Better support for JRuby in Travis, tests, gemspec

[olleolleolle]

On jruby-9k, we always fail on installing a development dependency which is used to generate documentation. Illustration: Example failure to build

This PR improves things for JRuby:

• uses Kramdown for Markdown on JRuby
• skips using the QUIT signal in the tests, on the JRuby platform
• configures JRUBY_OPTS=--debug in builds
• removes JRuby from Travis' allowed_failures
• relies on latest published JRuby: jruby-9.1.5.0
• has a fine explanation/theory on what could have caused a weird stacktrace
• (and as a bonus round) upgrades the Airbrake error handler to its modern form (5.x)

Result:

• Travis builds on JRuby pass, and can publish test coverage data.

[olleolleolle]

Oh, the QUIT handler must be skipped on this platform.

Hutch::Waiter
  .wait_until_signaled
    a QUIT signal is received
The signal QUIT is in use by the JVM and will not work correctly on this platform
2016-09-21 16:12:33
Full thread dump Java HotSpot(TM) 64-Bit Server VM (24.76-b04 mixed mode):

[olleolleolle]

Ah, also, the Airbrake gem no longer supports the method that the error handler here was testing and using.

So I included an upgraded spec.

[olleolleolle]

The allowed_failures is about avoiding errors like these in MarchHare's Session class line 505:

  1) Hutch::Broker#open_connection does not set #connection
     Failure/Error: Unable to find java.net.SocksSocketImpl.remainingMillis(java/net/SocksSocketImpl.java to read failed line
     Java::JavaNet::SocketTimeoutException:
     # java.net.SocksSocketImpl.remainingMillis(java/net/SocksSocketImpl.java:111)
     # java.net.SocksSocketImpl.connect(java/net/SocksSocketImpl.java:392)
     # java.net.Socket.connect(java/net/Socket.java:579)
     # com.rabbitmq.client.impl.FrameHandlerFactory.create(com/rabbitmq/client/impl/FrameHandlerFactory.java:47)
     # com.rabbitmq.client.ConnectionFactory.newConnection(com/rabbitmq/client/ConnectionFactory.java:822)
     # com.rabbitmq.client.ConnectionFactory.newConnection(com/rabbitmq/client/ConnectionFactory.java:778)
     # com.rabbitmq.client.ConnectionFactory.newConnection(com/rabbitmq/client/ConnectionFactory.java:868)
     # java.lang.reflect.Method.invoke(java/lang/reflect/Method.java:606)
     # RUBY.new_connection_impl(/home/travis/build/gocardless/hutch/vendor/bundle/jruby/2.2/gems/march_hare-2.18.0-java/lib/march_hare/session.rb:505)
     # RUBY.converting_rjc_exceptions_to_ruby(/home/travis/build/gocardless/hutch/vendor/bundle/jruby/2.2/gems/march_hare-2.18.0-java/lib/march_hare/session.rb:467)
     # RUBY.new_connection_impl(/home/travis/build/gocardless/hutch/vendor/bundle/jruby/2.2/gems/march_hare-2.18.0-java/lib/march_hare/session.rb:500)
     # RUBY.initialize(/home/travis/build/gocardless/hutch/vendor/bundle/jruby/2.2/gems/march_hare-2.18.0-java/lib/march_hare/session.rb:136)
     # RUBY.connect(/home/travis/build/gocardless/hutch/vendor/bundle/jruby/2.2/gems/march_hare-2.18.0-java/lib/march_hare/session.rb:109)
     # RUBY.connect(/home/travis/build/gocardless/hutch/vendor/bundle/jruby/2.2/gems/march_hare-2.18.0-java/lib/march_hare.rb:20)
     # RUBY.initialize(/home/travis/build/gocardless/hutch/lib/hutch/adapters/march_hare.rb:17)
     # RUBY.open_connection(/home/travis/build/gocardless/hutch/lib/hutch/broker.rb:76)
     # RUBY.(root)(/home/travis/build/gocardless/hutch/spec/hutch/broker_spec.rb:89)

https://github.com/newcontext/rabbitmq-java-client/blob/master/src/com/rabbitmq/client/impl/FrameHandlerFactory.java

Tom Enebo stared long at this stracktrace and came up with an explanation

[olleolleolle]

@michaelklishin Hi!

Now this long session of trial-and-error is over, and I've learned more about the Travis Matrix system than I care to remember.

I'm a JRuby user, and I'd like it if JRuby was kept a must-work platform for Hutch. I keep up to date with regard to versions.

The fluke build failure that appeared had an explanation (a theory and an explanation) from one of the makers of JRuby.

To counteract that issue, I selected a modern JRuby and ran on Java 8 from Oracle.

What do you say?

[michaelklishin]

Thank you!