Fix #6 by adding active_support require which ShardThreadRegistry depends on

[mwallba]

Hi @hsgubert !
Thanks for this awesome gem - helped me out big time in upgrading a legacy up while not wanting to give up on sharding

This PR fixes #6

The issue does not occur because of JRuby but because the necessary active_support dependency has not been loaded yet via one of the railties/engines in config/application.rb and bundler has not yet required the dependencies from the Gemfile, which also could've setup active_support.

I suspect OP in #6 probably had Sprockets and other pieces deactivated in their fresh new app.

By explicitly adding the dependency in ShardThreadRegistry this gets fixed.

You can reconstruct the scenario by not adding Sprockets to a fresh rails 5.1.7 install:
rails _5.1.7_ new -S broken_app
cd broken_app
bundle add rails-sharding

~/broken_app(master ✗) bundle exec rails g rails_sharding:scaffold
/Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/rails-sharding-1.1.3/lib/rails/sharding/shard_thread_registry.rb:7:in `<class:ShardThreadRegistry>': undefined method `thread_mattr_accessor' for Rails::Sharding::ShardThreadRegistry:Class (NoMethodError)
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/rails-sharding-1.1.3/lib/rails/sharding/shard_thread_registry.rb:2:in `<module:Sharding>'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/rails-sharding-1.1.3/lib/rails/sharding/shard_thread_registry.rb:1:in `<top (required)>'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/rails-sharding-1.1.3/lib/rails/sharding/core.rb:5:in `require'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/rails-sharding-1.1.3/lib/rails/sharding/core.rb:5:in `<top (required)>'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/rails-sharding-1.1.3/lib/rails/sharding.rb:4:in `require'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/rails-sharding-1.1.3/lib/rails/sharding.rb:4:in `<top (required)>'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/2.6.0/bundler/runtime.rb:95:in `require'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/2.6.0/bundler/runtime.rb:95:in `rescue in block in require'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/2.6.0/bundler/runtime.rb:72:in `block in require'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/2.6.0/bundler/runtime.rb:65:in `each'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/2.6.0/bundler/runtime.rb:65:in `require'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/2.6.0/bundler.rb:114:in `require'
	from /Users/mwallba/broken_app/config/application.rb:17:in `<top (required)>'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application.rb:92:in `require'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application.rb:92:in `preload'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application.rb:157:in `serve'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application.rb:145:in `block in run'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application.rb:139:in `loop'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application.rb:139:in `run'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/application/boot.rb:19:in `<top (required)>'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
	from /Users/mwallba/.rbenv/versions/2.6.5/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
	from -e:1:in `<main>'

After adding the dependency fix, everything works fine.

I ran into this issue while checking a client's Gemfile with bumbler

[hsgubert]

@mwallba this is probably long due. Just checking if you still need this change and if you confirm it fixes Issue #6

[mwallba]

@hsgubert yup this still fixes #6 - we're still using the gem just in case you consider rolling out a new release.

[mwallba]

@hsgubert do you want me to change/add anything to get this merged or is this good to go from your side?

[hsgubert]

No @mwallba, this looks good already. Thanks!