[rospy] Implement rospy.logXXX_throttle

[wkentaro]

Periodicall logging feature for python client.

[dirk-thomas]

Is the id sufficient for this? From the following code I would expect both messages to be printed every three seconds (which I would assume is not the case currently?):

while True:
    loginfo_throttle(3, 'foo') or loginfo_throttle(3, 'foo')

[wkentaro]

Maybe I need to get more detailed position where the function is called.
Currently, the inspect.stack()[1][1:] returns only line where the function is called:
Because there is the case where the logging functions, period and msg are all same.

% cat spam.py
import inspect


def loginfo_throttle():
    print(inspect.stack()[1])


def main():
    loginfo_throttle(); loginfo_throttle()


if __name__ == '__main__':
    main()

% python spam.py 
(<frame object at 0x7f3d6b2ed3a0>, 'spam.py', 9, 'main', ['    loginfo_throttle(); loginfo_throttle()\n'], 0)
(<frame object at 0x7f3d6b2ed3a0>, 'spam.py', 9, 'main', ['    loginfo_throttle(); loginfo_throttle()\n'], 0)

[wkentaro]

But currently I don't know how to get the called location with information about lines and columns.
inspect.stack()[1][1:] only returns the line and line number.

[wkentaro]

Posted on stackoverflow to asking about this: http://stackoverflow.com/questions/37606094/is-there-way-to-get-function-called-column-location-not-only-file-and-line-infor

[wkentaro]

I found the way to get column number where the function is called.
http://stackoverflow.com/questions/37606094/is-there-way-to-get-function-called-column-location-not-only-file-and-line-infor/37614347#37614347

[gavanderhoorn]

Just a data point: I've looked into this some time in the past as well, and could not arrive at a solution that was both portable (inspect and / or sys._getframe() are not supported 'everywhere' and may not return the same information on all platforms / runtimes) and relatively straightforward to implement.

See rospy: throttling logmessage rate? for the question on ROS Answers and (my own) answer. I'm not really a Python expert, so it is very well possible that I missed something or am just ignorant.

It would be really nice if this could be fixed though, so +1 for working on it @wkentaro.

[wkentaro]

@gavanderhoorn In what cases, the inspect and sys._getframe() do not work? On windows?

[gavanderhoorn]

I didn't say it doesn't work, I said it doesn't necessarily return the same information, and in the same format. I don't have my full notes anymore (it was 3 years ago), but iirc, some Python interpreters either don't return the required info, or don't return everything, or in a slightly different format. That makes it difficult to implement something that always works.

Now how much of a problem that is, I don't know. If we are happy with it working on the regular / official Python interpreters, fine by me. I just didn't want to implement something with if/else trees and / or special cases.

[wkentaro]

@dirk-thomas I have done the implementation. Could you please review again?

[dirk-thomas]

As long as the caller_id is unique for every invocation of these new log functions this should be working. It tried several different way to "bypass" it but it worked flawless.

The caller_id doesn't have to be "the same" for different Python interpreters as long as the result is unique this should work.

Thanks for iterating on this. I have squashed and cherry-picked this in 5daef56. Can you please update the wiki page to add some documentation about these new functions mentioning that they are new in Kinetic and comment with a link to the diff here.

[wkentaro]

Thanks for the review.
I updated the wiki: http://wiki.ros.org/action/diff/rospy/Overview/Logging?action=diff&rev1=18&rev2=19

BTW, Is that possible to add this feature also to Indigo and Jade?