Class GraphCache

Class Documentation

class GraphCache

Graph cache data structure.

Manages relationships between participants, nodes, and topics.

Public Types

using DemangleFunctionT = std::function<std::string(const std::string&)>

Callable used to demangle a name.

using NodeEntitiesInfoSeq = decltype(std::declval<rmw_dds_common::msg::ParticipantEntitiesInfo>().node_entities_info_seq)
using EntityGidToInfo = std::map<rmw_gid_t, EntityInfo, Compare_rmw_gid_t>
using ParticipantToNodesMap = std::map<rmw_gid_t, ParticipantInfo, Compare_rmw_gid_t>
using GidSeq = decltype(std::declval<rmw_dds_common::msg::NodeEntitiesInfo>().writer_gid_seq)

Public Functions

template<typename CallbackT>
inline void set_on_change_callback(CallbackT &&callback)

Set a callback that will be called when the state of the object changes.

Parameters:

callback – callback to be called.

void clear_on_change_callback()

Clear previously registered “on change” callback.

bool add_writer(const rmw_gid_t &writer_gid, const std::string &topic_name, const std::string &type_name, const rmw_gid_t &participant_gid, const rmw_qos_profile_t &qos)

Add a data writer.

Parameters:

  • writer_gid – GUID of the data writer.

  • topic_name – Name of the DDS topic for this data writer.

  • type_name – Type name of the DDS topic for this data writer.

  • participant_gid – GUID of the participant.

  • qos – QoS profile of the data writer.

Returns:

true if the cache was updated, false if the data writer was already present.

bool add_reader(const rmw_gid_t &reader_gid, const std::string &topic_name, const std::string &type_name, const rmw_gid_t &participant_gid, const rmw_qos_profile_t &qos)

Add a data reader based on discovery.

Parameters:

  • reader_gid – GUID of the The data reader.

  • topic_name – Name of the DDS topic for this data reader.

  • type_name – Type name of the DDS topic for this data reader.

  • participant_gid – GUID of the participant.

  • qos – QoS profile of the data reader.

Returns:

true if the cache was updated, false if the data reader was already present.

bool add_entity(const rmw_gid_t &gid, const std::string &topic_name, const std::string &type_name, const rmw_gid_t &participant_gid, const rmw_qos_profile_t &qos, bool is_reader)

Add a data reader or writer.

Parameters:

  • gid – GUID of the entity.

  • topic_name – Name of the DDS topic for this data reader.

  • type_name – Type name of the DDS topic for this entity

  • participant_gid – GUID of the participant.

  • qos – QoS profile of the entity.

  • is_reader – Whether the entity is a data reader or a writer.

Returns:

true if the cache was updated, false if the entity was already present.

bool remove_writer(const rmw_gid_t &gid)

Remove a data writer.

Parameters:

gid – GUID of the data writer.

Returns:

true if the cache was updated, false if the data writer was not present.

bool remove_reader(const rmw_gid_t &gid)

Remove a data reader.

Parameters:

gid – GUID of the The data reader.

Returns:

true if the cache was updated, false if the data reader was not present.

bool remove_entity(const rmw_gid_t &gid, bool is_reader)

Remove a data reader or writer.

Parameters:

  • gid – GUID of the entity.

  • is_reader – Whether the entity is a data reader or a writer.

Returns:

true when a the cache was upated, false if the entity was not present.

void add_participant(const rmw_gid_t &participant_gid, const std::string &enclave)

Add a participant.

Parameters:

  • participant_gid – GUID of the participant.

  • enclave – Name of the enclave.

bool remove_participant(const rmw_gid_t &participant_gid)

Remove a participant.

Parameters:

participant_gid – GUID of the participant.

Returns:

true when a change took place.

void update_participant_entities(const rmw_dds_common::msg::ParticipantEntitiesInfo &msg)

Update cached participant info from a ParticipantEntitiesInfo message.

Parameters:

msg – participant info to update cache from.

rmw_dds_common::msg::ParticipantEntitiesInfo add_node(const rmw_gid_t &participant_gid, const std::string &node_name, const std::string &node_namespace)

Add a node to the graph.

Parameters:

  • participant_gid – GUID of the participant.

  • node_name – Name of the node to be added.

  • node_namespace – Namespace of the node to be added.

