DirectPriorityMapper.h

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

#ifndef DIRECTPRIORITY_MAPPER_H
#define DIRECTPRIORITY_MAPPER_H

#include "dds/DCPS/dcps_export.h"

#include "PriorityMapper.h"
#include "ace/OS_NS_Thread.h"

namespace OpenDDS {
namespace DCPS {

/**
 * @class DirectPriorityMapper
 *
 * @brief map TRANSPORT_PRIORITY values directly.
 *
 * This implementation maps TRANSPORT_PRIORITY values directly to
 * both DiffServ codepoint and thread priority values.  The behavior
 * is saturating - that is when the TRANSPORT_PRIORITY value is out
 * of the target range, it is mapped to the nearest extremum.
 *
 * DiffServ codepoint values are mapped within the closed interval
 * [0,63], with the corresponding TRANSPORT_PRIORITY values mapped
 * directly within this range.
 *
 * Thread priorities are mapped to the system thread scheduler
 * minimum value (obtained from the sched_get_priority_min(sched)
 * system call, where available) up to the maximum value (obtained
 * from the sched_get_priority_max(sched) system call, where
 * available).  The TRANSPORT_PRIORITY value of 0 is mapped to the
 * minimum and a value of |max-min| is mapped to the maximum.
 */
class OpenDDS_Dcps_Export DirectPriorityMapper : public PriorityMapper {
public:
  /// Construct with a priority value.
  DirectPriorityMapper(Priority priority = 0);

  /// Virtual destructor.
  virtual ~DirectPriorityMapper();

  /// Access the mapped DiffServ codepoint value.
  virtual short codepoint() const;

  /// Access the mapped thread priority value.
  virtual short thread_priority() const;
};

} // namespace DCPS
} // namespace OpenDDS

#if defined (__ACE_INLINE__)
#include "DirectPriorityMapper.inl"
#endif /* __ACE_INLINE__ */

#endif  /* DIRECTPRIORITY_MAPPER_H */

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