/*

 * Copyright (c) 2001, 2019, 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/g1CollectedHeap.inline.hpp"

#include "gc/g1/g1DirtyCardQueue.hpp"

#include "gc/g1/g1FreeIdSet.hpp"

#include "gc/g1/g1RemSet.hpp"

#include "gc/g1/g1ThreadLocalData.hpp"

#include "gc/g1/heapRegionRemSet.hpp"

#include "gc/shared/suspendibleThreadSet.hpp"

#include "gc/shared/workgroup.hpp"

#include "runtime/atomic.hpp"

#include "runtime/flags/flagSetting.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/safepoint.hpp"

#include "runtime/thread.inline.hpp"

#include "runtime/threadSMR.hpp"

// Closure used for updating remembered sets and recording references that

// point into the collection set while the mutator is running.

// Assumed to be only executed concurrently with the mutator. Yields via

// SuspendibleThreadSet after every card.

class G1RefineCardConcurrentlyClosure: public G1CardTableEntryClosure {

public:

  bool do_card_ptr(CardValue* card_ptr, uint worker_i) {

    G1CollectedHeap::heap()->rem_set()->refine_card_concurrently(card_ptr, worker_i);

    if (SuspendibleThreadSet::should_yield()) {

      // Caller will actually yield.

      return false;

    }

    // Otherwise, we finished successfully; return true.

    return true;

  }

};

G1DirtyCardQueue::G1DirtyCardQueue(G1DirtyCardQueueSet* qset) :

  // Dirty card queues are always active, so we create them with their

  // active field set to true.

  PtrQueue(qset, true /* active */)

{ }

G1DirtyCardQueue::~G1DirtyCardQueue() {

  flush();

}

void G1DirtyCardQueue::handle_completed_buffer() {

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

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

  G1DirtyCardQueueSet* dcqs = dirty_card_qset();

  if (dcqs->process_or_enqueue_completed_buffer(node)) {

    reset();                    // Buffer fully processed, reset index.

  } else {

    allocate_buffer();          // Buffer enqueued, get a new one.

  }

}

G1DirtyCardQueueSet::G1DirtyCardQueueSet(bool notify_when_complete) :

  _max_completed_buffers(MaxCompletedBuffersUnlimited),

  _completed_buffers_padding(0),

  _free_ids(NULL),

  _processed_buffers_mut(0),

  _processed_buffers_rs_thread(0),

  _cur_par_buffer_node(NULL)

{

  _all_active = true;

}

G1DirtyCardQueueSet::~G1DirtyCardQueueSet() {

  delete _free_ids;

}

// Determines how many mutator threads can process the buffers in parallel.

uint G1DirtyCardQueueSet::num_par_ids() {

  return (uint)os::initial_active_processor_count();

}

void G1DirtyCardQueueSet::initialize(Monitor* cbl_mon,

                                     BufferNode::Allocator* allocator,

                                     bool init_free_ids) {

  if (init_free_ids) {

    _free_ids = new G1FreeIdSet(0, num_par_ids());

  }

}

void G1DirtyCardQueueSet::handle_zero_index_for_thread(Thread* t) {

  G1ThreadLocalData::dirty_card_queue(t).handle_zero_index();

}

bool G1DirtyCardQueueSet::apply_closure_to_buffer(G1CardTableEntryClosure* cl,

                                                  BufferNode* node,

                                                  bool consume,

                                                  uint worker_i) {

  if (cl == NULL) return true;

  bool result = true;

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

  size_t i = node->index();

  size_t limit = buffer_size();

  for ( ; i < limit; ++i) {

    CardTable::CardValue* card_ptr = static_cast<CardTable::CardValue*>(buf[i]);

    assert(card_ptr != NULL, "invariant");

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

      result = false;           // Incomplete processing.

      break;

    }

  }

  if (consume) {

    assert(i <= buffer_size(), "invariant");

    node->set_index(i);

  }

  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 G1DirtyCardQueueSet::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 max_buffers = max_completed_buffers();

    size_t limit = max_buffers + completed_buffers_padding();

    if ((completed_buffers_num() > limit) && (limit >= max_buffers)) {

      if (mut_process_buffer(node)) {

        return true;

      }

    }

  }

  enqueue_completed_buffer(node);

  return false;

}

bool G1DirtyCardQueueSet::mut_process_buffer(BufferNode* node) {

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

  uint worker_i = _free_ids->claim_par_id(); // temporarily claim an id

  G1RefineCardConcurrentlyClosure cl;

  bool result = apply_closure_to_buffer(&cl, 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;

}

bool G1DirtyCardQueueSet::refine_completed_buffer_concurrently(uint worker_i, size_t stop_at) {

  G1RefineCardConcurrentlyClosure cl;

  return apply_closure_to_completed_buffer(&cl, worker_i, stop_at, false);

}

bool G1DirtyCardQueueSet::apply_closure_during_gc(G1CardTableEntryClosure* cl, uint worker_i) {

  assert_at_safepoint();

  return apply_closure_to_completed_buffer(cl, worker_i, 0, true);

}

bool G1DirtyCardQueueSet::apply_closure_to_completed_buffer(G1CardTableEntryClosure* 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_completed_buffer(nd);

    }

    return true;

  }

}

void G1DirtyCardQueueSet::par_apply_closure_to_all_completed_buffers(G1CardTableEntryClosure* cl) {

  BufferNode* nd = _cur_par_buffer_node;

  while (nd != NULL) {

    BufferNode* next = nd->next();

    BufferNode* actual = Atomic::cmpxchg(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 = actual;

    }

  }

}

void G1DirtyCardQueueSet::abandon_logs() {

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

  abandon_completed_buffers();

  // Since abandon is done only at safepoints, we can safely manipulate

  // these queues.

  struct AbandonThreadLogClosure : public ThreadClosure {

    virtual void do_thread(Thread* t) {

      G1ThreadLocalData::dirty_card_queue(t).reset();

    }

  } closure;

  Threads::threads_do(&closure);

  G1BarrierSet::shared_dirty_card_queue().reset();

}

void G1DirtyCardQueueSet::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.

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

  size_t old_limit = max_completed_buffers();

  set_max_completed_buffers(MaxCompletedBuffersUnlimited);

  struct ConcatenateThreadLogClosure : public ThreadClosure {

    virtual void do_thread(Thread* t) {

      G1DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(t);

      if (!dcq.is_empty()) {

        dcq.flush();

      }

    }

  } closure;

  Threads::threads_do(&closure);

  G1BarrierSet::shared_dirty_card_queue().flush();

  set_max_completed_buffers(old_limit);

}