nt::NetworkTableListener Class Reference

Event listener. More...

#include <networktables/NetworkTableListener.h>

Public Member Functions
	NetworkTableListener ()=default
	NetworkTableListener (const NetworkTableListener &)=delete
NetworkTableListener &	operator= (const NetworkTableListener &)=delete
	NetworkTableListener (NetworkTableListener &&rhs)
NetworkTableListener &	operator= (NetworkTableListener &&rhs)
	~NetworkTableListener ()
	operator bool () const
NT_Listener	GetHandle () const
	Gets the native handle. More...
bool	WaitForQueue (double timeout)
	Wait for the listener queue to be empty. More...

Static Public Member Functions
static NetworkTableListener	CreateListener (NetworkTableInstance inst, std::span< const std::string_view > prefixes, unsigned int mask, ListenerCallback listener)
	Create a listener for changes to topics with names that start with any of the given prefixes. More...
static NetworkTableListener	CreateListener (Topic topic, unsigned int mask, ListenerCallback listener)
	Create a listener for changes on a particular topic. More...
static NetworkTableListener	CreateListener (Subscriber &subscriber, unsigned int mask, ListenerCallback listener)
	Create a listener for topic changes on a subscriber. More...
static NetworkTableListener	CreateListener (MultiSubscriber &subscriber, unsigned int mask, ListenerCallback listener)
	Create a listener for topic changes on a subscriber. More...
static NetworkTableListener	CreateListener (NetworkTableEntry &entry, unsigned int mask, ListenerCallback listener)
	Create a listener for topic changes on an entry. More...
static NetworkTableListener	CreateConnectionListener (NetworkTableInstance inst, bool immediate_notify, ListenerCallback listener)
	Create a connection listener. More...
static NetworkTableListener	CreateTimeSyncListener (NetworkTableInstance inst, bool immediate_notify, ListenerCallback listener)
	Create a time synchronization listener. More...
static NetworkTableListener	CreateLogger (NetworkTableInstance inst, unsigned int minLevel, unsigned int maxLevel, ListenerCallback listener)
	Create a listener for log messages. More...

Detailed Description

Event listener.

This calls back to a callback function when an event matching the specified mask occurs. The callback function is called asynchronously on a separate thread, so it's important to use synchronization or atomics when accessing any shared state from the callback function.

Constructor & Destructor Documentation

NetworkTableListener() [1/3]

nt::NetworkTableListener::NetworkTableListener ( )

default

NetworkTableListener() [2/3]

nt::NetworkTableListener::NetworkTableListener ( const NetworkTableListener &  )

delete

NetworkTableListener() [3/3]

nt::NetworkTableListener::NetworkTableListener ( NetworkTableListener &&  rhs )

inline

~NetworkTableListener()

nt::NetworkTableListener::~NetworkTableListener ( )

inline

Member Function Documentation

CreateConnectionListener()

NetworkTableListener nt::NetworkTableListener::CreateConnectionListener ( NetworkTableInstance  inst, bool  immediate_notify, ListenerCallback  listener  )

inlinestatic

Create a connection listener.

Parameters

inst	instance
immediate_notify	notify listener of all existing connections
listener	listener function

Returns

Listener

CreateListener() [1/5]

NetworkTableListener nt::NetworkTableListener::CreateListener ( MultiSubscriber &  subscriber, unsigned int  mask, ListenerCallback  listener  )

inlinestatic

Create a listener for topic changes on a subscriber.

This does NOT keep the subscriber active.

Parameters

subscriber	Subscriber
mask	Bitmask of EventFlags values
listener	Listener function

Returns

Listener

CreateListener() [2/5]

NetworkTableListener nt::NetworkTableListener::CreateListener ( NetworkTableEntry &  entry, unsigned int  mask, ListenerCallback  listener  )

inlinestatic

Create a listener for topic changes on an entry.

Parameters

entry	Entry
mask	Bitmask of EventFlags values
listener	Listener function

Returns

Listener

CreateListener() [3/5]

NetworkTableListener nt::NetworkTableListener::CreateListener ( NetworkTableInstance  inst, std::span< const std::string_view >  prefixes, unsigned int  mask, ListenerCallback  listener  )

inlinestatic

Create a listener for changes to topics with names that start with any of the given prefixes.

This creates a corresponding internal subscriber with the lifetime of the listener.

Parameters

inst	Instance
prefixes	Topic name string prefixes
mask	Bitmask of EventFlags values
listener	Listener function

Returns

Listener

CreateListener() [4/5]

NetworkTableListener nt::NetworkTableListener::CreateListener ( Subscriber &  subscriber, unsigned int  mask, ListenerCallback  listener  )

inlinestatic

Create a listener for topic changes on a subscriber.

This does NOT keep the subscriber active.

Parameters

subscriber	Subscriber
mask	Bitmask of EventFlags values
listener	Listener function

Returns

Listener

CreateListener() [5/5]

NetworkTableListener nt::NetworkTableListener::CreateListener ( Topic  topic, unsigned int  mask, ListenerCallback  listener  )

inlinestatic

Create a listener for changes on a particular topic.

This creates a corresponding internal subscriber with the lifetime of the listener.

Parameters

topic	Topic
mask	Bitmask of EventFlags values
listener	Listener function

Returns

Listener

CreateLogger()

NetworkTableListener nt::NetworkTableListener::CreateLogger ( NetworkTableInstance  inst, unsigned int  minLevel, unsigned int  maxLevel, ListenerCallback  listener  )

inlinestatic

Create a listener for log messages.

By default, log messages are sent to stderr; this function sends log messages with the specified levels to the provided callback function instead. The callback function will only be called for log messages with level greater than or equal to minLevel and less than or equal to maxLevel; messages outside this range will be silently ignored.

Parameters

inst	instance
minLevel	minimum log level
maxLevel	maximum log level
listener	listener function

Returns

Listener

CreateTimeSyncListener()

NetworkTableListener nt::NetworkTableListener::CreateTimeSyncListener ( NetworkTableInstance  inst, bool  immediate_notify, ListenerCallback  listener  )

inlinestatic

Create a time synchronization listener.

Parameters

inst	instance
immediate_notify	notify listener of current time synchronization value
listener	listener function

Returns

Listener

GetHandle()

NT_Listener nt::NetworkTableListener::GetHandle ( ) const

inline

Gets the native handle.

Returns

Handle

operator bool()

nt::NetworkTableListener::operator bool ( ) const

inlineexplicit

operator=() [1/2]

NetworkTableListener & nt::NetworkTableListener::operator= ( const NetworkTableListener &  )

delete

operator=() [2/2]

NetworkTableListener & nt::NetworkTableListener::operator= ( NetworkTableListener &&  rhs )

inline

WaitForQueue()

bool nt::NetworkTableListener::WaitForQueue ( double  timeout )

inline

Wait for the listener queue to be empty.

This is primarily useful for deterministic testing. This blocks until either the listener queue is empty (e.g. there are no more events that need to be passed along to callbacks or poll queues) or the timeout expires.

Parameters

timeout

timeout, in seconds. Set to 0 for non-blocking behavior, or a negative value to block indefinitely

Returns

False if timed out, otherwise true.

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

• networktables/NetworkTableListener.h
• networktables/NetworkTableListener.inc