Module: Daemontor

Defined in:
lib/daemontor.rb

Overview

This modules purpose is to daemonize processes so they can be run in the background like a standard UNIX daemon. When Daemontor::daemonize is called the parent process fork()s a new child process and calls Process.detach so we don’t have to wait for the child process to exit. The parent process then exits and the child process goes happily on. Since we are calling Process.detach we do not need to do a double-fork

Thanks to the PickAxe book for good process handling information as well as hints from Travis Whitton’s Daemonize module: grub.ath.cx/daemonize/

Constant Summary collapse

VERSION = 
'0.0.1'

Instance Method Summary collapse

Instance Method Details

#daemonize!(keep_parent_alive = false) ⇒ Object

This is the function that makes it all happen. By default the parent process will be killed off. If you want to do something with the parent afterword pass a boolean true value and you will get access to the process back once the child is detached.



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# File 'lib/daemontor.rb', line 40

def daemonize!(keep_parent_alive = false)
	puts "Doing fork " + Process.pid.to_s if $DEBUG


	if((cpid = fork).nil?)
		# Only the child processes should get here
		trap("INT", proc {p_int} )
		trap("QUIT", proc {p_quit} )
		trap("TERM", proc {p_term} )
		trap("KILL", proc {p_kill} )
		unless $DEBUG
			STDIN.reopen "/dev/null"
			STDOUT.reopen "/dev/null", "a"
			STDERR.reopen STDOUT
		end
	else
		# Only the parent processes should get here.  We detach from a specific
		# PID so we don't globally detach from all PIDs.  This may be handy when you need some
		# children to return and some not to.  The logic isn't here to do that yet, but it
		# should be relatively easy to implement with this already in place.
		puts "Detaching from child process #{cpid}" if $DEBUG
		Process.detach(cpid)
		exit unless keep_parent_alive
	end
	return cpid
end

#p_int ⇒ Object

********************************************************************************* You might want to overide the following methods to do something a little smarter. *********************************************************************************



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# File 'lib/daemontor.rb', line 72

def p_int
	warn "Process interupt recieved.  Killing process"
	p_kill
end

#p_kill ⇒ Object 



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# File 'lib/daemontor.rb', line 87

def p_kill
	warn "Killing process #{Process.pid.to_s}"
	exit
end

#p_quit ⇒ Object 



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# File 'lib/daemontor.rb', line 77

def p_quit
	warn "Process quit recieved.  Killing process"
	p_kill
end

#p_term ⇒ Object 



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# File 'lib/daemontor.rb', line 82

def p_term
	warn "Process termination recieved.  Killing process"
	p_kill
end