#include <stdint.h>
#include "rcl/allocator.h"
#include "rcl/macros.h"
#include "rcl/types.h"
#include "rcl/visibility_control.h"

Classes
struct	rcl_node_t
	Structure which encapsulates a ROS Node. More...

struct	rcl_node_options_t
	Structure which encapsulates the options for creating a rcl_node_t. More...

Macros
#define	RCL_NODE_OPTIONS_DEFAULT_DOMAIN_ID SIZE_MAX
	Constant which indicates that the default domain id should be used. More...

Typedefs
typedef struct rcl_node_t	rcl_node_t
	Structure which encapsulates a ROS Node. More...

typedef struct rcl_node_options_t	rcl_node_options_t
	Structure which encapsulates the options for creating a rcl_node_t. More...

Functions
rcl_node_t	rcl_get_zero_initialized_node (void)
	Return a rcl_node_t struct with members initialized to `NULL`. More...

rcl_ret_t	rcl_node_init (rcl_node_t node, const char name, const rcl_node_options_t *options)
	Initialize a ROS node. More...

rcl_ret_t	rcl_node_fini (rcl_node_t *node)
	Finalized a rcl_node_t. More...

rcl_node_options_t	rcl_node_get_default_options (void)
	Return the default node options in a rcl_node_options_t. More...

bool	rcl_node_is_valid (const rcl_node_t *node)
	Return `true` if the node is valid, else `false`. More...

const char *	rcl_node_get_name (const rcl_node_t *node)
	Return the name of the node. More...

const rcl_node_options_t *	rcl_node_get_options (const rcl_node_t *node)
	Return the rcl node options. More...

rcl_ret_t	rcl_node_get_domain_id (const rcl_node_t node, size_t domain_id)
	Return the ROS domain ID that the node is using. More...

rmw_node_t *	rcl_node_get_rmw_handle (const rcl_node_t *node)
	Return the rmw node handle. More...

uint64_t	rcl_node_get_rcl_instance_id (const rcl_node_t *node)
	Return the associated rcl instance id. More...

const struct rcl_guard_condition_t *	rcl_node_get_graph_guard_condition (const rcl_node_t *node)
	Return a guard condition which is triggered when the ROS graph changes. More...

Macro Definition Documentation

§ RCL_NODE_OPTIONS_DEFAULT_DOMAIN_ID

#define RCL_NODE_OPTIONS_DEFAULT_DOMAIN_ID SIZE_MAX

Constant which indicates that the default domain id should be used.

Typedef Documentation

§ rcl_node_t

typedef struct rcl_node_t rcl_node_t

Structure which encapsulates a ROS Node.

§ rcl_node_options_t

typedef struct rcl_node_options_t rcl_node_options_t

Structure which encapsulates the options for creating a rcl_node_t.

Function Documentation

§ rcl_get_zero_initialized_node()

rcl_node_t rcl_get_zero_initialized_node ( void )

Return a rcl_node_t struct with members initialized to NULL.

§ rcl_node_init()

rcl_ret_t rcl_node_init	(	rcl_node_t *	node,
		const char *	name,
		const rcl_node_options_t *	options
	)

Initialize a ROS node.

Calling this on a rcl_node_t makes it a valid node handle until rcl_shutdown is called or until rcl_node_fini is called on it.

After calling, the ROS node object can be used to create other middleware primitives like publishers, services, parameters, etc.

Todo:: TODO(wjwwood): node name uniqueness is no yet enforced

The name of the node cannot coincide with another node of the same name. If a node of the same name is already in the domain, it will be shutdown.

Todo:: TODO(wjwwood): Parameter infrastructure is currently initialized in the language specific client library, e.g. rclcpp for C++, but will be initialized here in the future. When that happens there will be an option to avoid parameter infrastructure with an option in the rcl_node_options_t struct.

A node contains infrastructure for ROS parameters, which include advertising publishers and service servers. This function will create those external parameter interfaces even if parameters are not used later.

The rcl_node_t given must be allocated and zero initialized. Passing an rcl_node_t which has already had this function called on it, more recently than rcl_node_fini, will fail. An allocated rcl_node_t with uninitialized memory is undefined behavior.

