rmw  master
C API providing a middleware abstraction layer which is used to implement the rest of ROS.
Functions
rmw.h File Reference
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include "rcutils/types.h"
#include "rosidl_generator_c/message_type_support_struct.h"
#include "rosidl_generator_c/service_type_support.h"
#include "rmw/macros.h"
#include "rmw/qos_profiles.h"
#include "rmw/types.h"
#include "rmw/visibility_control.h"

Go to the source code of this file.

Functions

const char * rmw_get_implementation_identifier (void)
 
rmw_ret_t rmw_init (void)
 
rmw_node_trmw_create_node (const char *name, const char *namespace_, size_t domain_id, const rmw_node_security_options_t *security_options)
 
rmw_ret_t rmw_destroy_node (rmw_node_t *node)
 
const rmw_guard_condition_trmw_node_get_graph_guard_condition (const rmw_node_t *node)
 Return a guard condition which is triggered when the ROS graph changes. More...
 
rmw_publisher_trmw_create_publisher (const rmw_node_t *node, const rosidl_message_type_support_t *type_support, const char *topic_name, const rmw_qos_profile_t *qos_policies)
 
rmw_ret_t rmw_destroy_publisher (rmw_node_t *node, rmw_publisher_t *publisher)
 
rmw_ret_t rmw_publish (const rmw_publisher_t *publisher, const void *ros_message)
 
rmw_subscription_trmw_create_subscription (const rmw_node_t *node, const rosidl_message_type_support_t *type_support, const char *topic_name, const rmw_qos_profile_t *qos_policies, bool ignore_local_publications)
 
rmw_ret_t rmw_destroy_subscription (rmw_node_t *node, rmw_subscription_t *subscription)
 
rmw_ret_t rmw_take (const rmw_subscription_t *subscription, void *ros_message, bool *taken)
 
rmw_ret_t rmw_take_with_info (const rmw_subscription_t *subscription, void *ros_message, bool *taken, rmw_message_info_t *message_info)
 
rmw_client_trmw_create_client (const rmw_node_t *node, const rosidl_service_type_support_t *type_support, const char *service_name, const rmw_qos_profile_t *qos_policies)
 
rmw_ret_t rmw_destroy_client (rmw_node_t *node, rmw_client_t *client)
 
rmw_ret_t rmw_send_request (const rmw_client_t *client, const void *ros_request, int64_t *sequence_id)
 
rmw_ret_t rmw_take_response (const rmw_client_t *client, rmw_request_id_t *request_header, void *ros_response, bool *taken)
 
rmw_service_trmw_create_service (const rmw_node_t *node, const rosidl_service_type_support_t *type_support, const char *service_name, const rmw_qos_profile_t *qos_policies)
 
rmw_ret_t rmw_destroy_service (rmw_node_t *node, rmw_service_t *service)
 
rmw_ret_t rmw_take_request (const rmw_service_t *service, rmw_request_id_t *request_header, void *ros_request, bool *taken)
 
rmw_ret_t rmw_send_response (const rmw_service_t *service, rmw_request_id_t *request_header, void *ros_response)
 
rmw_guard_condition_trmw_create_guard_condition (void)
 
rmw_ret_t rmw_destroy_guard_condition (rmw_guard_condition_t *guard_condition)
 
rmw_ret_t rmw_trigger_guard_condition (const rmw_guard_condition_t *guard_condition)
 
rmw_waitset_trmw_create_waitset (size_t max_conditions)
 Create a waitset to store conditions that the middleware will block on. More...
 
rmw_ret_t rmw_destroy_waitset (rmw_waitset_t *waitset)
 
rmw_ret_t rmw_wait (rmw_subscriptions_t *subscriptions, rmw_guard_conditions_t *guard_conditions, rmw_services_t *services, rmw_clients_t *clients, rmw_waitset_t *waitset, const rmw_time_t *wait_timeout)
 Waits on sets of different waitable entities and returns when one is ready. More...
 
rmw_ret_t rmw_get_node_names (const rmw_node_t *node, rcutils_string_array_t *node_names)
 
rmw_ret_t rmw_count_publishers (const rmw_node_t *node, const char *topic_name, size_t *count)
 
rmw_ret_t rmw_count_subscribers (const rmw_node_t *node, const char *topic_name, size_t *count)
 
rmw_ret_t rmw_get_gid_for_publisher (const rmw_publisher_t *publisher, rmw_gid_t *gid)
 
rmw_ret_t rmw_compare_gids_equal (const rmw_gid_t *gid1, const rmw_gid_t *gid2, bool *result)
 
rmw_ret_t rmw_service_server_is_available (const rmw_node_t *node, const rmw_client_t *client, bool *is_available)
 Check if a service server is available for the given service client. More...
 

