buffered_logger_format.rb

# BufferedLogger format patch.
# Install into config/initializer/buffered_logger_format.rb
# 
# - https://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/1307-bufferedlogger-should-support-message-formatting
# - http://saikyoline.jp/weblog/2008/07/01/013418.html
# - http://github.com/moro/logger_exception_format/tree/master

module ActiveSupport
  class BufferedLogger
    def add(severity, message = nil, progname = nil, &block)
      return if @level > severity

      # Exception
      if message.is_a? Exception
        message = "#{message.message}(#{message.class})\n" + 
          message.backtrace.to_a.map{|t| "  #{t}" }.join("\n")
      end

      message = (message || (block && block.call) || progname).to_s
      # If a newline is necessary then create a new message ending with a newline.
      # Ensures that the original message is not mutated.
      message = "#{message}\n" unless message[-1] == ?\n

      # Format.
      message = "#{Time.now.iso8601(3)} [#{SEV_LABEL[severity]}] #{message}"

      buffer << message
      auto_flush
      message
    end

    SEV_LABEL = {}
    for severity in Severity.constants
      SEV_LABEL[Severity.const_get(severity)] = severity
    end
  end
end