An Obervable class that listens for Signal K stream deltas and notifies any observers of value changes. This serves as a base class for code that needs to listen to the stream, with the most common descendant being SKValueListener More...

#include <sensesp/signalk/signalk_listener.h>

Inheritance diagram for sensesp::SKListener:

[legend]

Public Member Functions
	SKListener (const String &sk_path, int listen_delay, const String &config_path="")

virtual	~SKListener ()

String &	get_sk_path ()

int	get_listen_delay ()

virtual bool	matches (const String &path) const

virtual void	parse_value (const JsonObject &json)

virtual bool	wants_meta () const

virtual void	parse_meta (const std::shared_ptr< const JsonDocument > &meta_doc)

Public Member Functions inherited from sensesp::Observable
	Observable ()

	Observable (Observable &&other)
	Move constructor.

void	notify ()

int	attach (std::function< void()> observer)
	Attach an observer callback.

void	detach (int id)
	Remove a previously attached observer by its ID.

Public Member Functions inherited from sensesp::FileSystemSaveable
	FileSystemSaveable (const String &config_path)

virtual bool	load () override
	Load and populate the object from a persistent storage.

virtual bool	save () override
	Save the object to a persistent storage.

virtual bool	clear () override
	Delete the data from a persistent storage.

bool	find_config_file (const String &config_path, String &filename)

Public Member Functions inherited from sensesp::Saveable
	Saveable (const String &config_path)

virtual bool	refresh ()
	Refresh the object. This may or may not access the persistent storage but is not expected to overwrite the object's state.

const String &	get_config_path () const

Static Public Member Functions
static const std::vector< SKListener * > &	get_listeners ()

static void	clear_registry ()

static bool	take_semaphore (uint64_t timeout_ms=0)

static void	release_semaphore ()

Protected Attributes
String	sk_path {}

Protected Attributes inherited from sensesp::Saveable
const String	config_path_

Detailed Description

An Obervable class that listens for Signal K stream deltas and notifies any observers of value changes. This serves as a base class for code that needs to listen to the stream, with the most common descendant being SKValueListener

See also: SKValueListener

Definition at line 23 of file signalk_listener.h.

Constructor & Destructor Documentation

◆ SKListener()

sensesp::SKListener::SKListener	(	const String &	sk_path,
		int	listen_delay,
		const String &	config_path = `""`
	)

The constructor

Parameters

sk_path	The Signal K path that identifies this particular subscription to value
listen_delay	How often you want the SK Server to send the data you're subscribing to
config_path	The optional configuration path that allows an end user to change the configuration of this object. See the Configurable class for more information.

Definition at line 15 of file signalk_listener.cpp.

Here is the call graph for this function:

◆ ~SKListener()

sensesp::SKListener::~SKListener ( )

virtual

Unregisters this listener from the static registry so the registry never holds a dangling pointer. Takes the listener semaphore because the WS client task iterates the registry under the same lock.

Definition at line 24 of file signalk_listener.cpp.

Here is the call graph for this function:

Member Function Documentation

◆ clear_registry()

void sensesp::SKListener::clear_registry ( )

static

Empties the listener registry. Intended for clean app restart and test isolation; not for normal runtime use. Takes the listener semaphore.

Definition at line 31 of file signalk_listener.cpp.

Here is the call graph for this function:

Here is the caller graph for this function:

◆ get_listen_delay()

int sensesp::SKListener::get_listen_delay ( )

inline

Definition at line 52 of file signalk_listener.h.

◆ get_listeners()

static const std::vector< SKListener * > & sensesp::SKListener::get_listeners ( )

inlinestatic

Definition at line 86 of file signalk_listener.h.

Here is the caller graph for this function:

◆ get_sk_path()

String & sensesp::SKListener::get_sk_path ( )

inline

Returns the current Signal K path. An empty string is returned if this particular source is not configured or intended to return actual data.

Definition at line 50 of file signalk_listener.h.

◆ matches()

virtual bool sensesp::SKListener::matches ( const String & path ) const

inlinevirtual

Whether a received delta on path should be routed to this listener.

Defaults to an exact match against sk_path. Listeners that observe a family of paths (e.g. a prefix subscription like notifications.*, where the server publishes on paths the client cannot enumerate in advance) override this to widen the match. SKWSClient::process_received_updates calls it per delta instead of comparing paths directly, so the routing policy lives with the listener.

Reimplemented in sensesp::SKPrefixListener.

Definition at line 64 of file signalk_listener.h.

Here is the caller graph for this function:

◆ parse_meta()

virtual void sensesp::SKListener::parse_meta ( const std::shared_ptr< const JsonDocument > & meta_doc )

inlinevirtual

Consume a metadata delta for this listener's path. Mirrors parse_value for the meta stream: SKWSClient::process_received_updates calls it on the main task with an owned, read-only document (shape {path, value: {...meta...}}) that outlives any deferred consumer. Default is a no-op; SKMetadataListener overrides it.

Reimplemented in sensesp::SKMetadataListener.

Definition at line 84 of file signalk_listener.h.

Here is the caller graph for this function:

◆ parse_value()

virtual void sensesp::SKListener::parse_value ( const JsonObject & json )

inlinevirtual

Reimplemented in sensesp::SKPrefixListener, and sensesp::SKValueListener< T >.

Definition at line 66 of file signalk_listener.h.

Here is the caller graph for this function:

◆ release_semaphore()

void sensesp::SKListener::release_semaphore ( )

static

Definition at line 45 of file signalk_listener.cpp.

Here is the caller graph for this function:

◆ take_semaphore()

bool sensesp::SKListener::take_semaphore ( uint64_t timeout_ms = 0 )

static

Definition at line 37 of file signalk_listener.cpp.

Here is the caller graph for this function:

◆ wants_meta()

virtual bool sensesp::SKListener::wants_meta ( ) const

inlinevirtual

Whether this listener consumes metadata deltas (updates[].meta[]) rather than value deltas (updates[].values[]). Defaults to false; SKMetadataListener overrides it to true. Used by SKWSClient::process_received_updates to route a queued delta to the correct listener kind without RTTI (RTTI is commonly disabled on ESP32).

Reimplemented in sensesp::SKMetadataListener.

Definition at line 75 of file signalk_listener.h.

Here is the caller graph for this function:

Member Data Documentation

◆ sk_path

String sensesp::SKListener::sk_path {}

protected

Definition at line 98 of file signalk_listener.h.

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

src/sensesp/signalk/signalk_listener.h
src/sensesp/signalk/signalk_listener.cpp

Public Member Functions

Static Public Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ SKListener()

◆ ~SKListener()

Member Function Documentation

◆ clear_registry()

◆ get_listen_delay()

◆ get_listeners()

◆ get_sk_path()

◆ matches()

◆ parse_meta()

◆ parse_value()

◆ release_semaphore()

◆ take_semaphore()

◆ wants_meta()

Member Data Documentation

◆ sk_path