class ActiveRecord::ConnectionAdapters::PoolConfig

def connection_specification_name
  if connection_class.primary_class?
    "ActiveRecord::Base"
  else
    connection_class.name
  end
end

def discard_pool!
  return unless @pool
  synchronize do
    return unless @pool
    @pool.discard!
    @pool = nil
  end
end

def discard_pools!
  INSTANCES.each_key(&:discard_pool!)
end

def disconnect!
  ActiveSupport::ForkTracker.check!
  return unless @pool
  synchronize do
    return unless @pool
    @pool.automatic_reconnect = false
    @pool.disconnect!
  end
  nil
end

def initialize(connection_class, db_config, role, shard)
  super()
  @connection_class = connection_class
  @db_config = db_config
  @role = role
  @shard = shard
  @pool = nil
  INSTANCES[self] = self
end

def pool
  ActiveSupport::ForkTracker.check!
  @pool || synchronize { @pool ||= ConnectionAdapters::ConnectionPool.new(self) }
end