Issue #448 make state thread safe in consumer_partition and connection

[zzzming]

Motivation

Address Issue: #448 and connection.go also missing a few sync against state

Modifications

Use go sync/atomic to synchronize state and add to missing ones in connection.go

I did not use uber's atomic as suggested by @flowchartsman. The sync/atomic seems adequate and avoid another dependency. If uber's atomic is required, we should update other sync/atomic to be consistent. @merlimat @wolfstudy what do you think? thanks

Verifying this change

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API: no
• The schema: no
• The default values of configurations: no
• The wire protocol: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented?
• If a feature is not applicable for documentation, explain why?
• If a feature is not documented yet in this PR, please create a followup issue for adding the documentation

[flowchartsman]

I'm not particularly attached to uber's atomic, I used it for expediency's sake, but direct calls to atomic always make me nervous if I'm doing them from multiple places, so guarding it in a (probably inlined) method is usually the way I like to go. YMMV. But, if it works and it's consistent with other code, who am I to judge? ¯_ʕ◔ϖ◔ʔ_/¯ Aside from that, LGTM

[zzzming]

I'm not particularly attached to uber's atomic, I used it for expediency's sake, but direct calls to atomic always make me nervous if I'm doing them from multiple places, so guarding it in a (probably inlined) method is usually the way I like to go. YMMV. But, if it works and it's consistent with other code, who am I to judge? ¯_ʕ◔ϖ◔ʔ_/¯ Aside from that, LGTM

@flowchartsman I share the same sentiment that I would tend to forget about add sync.atomic too. Let's wait for Matteo to weight in. It's a minor change either way. cheers

[merlimat]

The uber/atomic looks indeed more readable and safer than the sync/atomic. It would be good to use that consistently

[zzzming]

The uber/atomic looks indeed more readable and safer than the sync/atomic. It would be good to use that consistently

updated all states with uber/atomic