/*

 * 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/shared/ptrQueue.hpp"

#include "memory/allocation.hpp"

#include "memory/allocation.inline.hpp"

#include "runtime/atomic.hpp"

#include "runtime/mutex.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/thread.inline.hpp"

#include <new>

PtrQueue::PtrQueue(PtrQueueSet* qset, bool permanent, bool active) :

  _qset(qset),

  _active(active),

  _permanent(permanent),

  _index(0),

  _capacity_in_bytes(0),

  _buf(NULL),

  _lock(NULL)

{}

PtrQueue::~PtrQueue() {

  assert(_permanent || (_buf == NULL), "queue must be flushed before delete");

}

void PtrQueue::flush_impl() {

  if (_buf != NULL) {

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

    if (is_empty()) {

      // No work to do.

      qset()->deallocate_buffer(node);

    } else {

      qset()->enqueue_completed_buffer(node);

    }

    _buf = NULL;

    set_index(0);

  }

}

void PtrQueue::enqueue_known_active(void* ptr) {

  while (_index == 0) {

    handle_zero_index();

  }

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

  assert(index() > 0, "postcondition");

  assert(index() <= capacity(), "invariant");

  _index -= _element_size;

  _buf[index()] = ptr;

}

BufferNode* BufferNode::allocate(size_t size) {

  size_t byte_size = size * sizeof(void*);

  void* data = NEW_C_HEAP_ARRAY(char, buffer_offset() + byte_size, mtGC);

  return new (data) BufferNode;

}

void BufferNode::deallocate(BufferNode* node) {

  node->~BufferNode();

  FREE_C_HEAP_ARRAY(char, node);

}

  _buffer_size(buffer_size),

{

}

BufferNode::Allocator::~Allocator() {

  }

}

size_t BufferNode::Allocator::free_count() const {

  return Atomic::load(&_free_count);

}

BufferNode* BufferNode::Allocator::allocate() {

  {

  }

}

void BufferNode::Allocator::release(BufferNode* node) {

}

    }

  }

  }

}

PtrQueueSet::PtrQueueSet(bool notify_when_complete) :

  _allocator(NULL),

  _cbl_mon(NULL),

  _completed_buffers_head(NULL),

  _completed_buffers_tail(NULL),

  _n_completed_buffers(0),

  _process_completed_buffers_threshold(ProcessCompletedBuffersThresholdNever),

  _process_completed_buffers(false),

  _notify_when_complete(notify_when_complete),

  _max_completed_buffers(MaxCompletedBuffersUnlimited),

  _completed_buffers_padding(0),

  _all_active(false)

{}

PtrQueueSet::~PtrQueueSet() {

  // There are presently only a couple (derived) instances ever

  // created, and they are permanent, so no harm currently done by

  // doing nothing here.

}

void PtrQueueSet::initialize(Monitor* cbl_mon,

                             BufferNode::Allocator* allocator) {

  assert(cbl_mon != NULL && allocator != NULL, "Init order issue?");

  _cbl_mon = cbl_mon;

  _allocator = allocator;

}

void** PtrQueueSet::allocate_buffer() {

  BufferNode* node = _allocator->allocate();

  return BufferNode::make_buffer_from_node(node);

}

void PtrQueueSet::deallocate_buffer(BufferNode* node) {

  _allocator->release(node);

}

void PtrQueue::handle_zero_index() {

  assert(index() == 0, "precondition");

  // This thread records the full buffer and allocates a new one (while

  // holding the lock if there is one).

  if (_buf != NULL) {

    if (!should_enqueue_buffer()) {

      assert(index() > 0, "the buffer can only be re-used if it's not full");

      return;

    }

    if (_lock) {

      assert(_lock->owned_by_self(), "Required.");

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

      _buf = NULL;         // clear shared _buf field

      qset()->enqueue_completed_buffer(node);

      assert(_buf == NULL, "multiple enqueuers appear to be racing");

    } else {

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

      if (qset()->process_or_enqueue_completed_buffer(node)) {

        // Recycle the buffer. No allocation.

        assert(_buf == BufferNode::make_buffer_from_node(node), "invariant");

        assert(capacity() == qset()->buffer_size(), "invariant");

        reset();

        return;

      }

    }

  }

  // Set capacity in case this is the first allocation.

  set_capacity(qset()->buffer_size());

  // Allocate a new buffer.

