Add wait set examples - Githubissues

carlossvg commented 3 years ago

This PR adds examples for how to use the new rclcpp::WaitSet classes. It is an extension of the existing PR https://github.com/ros2/examples/pull/262 created by @wjwwood.

This PR includes the following additional examples:

wait_set_subscriber.cpp uses a rclcpp::WaitSet to wait and poll for data
static_wait_set_subscriber.cpp uses a rclcpp::StaticWaitSet to wait and poll for data
time_triggered_wait_set_subscriber.cpp uses a rclcpp::Waitset and a timer to poll for data periodically
- wait_set.cpp: Simple example showing how to use the default wait-set with a dynamic storage policy and a sequential (no thread-safe) synchronization policy.
- static_wait_set.cpp: Simple example showing how to use the static wait-set with a static storage policy.
- thread_safe_wait_set.cpp: Simple example showing how to use the thread-safe wait-set with a thread-safe synchronization policy.
- wait_set_topics_and_timer.cpp: Simple example using multiple subscriptions, publishers, and a timer.
- wait_set_random_order.cpp: An example showing user-defined data handling and a random publisher. executor_random_order.cpp run the same node logic using SingleThreadedExecutor to compare the data handling order.
wait_set_and_executor_composition.cpp: An example showing how to combine a
SingleThreadedExecutor and a wait-set.
- wait_set_topics_with_different_rate.cpp: An example showing how to use a custom trigger condition to handle topics with different topic rates.

Some of the examples may be moved to ros2/tutorials or ros2/demos.

Connects to ros2/rclcpp#1047

carlossvg commented 3 years ago

@wjwwood I will add more comments, add a readme and probably rename the examples. Could briefly you take a look and see if you miss an example or a specific usage we want to show?

carlossvg commented 3 years ago

@wjwwood This PR should be ready to review.