DrakeLcm Class Reference

Detailed Description

A wrapper around a real LCM instance.

See DRAKE_ALLOW_NETWORK for an environment variable option to disable LCM network traffic (i.e., only allowing memq:// URLs).

For network issues on macOS, see https://drake.mit.edu/troubleshooting.html#lcm-macos.

#include <drake/lcm/drake_lcm.h>

Public Member Functions
	DrakeLcm ()
	Constructs using LCM's default URL (either the default hard-coded URL, or else LCM_DEFAULT_URL environment variable if it is set).
	DrakeLcm (std::string lcm_url)
	Constructs using the given URL.
	DrakeLcm (const DrakeLcmParams &params)
	Constructs using the given parameters.
	~DrakeLcm () override
	A destructor that forces the receive thread to be stopped.
void	Publish (const std::string &, const void *, int, std::optional< double >) override
	Most users should use the drake::lcm::Publish() free function, instead of this interface method.
std::string	get_lcm_url () const override
	Returns a URL describing the transport of this LCM interface.
std::shared_ptr< DrakeSubscriptionInterface >	Subscribe (const std::string &, HandlerFunction) override
	Most users should use the drake::lcm::Subscribe() free function or the drake::lcm::Subscriber wrapper class, instead of this interface method.
std::shared_ptr< DrakeSubscriptionInterface >	SubscribeMultichannel (std::string_view, MultichannelHandlerFunction) override
	Subscribes to all channels whose name matches the given regular expression.
std::shared_ptr< DrakeSubscriptionInterface >	SubscribeAllChannels (MultichannelHandlerFunction) override
	Subscribe to all channels; this is useful for logging and redirecting LCM traffic without regard to its content.
int	HandleSubscriptions (int) override
	Invokes the HandlerFunction callbacks for all subscriptions' pending messages.
Does not allow copy, move, or assignment
	DrakeLcm (const DrakeLcm &)=delete
DrakeLcm &	operator= (const DrakeLcm &)=delete
	DrakeLcm (DrakeLcm &&)=delete
DrakeLcm &	operator= (DrakeLcm &&)=delete
Public Member Functions inherited from DrakeLcmInterface
virtual	~DrakeLcmInterface ()
	DrakeLcmInterface (const DrakeLcmInterface &)=delete
DrakeLcmInterface &	operator= (const DrakeLcmInterface &)=delete
	DrakeLcmInterface (DrakeLcmInterface &&)=delete
DrakeLcmInterface &	operator= (DrakeLcmInterface &&)=delete

Static Public Member Functions
static bool	available ()
	Returns true if the LCM runtime library is enabled in this build of Drake.

Friends
class	DrakeLcmTester

Additional Inherited Members
Public Types inherited from DrakeLcmInterface
using	HandlerFunction = std::function<void(const void*, int)>
	A callback used by DrakeLcmInterface::Subscribe(), with arguments:
using	MultichannelHandlerFunction
	A callback used by DrakeLcmInterface::SubscribeMultipleChannels (which therefore needs the receiving channel passed in).
Protected Member Functions inherited from DrakeLcmInterface
	DrakeLcmInterface ()

Constructor & Destructor Documentation

DrakeLcm() [1/5]

DrakeLcm ( const DrakeLcm & )

delete

DrakeLcm() [2/5]

DrakeLcm ( DrakeLcm && )

delete

DrakeLcm() [3/5]

DrakeLcm

(

)

Constructs using LCM's default URL (either the default hard-coded URL, or else LCM_DEFAULT_URL environment variable if it is set).

DrakeLcm() [4/5]

DrakeLcm ( std::string lcm_url )

explicit

Constructs using the given URL.

If empty, it will use the default URL as per the no-argument constructor.

DrakeLcm() [5/5]

DrakeLcm ( const DrakeLcmParams & params )

explicit

Constructs using the given parameters.

~DrakeLcm()

~DrakeLcm ( )

override

A destructor that forces the receive thread to be stopped.

Member Function Documentation

available()

bool available ( )

static

Returns true if the LCM runtime library is enabled in this build of Drake.

When false, functions that require the runtime (e.g., HandleSubscriptions and Publish) will throw an error. See //tools/flags:with_lcm_runtime.

get_lcm_url()

std::string get_lcm_url ( ) const

overridevirtual

Returns a URL describing the transport of this LCM interface.

When the URL refers to a transport offered by LCM itself (e.g., memq or udpm), then this function must return the conventional URL spelling. If the implementation of DrakeLcmInterface is using a non-standard back end, the result implementation-defined.

In either case, it is always formatted using URI syntax rules per the RFC(s).

Implements DrakeLcmInterface.

HandleSubscriptions()

int HandleSubscriptions ( int timeout_millis )

overridevirtual

Invokes the HandlerFunction callbacks for all subscriptions' pending messages.

If timeout_millis is >0, blocks for up to that long until at least one message is handled.

Returns

the number of messages handled, or 0 on timeout.

Exceptions

std::exception

when a subscribed handler throws.

Implements DrakeLcmInterface.

operator=() [1/2]

DrakeLcm & operator= ( const DrakeLcm & )

delete

operator=() [2/2]

DrakeLcm & operator= ( DrakeLcm && )

delete

Publish()

void Publish ( const std::string & channel, const void * data, int data_size, std::optional< double > time_sec )

overridevirtual

Most users should use the drake::lcm::Publish() free function, instead of this interface method.

Publishes an LCM message on channel channel.

Parameters

channel	The channel on which to publish the message. Must not be the empty string.
data	A buffer containing the serialized bytes of the message to publish.
data_size	The length of @data in bytes.
time_sec	Time in seconds when the publish event occurred. If unknown, use nullopt or a default-constructed optional.

Implements DrakeLcmInterface.

Subscribe()

std::shared_ptr< DrakeSubscriptionInterface > Subscribe ( const std::string & channel, HandlerFunction  )

overridevirtual

Most users should use the drake::lcm::Subscribe() free function or the drake::lcm::Subscriber wrapper class, instead of this interface method.

Subscribes to an LCM channel without automatic message decoding. The handler will be invoked when a message arrives on channel channel.

The handler should never throw an exception, because it is indirectly called from C functions.

Parameters

channel

The channel to subscribe to. Must not be the empty string. To use a regex, see SubscribeMultichannel().

Returns

the object used to manage the subscription if that is supported, or else nullptr if not supported. The unsubscribe-on-delete default is false. Refer to the DrakeSubscriptionInterface class overview for details.

Implements DrakeLcmInterface.

SubscribeAllChannels()

std::shared_ptr< DrakeSubscriptionInterface > SubscribeAllChannels ( MultichannelHandlerFunction )

overridevirtual

Subscribe to all channels; this is useful for logging and redirecting LCM traffic without regard to its content.

Implements DrakeLcmInterface.

SubscribeMultichannel()

std::shared_ptr< DrakeSubscriptionInterface > SubscribeMultichannel ( std::string_view regex, MultichannelHandlerFunction  )

overridevirtual

Subscribes to all channels whose name matches the given regular expression.

The regex is treated as an anchored "match" not a "search", i.e., it must match the entire channel name. The specific regular expression grammar is left unspecified, so it's best to use only patterns that have identical semantics in all grammars, e.g., ".*".

Implements DrakeLcmInterface.

Friends And Related Symbol Documentation

DrakeLcmTester

friend class DrakeLcmTester

friend

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

• drake/lcm/drake_lcm.h