DurabilityQueue.h

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/*
 *
 *
 * Distributed under the OpenDDS License.
 * See: http://www.opendds.org/license.html
 */

#ifndef OPENDDS_DCPS_DURABILITYQUEUE_H
#define OPENDDS_DCPS_DURABILITYQUEUE_H

#include <ace/Unbounded_Queue.h>

#include <algorithm>
#include "PoolAllocator.h"

OPENDDS_BEGIN_VERSIONED_NAMESPACE_DECL

namespace OpenDDS {
namespace DCPS {

/**
 * @class DurabilityQueue
 *
 * @brief Queue class that provides a means to reset the
 *        underlying @c ACE_Allocator.
 *
 * This class only exists to provide a means to reset the
 * allocator used by the @c ACE_Unbounded_Queue base class.  It
 * has a specific use case, namely to correctly support instances
 * created by a persistent allocator.  The allocator address may
 * change between process runs, meaning the allocator address
 * stored in the persistent @c ACE_Unbounded_Queue instance will
 * be invalid.  Use the @c set_allocator() method to reset the
 * allocator address before performing any operations that will
 * require use of the allocator (e.g. enqueuing new items).
 */
template<typename T>
class DurabilityQueue : public ACE_Unbounded_Queue<T> {
public:

  DurabilityQueue(ACE_Allocator * allocator)
    : ACE_Unbounded_Queue<T> (allocator)
  {}

  DurabilityQueue(DurabilityQueue<T> const & rhs)
    : ACE_Unbounded_Queue<T> (rhs.allocator_)
    , fs_path_(rhs.fs_path_)
  {
    // Copied from ACE_Unbounded_Queue<>::copy_nodes().
    for (ACE_Node<T> *curr = rhs.head_->next_;
         curr != rhs.head_;
         curr = curr->next_)
      if (this->enqueue_tail(curr->item_) == -1)
        this->delete_nodes();
  }

  ~DurabilityQueue() {}

  void operator= (DurabilityQueue<T> const & rhs) {
    DurabilityQueue tmp(rhs);
    this->swap(rhs);
  }

  /// Reset allocator
  void set_allocator(ACE_Allocator * allocator) {
    if (allocator == 0)
      allocator = ACE_Allocator::instance();

    this->allocator_ = allocator;
  }

  void swap(DurabilityQueue<T> & rhs) {
    std::swap(this->head_, rhs.head_);
    std::swap(this->cur_size_, rhs.current_size_);
    std::swap(this->allocator_, rhs.allocator_);
    std::swap(this->fs_path_, rhs.fs_path_);
  }

  //filesystem path
  typedef OPENDDS_VECTOR(OPENDDS_STRING) fs_path_t;
  fs_path_t fs_path_;
};

} // namespace DCPS
} // namespace OpenDDS

OPENDDS_END_VERSIONED_NAMESPACE_DECL

#endif  /* OPENDDS_DURABILITY_QUEUE_H */