Expected usage:

rcl_node_t node = rcl_get_zero_initialized_node();
rcl_node_options_t * node_ops = rcl_node_get_default_options();
// ... node options customization
rcl_ret_t ret = rcl_node_init(&node, "node_name", node_ops);
// ... error handling and then use the node, but eventually deinitialize it:
ret = rcl_node_fini(&node);
// ... error handling for rcl_node_fini()

Attribute	Adherence
Allocates Memory	Yes
Thread-Safe	No
Uses Atomics	Yes
Lock-Free	Yes [1]

[1] if atomic_is_lock_free() returns true for atomic_uint_least64_t

Precondition: the node handle must be allocated, zero initialized, and invalid

Postcondition: the node handle is valid and can be used in other rcl_* functions

Parameters

[in,out]	node	a preallocated rcl_node_t
[in]	name	the name of the node
[in]	options	the node options

Returns: RCL_RET_OK if the node was initialized successfully, or; RCL_RET_ALREADY_INIT if the node has already be initialized, or; RCL_RET_INVALID_ARGUMENT if any arguments are invalid, or; RCL_RET_BAD_ALLOC if allocating memory failed, or; RCL_RET_ERROR if an unspecified error occurs.

§ rcl_node_fini()

rcl_ret_t rcl_node_fini ( rcl_node_t * node )

Finalized a rcl_node_t.

Destroys any automatically created infrastructure and deallocates memory. After calling, the rcl_node_t can be safely deallocated.

Any middleware primitives created by the user, e.g. publishers, services, etc., are invalid after deinitialization.

Attribute	Adherence
Allocates Memory	Yes
Thread-Safe	No
Uses Atomics	Yes
Lock-Free	Yes [1]

[1] if atomic_is_lock_free() returns true for atomic_uint_least64_t

Parameters

[in] node rcl_node_t to be finalized

Returns: RCL_RET_OK if node was finalized successfully, or; RCL_RET_INVALID_ARGUMENT if any arguments are invalid, or; RCL_RET_ERROR if an unspecified error occurs.

§ rcl_node_get_default_options()

rcl_node_options_t rcl_node_get_default_options ( void )

Return the default node options in a rcl_node_options_t.

The default values are:

domain_id = RCL_NODE_OPTIONS_DEFAULT_DOMAIN_ID
allocator = rcl_get_default_allocator()

§ rcl_node_is_valid()

bool rcl_node_is_valid ( const rcl_node_t * node )

Return true if the node is valid, else false.

Also return false if the node pointer is NULL.

A node is invalid if:

the implementation is NULL (rcl_node_init not called or failed)
rcl_shutdown has been called since the node has been initialized
the node has been finalized with rcl_node_fini

There is a possible validity race condition.

Consider:

assert(rcl_node_is_valid(node));  // <-- thread 1
rcl_shutdown();                   // <-- thread 2
// use node as if valid           // <-- thread 1

In the third line the node is now invalid, even though on the previous line of thread 1 it was checked to be valid. This is why this function is considered not thread-safe.

Attribute	Adherence
Allocates Memory	No
Thread-Safe	No
Uses Atomics	Yes
Lock-Free	Yes [1]

[1] if atomic_is_lock_free() returns true for atomic_uint_least64_t

Parameters

[in] node rcl_node_t to be validated

Returns: true if the node is valid, otherwise false.

§ rcl_node_get_name()

const char* rcl_node_get_name ( const rcl_node_t * node )

Return the name of the node.

This function returns the node's internal name string. This function can fail, and therefore return NULL, if:

node is NULL
node has not been initialized (the implementation is invalid)

The returned string is only valid as long as the given rcl_node_t is valid. The value of the string may change if the value in the rcl_node_t changes, and therefore copying the string is recommended if this is a concern.

Attribute	Adherence
Allocates Memory	No
Thread-Safe	No
Uses Atomics	No
Lock-Free	Yes

Parameters

[in] node pointer to the node

Returns: name string if successful, otherwise NULL

§ rcl_node_get_options()

const rcl_node_options_t* rcl_node_get_options ( const rcl_node_t * node )

Return the rcl node options.

This function returns the node's internal options struct. This function can fail, and therefore return NULL, if:

node is NULL
node has not been initialized (the implementation is invalid)

The returned struct is only valid as long as the given rcl_node_t is valid. The values in the struct may change if the options of the rcl_node_t changes, and therefore copying the struct is recommended if this is a concern.

