Class: Process::Daemon::Controller

Inherits:
Object
  • Object
show all
Defined in:
lib/process/daemon/controller.rb

Overview

This module contains functionality related to starting and stopping the @daemon, and code for processing command line input.

Constant Summary collapse

STOP_PERIOD =

How long to wait between checking the daemon process when shutting down:

0.1

Instance Method Summary collapse

Constructor Details

#initialize(daemon, options = {}) ⇒ Controller

options[:output] specifies where to write textual output describing what is going on.



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# File 'lib/process/daemon/controller.rb', line 31

def initialize(daemon, options = {})
	@daemon = daemon
	
	@output = options[:output] || $stdout
	
	# How long to wait until sending SIGTERM and eventually SIGKILL to the daemon process group when asking it to stop:
	@stop_timeout = options[:stop_timeout] || 10.0
end

Instance Method Details

#daemonize(argv = ARGV) ⇒ Object

This function is called from the daemon executable. It processes ARGV and checks whether the user is asking for start, stop, restart, status.



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# File 'lib/process/daemon/controller.rb', line 41

def daemonize(argv = ARGV)
	case argv.shift.to_sym
	when :start
		start
		status
	when :stop
		stop
		status
		ProcessFile.cleanup(@daemon)
	when :restart
		stop
		ProcessFile.cleanup(@daemon)
		start
		status
	when :status
		status
	else
		@stderr.puts Rainbow("Invalid command. Please specify start, restart, stop or status.").red
	end
end

#pid ⇒ Object 



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# File 'lib/process/daemon/controller.rb', line 157

def pid
	ProcessFile.recall(@daemon)
end

#spawn ⇒ Object

Fork a child process, detatch it and run the daemon code.



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# File 'lib/process/daemon/controller.rb', line 63

def spawn
	@daemon.prefork
	@daemon.mark_log

	fork do
		Process.setsid
		exit if fork

		ProcessFile.store(@daemon, Process.pid)

		File.umask 0000
		Dir.chdir @daemon.working_directory

		$stdin.reopen "/dev/null"
		$stdout.reopen @daemon.log_file_path, "a"
		$stdout.sync = true
	
		$stderr.reopen $stdout
		$stderr.sync = true

		begin
			@daemon.run
		rescue Exception => error
			$stderr.puts "=== Daemon Exception Backtrace @ #{Time.now.to_s} ==="
			$stderr.puts "#{error.class}: #{error.message}"
			$!.backtrace.each { |at| $stderr.puts at }
			$stderr.puts "=== Daemon Crashed ==="
			$stderr.flush
		ensure
			$stderr.puts "=== Daemon Stopping @ #{Time.now.to_s} ==="
			$stderr.flush
		end
	end
end

#start ⇒ Object

This function starts the daemon process in the background.



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# File 'lib/process/daemon/controller.rb', line 99

def start
	@output.puts Rainbow("Starting #{@daemon.name} daemon...").blue

	case ProcessFile.status(@daemon)
	when :running
		@output.puts Rainbow("Daemon already running!").blue
		return
	when :stopped
		# We are good to go...
	else
		@output.puts Rainbow("Daemon in unknown state! Will clear previous state and continue.").red
		ProcessFile.clear(@daemon)
	end

	spawn

	sleep 0.1
	timer = TIMEOUT
	pid = ProcessFile.recall(@daemon)

	while pid == nil and timer > 0
		# Wait a moment for the forking to finish...
		@output.puts Rainbow("Waiting for daemon to start (#{timer}/#{TIMEOUT})").blue
		sleep 1

		# If the @daemon has crashed, it is never going to start...
		break if @daemon.crashed?

		pid = ProcessFile.recall(@daemon)

		timer -= 1
	end
end

#status ⇒ Object

Prints out the status of the daemon



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# File 'lib/process/daemon/controller.rb', line 134

def status
	daemon_state = ProcessFile.status(@daemon)
	
	case daemon_state
	when :running
		@output.puts Rainbow("Daemon status: running pid=#{ProcessFile.recall(@daemon)}").green
	when :unknown
		if @daemon.crashed?
			@output.puts Rainbow("Daemon status: crashed").red

			@output.flush
			@output.puts Rainbow("Dumping daemon crash log:").red
			@daemon.tail_log(@output)
		else
			@output.puts Rainbow("Daemon status: unknown").red
		end
	when :stopped
		@output.puts Rainbow("Daemon status: stopped").blue
	end
	
	return daemon_state
end

#stop ⇒ Object

Stops the daemon process.



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# File 'lib/process/daemon/controller.rb', line 165

def stop
	@output.puts Rainbow("Stopping #{@daemon.name} daemon...").blue

	# Check if the pid file exists...
	unless File.file?(@daemon.process_file_path)
		@output.puts Rainbow("Pid file not found. Is the daemon running?").red
		return
	end

	pid = ProcessFile.recall(@daemon)

	# Check if the @daemon is already stopped...
	unless ProcessFile.running(@daemon)
		@output.puts Rainbow("Pid #{pid} is not running. Has daemon crashed?").red

		@daemon.tail_log($stderr)

		return
	end

	# Interrupt the process group:
	pgid = -Process.getpgid(pid)
	Process.kill("INT", pgid)

	(@stop_timeout / STOP_PERIOD).to_i.times do
		sleep STOP_PERIOD if ProcessFile.running(@daemon)
	end

	# Kill/Term loop - if the @daemon didn't die easily, shoot
	# it a few more times.
	attempts = 5
	while ProcessFile.running(@daemon) and attempts > 0
		sig = (attempts <= 2) ? "KILL" : "TERM"

		@output.puts Rainbow("Sending #{sig} to process group #{pgid}...").red
		Process.kill(sig, pgid)

		attempts -= 1
		sleep 1
	end

	# If after doing our best the @daemon is still running (pretty odd)...
	if ProcessFile.running(@daemon)
		@output.puts Rainbow("Daemon appears to be still running!").red
		return
	end

	# Otherwise the @daemon has been stopped.
	ProcessFile.clear(@daemon)
end