Add example showing usage of callback tracing

Author: skoudmar

r2r/examples/callback_tracing.rs

@@ -0,0 +1,66 @@
+use std::time::Duration;
+
+use futures::{executor::LocalPool, task::LocalSpawnExt};
+
+use r2r::{std_msgs::msg, std_srvs::srv, QosProfile};
+
+
+/// This example demonstrates creation of a service,
+/// subscriber and timers with their callback execution traced.
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let ctx = r2r::Context::create()?;
+    let mut node = r2r::Node::create(ctx, "testnode", "")?;
+
+    let mut pool = LocalPool::new();
+    let spawner = pool.spawner();
+
+    // The traced callback is supplied directly to `subscribe_traced`
+    // and `create_service_traced`functions.
+    let subscriber_future =
+        node.subscribe_traced("/print", QosProfile::default(), |msg: msg::String| {
+            println!("Received message: '{}'", msg.data);
+        })?;
+    spawner.spawn_local(subscriber_future)?;
+
+    let mut value = false;
+    let service_future = node.create_service_traced::<srv::SetBool::Service, _>(
+        "/set_value",
+        QosProfile::default(),
+        move |req| {
+            if value == req.message.data {
+                req.respond(srv::SetBool::Response {
+                    success: false,
+                    message: format!("Value is already {value}."),
+                })
+                .expect("could not send service response");
+            } else {
+                value = req.message.data;
+                req.respond(srv::SetBool::Response {
+                    success: true,
+                    message: format!("Value set to {value}."),
+                })
+                .expect("could not send service response");
+            }
+        },
+    )?;
+    spawner.spawn_local(service_future)?;
+
+    let mut counter = 0;
+    let wall_timer_future =
+        node.create_wall_timer(Duration::from_millis(500))?
+            .on_tick(move |_| {
+                counter += 1;
+                println!("Wall timer tick: {counter}");
+            });
+    spawner.spawn_local(wall_timer_future)?;
+
+    let ros_timer_future = node.create_timer(Duration::from_secs(1))?.on_tick(|diff| {
+        println!("ROS timer tick. Time elapsed since last tick: {diff:?}");
+    });
+    spawner.spawn_local(ros_timer_future)?;
+
+    loop {
+        node.spin_once(std::time::Duration::from_millis(5));
+        pool.run_until_stalled();
+    }
+}