Returns:

Message to update other caches.

rmw_dds_common::msg::ParticipantEntitiesInfo remove_node(const rmw_gid_t &participant_gid, const std::string &node_name, const std::string &node_namespace)

Remove a node from the graph.

Parameters:

  • participant_gid – GUID of the participant.

  • node_name – Name of the node to be removed.

  • node_namespace – Namespace of the node to be removed.

Returns:

Message to update other caches.

rmw_dds_common::msg::ParticipantEntitiesInfo associate_writer(const rmw_gid_t &writer_gid, const rmw_gid_t &participant_gid, const std::string &node_name, const std::string &node_namespace)

Associate a data writer with a node.

Parameters:

  • writer_gid – GUID of the data writer.

  • participant_gid – GUID of the participant.

  • node_name – Name of the target node.

  • node_namespace – Namespace of the target node.

Returns:

Message to update other caches.

rmw_dds_common::msg::ParticipantEntitiesInfo dissociate_writer(const rmw_gid_t &writer_gid, const rmw_gid_t &participant_gid, const std::string &node_name, const std::string &node_namespace)

Dissociate a data writer from a node.

Parameters:

  • writer_gid – GUID of the data writer.

  • participant_gid – GUID of the participant.

  • node_name – Name of the target node.

  • node_namespace – Namespace of the target node.

Returns:

Message to update other caches.

rmw_dds_common::msg::ParticipantEntitiesInfo associate_reader(const rmw_gid_t &reader_gid, const rmw_gid_t &participant_gid, const std::string &node_name, const std::string &node_namespace)

Associate a data reader with a node.

Parameters:

  • reader_gid – GUID of the data reader.

  • participant_gid – GUID of the participant.

  • node_name – Name of the target node.

  • node_namespace – Namespace of target node.

Returns:

Message to update other caches.

rmw_dds_common::msg::ParticipantEntitiesInfo dissociate_reader(const rmw_gid_t &reader_gid, const rmw_gid_t &participant_gid, const std::string &node_name, const std::string &node_namespace)

Dissociate a data reader from a node.

Parameters:

  • reader_gid – GUID of the data reader.

  • participant_gid – GUID of the participant.

  • node_name – Name of the target node.

  • node_namespace – Namespace of target node.

Returns:

Message to update other caches.

rmw_ret_t get_writer_count(const std::string &topic_name, size_t *count) const

Get the number of data writers for a DDS topic.

Parameters:

  • topic_name – [in] Name of the DDS topic.

  • count – [out] Number of data writers.

Returns:

RMW_RET_INVALID_ARGUMENT if count is nullptr, or

Returns:

RMW_RET_ERROR if an unexpected error take place, or

Returns:

RMW_RET_OK.

rmw_ret_t get_reader_count(const std::string &topic_name, size_t *count) const

Get the number of data readers for a DDS topic.

Parameters:

  • topic_name – [in] Name of the DDS topic.

  • count – [out] Number of data readers.

Returns:

RMW_RET_INVALID_ARGUMENT if count is nullptr, or

Returns:

RMW_RET_ERROR if an unexpected error take place, or

Returns:

RMW_RET_OK.

rmw_ret_t get_writers_info_by_topic(const std::string &topic_name, DemangleFunctionT demangle_type, rcutils_allocator_t *allocator, rmw_topic_endpoint_info_array_t *endpoints_info) const

Get an array with information about the data writers for a DDS topic.

Parameters:

  • topic_name – [in] Name of the DDS topic.

  • demangle_type – [in] Function to demangle DDS topic type names.

  • allocator – [in] To allocate memory when populating endpoints_info.

  • endpoints_info – [out] A zero initialized topic endpoint information array to be populated with data writers’ info.

Returns:

RMW_RET_INVALID_ARGUMENT if count is nullptr, or

Returns:

RMW_RET_ERROR if an unexpected error take place, or

Returns:

RMW_RET_OK.

rmw_ret_t get_readers_info_by_topic(const std::string &topic_name, DemangleFunctionT demangle_type, rcutils_allocator_t *allocator, rmw_topic_endpoint_info_array_t *endpoints_info) const

Get an array with information about the data readers for a DDS topic.

Parameters:

  • topic_name – [in] Name of the DDS topic.

  • demangle_type – [in] Function to demangle DDS topic type names.

  • allocator – [in] To allocate memory when populating endpoints_info.

  • endpoints_info – [out] A zero initialized topic endpoint information array to be populated with data readers’ info.

