Checkout of Instiki Trunk 1/21/2007.

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

@@ -0,0 +1,57 @@
+require 'optparse'
+
+def daemonize #:nodoc:
+  exit if fork                   # Parent exits, child continues.
+  Process.setsid                 # Become session leader.
+  exit if fork                   # Zap session leader. See [1].
+  Dir.chdir "/"                  # Release old working directory.
+  File.umask 0000                # Ensure sensible umask. Adjust as needed.
+  STDIN.reopen "/dev/null"       # Free file descriptors and
+  STDOUT.reopen "/dev/null", "a" # point them somewhere sensible.
+  STDERR.reopen STDOUT           # STDOUT/ERR should better go to a logfile.
+end
+
+OPTIONS = {
+  :interval => 5.0,
+  :command  => File.expand_path(RAILS_ROOT + '/script/process/spawner'),
+  :daemon   => false
+}
+
+ARGV.options do |opts|
+  opts.banner = "Usage: spinner [options]"
+
+  opts.separator ""
+
+  opts.on <<-EOF
+  Description:
+    The spinner is a protection loop for the spawner, which will attempt to restart any FCGI processes
+    that might have been exited or outright crashed. It's a brute-force attempt that'll just try
+    to run the spawner every X number of seconds, so it does pose a light load on the server.
+
+  Examples:
+    spinner # attempts to run the spawner with default settings every second with output on the terminal
+    spinner -i 3 -d # only run the spawner every 3 seconds and detach from the terminal to become a daemon
+    spinner -c '/path/to/app/script/process/spawner -p 9000 -i 10' -d # using custom spawner
+  EOF
+
+  opts.on("  Options:")
+
+  opts.on("-c", "--command=path",    String) { |v| OPTIONS[:command] = v }
+  opts.on("-i", "--interval=seconds", Float) { |v| OPTIONS[:interval] = v }
+  opts.on("-d", "--daemon")                  { |v| OPTIONS[:daemon] = v }
+
+  opts.separator ""
+
+  opts.on("-h", "--help", "Show this help message.") { puts opts; exit }
+
+  opts.parse!
+end
+
+daemonize if OPTIONS[:daemon]
+
+trap(OPTIONS[:daemon] ? "TERM" : "INT") { exit }
+
+loop do
+  system(OPTIONS[:command])
+  sleep(OPTIONS[:interval])
+end