Shared state pattern (spin-off of #427) (#430)

* Migrate Node to shared state pattern

Signed-off-by: Michael X. Grey <greyxmike@gmail.com>

* Migrate primitives to state pattern

Signed-off-by: Michael X. Grey <greyxmike@gmail.com>

* Fix examples

Signed-off-by: Michael X. Grey <greyxmike@gmail.com>

* Fix merge errors

Signed-off-by: Michael X. Grey <mxgrey@intrinsic.ai>

* Fix style

Signed-off-by: Michael X. Grey <mxgrey@intrinsic.ai>

* Fix doc

Signed-off-by: Michael X. Grey <mxgrey@intrinsic.ai>

---------

Signed-off-by: Michael X. Grey <greyxmike@gmail.com>
Signed-off-by: Michael X. Grey <mxgrey@intrinsic.ai>

Author: mxgrey

rclrs/minimal_pub_sub/src/minimal_two_nodes.rs

@@ -8,8 +8,8 @@ use anyhow::{Error, Result};
 
 struct MinimalSubscriber {
     num_messages: AtomicU32,
-    node: Arc<Node>,
-    subscription: Mutex<Option<Arc<Subscription<std_msgs::msg::String>>>>,
+    node: Node,
+    subscription: Mutex<Option<Subscription<std_msgs::msg::String>>>,
 }
 
 impl MinimalSubscriber {

rclrs/rust_pubsub/src/simple_publisher.rs

@@ -1,9 +1,9 @@
 use rclrs::*;
-use std::{sync::Arc, thread, time::Duration};
+use std::{thread, time::Duration};
 use std_msgs::msg::String as StringMsg;
 
 struct SimplePublisher {
-    publisher: Arc<Publisher<StringMsg>>,
+    publisher: Publisher<StringMsg>,
 }
 
 impl SimplePublisher {
@@ -24,12 +24,11 @@ impl SimplePublisher {
 
 fn main() -> Result<(), RclrsError> {
     let mut executor = Context::default_from_env().unwrap().create_basic_executor();
-    let publisher = Arc::new(SimplePublisher::new(&executor).unwrap());
-    let publisher_other_thread = Arc::clone(&publisher);
+    let publisher = SimplePublisher::new(&executor).unwrap();
     let mut count: i32 = 0;
     thread::spawn(move || loop {
         thread::sleep(Duration::from_millis(1000));
-        count = publisher_other_thread.publish_data(count).unwrap();
+        count = publisher.publish_data(count).unwrap();
     });
     executor.spin(SpinOptions::default()).first_error()
 }

rclrs/rust_pubsub/src/simple_subscriber.rs

@@ -7,7 +7,7 @@ use std::{
 use std_msgs::msg::String as StringMsg;
 
 pub struct SimpleSubscriptionNode {
-    _subscriber: Arc<Subscription<StringMsg>>,
+    _subscriber: Subscription<StringMsg>,
     data: Arc<Mutex<Option<StringMsg>>>,
 }
 
@@ -34,11 +34,10 @@ impl SimpleSubscriptionNode {
 }
 fn main() -> Result<(), RclrsError> {
     let mut executor = Context::default_from_env().unwrap().create_basic_executor();
-    let subscription = Arc::new(SimpleSubscriptionNode::new(&executor).unwrap());
-    let subscription_other_thread = Arc::clone(&subscription);
+    let subscription = SimpleSubscriptionNode::new(&executor).unwrap();
     thread::spawn(move || loop {
         thread::sleep(Duration::from_millis(1000));
-        subscription_other_thread.data_callback().unwrap()
+        subscription.data_callback().unwrap()
     });
     executor.spin(SpinOptions::default()).first_error()
 }