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Add publisher with member function example #261

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4 changes: 4 additions & 0 deletions examples/minimal_pub_sub/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,10 @@ path = "src/zero_copy_subscriber.rs"
name = "zero_copy_publisher"
path = "src/zero_copy_publisher.rs"

[[bin]]
name = "publisher_member_function"
path = "src/publisher_member_function.rs"

[dependencies]
anyhow = {version = "1", features = ["backtrace"]}

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59 changes: 59 additions & 0 deletions examples/minimal_pub_sub/src/publisher_member_function.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,59 @@
use std::{
env,
sync::{Arc, Mutex},
thread,
time::Duration,
};

use anyhow::Result;

struct Publisher {
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Could you name this differently? It'd make it clear that it's not the Publsher from rclrs. For example,MinimalPublisher from the similar rclcpp example.

publisher: Arc<Mutex<rclrs::Publisher<std_msgs::msg::String>>>,
publish_count: Arc<Mutex<u32>>,
}

unsafe impl Send for Publisher {}

impl Publisher {
pub fn new(context: &rclrs::Context) -> Self {
let node = rclrs::create_node(context, "publisher").unwrap();

let publisher = node
.create_publisher::<std_msgs::msg::String>("topic", rclrs::QOS_PROFILE_DEFAULT)
.unwrap();

Self {
publisher: Arc::new(Mutex::new(publisher)),
publish_count: Arc::new(Mutex::new(0)),
}
}

fn init(&mut self) {
let publish_count = self.publish_count.clone();
let publisher = self.publisher.clone();

thread::spawn(move || loop {
thread::sleep(Duration::from_secs(1));

let msg = std_msgs::msg::String {
data: format!("Hello, world! {}", publish_count.lock().unwrap()),
};

println!("Publishing: [{}]", msg.data);

publisher.lock().unwrap().publish(msg).unwrap();
let mut num_count = publish_count.lock().unwrap();
*num_count += 1;
});
}
}

fn main() -> Result<(), rclrs::RclrsError> {
let context = rclrs::Context::new(env::args())?;
let mut publisher = Publisher::new(&context);
publisher.init();
while context.ok() {
std::thread::sleep(std::time::Duration::from_millis(100));
}
Ok(())
}
Comment on lines +1 to +59
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Here's what I would change:

  • add a timer_callback() like in the original rclcpp version
  • use an atomic variable instead of a Mutex for the counter
  • make all fallible methods return Result
  • remove unneeded lines (e.g. unsafe impl Send for Publisher {} and use anyhow::Result)
Suggested change
use std::{
env,
sync::{Arc, Mutex},
thread,
time::Duration,
};
use anyhow::Result;
struct Publisher {
publisher: Arc<Mutex<rclrs::Publisher<std_msgs::msg::String>>>,
publish_count: Arc<Mutex<u32>>,
}
unsafe impl Send for Publisher {}
impl Publisher {
pub fn new(context: &rclrs::Context) -> Self {
let node = rclrs::create_node(context, "publisher").unwrap();
let publisher = node
.create_publisher::<std_msgs::msg::String>("topic", rclrs::QOS_PROFILE_DEFAULT)
.unwrap();
Self {
publisher: Arc::new(Mutex::new(publisher)),
publish_count: Arc::new(Mutex::new(0)),
}
}
fn init(&mut self) {
let publish_count = self.publish_count.clone();
let publisher = self.publisher.clone();
thread::spawn(move || loop {
thread::sleep(Duration::from_secs(1));
let msg = std_msgs::msg::String {
data: format!("Hello, world! {}", publish_count.lock().unwrap()),
};
println!("Publishing: [{}]", msg.data);
publisher.lock().unwrap().publish(msg).unwrap();
let mut num_count = publish_count.lock().unwrap();
*num_count += 1;
});
}
}
fn main() -> Result<(), rclrs::RclrsError> {
let context = rclrs::Context::new(env::args())?;
let mut publisher = Publisher::new(&context);
publisher.init();
while context.ok() {
std::thread::sleep(std::time::Duration::from_millis(100));
}
Ok(())
}
use std::{
env,
sync::atomic::{AtomicU32, Ordering},
sync::{Arc, Mutex},
thread,
time::Duration,
};
use rclrs::RclrsError;
struct MinimalPublisher {
publisher: Arc<Mutex<rclrs::Publisher<std_msgs::msg::String>>>,
publish_count: AtomicU32,
}
impl MinimalPublisher {
pub fn new(context: &rclrs::Context) -> Result<Self, RclrsError> {
let node = rclrs::create_node(context, "publisher")?;
let publisher =
node.create_publisher::<std_msgs::msg::String>("topic", rclrs::QOS_PROFILE_DEFAULT)?;
Ok(Self {
publisher: Arc::new(Mutex::new(publisher)),
publish_count: AtomicU32::new(0),
})
}
fn timer_callback(&self) -> Result<(), RclrsError> {
let cur_publish_count = self.publish_count.fetch_add(1, Ordering::Relaxed);
let msg = std_msgs::msg::String {
data: format!("Hello, world! {}", cur_publish_count),
};
println!("Publishing: [{}]", msg.data);
self.publisher.lock().unwrap().publish(msg)
}
// Simulates a timer
fn run(&self) -> Result<(), RclrsError> {
loop {
thread::sleep(Duration::from_secs(1));
self.timer_callback()?;
}
}
}
fn main() -> Result<(), rclrs::RclrsError> {
let context = rclrs::Context::new(env::args())?;
let publisher = MinimalPublisher::new(&context)?;
publisher.run()
}

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That said, I'm on the fence on whether adding this example makes sense before we have timers. With timers, it may look very different.