/*
 * Copyright (c) 2001, 2016, 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,
                                   size_t process_completed_threshold,
                                   size_t 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");

  // claim a par id
  uint worker_i = _free_ids->claim_par_id();

  bool b = DirtyCardQueue::apply_closure_to_buffer(_mut_process_closure, buf, 0,
                                                   _sz, true, worker_i);
  if (b) {
    Atomic::inc(&_processed_buffers_mut);
  }

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

  return b;
}


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 {
    void** buf = BufferNode::make_buffer_from_node(nd);
    size_t index = nd->index();
    if (DirtyCardQueue::apply_closure_to_buffer(cl,
                                                buf, index, _sz,
                                                true, worker_i)) {
      // Done with fully processed buffer.
      deallocate_buffer(buf);
      Atomic::inc(&_processed_buffers_rs_thread);
      return true;
    } else {
      // Return partially processed buffer to the queue.
      enqueue_complete_buffer(buf, index);
      return false;
    }
  }
}

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.
  size_t save_max_completed_queue = _max_completed_queue;
  _max_completed_queue = SIZE_MAX;
  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;
}