log_pid.rb

require 'logger'

class Logger
  class Formatter
    private
    def msg2str(msg)
      case msg
      when ::String
        "msg (pid: #{$$})"
      when ::Exception
        "#{ msg.message } (#{ msg.class }) (pid: #{$$})\n" <<
          (msg.backtrace || []).join("(pid: #{$$})\n")
      else
        "#{msg.inspect} (pid: #{$$})"
      end
    end
  end

  # Simple formatter which only displays the message.
  class SimpleFormatter < Logger::Formatter
    # This method is invoked when a log event occurs
    def call(severity, timestamp, progname, msg)
      "#{String === msg ? msg : msg.inspect} (pid: #{$$})\n"
    end
  end
  
  private
  def msg2str(msg) "msg (pid: #{$$})" end
end

module ActiveSupport
  # Inspired by the buffered logger idea by Ezra
  class BufferedLogger
    def add(severity, message = nil, progname = nil, &block)
      return if @level > severity
      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.
      if message[-1] == ?\n
        message = "#{message[0..-2]} (pid: #{$$})\n" 
      else
        message = "#{message} (pid: #{$$})\n" 
      end
      buffer << message
      auto_flush
      message
    end
  end
end