/*

 * 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/dirtyCardQueue.hpp"

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

#include "gc/g1/heapRegionRemSet.hpp"

#include "gc/shared/workgroup.hpp"

#include "runtime/atomic.inline.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();

  }

}

bool DirtyCardQueue::apply_closure(CardTableEntryClosure* cl,

                                   bool consume,

                                   uint worker_i) {

  bool res = true;

  if (_buf != NULL) {

    res = apply_closure_to_buffer(cl, _buf, _index, _sz,

                                  consume,

                                  worker_i);

    if (res && consume) {

      _index = _sz;

    }

  }

  return res;

}

bool DirtyCardQueue::apply_closure_to_buffer(CardTableEntryClosure* cl,

                                             void** buf,

                                             size_t index, size_t sz,

                                             bool consume,

                                             uint worker_i) {

  if (cl == NULL) return true;

  size_t limit = byte_index_to_index(sz);

  for (size_t i = byte_index_to_index(index); i < limit; ++i) {

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

    if (card_ptr != NULL) {

      // Set the entry to null, so we don't do it again (via the test

      // above) if we reconsider this buffer.

      if (consume) {

        buf[i] = NULL;

      }

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

        return false;

      }

    }

  }

  return true;

}

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::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::mut_process_buffer(void** buf) {

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

  }

  return b;

}

BufferNode* DirtyCardQueueSet::get_completed_buffer(int stop_at) {

  BufferNode* nd = NULL;

  MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);

  if ((int)_n_completed_buffers <= stop_at) {

    _process_completed = false;

    return NULL;

  }

  if (_completed_buffers_head != NULL) {

    nd = _completed_buffers_head;

    _completed_buffers_head = nd->next();

    if (_completed_buffers_head == NULL)

      _completed_buffers_tail = NULL;

    _n_completed_buffers--;

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

  }

  DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());

  return nd;

}

bool DirtyCardQueueSet::apply_closure_to_completed_buffer_helper(CardTableEntryClosure* cl,

                                                                 uint worker_i,

                                                                 BufferNode* nd) {

  if (nd != NULL) {

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

    size_t index = nd->index();

    bool b =

      DirtyCardQueue::apply_closure_to_buffer(cl, buf,

                                              index, _sz,

                                              true, worker_i);

    if (b) {

      deallocate_buffer(buf);

      return true;  // In normal case, go on to next buffer.

    } else {

      enqueue_complete_buffer(buf, index);

      return false;

    }

  } else {

    return false;

  }

}

bool DirtyCardQueueSet::apply_closure_to_completed_buffer(CardTableEntryClosure* cl,

                                                          uint worker_i,

                                                          int 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);

  bool res = apply_closure_to_completed_buffer_helper(cl, worker_i, nd);

  if (res) Atomic::inc(&_processed_buffers_rs_thread);

  return res;

}

void DirtyCardQueueSet::apply_closure_to_all_completed_buffers(CardTableEntryClosure* cl) {

  BufferNode* nd = _completed_buffers_head;

  while (nd != NULL) {

    bool b =

      DirtyCardQueue::apply_closure_to_buffer(cl,

                                              BufferNode::make_buffer_from_node(nd),

                                              0, _sz, false);

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

    nd = nd->next();

  }

}

void DirtyCardQueueSet::par_apply_closure_to_all_completed_buffers(CardTableEntryClosure* cl) {

  BufferNode* nd = _cur_par_buffer_node;

  while (nd != NULL) {

    BufferNode* next = (BufferNode*)nd->next();

    BufferNode* actual = (BufferNode*)Atomic::cmpxchg_ptr((void*)next, (volatile void*)&_cur_par_buffer_node, (void*)nd);

    if (actual == nd) {

      bool b =

        DirtyCardQueue::apply_closure_to_buffer(cl,

                                                BufferNode::make_buffer_from_node(actual),

                                                0, _sz, 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(BufferNode::make_buffer_from_node(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_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()) {

    DirtyCardQueue& dcq = t->dirty_card_queue();

    if (dcq.size() != 0) {

      void** buf = dcq.get_buf();

      // We must NULL out the unused entries, then enqueue.

      size_t limit = dcq.byte_index_to_index(dcq.get_index());

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

        buf[i] = NULL;

      }

      enqueue_complete_buffer(dcq.get_buf(), dcq.get_index());

      dcq.reinitialize();

    }

  }

  if (_shared_dirty_card_queue.size() != 0) {

    enqueue_complete_buffer(_shared_dirty_card_queue.get_buf(),

                            _shared_dirty_card_queue.get_index());

    _shared_dirty_card_queue.reinitialize();

  }

  // Restore the completed buffer queue limit.

  _max_completed_queue = save_max_completed_queue;

}