get_service_names_and_types.h File Reference

#include "rmw/macros.h"
#include "rmw/names_and_types.h"
#include "rmw/types.h"
#include "rmw/visibility_control.h"

Include dependency graph for get_service_names_and_types.h:

Go to the source code of this file.

Functions
rmw_ret_t	rmw_get_service_names_and_types (const rmw_node_t *node, rcutils_allocator_t *allocator, rmw_names_and_types_t *service_names_and_types)
	Return all service names and types in the ROS graph. More...

Function Documentation

rmw_get_service_names_and_types()

rmw_ret_t rmw_get_service_names_and_types	(	const rmw_node_t *	node,
		rcutils_allocator_t *	allocator,
		rmw_names_and_types_t *	service_names_and_types
	)

Return all service names and types in the ROS graph.

This function returns an array of all service names and types in the ROS graph i.e. for which a server and/or client exists, as discovered so far by the given local node.

---

Attribute	Adherence
Allocates Memory	Yes
Thread-Safe	Yes
Uses Atomics	Maybe [1]
Lock-Free	Maybe [1]

[1] rmw implementation defined, check the implementation documentation

Runtime behavior

To query the ROS graph is a synchronous operation. It is also non-blocking, but it is not guaranteed to be lock-free. Generally speaking, implementations may synchronize access to internal resources using locks but are not allowed to wait for events with no guaranteed time bound (barring the effects of starvation due to OS scheduling).

Thread-safety

Nodes are thread-safe objects, and so are all operations on them except for finalization. Therefore, it is safe to query the ROS graph using the same node concurrently. However, when querying services names and types:

• Access to the array of names and types is not synchronized. It is not safe to read or write service_names_and_types while rmw_get_service_names_and_types() uses it.
• The default allocators are thread-safe objects, but any custom allocator may not be. Check your allocator documentation for further reference.

Precondition

Given node must be a valid node handle, as returned by rmw_create_node().

Given services_names_and_types must be a zero-initialized array of names and types, as returned by rmw_get_zero_initialized_names_and_types().

Parameters

[in]	node	Node to query the ROS graph.
[in]	allocator	Allocator to be used when populating the service_names_and_types array.
[out]	service_names_and_types	Array of service names and their types, populated on success but left unchanged on failure. If populated, it is up to the caller to finalize this array later on using rmw_names_and_types_fini().

Returns

RMW_RET_OK if the query was successful, or

RMW_RET_INVALID_ARGUMENT if node is NULL, or

RMW_RET_INVALID_ARGUMENT if allocator is not valid, by rcutils_allocator_is_valid() definition, or

RMW_RET_INVALID_ARGUMENT if service_names_and_types is NULL, or

RMW_RET_INVALID_ARGUMENT if service_names_and_types is not a zero-initialized array, or

RMW_RET_INCORRECT_RMW_IMPLEMENTATION if the node implementation identifier does not match this implementation, or

RMW_RET_BAD_ALLOC if memory allocation fails, or

RMW_RET_ERROR if an unspecified error occurs.