Typo in Curb instrumentation causes ArgumentError

[knarewski]

Description

When instrumented by NewRelic, following code:

Curl::Easy.new.method(:to_s)

raises `method_with_tracing': wrong number of arguments (given 0, expected 1) (ArgumentError):

Expected Behavior

An object like #<Method: Curl::Easy(Kernel)#to_s()> should be returned

Steps to Reproduce

Paste following code into newrelic_test.rb and invoke ruby newrelic_test.rb

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'curb', '= 1.0.0'
  gem 'newrelic_rpm', '= 8.5.0'
end

Curl::Easy.new.method(:to_s)

Your Environment

ruby 2.7.1p83 (2020-03-31 revision a0c7c23c9c) [x86_64-darwin19]

Additional context

I believe the problem can be solved by changing this line to

method_with_tracing(verb) { super }

[fallwith]

Hello @knarewski,

Thanks very much for bringing this to our attention. Your explanation of the issue, steps to reproduce, and suggestion for a fix are all terrific and very much appreciated!

I believe you are spot on with your recommended fix. Via the instrumentation.curb setting inside of newrelic.yml, Curb can be instrumented via either prepend or chain. The chain implementation (curb/chain.rb) appears to correctly pass the verb variable over to Curb, but the prepend implementation does not. I believe this is an oversight/typo on our part and that we should be using verb in the manner that you suggest.

Would you be interesting in submitting a GitHub Pull Request against the dev branch of this repository with your recommended fix? The only requirement for doing so would be to sign our Contributor License Agreement when prompted to on the GitHub PR page after submitting. See the Contributor License Agreement section of our contributing guide for more details.

If you would prefer instead for the repo maintainers to make this change, we will be quite happy to do so.

[knarewski]

Hi @fallwith , thank you for a swift response and for confirming my suspicions! I'd prefer the repo maintainers to make the change if possible, thank you.

[fallwith]

Sure thing, @knarewski, the maintainers will work on the change and keep you posted.

[fallwith]

@knarewski's fix for this bug (thank you!) was merged with #1036 and should become available with the upcoming v8.6.0 release (ETA next 1-3 weeks).

If anyone wishes to leverage the fix before then, they are welcome to use the curb_pass_verb_argument_to_method_with_tracing branch of this repository.