Function Documentation

◆ rmw_get_implementation_identifier()

const char* rmw_get_implementation_identifier ( void  )

◆ rmw_init()

rmw_ret_t rmw_init ( void  )

◆ rmw_create_node()

rmw_node_t* rmw_create_node ( const char *  name,
const char *  namespace_,
size_t  domain_id,
const rmw_node_security_options_t security_options 
)

◆ rmw_destroy_node()

rmw_ret_t rmw_destroy_node ( rmw_node_t node)

◆ rmw_node_get_graph_guard_condition()

const rmw_guard_condition_t* rmw_node_get_graph_guard_condition ( const rmw_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 rmw 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 destroyed or if rmw_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.


Attribute Adherence
Allocates Memory No
Thread-Safe Yes
Uses Atomics No
Lock-Free Yes
Parameters
[in]nodepointer to the rmw node
Returns
rmw guard condition handle if successful, otherwise NULL

◆ rmw_create_publisher()

rmw_publisher_t* rmw_create_publisher ( const rmw_node_t node,
const rosidl_message_type_support_t *  type_support,
const char *  topic_name,
const rmw_qos_profile_t qos_policies 
)

◆ rmw_destroy_publisher()

rmw_ret_t rmw_destroy_publisher ( rmw_node_t node,
rmw_publisher_t publisher 
)

◆ rmw_publish()

rmw_ret_t rmw_publish ( const rmw_publisher_t publisher,
const void *  ros_message 
)

◆ rmw_create_subscription()

rmw_subscription_t* rmw_create_subscription ( const rmw_node_t node,
const rosidl_message_type_support_t *  type_support,
const char *  topic_name,
const rmw_qos_profile_t qos_policies,
bool  ignore_local_publications 
)

◆ rmw_destroy_subscription()

rmw_ret_t rmw_destroy_subscription ( rmw_node_t node,
rmw_subscription_t subscription 
)

◆ rmw_take()

rmw_ret_t rmw_take ( const rmw_subscription_t subscription,
void *  ros_message,
bool *  taken 
)

◆ rmw_take_with_info()

rmw_ret_t rmw_take_with_info ( const rmw_subscription_t subscription,
void *  ros_message,
bool *  taken,
rmw_message_info_t message_info 
)

◆ rmw_create_client()

rmw_client_t* rmw_create_client ( const rmw_node_t node,
const rosidl_service_type_support_t *  type_support,
const char *  service_name,
const rmw_qos_profile_t qos_policies 
)

◆ rmw_destroy_client()

rmw_ret_t rmw_destroy_client ( rmw_node_t node,
rmw_client_t client 
)

◆ rmw_send_request()

rmw_ret_t rmw_send_request ( const rmw_client_t client,
const void *  ros_request,
int64_t *  sequence_id 
)

◆ rmw_take_response()

rmw_ret_t rmw_take_response ( const rmw_client_t client,
rmw_request_id_t request_header,
void *  ros_response,
bool *  taken 
)

◆ rmw_create_service()

rmw_service_t* rmw_create_service ( const rmw_node_t node,
const rosidl_service_type_support_t *  type_support,
const char *  service_name,
const rmw_qos_profile_t qos_policies 
)

◆ rmw_destroy_service()

rmw_ret_t rmw_destroy_service ( rmw_node_t node,
rmw_service_t service 
)

◆ rmw_take_request()

rmw_ret_t rmw_take_request ( const rmw_service_t service,
rmw_request_id_t request_header,
void *  ros_request,
bool *  taken 
)

◆ rmw_send_response()

rmw_ret_t rmw_send_response ( const rmw_service_t service,
rmw_request_id_t request_header,
void *  ros_response 
)

◆ rmw_create_guard_condition()

rmw_guard_condition_t* rmw_create_guard_condition ( void  )

◆ rmw_destroy_guard_condition()

rmw_ret_t rmw_destroy_guard_condition ( rmw_guard_condition_t guard_condition)

◆ rmw_trigger_guard_condition()

rmw_ret_t rmw_trigger_guard_condition ( const rmw_guard_condition_t guard_condition)

◆ rmw_create_waitset()

rmw_waitset_t* rmw_create_waitset ( size_t  max_conditions)

Create a waitset to store conditions that the middleware will block on.

