passenger-status

#!/usr/bin/env ruby
#  Phusion Passenger - http://www.modrails.com/
#  Copyright (C) 2008  Phusion
#
#  Phusion Passenger is a trademark of Hongli Lai & Ninh Bui.
#
#  This program is free software; you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation; version 2 of the License.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License along
#  with this program; if not, write to the Free Software Foundation, Inc.,
#  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

$LOAD_PATH << File.expand_path(File.dirname(__FILE__) + "/../lib")
$LOAD_PATH << File.expand_path(File.dirname(__FILE__) + "/../ext")

class StatusFifo
	attr_accessor :filename
	attr_accessor :pid
	
	def initialize(filename, pid)
		@filename = filename
		@pid = pid
	end
end

# Returns an array of all status FIFO files that are alive,
# and attempt to remove stale status FIFO files.
def list_and_clean_status_fifos
	result = []
	Dir["/tmp/passenger_status.*.fifo"].each do |filename|
		filename =~ /(\d+).fifo$/
		pid = $1.to_i
		if process_is_alive?(pid)
			result << StatusFifo.new(filename, pid)
		else
			puts "*** NOTICE: Removing stale status FIFO file #{filename}"
			File.unlink(filename) rescue nil
		end
	end
	return result
end

def process_is_alive?(pid)
	begin
		Process.kill(0, pid)
		return true
	rescue Errno::ESRCH
		return false
	rescue SystemCallError => e
		return true
	end
end

def show_status(status_fifo)
	begin
		puts File.read(status_fifo.filename)
	rescue => e
		STDERR.puts "*** ERROR: Cannot query status for Passenger instance #{status_fifo.pid}:"
		STDERR.puts e.to_s
		exit 2
	end
end

def start
	if ARGV.empty?
		status_fifos = list_and_clean_status_fifos
		if status_fifos.size == 0
			STDERR.puts("ERROR: Phusion Passenger doesn't seem to be running.")
			exit 2
		elsif status_fifos.size == 1
			show_status(status_fifos[0])
		else
			puts "It appears that multiple Passenger instances are running. Please select a"
			puts "specific one by running:"
			puts
			puts "  passenger-status <PID>"
			puts
			puts "The following Passenger instances are running:"
			status_fifos.each do |status_fifo|
				puts "  PID: #{status_fifo.pid}"
			end
			exit 1
		end
	else
		show_status(StatusFifo.new("/tmp/passenger_status.#{ARGV[0]}.fifo", ARGV[0].to_i))
	end
end

start