Use Redis#exists? to fix deprecation warning

[dferrazm]

When using redis-rb 4+:

Redis#exists(key)` will return an Integer in redis-rb 4.3. `exists?` returns a boolean, you should use it instead.

[latortuga]

Ran into this same thing and just monkeypatched it myself in an initializer:

# Patch remote_lock/adapters/redis.rb to use #exists? instead of deprecated
# #exists.
class RemoteLock::Adapters::Redis
  def store(key, expires_in_seconds)
    @connection.watch(key)

    have_competition = @connection.exists?(key)

    !! @connection.multi do
      break if have_competition
      @connection.setex(key, expires_in_seconds, uid)
    end
  end
end

RemoteLock.new(RemoteLock::Adapters::Redis.new(Redis.connection))

[cprodhomme]

Any news ? ping @mrship ?

[latortuga]

@cprodhomme if it's helpful at all, I ended up migrating away from this gem to https://github.com/leandromoreira/redlock-rb which appears to have slightly more maintenance activity.