If max_conditions is 0, the waitset can store an unbounded number of conditions to wait on. If max_conditions is greater than 0, the number of conditions that can be attached to the waitset is bounded at max_conditions.

Parameters
[in]max_conditionsThe maximum number of conditions that can be attached to the waitset.
Returns
A pointer to the created waitset, NULL if an error occurred.

◆ rmw_destroy_waitset()

rmw_ret_t rmw_destroy_waitset ( rmw_waitset_t waitset)

◆ rmw_wait()

rmw_ret_t rmw_wait ( rmw_subscriptions_t subscriptions,
rmw_guard_conditions_t guard_conditions,
rmw_services_t services,
rmw_clients_t clients,
rmw_waitset_t waitset,
const rmw_time_t wait_timeout 
)

Waits on sets of different waitable entities and returns when one is ready.

Add conditions to the wait set and wait until a response comes in, or until the timeout is reached. The arrays contain type-erased representations of waitable entities. This function casts the pointers to middleware-specific conditions and adds them to the waitset.

The count variables in the arrays represents the number of valid pointers in the array. NULL pointers are in the array considered invalid. If they are encountered, an error is returned.

The array structs are allocated and deallocated outside of this function. They do not have any information about how much memory is allocated for the arrays.

After the wait wakes up, the entries in each array that correspond to conditions that were not triggered are set to NULL.

Parameters
subscriptionsArray of subscriptions to wait on
guard_conditionsArray of guard conditions to wait on
servicesArray of services to wait on
clientsArray of clients to wait on
waitsetStorage for the waitset
wait_timeoutIf negative, block indefinitely or until a condition is ready. If zero, check only for immediately available conditions and don't block. Else, this represents the maximum time to wait for a response from the waitset.
Returns
RMW_RET_OK if success, or
RMW_RET_ERROR if error, or
RMW_RET_TIMEOUT if wait timed out.

◆ rmw_get_node_names()

rmw_ret_t rmw_get_node_names ( const rmw_node_t node,
rcutils_string_array_t node_names 
)

◆ rmw_count_publishers()

rmw_ret_t rmw_count_publishers ( const rmw_node_t node,
const char *  topic_name,
size_t *  count 
)

◆ rmw_count_subscribers()

rmw_ret_t rmw_count_subscribers ( const rmw_node_t node,
const char *  topic_name,
size_t *  count 
)

◆ rmw_get_gid_for_publisher()

rmw_ret_t rmw_get_gid_for_publisher ( const rmw_publisher_t publisher,
rmw_gid_t gid 
)

◆ rmw_compare_gids_equal()

rmw_ret_t rmw_compare_gids_equal ( const rmw_gid_t gid1,
const rmw_gid_t gid2,
bool *  result 
)

◆ rmw_service_server_is_available()

rmw_ret_t rmw_service_server_is_available ( const rmw_node_t node,
const rmw_client_t client,
bool *  is_available 
)

Check if a service server is available for the given service client.

This function will return true for is_available if there is a service server available for the given client.

The node parameter must not be NULL, and must point to a valid node.

The client parameter must not be NULL, and must point to a valid client.

The given client and node must match, i.e. the client must have been created using the given node.

The is_available parameter must not be NULL, and must point to a bool variable. The result of the check will be stored in the is_available parameter.

This function does manipulate heap memory. This function is not thread-safe. This function is lock-free.

Parameters
[in]nodethe handle to the node being used to query the ROS graph
[in]clientthe handle to the service client being queried
[out]is_availableset to true if there is a service server available, else false
Returns
RMW_RET_OK if node the check was made successfully, or
RMW_RET_ERROR if an unspecified error occurs.