Change the system default depth to 1.

[clalancette]

This is what the RMWs were doing anyway, and setting it to a number here (and not an unknown of 0) means that we won't get warnings from the rclcpp and rclpy layers.

Signed-off-by: Chris Lalancette clalancette@openrobotics.org

Fixes #341

[clalancette]

CI:

• Linux
• Linux-aarch64
• Windows

[fujitatomoya]

@clalancette it looks good for now, but according to https://docs.ros.org/en/rolling/Concepts/About-Quality-of-Service-Settings.html

Different RMW implementations may have different defaults.

that means, we should ask RMW implementation what the default value is?

[clalancette]

that means, we should ask RMW implementation what the default value is?

Hm, that's a good point. Maybe this isn't the correct thing to do, then. Maybe the correct thing to do is to special-case SystemDefaultsQoS to avoid the warning message, since in that case the user very specifically asked to use whatever the underlying middleware defaults are.

What do you think?

[fujitatomoya]

Maybe the correct thing to do is to special-case SystemDefaultsQoS to avoid the warning message, since in that case the user very specifically asked to use whatever the underlying middleware defaults are.

this sounds right to me. and then rmw implementation sets the implementation specific QoS depth accordingly. (e.g rmw_fastftps case, it will set 1 for depth.)

[clalancette]

See ros2/rclcpp#2082 instead. I'm going to close this one out.