Attribute	Adherence
Allocates Memory	No
Thread-Safe	No
Uses Atomics	No
Lock-Free	Yes

Parameters

[in] node pointer to the node

Returns: options struct if successful, otherwise NULL

§ rcl_node_get_domain_id()

rcl_ret_t rcl_node_get_domain_id	(	const rcl_node_t *	node,
		size_t *	domain_id
	)

Return the ROS domain ID that the node is using.

This function returns the ROS domain ID that the node is in.

This function should be used to determine what domain_id was used rather than checking the domin_id field in the node options, because if RCL_NODE_OPTIONS_DEFAULT_DOMAIN_ID is used when creating the node then it is not changed after creation, but this function will return the actual domain_id used.

The domain_id field must point to an allocated size_t object to which the ROS domain ID will be written.

Attribute	Adherence
Allocates Memory	No
Thread-Safe	No
Uses Atomics	No
Lock-Free	Yes

Parameters

[in]	node	the handle to the node being queried
[out]	domain_id	storage for the domain id

Returns: RCL_RET_OK if node the domain ID was retrieved successfully, or; RCL_RET_NODE_INVALID if the node is invalid, or; RCL_RET_INVALID_ARGUMENT if any arguments are invalid, or; RCL_RET_ERROR if an unspecified error occurs.

§ rcl_node_get_rmw_handle()

rmw_node_t* rcl_node_get_rmw_handle ( const rcl_node_t * node )

Return the rmw node handle.

The handle returned is a pointer to the internally held rmw handle. This function can fail, and therefore return NULL, if:

node is NULL
node has not been initialized (the implementation is invalid)

The returned handle is made invalid if the node is finalized or if rcl_shutdown() is called. The returned handle is not guaranteed to be valid for the life time of the node as it may be finalized and recreated itself. Therefore it is recommended to get the handle from the node using this function each time it is needed and avoid use of the handle concurrently with functions that might change it.

Attribute	Adherence
Allocates Memory	No
Thread-Safe	No
Uses Atomics	No
Lock-Free	Yes

Parameters

[in] node pointer to the rcl node

Returns: rmw node handle if successful, otherwise NULL

§ rcl_node_get_rcl_instance_id()

uint64_t rcl_node_get_rcl_instance_id ( const rcl_node_t * node )

Return the associated rcl instance id.

This id is stored when rcl_node_init is called and can be compared with the value returned by rcl_get_instance_id() to check if this node was created in the current rcl context (since the latest call to rcl_init().

This function can fail, and therefore return 0, if:

node is NULL
node has not been initialized (the implementation is invalid)

This function will succeed even if rcl_shutdown() has been called since the node was created.

Attribute	Adherence
Allocates Memory	No
Thread-Safe	No
Uses Atomics	No
Lock-Free	Yes

Parameters

[in] node pointer to the rcl node

Returns: rcl instance id captured during node init or 0 on error

§ rcl_node_get_graph_guard_condition()

const struct rcl_guard_condition_t* rcl_node_get_graph_guard_condition ( const rcl_node_t * node )

Return a guard condition which is triggered when the ROS graph changes.

The handle returned is a pointer to an internally held rcl guard condition. This function can fail, and therefore return NULL, if:

node is NULL
node is invalid

The returned handle is made invalid if the node is finialized or if rcl_shutdown() is called.

The guard condition will be triggered anytime a change to the ROS graph occurs. A ROS graph change includes things like (but not limited to) a new publisher advertises, a new subscription is created, a new service becomes available, a subscription is canceled, etc.

Todo:: TODO(wjwwood): link to exhaustive list of graph events

Attribute	Adherence
Allocates Memory	No
Thread-Safe	No
Uses Atomics	No
Lock-Free	Yes

Parameters

[in] node pointer to the rcl node

Returns: rcl guard condition handle if successful, otherwise NULL

Classes

Macros

Typedefs

Functions

Macro Definition Documentation

§ RCL_NODE_OPTIONS_DEFAULT_DOMAIN_ID

Typedef Documentation

§ rcl_node_t

§ rcl_node_options_t

Function Documentation

§ rcl_get_zero_initialized_node()

§ rcl_node_init()

§ rcl_node_fini()

§ rcl_node_get_default_options()

§ rcl_node_is_valid()

§ rcl_node_get_name()

§ rcl_node_get_options()

§ rcl_node_get_domain_id()

§ rcl_node_get_rmw_handle()

§ rcl_node_get_rcl_instance_id()

§ rcl_node_get_graph_guard_condition()