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 * Copyright (c) 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.

 *

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#ifndef SHARE_GC_G1_G1REDIRTYCARDSQUEUE_HPP

#define SHARE_GC_G1_G1REDIRTYCARDSQUEUE_HPP

#include "gc/g1/g1BufferNodeList.hpp"

#include "gc/shared/ptrQueue.hpp"

#include "memory/allocation.hpp"

#include "memory/padded.hpp"

class G1CardTableEntryClosure;

class G1RedirtyCardsQueue;

class G1RedirtyCardsQueueSet;

// Provide G1RedirtyCardsQueue with a thread-local qset.  It provides an

// uncontended staging area for completed buffers, to be flushed to the

// shared qset en masse.  Using the "base from member" idiom so the local

// qset is constructed before being passed to the PtrQueue constructor.

class G1RedirtyCardsQueueBase {

  friend class G1RedirtyCardsQueue;

  friend class G1RedirtyCardsQueueSet;

  class LocalQSet : public PtrQueueSet {

    G1RedirtyCardsQueueSet* _shared_qset;

    G1BufferNodeList _buffers;

  public:

    LocalQSet(G1RedirtyCardsQueueSet* shared_qset);

    ~LocalQSet();

    // Add the buffer to the local list.

    virtual void enqueue_completed_buffer(BufferNode* node);

    // Transfer all completed buffers to the shared qset.

    void flush();

    G1BufferNodeList take_all_completed_buffers();

  };

  G1RedirtyCardsQueueBase(G1RedirtyCardsQueueSet* shared_qset) :

    _local_qset(shared_qset) {}

  ~G1RedirtyCardsQueueBase() {}

  LocalQSet _local_qset;

};

// Worker-local queues of card table entries.

class G1RedirtyCardsQueue : private G1RedirtyCardsQueueBase, public PtrQueue {

protected:

  virtual void handle_completed_buffer();

public:

  G1RedirtyCardsQueue(G1RedirtyCardsQueueSet* qset);

  // Flushes the queue.

  ~G1RedirtyCardsQueue();

  // Flushes all enqueued cards to qset.

  void flush();

};

// Card table entries to be redirtied and the cards reprocessed later.

// Has two phases, collecting and processing.  During the collecting

// phase buffers are added to the set.  Once collecting is complete and

// processing starts, buffers can no longer be added.  Taking all the

// collected (and processed) buffers reverts back to collecting, allowing

// the set to be reused for another round of redirtying.

class G1RedirtyCardsQueueSet : public PtrQueueSet {

  DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);

  BufferNode::Stack _list;

  DEFINE_PAD_MINUS_SIZE(2, DEFAULT_CACHE_LINE_SIZE, sizeof(size_t));

  volatile size_t _entry_count;

  DEFINE_PAD_MINUS_SIZE(3, DEFAULT_CACHE_LINE_SIZE, sizeof(BufferNode*));

  BufferNode* _tail;

  DEBUG_ONLY(mutable bool _collecting;)

  typedef G1RedirtyCardsQueueBase::LocalQSet LocalQSet;

  void update_tail(BufferNode* node);

public:

  G1RedirtyCardsQueueSet(BufferNode::Allocator* allocator);

  ~G1RedirtyCardsQueueSet();

  void verify_empty() const NOT_DEBUG_RETURN;

  // Collect buffers.  These functions are thread-safe.

  // precondition: Must not be concurrent with buffer processing.

  virtual void enqueue_completed_buffer(BufferNode* node);

  void merge_bufferlist(LocalQSet* src);

  // Processing phase operations.

  // precondition: Must not be concurrent with buffer collection.

  BufferNode* all_completed_buffers() const;

  G1BufferNodeList take_all_completed_buffers();

};

#endif // SHARE_GC_G1_G1REDIRTYCARDSQUEUE_HPP