bool add_handles_to_wait_set(rcl_wait_set_t * wait_set)
{
for (auto subscription : subscription_handles_) {
if (rcl_wait_set_add_subscription(wait_set, subscription) != RCL_RET_OK) {
RCUTILS_LOG_ERROR_NAMED(
"rclcpp",
"Couldn't add subscription to wait set: %s", rcl_get_error_string_safe());
return false;
}
}
for (auto client : client_handles_) {
if (rcl_wait_set_add_client(wait_set, client) != RCL_RET_OK) {
RCUTILS_LOG_ERROR_NAMED(
"rclcpp",
"Couldn't add client to wait set: %s", rcl_get_error_string_safe());
return false;
}
}
for (auto service : service_handles_) {
if (rcl_wait_set_add_service(wait_set, service) != RCL_RET_OK) {
RCUTILS_LOG_ERROR_NAMED(
"rclcpp",
"Couldn't add service to wait set: %s", rcl_get_error_string_safe());
return false;
}
}
for (auto timer : timer_handles_) {
if (rcl_wait_set_add_timer(wait_set, timer) != RCL_RET_OK) {
RCUTILS_LOG_ERROR_NAMED(
"rclcpp",
"Couldn't add timer to wait set: %s", rcl_get_error_string_safe());
return false;
}
}
for (auto guard_condition : guard_conditions_) {
if (rcl_wait_set_add_guard_condition(wait_set, guard_condition) != RCL_RET_OK) {
RCUTILS_LOG_ERROR_NAMED(
"rclcpp",
"Couldn't add guard_condition to wait set: %s",
rcl_get_error_string_safe());
return false;
}
}
return true;
}
void
GraphListener::run_loop()
{
while (true) {
// If shutdown() was called, exit.
if (is_shutdown_.load()) {
return;
}
rcl_ret_t ret;
{
// This "barrier" lock ensures that other functions can acquire the
// node_graph_interfaces_mutex_ after waking up rcl_wait.
std::lock_guard<std::mutex> nodes_barrier_lock(node_graph_interfaces_barrier_mutex_);
// This is ownership is passed to nodes_lock in the next line.
node_graph_interfaces_mutex_.lock();
}
// This lock is released when the loop continues or exits.
std::lock_guard<std::mutex> nodes_lock(node_graph_interfaces_mutex_, std::adopt_lock);
// Resize the wait set if necessary.
if (wait_set_.size_of_guard_conditions < (node_graph_interfaces_.size() + 2)) {
ret = rcl_wait_set_resize_guard_conditions(&wait_set_, node_graph_interfaces_.size() + 2);
if (RCL_RET_OK != ret) {
throw_from_rcl_error(ret, "failed to resize wait set");
}
}
// Clear the wait set's guard conditions.
ret = rcl_wait_set_clear_guard_conditions(&wait_set_);
if (RCL_RET_OK != ret) {
throw_from_rcl_error(ret, "failed to clear wait set");
}
// Put the interrupt guard condition in the wait set.
ret = rcl_wait_set_add_guard_condition(&wait_set_, &interrupt_guard_condition_);
if (RCL_RET_OK != ret) {
throw_from_rcl_error(ret, "failed to add interrupt guard condition to wait set");
}
// Put the shutdown guard condition in the wait set.
ret = rcl_wait_set_add_guard_condition(&wait_set_, shutdown_guard_condition_);
if (RCL_RET_OK != ret) {
throw_from_rcl_error(ret, "failed to add shutdown guard condition to wait set");
}
// Put graph guard conditions for each node into the wait set.
for (const auto node_ptr : node_graph_interfaces_) {
// Only wait on graph changes if some user of the node is watching.
if (node_ptr->count_graph_users() == 0) {
continue;
}
// Add the graph guard condition for the node to the wait set.
auto graph_gc = node_ptr->get_graph_guard_condition();
if (!graph_gc) {
throw_from_rcl_error(RCL_RET_ERROR, "failed to get graph guard condition");
}
ret = rcl_wait_set_add_guard_condition(&wait_set_, graph_gc);
if (RCL_RET_OK != ret) {
throw_from_rcl_error(ret, "failed to add graph guard condition to wait set");
}
}
// Wait for: graph changes, interrupt, or shutdown/SIGINT
ret = rcl_wait(&wait_set_, -1); // block for ever until a guard condition is triggered
if (RCL_RET_TIMEOUT == ret) {
throw std::runtime_error("rcl_wait unexpectedly timed out");
}
if (RCL_RET_OK != ret) {
throw_from_rcl_error(ret, "failed to wait on wait set");
}
bool shutdown_guard_condition_triggered = false;
// Check to see if the shutdown guard condition has been triggered.
for (size_t i = 0; i < wait_set_.size_of_guard_conditions; ++i) {
if (shutdown_guard_condition_ == wait_set_.guard_conditions[i]) {
shutdown_guard_condition_triggered = true;
}
}
// Notify nodes who's guard conditions are set (triggered).
for (const auto node_ptr : node_graph_interfaces_) {
auto graph_gc = node_ptr->get_graph_guard_condition();
if (!graph_gc) {
throw_from_rcl_error(RCL_RET_ERROR, "failed to get graph guard condition");
}
for (size_t i = 0; i < wait_set_.size_of_guard_conditions; ++i) {
if (graph_gc == wait_set_.guard_conditions[i]) {
node_ptr->notify_graph_change();
}
}
if (shutdown_guard_condition_triggered) {
// If shutdown, then notify the node of this as well.
node_ptr->notify_shutdown();
}
}
} // while (true)
}
