/*

 * Copyright (c) 2001, 2017, 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/heapRegionRemSet.hpp"

#include "gc/shared/workgroup.hpp"

#include "runtime/atomic.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/safepoint.hpp"

#include "runtime/thread.inline.hpp"

// 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),

  _mut_process_closure(NULL),

  _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(CardTableEntryClosure* cl,

                                   Monitor* cbl_mon,

                                   Mutex* fl_lock,

                                   int process_completed_threshold,

                                   int max_completed_queue,

                                   Mutex* lock,

                                   DirtyCardQueueSet* fl_owner,

                                   bool init_free_ids) {

  _mut_process_closure = cl;

  PtrQueueSet::initialize(cbl_mon,

                          fl_lock,

                          process_completed_threshold,

                          max_completed_queue,

                          fl_owner);

  set_buffer_size(G1UpdateBufferSize);

  _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) {

  t->dirty_card_queue().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);

  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) {

  }

  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

  bool result = apply_closure_to_buffer(_mut_process_closure, 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) {

  BufferNode* nd = NULL;

  MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);

  if (_n_completed_buffers <= stop_at) {

    _process_completed = false;

    return NULL;

  }

  if (_completed_buffers_head != NULL) {

    nd = _completed_buffers_head;

    assert(_n_completed_buffers > 0, "Invariant");

    _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::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();

    void* actual = Atomic::cmpxchg_ptr(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 = static_cast<BufferNode*>(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 (JavaThread* t = Threads::first(); t; t = t->next()) {

    t->dirty_card_queue().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.

  int save_max_completed_queue = _max_completed_queue;

  _max_completed_queue = max_jint;

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

  for (JavaThread* t = Threads::first(); t; t = t->next()) {

    concatenate_log(t->dirty_card_queue());

  }

  concatenate_log(_shared_dirty_card_queue);

  // Restore the completed buffer queue limit.

  _max_completed_queue = save_max_completed_queue;

}