log in json format

log.rb

require 'json'

$log_filename ||= File.expand_path(File.join("..", "ruby.log.json"), File.dirname(__FILE__))

begin
  if !File.exist?($log_filename)
    File.open($log_filename, "w") do |f|
      f.write "["
    end
  end
rescue Exception => e
  puts "Unable to create log file #{$log_filename}"
end
  

def log(msg, tags = {})
  tags[:msg] = msg
  tags[:time] = Time.now
  tags[:caller] = caller[0..2]
  File.open($log_filename, "a") do |f|
    f.write tags.to_json + ",\n"
  end
end