Module: Daemonize
- Defined in:
- lib/daemons/daemonize.rb
Class Method Summary collapse
-
.call_as_daemon(block, logfile_name = nil, app_name = nil) ⇒ Object
Call a given block as a daemon.
- .close_io ⇒ Object
-
.daemonize(logfile_name = nil, app_name = nil) ⇒ Object
Transform the current process into a daemon.
-
.redirect_io(logfile_name) ⇒ Object
Free STDIN/STDOUT/STDERR file descriptors and point them somewhere sensible.
-
.safefork ⇒ Object
Try to fork if at all possible retrying every 5 sec if the maximum process limit for the system has been reached.
-
.simulate(logfile_name = nil) ⇒ Object
Simulate the daemonization process (:ontop mode) NOTE: STDOUT and STDERR will not be redirected to the logfile, because in :ontop mode, we normally want to see the output.
Class Method Details
.call_as_daemon(block, logfile_name = nil, app_name = nil) ⇒ Object
Call a given block as a daemon
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# File 'lib/daemons/daemonize.rb', line 39 def call_as_daemon(block, logfile_name = nil, app_name = nil) # we use a pipe to return the PID of the daemon rd, wr = IO.pipe if tmppid = safefork # in the parent wr.close pid = rd.read.to_i rd.close Process.waitpid(tmppid) return pid else # in the child rd.close # Detach from the controlling terminal unless sess_id = Process.setsid raise Daemons.RuntimeException.new('cannot detach from controlling terminal') end # Prevent the possibility of acquiring a controlling terminal trap 'SIGHUP', 'IGNORE' exit if pid = safefork wr.write Process.pid wr.close $0 = app_name if app_name # Release old working directory Dir.chdir "/" close_io() redirect_io(logfile_name) # Split rand streams between spawning and daemonized process srand block.call exit end end |
.close_io ⇒ Object
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# File 'lib/daemons/daemonize.rb', line 121 def close_io() # Make sure all input/output streams are closed # Part I: close all IO objects (except for STDIN/STDOUT/STDERR) ObjectSpace.each_object(IO) do |io| unless [STDIN, STDOUT, STDERR].include?(io) begin unless io.closed? io.close end rescue ::Exception end end end # Make sure all input/output streams are closed # Part II: close all file decriptors (except for STDIN/STDOUT/STDERR) ios = Array.new(8192) {|i| IO.for_fd(i) rescue nil}.compact ios.each do |io| next if io.fileno < 3 io.close end end |
.daemonize(logfile_name = nil, app_name = nil) ⇒ Object
Transform the current process into a daemon
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# File 'lib/daemons/daemonize.rb', line 91 def daemonize(logfile_name = nil, app_name = nil) # Fork and exit from the parent safefork and exit # Detach from the controlling terminal unless sess_id = Process.setsid raise Daemons.RuntimeException.new('cannot detach from controlling terminal') end # Prevent the possibility of acquiring a controlling terminal trap 'SIGHUP', 'IGNORE' exit if pid = safefork $0 = app_name if app_name # Release old working directory Dir.chdir "/" close_io() redirect_io(logfile_name) # Split rand streams between spawning and daemonized process srand return sess_id end |
.redirect_io(logfile_name) ⇒ Object
Free STDIN/STDOUT/STDERR file descriptors and point them somewhere sensible
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# File 'lib/daemons/daemonize.rb', line 148 def redirect_io(logfile_name) begin; STDIN.reopen "/dev/null"; rescue ::Exception; end if logfile_name begin STDOUT.reopen logfile_name, "a" File.chmod(0644, logfile_name) STDOUT.sync = true rescue ::Exception begin; STDOUT.reopen "/dev/null"; rescue ::Exception; end end else begin; STDOUT.reopen "/dev/null"; rescue ::Exception; end end begin; STDERR.reopen STDOUT; rescue ::Exception; end STDERR.sync = true end |
.safefork ⇒ Object
Try to fork if at all possible retrying every 5 sec if the maximum process limit for the system has been reached
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# File 'lib/daemons/daemonize.rb', line 5 def safefork tryagain = true while tryagain tryagain = false begin if pid = fork return pid end rescue Errno::EWOULDBLOCK sleep 5 tryagain = true end end end |
.simulate(logfile_name = nil) ⇒ Object
Simulate the daemonization process (:ontop mode) NOTE: STDOUT and STDERR will not be redirected to the logfile, because in :ontop mode, we normally want to see the output
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# File 'lib/daemons/daemonize.rb', line 26 def simulate(logfile_name = nil) # Release old working directory Dir.chdir "/" close_io() # Free STDIN and point them somewhere sensible begin; STDIN.reopen "/dev/null"; rescue ::Exception; end end |