Digest::Base cannot be directly inherited in Ruby

[werleo]

We call aerospike in sidekiq workers which requires to have all classes thread safe.

Calling Aerospike::Key.new(arguments)

raises Digest::Base cannot be directly inherited in Ruby

1 gems/aerospike-2.3.0/lib/aerospike/key.rb" line 31 in new
2 gems/aerospike-2.3.0/lib/aerospike/key.rb" line 31 in block in <class:Key>
3 gems/aerospike-2.3.0/lib/aerospike/utils/pool.rb" line 46 in rescue in poll
4 gems/aerospike-2.3.0/lib/aerospike/utils/pool.rb" line 43 in poll
5 gems/aerospike-2.3.0/lib/aerospike/key.rb" line 117 in compute_digest
6 gems/aerospike-2.3.0/lib/aerospike/key.rb" line 61 in initialize

From ruby docs we can call Digest classes in thread safe manner:
https://docs.ruby-lang.org/en/2.2.0/Object.html#method-i-Digest

I think it should be done here:
https://github.com/aerospike/aerospike-client-ruby/blob/master/lib/aerospike/key.rb#L31

[jhecking]

Interesting! I found similar issues raised in various other projects, e.g. for the AWS SDK or Chef. But it's not yet clear to me what the right solution is:

• Replace usage of Digest with OpenSSL::Digest - Are there any downsides to using OpenSSL::Digest? Need to clarify why we are using Digest on MRI in the first place.
• Use Digest(:RMD160) instead of Digest::RMD160.new - But looks like Digest() was only made thread-safe in Ruby 2.2, so might not be solving the issue in older versions of Ruby.

Will need to do a bit more research on this.

[werleo]

List of not thread safe gems from sidekiq wiki:

https://github.com/mperham/sidekiq/wiki/Problems-and-Troubleshooting#not-thread-safe-gems

I don't know details about OpenSSl::Digest so I am not able to help here.

We use ruby 2.3.3.