Don't raise exceptions from within AMQP callbacks

[miha-plesko]

Raising exceptions from within AMQP callbacks (defined in MessagingHandler) prevents qpid_proton gem from closing TCP connection properly which results in file descriptor leakage (see https://issues.apache.org/jira/browse/PROTON-1791). It's a bug in gem (sockets shouldn't leak no matter what) which will be resolved with next release (qpid_proton 0.22.0) in a month, but with this commit we avoid raising exceptions in callbacks to resolve file descriptor problem immediately.

Replacement for #76
BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1554771

@miq-bot assign @juliancheal
@miq-bot add_label enhancement,gaprindashvili/yes

/cc @gberginc

[miha-plesko]

@juliancheal I apologize for opening the 3rd PR on same topic! We had hard time figuring out what was causing file descriptor leakage. Eventually, with kind and fast help from qpid_proton maintainers we discovered that sockets are leaking because we're raising exceptions in callbacks which is not accepted well by the gem 🔥 💥 🎆 😄

I think this PR should actually be fine since we're not monkey-patching anything. Therefore I kindly ask for a review. This time I do not intend to close it after a day or two 👼

[miq-bot]

Checked commit miha-plesko@acf3949 with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
3 files checked, 0 offenses detected
Everything looks fine. 🍪

[juliancheal]

@miha-plesko LGTM, want me to merge?

[miha-plesko]

@juliancheal yes please, I'm confident it will work.

[miha-plesko]

@juliancheal ping

[agrare]

Slick workaround, lgtm

[agrare]

Let's remember to remove this once the gem is fixed

[simaishi]

Gaprindashvili backport details:

$ git log -1
commit 57c3a3be118fbf3271853934cd07bd29eff11267
Author: Adam Grare <[email protected]>
Date:   Thu Mar 29 10:45:22 2018 -0400

    Merge pull request #78 from miha-plesko/remove-raise-from-callbacks
    
    Don't raise exceptions from within AMQP callbacks
    (cherry picked from commit 83177915d725198c81c357279e5ca1672fed6aac)
    
    Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1563361