forgetful.js

forgetful.js

// Forgetful.js is what I use on SSDs to prevent disk wear.
// Because each SSD sector can only be written a set # of times
// it's important not to write huge log files for no reason.
// So my test logs (and some others) are all outputted to this
// node.js instance which keeps track of the throughput
// in simply-named channels.
//
// To use this in, e.g., Rails, put this in environments/test.rb:
//
// class NamedChannelSocket < TCPSocket
//   def write(message)
//     # anything subscribed to 'test' will receive these messages
//     super "#{Rails.env}|#{message}"
//   end
// end
// config.logger = Logger.new(NamedLogSocket.new 'localhost', '1050')
//
// And read it in your terminal like so:
// (replace 'test' with whatever channel you want to subscribe to)
//
//   echo 'test' | netcat localhost 9050
//

var net         = require('net'),
    system      = require('sys'),
    channels    = {},
    loggerPort  = 1050,
    readerPort  = 9050


net.createServer(function (reader) {

  reader.setEncoding('utf8')
  reader.addListener('connect', function () {
    system.puts( 'client connected' )
  })
  reader.addListener('data', function (line) {
    if ( reader.channelNames && [] != reader.channelNames)
      return

    var channelNames = line.toString().split( ' ' )
    reader.channelNames = channelNames

    reader.write( "You are now listening to the "+channelNames.length+" channels: "+channelNames )

    for ( var i = 0, max = channelNames.length; i < max; i++ ) {
      var name = channelNames[i]
      if ( !channels[name] )
        channels[name] = []

      channels[name].push( reader )
    }
  })

  reader.addListener('end', function () {

    for ( var i = 0, max = reader.channels.length; i < max; i++ ) {
      var channel = channels[reader.channelNames[i]]
      for ( var j = 0; j < channel.length; j++)
        if ( channel[j] == reader )
          delete channel[j]
    }
    reader.end()
  })
  reader.addListener('unhandledException', function (error) {
    system.puts( 'unhandledException:' + system.inspect(error) )
  })
  reader.addListener('error', function (error) {
    if('ECONNRESET, Connection reset by peer' == error.message)
      system.puts( 'client disconnected')
    else
      system.puts( 'error:' + system.inspect(error) )
  })

}).listen(readerPort, '127.0.0.1')

net.createServer(function (logger) {

  logger.setEncoding('utf8')
  logger.addListener('data', function (data) {

    // var data = JSON.parse( data )
    // ^ fails on colored text markup sent as utf-8
    // using stupid |-delimited non-JSON format.
    var parts   = data.split( '|' )
    var channel = channels[parts.shift()]
    var message = parts.join( '|' )

    if (!channel)
      return

    for ( var i = 0, max = channel.length; i < max; i++ )
      channel[i].write( message )

  })
  logger.addListener('end', function () { logger.end() })
  logger.addListener('unhandledException', function (error) {
    system.puts( 'server::error::' + system.inspect(error) )
  })

}).listen(loggerPort, '127.0.0.1')

forgetful.rake

# add this to your Rake load path to start forgetful in the current terminal window
#
# run with:
#    rake forgetful
#

js = 'lib/forgetful.js'

desc "Start the Forgetful.js server logging to memory"
task 'forgetful:start' do
  system "(node #{js} &) && sleep 1"
end
task :forgetful => 'forgetful:start' do
  exec 'echo test forgetful | netcat localhost 9050'
end