Handle ECONNREFUSED and typo fix

[redhotpenguin]

This PR adds error handling for ECONNREFUSED, and also fixes a small typo. This allows requests that fail due to a previous request encountering ECONNREFUSED to retry if the service on 8125 is available. Small edge case.

[KSerrania]

Thanks for the PR!

Could you add a test case for this scenario, akin to the one we have for ENOTCONN here?

[KSerrania]

Nit: now that we have three cases, we could refactor this condition like that:

if retries <= 1 &&
   (boom.is_a?(Errno::ENOTCONN) or 
    boom.is_a?(Errno::ECONNREFUSED) or 
    boom.is_a?(IOError) && boom.message =~ /closed stream/i)

[redhotpenguin]

Sure thing - added refactor and unit test. Thanks for your patience, was offline last couple weeks.

Oddly I was seeing these test failures - not sure if it's my environment:

  1) Failure:
Datadog::Statsd::GC#test_0001_produces low amounts of garbage for simple methods [/Users/fmoyer/Code/dogstatsd-ruby/spec/statsd_spec.rb:1047]:
                      sourcefile                         sourceline  class   count
-------------------------------------------------------  ----------  ------  -----
/Users/fmoyer/Code/dogstatsd-ruby/spec/helper.rb                 23  Array       1
/Users/fmoyer/Code/dogstatsd-ruby/lib/datadog/statsd.rb          88  Array       1
/Users/fmoyer/Code/dogstatsd-ruby/lib/datadog/statsd.rb         578  String      1
/Users/fmoyer/Code/dogstatsd-ruby/lib/datadog/statsd.rb         571  String      1
/Users/fmoyer/Code/dogstatsd-ruby/lib/datadog/statsd.rb         568  String      1.
Expected: 6
  Actual: 5

  2) Failure:
Datadog::Statsd::GC#test_0002_produces low amounts of garbage for timing [/Users/fmoyer/Code/dogstatsd-ruby/spec/statsd_spec.rb:1051]:
                      sourcefile                         sourceline  class   count
-------------------------------------------------------  ----------  ------  -----
/Users/fmoyer/Code/dogstatsd-ruby/spec/helper.rb                 23  Array       1
/Users/fmoyer/Code/dogstatsd-ruby/lib/datadog/statsd.rb          88  Array       1
/Users/fmoyer/Code/dogstatsd-ruby/lib/datadog/statsd.rb         578  String      1
/Users/fmoyer/Code/dogstatsd-ruby/lib/datadog/statsd.rb         571  String      1
/Users/fmoyer/Code/dogstatsd-ruby/lib/datadog/statsd.rb         568  String      1.
Expected: 6
  Actual: 5

[KSerrania]

Yeah, this is strange, seems like there's one allocation that's not done on line 87 (88 in your output).
The CI tests passed, and I tested locally your fork with success, so that may be due to a specific environment.
I'll keep this in mind, but it shouldn't block this PR.
If the problem persists on your environment, could you create an issue so that we can keep track of it?

[KSerrania]

Thanks for the fix!

[redhotpenguin]

Sure thing, feel free to merge when ready.