qos() method is not working correctly.

[alexzeit]

Hi,
rclrs 0.6.0! The [IntoPrimitiveOptions] trait's .qos() method is not working correctly.

I want use qos BestEffort.
So the Rust code is reading BestEffort correctly, but the subscription is still being created with Reliable QoS

The bug location is in: [subscription.rs] lines 245-251:

impl<'a, T: IntoPrimitiveOptions<'a>> From<T> for SubscriptionOptions<'a> { fn from(value: T) -> Self { let primitive = value.into_primitive_options(); let mut options = Self::new(primitive.name); primitive.apply_to(&mut options.qos); // <-- This SHOULD work but doesn't! options } }

The apply_to() method should be overriding the QoS, but something in the conversion to rcl is broken.

[alexzeit]

this works for me: ` // SAFETY: No preconditions for this function.
let mut rcl_subscription_options = unsafe { rcl_subscription_get_default_options() };

    // PATCH FIX: Manually construct rmw_qos_profile_t and assign each field explicitly
    // This works around a bug where the From<QoSProfile> conversion doesn't properly apply
    use crate::rcl_bindings::*;
    rcl_subscription_options.qos.history = qos.history.into();
    rcl_subscription_options.qos.depth = match qos.history {
        crate::QoSHistoryPolicy::SystemDefault { depth } => depth as usize,
        crate::QoSHistoryPolicy::KeepLast { depth } => depth as usize,
        crate::QoSHistoryPolicy::KeepAll => 0,
    };
    rcl_subscription_options.qos.reliability = qos.reliability.into();
    rcl_subscription_options.qos.durability = qos.durability.into();
    rcl_subscription_options.qos.deadline = qos.deadline.into();
    rcl_subscription_options.qos.lifespan = qos.lifespan.into();
    rcl_subscription_options.qos.liveliness = qos.liveliness.into();
    rcl_subscription_options.qos.liveliness_lease_duration = qos.liveliness_lease.into();
    rcl_subscription_options.qos.avoid_ros_namespace_conventions = qos.avoid_ros_namespace_conventions;

`

[esteve]

@alexzeit thank you for looking into this and figuring out how to fix it. Could you please open a new PR with these changes so I can review and merge them? Thanks.

[mxgrey]

FWIW I'm working on a PR right now to add a unit test for this and also introduce best available QOS since that has been missing after it was introduced in Iron.

So far I haven't actually seen anywhere that an error would be present, but I'll see what I get once the unit test is finished.

[alexzeit]

@alexzeit thank you for looking into this and figuring out how to fix it. Could you please open a new PR with these changes so I can review and merge them? Thanks.

Hm , I don’t know how to fix that in a right way, the patch above is just a workaround that works for me , so I cannot propose a PR

[alexzeit]

FWIW I'm working on a PR right now to add a unit test for this and also introduce best available QOS since that has been missing after it was introduced in Iron.

So far I haven't actually seen anywhere that an error would be present, but I'll see what I get once the unit test is finished.

Regarding test , there is no build or runtime error, there is only a warning that would happen if you try to publish a message with besteffort in rclcpp and try to subscribe it in rclrs with besteffort. Since the rust subscriber would have because of bug reliable qos , the ros2 will fire in runtime a warning -> message will not be published because of qos mismatch.

[mxgrey]

@alexzeit I've opened #555 to include a unit test that verifies the QoS is being set correctly. The test passed right away without needing any fixes.

I also tweaked the minimal_subscriber example to contain

    let _subscription = worker.create_subscription::<example_interfaces::msg::String, _>(
        "topic"
        .best_effort(),
        move |num_messages: &mut usize, msg: example_interfaces::msg::String| {
            *num_messages += 1;
            println!("#{} | I heard: '{}'", *num_messages, msg.data);
        },
    )?;

and I saw this using ros2 topic info /topic --verbose:

You can see that the CLI tool correctly detects that the subscription is using "best effort" quality of service.

Then I also tweaked the minimal_publisher example to use best effort:

    let publisher = node.create_publisher::<example_interfaces::msg::String>(
        "topic"
        .best_effort()
    )?;

Running the minimal publisher and minimal subscriber both with best effort settings, there was no problem with messages being sent.

I'm not sure what problem you ran into, but either you're not using the latest main branch of rclrs or else something else is getting criss-crossed during your tests.

[mxgrey]

the ros2 will fire in runtime a warning -> message will not be published because of qos mismatch.

@alexzeit Maybe if you copy/paste this warning message that you're seeing, it could help us narrow down the issue. And make sure we understand what kind of node it's coming from (rclcpp or rclrs or rclpy).

[alexzeit]

I will post my sketch next week, I did not use .best_effort() I have prepared it with qos() method that used overall code for publishers and subscribers

[alexzeit]

the ros2 will fire in runtime a warning -> message will not be published because of qos mismatch.

@alexzeit Maybe if you copy/paste this warning message that you're seeing, it could help us narrow down the issue. And make sure we understand what kind of node it's coming from (rclcpp or rclrs or rclpy).

I have a mixture of rclcpp and rclrs nodes in my project , the qos reliability is just a common launch argument for all nodes. So that argument change works for rclcpp but not for rclrs after I upgrade the rust-ros 0.4.c-> 0.6.0, I saw it in output ros2 topic info /topic --verbose

[mxgrey]

I see, how are you constructing the context for your rclrs node? Are you using Context::default_from_env()? If not then the problem would be that rcl isn't receiving your launch arguments.

[alexzeit]

Yes, from env, since ros2 parameters not working with rclrs

[mxgrey]

I'll have to do some research on how QoS overrides are implemented in rclcpp. That's not a client library feature that I'm familiar with, and I don't see any clues in the rmw or rcl APIs. I also don't see any way that the patch you posted earlier could have changed the outcome for you.

Also are you certain that the problem wasn't present in rclrs 0.4?

[alexzeit]

As I wrote, that was working fine in my project with rust-ros v0.4.x . Toda I did upgrade to 0.6.0 and what a surprise API is changed :( , ok will need to update all my code again, then after qos issue .

[mxgrey]

As I wrote, that was working fine in my project with rust-ros v0.4.x .

I just checked and the QoS conversion hasn't changed since 0.4.

The only notable change is in constructing the context. You could try using Context::new() and manually passing in the args, the same way you needed to in 0.4. For the second argument you can just put InitOptions::default().