TAO_LF_Event Class Reference

Use the Leader/Follower loop to wait for one specific event. More...

#include <LF_Event.h>

Inheritance diagram for TAO_LF_Event:

Collaboration diagram for TAO_LF_Event:

Public Member Functions
	TAO_LF_Event ()
	Constructor.
virtual	~TAO_LF_Event ()
	Destructor.
virtual int	bind (TAO_LF_Follower *follower)
	Bind a follower.
virtual int	unbind (TAO_LF_Follower *follower)
	Unbind the follower.

Friends
class	TAO_Leader_Follower

State management
A Leader/Followers event goes through several states during its lifetime. We use an enum to represent those states and state changes are validated according to the rules defined in the concrete classes. We treat the states as finite states in a FSM. The possible sequence of states through which the FSM migrates is defined in the concrete classes.
enum	LFS_STATE {   LFS_IDLE = 0 , LFS_ACTIVE , LFS_CONNECTION_WAIT , LFS_SUCCESS ,   LFS_FAILURE , LFS_TIMEOUT , LFS_CONNECTION_CLOSED }
	The current state. More...
LFS_STATE	state_
	The current state.
TAO_LF_Follower *	follower_
	The bounded follower.
void	state_changed (LFS_STATE new_state, TAO_Leader_Follower &lf)
bool	successful (TAO_Leader_Follower &lf) const
bool	error_detected (TAO_Leader_Follower &lf) const
bool	keep_waiting (TAO_Leader_Follower &lf) const
	Check if we should keep waiting.
void	reset_state (LFS_STATE new_state)
	Reset the state, irrespective of the previous states.
static const char *	state_name (LFS_STATE st)
	The current state.
virtual void	state_changed_i (LFS_STATE new_state)=0
	Validate the state change.
bool	keep_waiting_i () const
	Check if we should keep waiting.
virtual bool	successful_i () const =0
virtual bool	error_detected_i () const =0
virtual bool	is_state_final () const =0
	Check whether we have reached the final state..
virtual void	set_state (LFS_STATE new_state)
	Set the state irrespective of anything.

Detailed Description

Use the Leader/Follower loop to wait for one specific event.

The Leader/Follower event loop is used to wait for incoming responses, as well as to wait for all the data to be flushed. This class encapsulates this event loop. It uses Template Method to parametrize the 'waited for' predicate (i.e. reply received or message sent or connection establishment etc.)

Todo

Implementing the Leader/Followers loop in this class, as well as the callbacks to communicate that an event has completed leads to excessive coupling. A better design would use a separate class to signal the events, that would allow us to remove the Leader/Followers logic from the ORB. However, that requires other major changes and it somewhat complicates the design.

Member Enumeration Documentation

LFS_STATE

enum TAO_LF_Event::LFS_STATE

The current state.

Enumerator
LFS_IDLE	The event is created, and is in initial state.
LFS_ACTIVE	The event is active.
LFS_CONNECTION_WAIT	The event is waiting for connection completion.
LFS_SUCCESS	The event has completed successfully.
LFS_FAILURE	A failure has been detected while the event was active.
LFS_TIMEOUT	The event has timed out.
LFS_CONNECTION_CLOSED	The connection was closed.

Constructor & Destructor Documentation

TAO_LF_Event()

TAO_LF_Event::TAO_LF_Event

(

)

Constructor.

~TAO_LF_Event()

TAO_LF_Event::~TAO_LF_Event ( )

virtual

Destructor.

Member Function Documentation

bind()

int TAO_LF_Event::bind ( TAO_LF_Follower * follower )

virtual

Bind a follower.

An event can be waited on by at most one follower thread, this method is used to bind the waiting thread to the event, in order to let the event signal any important state changes.

This is virtual to allow the LF_Multi_Event derived type share the follower with all the subordinate LF_CH_Events.

Returns

-1 if the LF_Event is already bound, 0 otherwise

Reimplemented in TAO_LF_CH_Event, and TAO_LF_Multi_Event.

error_detected()

bool TAO_LF_Event::error_detected

(

TAO_Leader_Follower &

lf

)

const

Return true if an error was detected while waiting for the event

error_detected_i()

virtual bool TAO_LF_Event::error_detected_i ( ) const

protectedpure virtual

Return true if an error was detected while waiting for the event

Implemented in TAO_LF_CH_Event, TAO_LF_Invocation_Event, and TAO_LF_Multi_Event.

is_state_final()

virtual bool TAO_LF_Event::is_state_final ( ) const

protectedpure virtual

Check whether we have reached the final state..

Implemented in TAO_LF_CH_Event, TAO_LF_Invocation_Event, and TAO_LF_Multi_Event.

keep_waiting()

bool TAO_LF_Event::keep_waiting

(

TAO_Leader_Follower &

lf

)

const

Check if we should keep waiting.

keep_waiting_i()

bool TAO_LF_Event::keep_waiting_i ( ) const

protected

Check if we should keep waiting.

reset_state()

void TAO_LF_Event::reset_state

(

LFS_STATE

new_state

)

Reset the state, irrespective of the previous states.

set_state()

void TAO_LF_Event::set_state ( LFS_STATE new_state )

privatevirtual

Set the state irrespective of anything.

Reimplemented in TAO_LF_CH_Event.

state_changed()

void TAO_LF_Event::state_changed	(	LFS_STATE	new_state,
		TAO_Leader_Follower &	lf )

Accessor to change the state. The state isn't changed unless certain conditions are satisfied.

Sort of double-checked optimization..

state_changed_i()

virtual void TAO_LF_Event::state_changed_i ( LFS_STATE new_state )

protectedpure virtual

Validate the state change.

Implemented in TAO_LF_CH_Event, TAO_LF_Invocation_Event, and TAO_LF_Multi_Event.

state_name()

const char * TAO_LF_Event::state_name ( LFS_STATE st )

static

The current state.

successful()

bool TAO_LF_Event::successful

(

TAO_Leader_Follower &

lf

)

const

Return true if the condition was satisfied successfully, false if it has not

successful_i()

virtual bool TAO_LF_Event::successful_i ( ) const

protectedpure virtual

Return true if the condition was satisfied successfully, false if it has not

Implemented in TAO_LF_CH_Event, TAO_LF_Invocation_Event, and TAO_LF_Multi_Event.

unbind()

int TAO_LF_Event::unbind ( TAO_LF_Follower * follower )

virtual

Unbind the follower.

Reimplemented in TAO_LF_CH_Event, and TAO_LF_Multi_Event.

Friends And Related Symbol Documentation

TAO_Leader_Follower

friend class TAO_Leader_Follower

friend

Member Data Documentation

follower_

TAO_LF_Follower* TAO_LF_Event::follower_

protected

The bounded follower.

state_

LFS_STATE TAO_LF_Event::state_

protected

The current state.

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The documentation for this class was generated from the following files:

• LF_Event.h
• LF_Event.cpp
• LF_Event.inl