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/* -*- C++ -*- */
// $Id$
//
// ============================================================================
//
// = LIBRARY
// ORBSVCS Real-time Event Channel
//
// = FILENAME
// EC_Filter
//
// = AUTHOR
// Carlos O'Ryan (coryan@cs.wustl.edu)
//
// = CREDITS
// Based on previous work by Tim Harrison (harrison@cs.wustl.edu)
// and other members of the DOC group.
// More details can be found in:
// http://www.cs.wustl.edu/~schmidt/oopsla.ps.gz
// http://www.cs.wustl.edu/~schmidt/JSAC-98.ps.gz
//
//
// ============================================================================
#ifndef TAO_EC_FILTER_H
#define TAO_EC_FILTER_H
#include "orbsvcs/RtecEventCommC.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
class TAO_EC_QOS_Info;
class TAO_ORBSVCS_Export TAO_EC_Filter
{
// = TITLE
// Abstract base class for the filter hierarchy.
//
// = DESCRIPTION
// The per-consumer filtering mechanisms.
// The EC needs to filter data passed to the consumers, so it can
// correctly satisfy its subscription requirements.
// This filtering can include correlations, sequences, timeouts,
// etc. each consumer can request different filtering criteria.
//
// Different filtering objects are associated with each consumer,
// the filters are organized in a hierarchical structure,
// corresponding to the subscription "expression" that the events
// must satisfy.
// The hierarchy is constructed using the "Builder" pattern.
//
// = MEMORY MANAGMENT
// It does *not* assume ownership of its parent.
//
public:
TAO_EC_Filter (void);
// constructor...
virtual ~TAO_EC_Filter (void);
// destructor...
TAO_EC_Filter* parent (void) const;
// Obtain the parent of this filter.
void adopt_child (TAO_EC_Filter* child);
// Become the parent of <child>
static int matches (const RtecEventComm::EventHeader& rhs,
const RtecEventComm::EventHeader& lhs);
// matches two event headers.
// @@ TODO: strategize this...
virtual int filter (const RtecEventComm::EventSet& event,
TAO_EC_QOS_Info& qos_info,
CORBA::Environment& env) = 0;
virtual int filter_nocopy (RtecEventComm::EventSet& event,
TAO_EC_QOS_Info& qos_info,
CORBA::Environment& env) = 0;
// Filter this event, returns 1 if the event is accepted, 0
// otherwise.
// Notice that there are two versions of the method, if the event is
// not const then filter can take ownership of the event.
virtual void push (const RtecEventComm::EventSet& event,
TAO_EC_QOS_Info& qos_info,
CORBA::Environment& env) = 0;
virtual void push_nocopy (RtecEventComm::EventSet& event,
TAO_EC_QOS_Info& qos_info,
CORBA::Environment& env) = 0;
// This is called by the children when they accept an event and
// which to pass it up.
// Notice that there are two versions of the method, if the event is
// not const then filter can take ownership of the event.
virtual void clear (void) = 0;
// Clear any saved state, must reset and assume no events have been
// received.
virtual CORBA::ULong max_event_size (void) const = 0;
// Returns the maximum size of the events pushed by this filter.
virtual int can_match (const RtecEventComm::EventHeader& header) const = 0;
// Returns 0 if an event with that header could never be accepted.
// This can used by the suppliers to filter out consumers that
// couldn't possibly be interested in their events.
private:
TAO_EC_Filter* parent_;
// The parent...
};
// ****************************************************************
class TAO_ORBSVCS_Export TAO_EC_Null_Filter : public TAO_EC_Filter
{
// = TITLE
// A null filter
//
// = DESCRIPTION
// This filter accepts any kind of event, it is useful for the
// implementation:
// a) Consumers that accept all events
// b) Consumers that trust the filtering done at the Supplier
// layer.
// c) Event Channels that don't do filtering (such as CosEC
// backends)
//
// = MEMORY MANAGMENT
//
public:
TAO_EC_Null_Filter (void);
// constructor.
// = The TAO_EC_Filter methods, please check the documentation in
// TAO_EC_Filter.
virtual int filter (const RtecEventComm::EventSet& event,
TAO_EC_QOS_Info& qos_info,
CORBA::Environment& env);
virtual int filter_nocopy (RtecEventComm::EventSet& event,
TAO_EC_QOS_Info& qos_info,
CORBA::Environment& env);
virtual void push (const RtecEventComm::EventSet& event,
TAO_EC_QOS_Info& qos_info,
CORBA::Environment& env);
virtual void push_nocopy (RtecEventComm::EventSet& event,
TAO_EC_QOS_Info& qos_info,
CORBA::Environment& env);
virtual void clear (void);
virtual CORBA::ULong max_event_size (void) const;
virtual int can_match (const RtecEventComm::EventHeader& header) const;
};
// ****************************************************************
// @@ Add more types of filters like:
// - Events in a sequence.
// - Events in a sequence with timeouts.
// - Conjunction with timeout [as opposed to disjunction of
// conjunction and a timeout]
// - etc.
// ****************************************************************
#if defined (__ACE_INLINE__)
#include "EC_Filter.i"
#endif /* __ACE_INLINE__ */
#endif /* TAO_EC_FILTER_H */
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