  _buf = qset()->allocate_buffer();

  reset();

}

bool PtrQueueSet::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_completed_buffers + _completed_buffers_padding;

    if ((_n_completed_buffers > limit) && (limit >= _max_completed_buffers)) {

      if (mut_process_buffer(node)) {

        // Successfully processed; return true to allow buffer reuse.

        return true;

      }

    }

  }

  // The buffer will be enqueued. The caller will have to get a new one.

  enqueue_completed_buffer(node);

  return false;

}

void PtrQueueSet::enqueue_completed_buffer(BufferNode* cbn) {

  MutexLockerEx x(_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;

  }

  _n_completed_buffers++;

  if (!_process_completed_buffers &&

      (_n_completed_buffers > _process_completed_buffers_threshold)) {

    _process_completed_buffers = true;

    if (_notify_when_complete) {

      _cbl_mon->notify();

    }

  }

  assert_completed_buffers_list_len_correct_locked();

}

BufferNode* PtrQueueSet::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* bn = _completed_buffers_head;

  _n_completed_buffers--;

  _completed_buffers_head = bn->next();

  if (_completed_buffers_head == NULL) {

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

    _completed_buffers_tail = NULL;

    _process_completed_buffers = false;

  }

  assert_completed_buffers_list_len_correct_locked();

  bn->set_next(NULL);

  return bn;

}

void PtrQueueSet::abandon_completed_buffers() {

  BufferNode* buffers_to_delete = NULL;

  {

    MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);

    buffers_to_delete = _completed_buffers_head;

    _completed_buffers_head = NULL;

    _completed_buffers_tail = NULL;

    _n_completed_buffers = 0;

    _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);

  }

}

#ifdef ASSERT

void PtrQueueSet::assert_completed_buffers_list_len_correct_locked() {

  assert_lock_strong(_cbl_mon);

  size_t n = 0;

  for (BufferNode* bn = _completed_buffers_head; bn != NULL; bn = bn->next()) {

    ++n;

  }

  assert(n == _n_completed_buffers,

         "Completed buffer length is wrong: counted: " SIZE_FORMAT

         ", expected: " SIZE_FORMAT, n, _n_completed_buffers);

}

#endif // ASSERT

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

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

// must share the monitor.

void PtrQueueSet::merge_bufferlists(PtrQueueSet *src) {

  assert(_cbl_mon == src->_cbl_mon, "Should share the same lock");

  MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);

  if (_completed_buffers_tail == NULL) {

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

    _completed_buffers_head = src->_completed_buffers_head;

    _completed_buffers_tail = src->_completed_buffers_tail;

  } else {

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

    if (src->_completed_buffers_head != NULL) {

      _completed_buffers_tail->set_next(src->_completed_buffers_head);

      _completed_buffers_tail = src->_completed_buffers_tail;

    }

  }

  _n_completed_buffers += src->_n_completed_buffers;

  src->_n_completed_buffers = 0;

  src->_completed_buffers_head = NULL;

  src->_completed_buffers_tail = NULL;

  src->_process_completed_buffers = false;

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

         _completed_buffers_head != NULL && _completed_buffers_tail != NULL,

         "Sanity");

  assert_completed_buffers_list_len_correct_locked();

}

void PtrQueueSet::notify_if_necessary() {

  MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);

  if (_n_completed_buffers > _process_completed_buffers_threshold) {

    _process_completed_buffers = true;

    if (_notify_when_complete)

      _cbl_mon->notify();

  }

}