vendor/rails/railties/lib/commands/process/spinner.rb

   1 require 'optparse'
   2
   3 def daemonize #:nodoc:
   4   exit if fork                   # Parent exits, child continues.
   5   Process.setsid                 # Become session leader.
   6   exit if fork                   # Zap session leader. See [1].
   7   Dir.chdir "/"                  # Release old working directory.
   8   File.umask 0000                # Ensure sensible umask. Adjust as needed.
   9   STDIN.reopen "/dev/null"       # Free file descriptors and
  10   STDOUT.reopen "/dev/null", "a" # point them somewhere sensible.
  11   STDERR.reopen STDOUT           # STDOUT/ERR should better go to a logfile.
  12 end
  13
  14 OPTIONS = {
  15   :interval => 5.0,
  16   :command  => File.expand_path(RAILS_ROOT + '/script/process/spawner'),
  17   :daemon   => false
  18 }
  19
  20 ARGV.options do |opts|
  21   opts.banner = "Usage: spinner [options]"
  22
  23   opts.separator ""
  24
  25   opts.on <<-EOF
  26   Description:
  27     The spinner is a protection loop for the spawner, which will attempt to restart any FCGI processes
  28     that might have been exited or outright crashed. It's a brute-force attempt that'll just try
  29     to run the spawner every X number of seconds, so it does pose a light load on the server.
  30
  31   Examples:
  32     spinner # attempts to run the spawner with default settings every second with output on the terminal
  33     spinner -i 3 -d # only run the spawner every 3 seconds and detach from the terminal to become a daemon
  34     spinner -c '/path/to/app/script/process/spawner -p 9000 -i 10' -d # using custom spawner
  35   EOF
  36
  37   opts.on("  Options:")
  38
  39   opts.on("-c", "--command=path",    String) { |v| OPTIONS[:command] = v }
  40   opts.on("-i", "--interval=seconds", Float) { |v| OPTIONS[:interval] = v }
  41   opts.on("-d", "--daemon")                  { |v| OPTIONS[:daemon] = v }
  42
  43   opts.separator ""
  44
  45   opts.on("-h", "--help", "Show this help message.") { puts opts; exit }
  46
  47   opts.parse!
  48 end
  49
  50 daemonize if OPTIONS[:daemon]
  51
  52 trap(OPTIONS[:daemon] ? "TERM" : "INT") { exit }
  53
  54 loop do
  55   system(OPTIONS[:command])
  56   sleep(OPTIONS[:interval])
  57 end