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// -*- C++ -*-
//=============================================================================
/**
* @file Transport_Queueing_Strategies.h
*
* $Id$
*
* Queueing strategies for the ORB Messaging layer.
*
* @author Irfan Pyarali
*/
//=============================================================================
#ifndef TAO_TRANSPORT_QUEUEING_STRATEGIES_H
#define TAO_TRANSPORT_QUEUEING_STRATEGIES_H
#include /**/ "ace/pre.h"
#include "tao/TAO_Export.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
#include "tao/orbconf.h"
#include "tao/Basic_Types.h"
class TAO_Stub;
class ACE_Time_Value;
namespace TAO
{
struct BufferingConstraint;
}
namespace TimeBase
{
typedef CORBA::ULongLong TimeT;
}
namespace TAO
{
/// Define the interface for the Queueing Strategy
/**
* The low-level I/O components in the ORB use this strategy to
* determine when messages must be queued, immediately sent or
* flushed.
*
* The strategy isolates this low-level components from the higher
* level strategies used by the application developer.
*/
class Transport_Queueing_Strategy
{
public:
/// Destructor
virtual ~Transport_Queueing_Strategy (void);
/// Return true if a message must be queued
virtual bool must_queue (bool queue_empty) const = 0;
/// Return true if it is time to start
/**
* @param stub The object used to make the request, this is used to
* obtain the policies currently in effect for the request
* @param msg_count The number of messages currently queued
* @param total_bytes Number of bytes currently queued
* @param set_timer Returns true if a timer should be set to drain the
* queue
* @param interval If set_timer returns 1, this parameter contains
* the timer interval
* @param must_flush Is set to true if things must be flushed at this
* moment
*/
virtual bool buffering_constraints_reached (
TAO_Stub *stub,
size_t msg_count,
size_t total_bytes,
bool &must_flush,
const ACE_Time_Value ¤t_deadline,
bool &set_timer,
ACE_Time_Value &interval) const = 0;
};
class Default_Transport_Queueing_Strategy : public Transport_Queueing_Strategy
{
public:
virtual bool must_queue (bool queue_empty) const;
virtual bool buffering_constraints_reached (
TAO_Stub *stub,
size_t msg_count,
size_t total_bytes,
bool &must_flush,
const ACE_Time_Value ¤t_deadline,
bool &set_timer,
ACE_Time_Value &interval) const;
};
/**
* This strategy doesn't not queue by default, but when a message is queued
* we always flush it to the transport. This is used for oneways with
* SYNC_WITH_TRANSPORT, SYNC_WITH_SERVER and SYNC_WITH_TARGET
*/
class Flush_Transport_Queueing_Strategy : public Transport_Queueing_Strategy
{
public:
virtual bool must_queue (bool queue_empty) const;
virtual bool buffering_constraints_reached (
TAO_Stub *stub,
size_t msg_count,
size_t total_bytes,
bool &must_flush,
const ACE_Time_Value ¤t_deadline,
bool &set_timer,
ACE_Time_Value &interval) const;
};
#if (TAO_HAS_BUFFERING_CONSTRAINT_POLICY == 1)
class Eager_Transport_Queueing_Strategy : public Transport_Queueing_Strategy
{
public:
virtual bool must_queue (bool queue_empty) const;
virtual bool buffering_constraints_reached (
TAO_Stub *stub,
size_t msg_count,
size_t total_bytes,
bool &must_flush,
const ACE_Time_Value ¤t_deadline,
bool &set_timer,
ACE_Time_Value &new_deadline) const;
private:
/// Check if the buffering constraint includes any timeouts and
/// compute the right timeout interval if needed.
/**
* @param buffering_constraint The constraints defined by the
* application
* @param current_deadline The current deadline
* @param set_timer Return true if the timer should be set
* @param new_deadline Return the timer interval value
*
* @return Returns true if the deadline has already expired and
* flushing must commence immediately. If the function
* returns false then flushing may need to be delayed, use @c
* set_timer and
*/
bool timer_check (const TAO::BufferingConstraint &buffering_constraint,
const ACE_Time_Value ¤t_deadline,
bool &set_timer,
ACE_Time_Value &new_deadline) const;
/// Convert from standard CORBA time units to seconds/microseconds.
ACE_Time_Value time_conversion (const TimeBase::TimeT &time) const;
};
/// Delay the buffering decision until the transport blocks
/**
* If the queue is empty the transport will try to send immediately.
*/
class Delayed_Transport_Queueing_Strategy
: public Eager_Transport_Queueing_Strategy
{
public:
virtual bool must_queue (bool queue_empty) const;
};
#endif /* TAO_HAS_BUFFERING_CONSTRAINT_POLICY == 1 */
}
#include /**/ "ace/post.h"
#endif /* TAO_TRANSPORT_QUEUEING_STRATEGY_H */
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