/*

 * 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/shared/satbMarkQueue.hpp"

#include "gc/shared/collectedHeap.hpp"

#include "logging/log.hpp"

#include "memory/allocation.inline.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/os.hpp"

#include "runtime/safepoint.hpp"

#include "runtime/thread.hpp"

#include "runtime/threadSMR.hpp"

#include "runtime/vmThread.hpp"

SATBMarkQueue::SATBMarkQueue(SATBMarkQueueSet* qset, bool permanent) :

  // SATB queues are only active during marking cycles. We create

  // them with their active field set to false. If a thread is

  // created during a cycle and its SATB queue needs to be activated

  // before the thread starts running, we'll need to set its active

  // field to true. This must be done in the collector-specific

  // BarrierSet::on_thread_attach() implementation.

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

{ }

void SATBMarkQueue::flush() {

  // Filter now to possibly save work later.  If filtering empties the

  // buffer then flush_impl can deallocate the buffer.

  filter();

  flush_impl();

}

// This method will first apply filtering to the buffer. If filtering

// retains a small enough collection in the buffer, we can continue to

// use the buffer as-is, instead of enqueueing and replacing it.

bool SATBMarkQueue::should_enqueue_buffer() {

  assert(_lock == NULL || _lock->owned_by_self(),

         "we should have taken the lock before calling this");

  // This method should only be called if there is a non-NULL buffer

  // that is full.

  assert(index() == 0, "pre-condition");

  assert(_buf != NULL, "pre-condition");

  filter();

  SATBMarkQueueSet* satb_qset = static_cast<SATBMarkQueueSet*>(qset());

  size_t threshold = satb_qset->buffer_enqueue_threshold();

  // Ensure we'll enqueue completely full buffers.

  assert(threshold > 0, "enqueue threshold = 0");

  // Ensure we won't enqueue empty buffers.

  assert(threshold <= capacity(),

         "enqueue threshold " SIZE_FORMAT " exceeds capacity " SIZE_FORMAT,

         threshold, capacity());

  return index() < threshold;

}

void SATBMarkQueue::apply_closure_and_empty(SATBBufferClosure* cl) {

  assert(SafepointSynchronize::is_at_safepoint(),

         "SATB queues must only be processed at safepoints");

  if (_buf != NULL) {

    cl->do_buffer(&_buf[index()], size());

    reset();

  }

}

#ifndef PRODUCT

// Helpful for debugging

static void print_satb_buffer(const char* name,

                              void** buf,

                              size_t index,

                              size_t capacity) {

  tty->print_cr("  SATB BUFFER [%s] buf: " PTR_FORMAT " index: " SIZE_FORMAT

                " capacity: " SIZE_FORMAT,

                name, p2i(buf), index, capacity);

}

void SATBMarkQueue::print(const char* name) {

  print_satb_buffer(name, _buf, index(), capacity());

}

#endif // PRODUCT

SATBMarkQueueSet::SATBMarkQueueSet() :

  PtrQueueSet(),

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

  _buffer_enqueue_threshold(0)

{}

void SATBMarkQueueSet::initialize(Monitor* cbl_mon, Mutex* fl_lock,

                                  int process_completed_threshold,

                                  uint buffer_enqueue_threshold_percentage,

                                  Mutex* lock) {

  PtrQueueSet::initialize(cbl_mon, fl_lock, process_completed_threshold, -1);

  _shared_satb_queue.set_lock(lock);

  assert(buffer_size() != 0, "buffer size not initialized");

  // Minimum threshold of 1 ensures enqueuing of completely full buffers.

  size_t size = buffer_size();

  size_t enqueue_qty = (size * buffer_enqueue_threshold_percentage) / 100;

  _buffer_enqueue_threshold = MAX2(size - enqueue_qty, (size_t)1);

}

#ifdef ASSERT

void SATBMarkQueueSet::dump_active_states(bool expected_active) {

  log_error(gc, verify)("Expected SATB active state: %s", expected_active ? "ACTIVE" : "INACTIVE");

  log_error(gc, verify)("Actual SATB active states:");

  log_error(gc, verify)("  Queue set: %s", is_active() ? "ACTIVE" : "INACTIVE");

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

    log_error(gc, verify)("  Thread \"%s\" queue: %s", t->name(), satb_queue_for_thread(t).is_active() ? "ACTIVE" : "INACTIVE");

  }

  log_error(gc, verify)("  Shared queue: %s", shared_satb_queue()->is_active() ? "ACTIVE" : "INACTIVE");

}

void SATBMarkQueueSet::verify_active_states(bool expected_active) {

  // Verify queue set state

  if (is_active() != expected_active) {

    dump_active_states(expected_active);

    guarantee(false, "SATB queue set has an unexpected active state");

  }

  // Verify thread queue states

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

    if (satb_queue_for_thread(t).is_active() != expected_active) {

      dump_active_states(expected_active);

      guarantee(false, "Thread SATB queue has an unexpected active state");

    }

  }

  // Verify shared queue state

  if (shared_satb_queue()->is_active() != expected_active) {

    dump_active_states(expected_active);

    guarantee(false, "Shared SATB queue has an unexpected active state");

  }

}

#endif // ASSERT

void SATBMarkQueueSet::set_active_all_threads(bool active, bool expected_active) {

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

#ifdef ASSERT

  verify_active_states(expected_active);

#endif // ASSERT

  _all_active = active;

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

    satb_queue_for_thread(t).set_active(active);

  }

  shared_satb_queue()->set_active(active);

}

void SATBMarkQueueSet::filter_thread_buffers() {

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

    satb_queue_for_thread(t).filter();

  }

  shared_satb_queue()->filter();

}

bool SATBMarkQueueSet::apply_closure_to_completed_buffer(SATBBufferClosure* cl) {

  BufferNode* nd = NULL;

  {

    MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);

    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--;

      if (_n_completed_buffers == 0) _process_completed = false;

    }

  }

  if (nd != NULL) {

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

    size_t index = nd->index();

    size_t size = buffer_size();

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

    cl->do_buffer(buf + index, size - index);

    deallocate_buffer(nd);

    return true;

  } else {

    return false;

  }

}

#ifndef PRODUCT

// Helpful for debugging

#define SATB_PRINTER_BUFFER_SIZE 256

void SATBMarkQueueSet::print_all(const char* msg) {

  char buffer[SATB_PRINTER_BUFFER_SIZE];

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

  tty->cr();

  tty->print_cr("SATB BUFFERS [%s]", msg);

  BufferNode* nd = _completed_buffers_head;

  int i = 0;

  while (nd != NULL) {

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

    os::snprintf(buffer, SATB_PRINTER_BUFFER_SIZE, "Enqueued: %d", i);

    print_satb_buffer(buffer, buf, nd->index(), buffer_size());

    nd = nd->next();

    i += 1;

  }

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

    os::snprintf(buffer, SATB_PRINTER_BUFFER_SIZE, "Thread: %s", t->name());

    satb_queue_for_thread(t).print(buffer);

  }

  shared_satb_queue()->print("Shared");

  tty->cr();

}

#endif // PRODUCT

void SATBMarkQueueSet::abandon_partial_marking() {

  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;

    }

    _completed_buffers_tail = NULL;

    _n_completed_buffers = 0;

    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);

  }

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

  // So we can safely manipulate these queues.

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

    satb_queue_for_thread(t).reset();

  }

  shared_satb_queue()->reset();

}