Remove ServerVariables module

This module adds confusion to the implementation, one could mistakenly
think it's how to configure a production database, instead,
remove it and rely on the database.yml to have the variables set on
in the dev and test environment for this gem.

For production, clients should be setting the values directly in their
MySQL configuration.
https://dev.mysql.com/doc/refman/5.6/en/replication-options-master.html#sysvar_auto_increment_increment

The `offset` variables were also unused and have been removed

lib/global_uid.rb

@@ -12,8 +12,6 @@ class ConnectionTimeoutException < StandardError ; end
   class TimeoutException < StandardError ; end
   class InvalidIncrementException < StandardError ; end
   class InvalidIncrementPreventionException < StandardError ; end
-
-  autoload :ServerVariables, "global_uid/server_variables"
 end
 
 ActiveRecord::Base.send(:include, GlobalUid::ActiveRecordExtension)

lib/global_uid/base.rb

@@ -50,7 +50,7 @@ def self.drop_uid_tables(id_table_name, options={})
       end
     end
 
-    def self.new_connection(name, connection_timeout, offset, increment_by)
+    def self.new_connection(name, connection_timeout)
       raise "No id server '#{name}' configured in database.yml" unless ActiveRecord::Base.configurations.to_h.has_key?(name)
       config = ActiveRecord::Base.configurations.to_h[name]
       c = config.symbolize_keys
@@ -76,18 +76,14 @@ def self.init_server_info(options)
       raise "You haven't configured any id servers" if id_servers.nil? or id_servers.empty?
       raise "More servers configured than increment_by: #{id_servers.size} > #{options[:increment_by]} -- this will create duplicate IDs." if id_servers.size > options[:increment_by]
 
-      offset = 1
-
       id_servers.map do |name, i|
         info = {}
         info[:cx]       = nil
         info[:name]     = name
         info[:retry_at] = nil
-        info[:offset]   = offset
         info[:rand]     = rand
         info[:new?]     = true
         info[:allocated_ids] = Allocations.new(incrementing_by: self.global_uid_increment_by)
-        offset +=1
         info
       end
     end
@@ -113,7 +109,7 @@ def self.setup_connections!(options)
           info[:new?] = false
 
           begin
-            connection = new_connection(info[:name], connection_timeout, info[:offset], increment_by)
+            connection = new_connection(info[:name], connection_timeout)
             if !connection.nil? && increment_by != (db_increment = connection.select_value("SELECT @@auto_increment_increment"))
               raise InvalidIncrementPreventionException, "Configured: '#{increment_by}', Found: '#{db_increment}' on '#{connection.current_database}'"
             end

test/config/database.yml

@@ -15,7 +15,13 @@ test:
 test_id_server_1:
   <<: *MYSQL
   database: global_uid_test_id_server_1
+  variables:
+    auto_increment_increment: 5
+    auto_increment_offset: 1
 
 test_id_server_2:
   <<: *MYSQL
   database: global_uid_test_id_server_2
+  variables:
+    auto_increment_increment: 5
+    auto_increment_offset: 2

test/global_uid_test.rb

@@ -338,7 +338,7 @@ def table_exists?(connection, table)
     describe "With a timing out server" do
       before do
         reset_connections!
-        @a_decent_cx = GlobalUid::Base.new_connection(GlobalUid::Base.global_uid_servers.first, 50, 1, 5)
+        @a_decent_cx = GlobalUid::Base.new_connection(GlobalUid::Base.global_uid_servers.first, 50)
         ActiveRecord::Base.stubs(:mysql2_connection).raises(GlobalUid::ConnectionTimeoutException).then.returns(@a_decent_cx)
         @connections = GlobalUid::Base.get_connections
       end

test/test_helper.rb

@@ -8,8 +8,6 @@
 require 'global_uid'
 require 'phenix'
 
-GlobalUid::Base.extend(GlobalUid::ServerVariables)
-
 Phenix.configure do |config|
   config.database_config_path = File.join(File.dirname(__FILE__), "config/database.yml")
 end