feat: remove is_available's node mut-ref dependency, also remove the !Sync constraint

on the future returned

r2r/examples/action_client.rs

@@ -10,7 +10,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let ctx = r2r::Context::create()?;
     let mut node = r2r::Node::create(ctx, "testnode", "")?;
     let client = node.create_action_client::<Fibonacci::Action>("/fibonacci")?;
-    let action_server_available = node.is_available(&client)?;
+    let action_server_available = r2r::Node::is_available(&client)?;
 
     // signal that we are done
     let done = Arc::new(Mutex::new(false));

r2r/examples/action_client_untyped.rs

@@ -13,7 +13,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let mut node = r2r::Node::create(ctx, "testnode", "")?;
     let client =
         node.create_action_client_untyped("/fibonacci", "example_interfaces/action/Fibonacci")?;
-    let action_server_available = node.is_available(&client)?;
+    let action_server_available = r2r::Node::is_available(&client)?;
 
     // signal that we are done
     let done = Arc::new(Mutex::new(false));

r2r/examples/client.rs

@@ -33,7 +33,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let mut node = r2r::Node::create(ctx, "testnode", "")?;
     let client = node.create_client::<AddTwoInts::Service>("/add_two_ints")?;
 
-    let service_available = node.is_available(&client)?;
+    let service_available = r2r::Node::is_available(&client)?;
 
     let mut pool = LocalPool::new();
     let spawner = pool.spawner();

r2r/examples/service.rs

@@ -22,7 +22,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let mut timer = node.create_wall_timer(std::time::Duration::from_millis(250))?;
     let mut timer2 = node.create_wall_timer(std::time::Duration::from_millis(2000))?;
     // wait for service to be available
-    let service_available = node.is_available(&client)?;
+    let service_available = r2r::Node::is_available(&client)?;
     let mut pool = LocalPool::new();
     let spawner = pool.spawner();
 

r2r/examples/tokio_client.rs

@@ -7,7 +7,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
     use r2r::example_interfaces::srv::AddTwoInts;
     let client = node.create_client::<AddTwoInts::Service>("/add_two_ints")?;
     let mut timer = node.create_wall_timer(duration)?;
-    let waiting = node.is_available(&client)?;
+    let waiting = r2r::Node::is_available(&client)?;
 
     let handle = tokio::task::spawn_blocking(move || loop {
         node.spin_once(std::time::Duration::from_millis(100));

r2r/examples/tokio_examples.rs

@@ -78,7 +78,7 @@ async fn client(arc_node: Arc<Mutex<r2r::Node>>) -> Result<(), r2r::Error> {
         let mut node = arc_node.lock().unwrap();
         let client = node.create_client::<AddTwoInts::Service>("/add_two_ints")?;
         let timer = node.create_wall_timer(std::time::Duration::from_secs(2))?;
-        let service_available = node.is_available(&client)?;
+        let service_available = r2r::Node::is_available(&client)?;
         (client, timer, service_available)
     };
     println!("waiting for service...");

r2r/examples/untyped_client.rs

@@ -29,7 +29,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let client =
         node.create_client_untyped("/add_two_ints", "example_interfaces/srv/AddTwoInts")?;
 
-    let service_available = node.is_available(&client)?;
+    let service_available = r2r::Node::is_available(&client)?;
 
     let mut pool = LocalPool::new();
     let spawner = pool.spawner();

r2r/src/nodes.rs

@@ -707,7 +707,7 @@ impl Node {
     /// `spin_once` until available, so spin_once must be called
     /// repeatedly in order to get the wakeup.
     pub fn is_available(
-        &mut self, client: &dyn IsAvailablePollable,
+        client: &dyn IsAvailablePollable,
     ) -> Result<impl Future<Output = Result<()>>> {
         let (sender, receiver) = oneshot::channel();
         client.register_poll_available(sender)?;