id_server.rb

ODBA - id_server.rb

require 'odba/persistable'
require 'thread'

module ODBA
  class IdServer
    include Persistable
    ODBA_SERIALIZABLE = ['@ids']
    ODBA_EXCLUDE_VARS = ['@mutex']
    def initialize
      @ids = {}
    end
    def next_id(key, startval=1)
      @mutex ||= Mutex.new
      res = nil
      @mutex.synchronize { 
        @ids[key] ||= (startval - 1)
        res = @ids[key] += 1
      }
      odba_store
      res
    end
  end
end

'@ids'
'@mutex'

is string data, not variable.