Returns:

RMW_RET_INVALID_ARGUMENT if count is nullptr, or

Returns:

RMW_RET_ERROR if an unexpected error take place, or

Returns:

RMW_RET_OK.

rmw_ret_t get_names_and_types(DemangleFunctionT demangle_topic, DemangleFunctionT demangle_type, rcutils_allocator_t *allocator, rmw_names_and_types_t *topic_names_and_types) const

Get all topic names and types.

Parameters:

  • demangle_topic – [in] Function to demangle DDS topic names.

  • demangle_type – [in] Function to demangle DDS topic type names.

  • allocator – [in] To allocate memory when populating topic_names_and_types.

  • topic_names_and_types – [inout] A zero initialized names and types collection to be populated with the result.

Returns:

RMW_RET_INVALID_ARGUMENT if an argument is invalid, or

Returns:

RMW_RET_BAD_ALLOC if an allocation failed, or

Returns:

RMW_RET_ERROR if an unexpected error happened, or

Returns:

RMW_RET_OK.

rmw_ret_t get_writer_names_and_types_by_node(const std::string &node_name, const std::string &namespace_, DemangleFunctionT demangle_topic, DemangleFunctionT demangle_type, rcutils_allocator_t *allocator, rmw_names_and_types_t *topic_names_and_types) const

Get topic names and types for all data writers associated to a node.

Parameters:

  • node_name – [in] Name of the node.

  • namespace_ – [in] Namespace of the node.

  • demangle_topic – [in] Function to demangle DDS topic names.

  • demangle_type – [in] Function to demangle DDS topic type names.

  • allocator – [in] To allocate memory when populating topic_names_and_types.

  • topic_names_and_types – [inout] A zero initialized names and types collection to be populated with the result.

Returns:

RMW_RET_NODE_NAME_NON_EXISTENT if the node doesn’t exist, or

Returns:

RMW_RET_INVALID_ARGUMENT if an argument is invalid, or

Returns:

RMW_RET_BAD_ALLOC if an allocation failed, or

Returns:

RMW_RET_ERROR if an unexpected error happened, or

Returns:

RMW_RET_OK.

rmw_ret_t get_reader_names_and_types_by_node(const std::string &node_name, const std::string &namespace_, DemangleFunctionT demangle_topic, DemangleFunctionT demangle_type, rcutils_allocator_t *allocator, rmw_names_and_types_t *topic_names_and_types) const

Get the topic names and types for all data readers associated to a node.

Parameters:

  • node_name – [in] Name of the node.

  • namespace_ – [in] Namespace of the node.

  • demangle_topic – [in] Function to demangle DDS topic names.

  • demangle_type – [in] Function to demangle DDS topic type names.

  • allocator – [in] To allocate memory when populating topic_names_and_types.

  • topic_names_and_types – [inout] A zero initialized names and types collection to be populated with the result.

Returns:

RMW_RET_NODE_NAME_NON_EXISTENT if the node doesn’t exist, or

Returns:

RMW_RET_INVALID_ARGUMENT if an argument is invalid, or

Returns:

RMW_RET_BAD_ALLOC if an allocation failed, or

Returns:

RMW_RET_ERROR if an unexpected error happened, or

Returns:

RMW_RET_OK.

size_t get_number_of_nodes() const

Get the number of nodes that have been discovered.

rmw_ret_t get_node_names(rcutils_string_array_t *node_names, rcutils_string_array_t *node_namespaces, rcutils_string_array_t *enclaves, rcutils_allocator_t *allocator) const

Get the names, namespaces, and enclaves of all nodes.

Parameters:

  • node_names – [inout] A zero initialized string array to be populated with node names.

  • node_namespaces – [inout] A zero initialized string array to be populated with node namespaces. Each item in this array corresponds to the item at the same position in node_names.

  • enclaves – [inout] A zero initialized string array to be populated with node enclaves. Each item in this array corresponds to the item at the same position in node_names. If nullptr, it will be ignored.

  • allocator – [in] To allocate memory when populating node_names, node_namespaces, and enclaves.

Returns:

RMW_RET_INVALID_ARGUMENT if an argument is invalid, or

Returns:

RMW_RET_BAD_ALLOC if an allocation failed, or

Returns:

RMW_RET_ERROR if an unexpected error occurred, or

Returns:

RMW_RET_OK.