[bug] tf2_ros::Buffer:transform always assumes timeout

[Aposhian]

Bug report

Required Info:

• Operating System:
  • Ubuntu 22.04
• Installation type:
  • binaries
• Version or commit hash:
  • humble
• DDS implementation:
  • n/a
• Client library (if applicable):
  • rclcpp

Steps to reproduce issue

• don't set setUsingDedicatedThread(true)
• try to call transform() on a tf2_ros::Buffer
• see the tf2_ros::threading_error

Expected behavior

I just want to call transform using the latest transform in the tf buffer.

Actual behavior

lookupTransform allows for this, but transform always calls an overloaded version of lookupTransform that takes a timeout, which then checks for a dedicated thread. This means I get spam ERROR logs about not using a dedicated thread.

Additional details

This could be fixed two ways:

• removing timeout as default argument on transform and making a separate overload that takes an explicit timeout arg
• on canTransform, only check for threading if the timeout is non-zero.

[clalancette]

This seems like a reasonable feature request. We'd be happy to review a PR that implements this.

[vineet131]

Hi @clalancette
I can help out with this. Does using approach 2 in buffer.cpp look right to you? Something like:

if (!checkAndErrorDedicatedThreadPresent(errstr) && timeout != tf2::Duration(0.0)) {
    return false;
  }

[Aposhian]

You will want to switch the order of those checks, since checkAndErrorDedicatedThreadPresent logs if it fails the check. If you check for timeout first then it will shortcut and not evaluate the check.

[vineet131]

You will want to switch the order of those checks, since checkAndErrorDedicatedThreadPresent logs if it fails the check. If you check for timeout first then it will shortcut and not evaluate the check.

You're right about that, that's my bad. I preferred approach 2 to approach 1 because those who have implemented this code should be able to transform as is without having to pass another kind of signature. I'll write up a PR for this.