Add support for publishing events with em-synchrony

[alexkwolfe]

This pull request adds support for asynchronous publishing using synchronous-style em-synchrony calls.

Specs are run using a separate rake task because requiring em-synchrony/em-http is destructive to em-http-request and therefore affects non-em-synchrony specs run in the same process.

[joshed-io]

Thanks for the pull request, will be looking at this today.

[joshed-io]

Will wait for the Fibers commit than I am happy to pull this in.

[alexkwolfe]

I'm not sure why, but there's a problem running this under JRuby. I'll investigate and see what I can find out.

https://travis-ci.org/alexkwolfe/keen-gem/jobs/4291148

[joshed-io]

That's ok - I'm not running the async/EM specs in jRuby (there's a JRUBY_VERSION defined check in client_spec.rb and api_spec.rb). TLS isn't implemented in jRuby EM so we're out of luck with SSL connections. So you can just add that same check around the synchrony specs.

[joshed-io]

FWIW for anyone who stumbles on this - If you're trying to publish asynchronously from jRuby I'd suggest using the synchronous publish method wrapped in a Fiber or a Thread (or ideally a Thread or Fiber Pool). You'll still get the performance gains while avoiding jRuby+EM problems.

# asynchronous publishing without EM
Fiber.new {
  Keen.publish("sign_ups", name: "Bob")
}