no_safepoint_check_flag);

    _waiters--;

  }

  uint res = _hd;

  _hd = _ids[res];

  _ids[res] = claimed;  // For debugging.

  _claimed++;

  return res;

}

void FreeIdSet::release_par_id(uint id) {

  MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);

  assert(_ids[id] == claimed, "Precondition.");

  _ids[id] = _hd;

  _hd = id;

  _claimed--;

  if (_waiters > 0) {

    _mon->notify_all();

  }

}

DirtyCardQueue::DirtyCardQueue(DirtyCardQueueSet* qset, bool permanent) :

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

  // active field set to true.

  PtrQueue(qset, permanent, true /* active */)

{ }

DirtyCardQueue::~DirtyCardQueue() {

  if (!is_permanent()) {

    flush();

  }

}

DirtyCardQueueSet::DirtyCardQueueSet(bool notify_when_complete) :

  PtrQueueSet(notify_when_complete),

  _shared_dirty_card_queue(this, true /* permanent */),

  _free_ids(NULL),

  _processed_buffers_mut(0), _processed_buffers_rs_thread(0)

{

  _all_active = true;

}

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

uint DirtyCardQueueSet::num_par_ids() {

  return (uint)os::initial_active_processor_count();

}

void DirtyCardQueueSet::initialize(Monitor* cbl_mon,

                                   BufferNode::Allocator* allocator,

                                   Mutex* lock,

                                   bool init_free_ids) {

  _shared_dirty_card_queue.set_lock(lock);

  if (init_free_ids) {

    _free_ids = new FreeIdSet(num_par_ids(), _cbl_mon);

  }

}

void DirtyCardQueueSet::handle_zero_index_for_thread(JavaThread* t) {

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

}

bool DirtyCardQueueSet::apply_closure_to_buffer(CardTableEntryClosure* cl,

                                                BufferNode* node,

                                                bool consume,

                                                uint worker_i) {

  if (cl == NULL) return true;

  bool result = true;

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

  size_t i = node->index();

  size_t limit = buffer_size();

  for ( ; i < limit; ++i) {

    jbyte* card_ptr = static_cast<jbyte*>(buf[i]);

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

    if (!cl->do_card_ptr(card_ptr, worker_i)) {

      result = false;           // Incomplete processing.

      break;

    }

  }

  if (consume) {

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

    node->set_index(i);

  }

  return result;

}

#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 DirtyCardQueueSet::mut_process_buffer(BufferNode* node) {

  guarantee(_free_ids != NULL, "must be");

  uint worker_i = _free_ids->claim_par_id(); // temporarily claim an id

  G1RefineCardConcurrentlyClosure cl;

  bool result = apply_closure_to_buffer(&cl, node, true, worker_i);

  _free_ids->release_par_id(worker_i); // release the id

  if (result) {

    assert_fully_consumed(node, buffer_size());

    Atomic::inc(&_processed_buffers_mut);

  }

  return result;

}

BufferNode* DirtyCardQueueSet::get_completed_buffer(size_t stop_at) {

  MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);

  if (_n_completed_buffers <= stop_at) {

    return NULL;

  }

  assert(_n_completed_buffers > 0, "invariant");

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

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

  BufferNode* nd = _completed_buffers_head;

  _completed_buffers_head = nd->next();

  _n_completed_buffers--;

  if (_completed_buffers_head == NULL) {

    assert(_n_completed_buffers == 0, "Invariant");

    _completed_buffers_tail = NULL;

  }

  DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());

  return nd;

}

bool DirtyCardQueueSet::refine_completed_buffer_concurrently(uint worker_i, size_t stop_at) {

  G1RefineCardConcurrentlyClosure cl;

  return apply_closure_to_completed_buffer(&cl, worker_i, stop_at, false);

}

bool DirtyCardQueueSet::apply_closure_during_gc(CardTableEntryClosure* cl, uint worker_i) {

  assert_at_safepoint();

  return apply_closure_to_completed_buffer(cl, worker_i, 0, true);

}

bool DirtyCardQueueSet::apply_closure_to_completed_buffer(CardTableEntryClosure* cl,

                                                          uint worker_i,

                                                          size_t stop_at,

                                                          bool during_pause) {

  assert(!during_pause || stop_at == 0, "Should not leave any completed buffers during a pause");

  BufferNode* nd = get_completed_buffer(stop_at);

  if (nd == NULL) {

    return false;

  } else {

    if (apply_closure_to_buffer(cl, nd, true, worker_i)) {

      assert_fully_consumed(nd, buffer_size());

      // Done with fully processed buffer.

      deallocate_buffer(nd);

      Atomic::inc(&_processed_buffers_rs_thread);

    } else {

      // Return partially processed buffer to the queue.

      guarantee(!during_pause, "Should never stop early");

      enqueue_complete_buffer(nd);

    }

    return true;

  }

}

void DirtyCardQueueSet::par_apply_closure_to_all_completed_buffers(CardTableEntryClosure* cl) {

  BufferNode* nd = _cur_par_buffer_node;

  while (nd != NULL) {

    BufferNode* next = nd->next();

    BufferNode* actual = Atomic::cmpxchg(next, &_cur_par_buffer_node, nd);

    if (actual == nd) {

      bool b = apply_closure_to_buffer(cl, nd, false);

      guarantee(b, "Should not stop early.");

      nd = next;

    } else {

      nd = actual;

    }

  }

}

// Deallocates any completed log buffers

void DirtyCardQueueSet::clear() {

  BufferNode* buffers_to_delete = NULL;

  {

    MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);

    while (_completed_buffers_head != NULL) {

      BufferNode* nd = _completed_buffers_head;

      _completed_buffers_head = nd->next();

      nd->set_next(buffers_to_delete);

      buffers_to_delete = nd;

    }

    _n_completed_buffers = 0;

    _completed_buffers_tail = NULL;

    DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());

  }

  while (buffers_to_delete != NULL) {

    BufferNode* nd = buffers_to_delete;

    buffers_to_delete = nd->next();

    deallocate_buffer(nd);

  }

}

void DirtyCardQueueSet::abandon_logs() {

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

  clear();

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

  // these queues.

  for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {

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

  }

  shared_dirty_card_queue()->reset();

}

void DirtyCardQueueSet::concatenate_log(DirtyCardQueue& dcq) {

  if (!dcq.is_empty()) {

    dcq.flush();

  }

}

void DirtyCardQueueSet::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.");

  for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {

    concatenate_log(G1ThreadLocalData::dirty_card_queue(t));

  }

  concatenate_log(_shared_dirty_card_queue);

}