Class: Daemons::Application

Inherits:
Object
  • Object
show all
Defined in:
lib/daemons/application.rb

Constant Summary collapse

SIGNAL = 
(RUBY_PLATFORM =~ /win32/ ? 'KILL' : 'TERM')

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(group, add_options = {}, pid = nil) ⇒ Application

Returns a new instance of Application.



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# File 'lib/daemons/application.rb', line 25

def initialize(group, add_options = {}, pid = nil)
  @group = group
  @options = group.options.dup
  @options.update(add_options)
  
  @dir_mode = @dir = @script = nil
  
  unless @pid = pid
    if dir = pidfile_dir
      @pid = PidFile.new(dir, @group.app_name, @group.multiple)
    else
      @pid = PidMem.new
    end
  end
end

Instance Attribute Details

#app_argv ⇒ Object

Returns the value of attribute app_argv.



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# File 'lib/daemons/application.rb', line 9

def app_argv
  @app_argv
end

#controller_argv ⇒ Object

Returns the value of attribute controller_argv.



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# File 'lib/daemons/application.rb', line 10

def controller_argv
  @controller_argv
end

#group ⇒ Object (readonly)

the ApplicationGroup the application belongs to



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# File 'lib/daemons/application.rb', line 16

def group
  @group
end

#options ⇒ Object (readonly)

my private options



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# File 'lib/daemons/application.rb', line 19

def options
  @options
end

#pid ⇒ Object (readonly)

the Pid instance belonging to this application



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# File 'lib/daemons/application.rb', line 13

def pid
  @pid
end

Instance Method Details

#exception_log ⇒ Object

This is a nice little function for debugging purposes: In case a multi-threaded ruby script exits due to an uncaught exception it may be difficult to find out where the exception came from because one cannot catch exceptions that are thrown in threads other than the main thread.

This function searches for all exceptions in memory and outputs them to STDERR (if it is connected) and to a log file in the pid-file directory.



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# File 'lib/daemons/application.rb', line 287

def exception_log
  return unless logfile
  
  require 'logger'
  
  l_file = Logger.new(logfile)
  
  # the code below finds the last exception
  e = nil
  
  ObjectSpace.each_object {|o|
    if ::Exception === o
      e = o
    end
  }
 
  l_file.info "*** below you find the most recent exception thrown, this will be likely (but not certainly) the exception that made the application exit abnormally ***"
  l_file.error e
  
  l_file.info "*** below you find all exception objects found in memory, some of them may have been thrown in your application, others may just be in memory because they are standard exceptions ***"
  
  # this code logs every exception found in memory
  ObjectSpace.each_object {|o|
    if ::Exception === o
      l_file.error o
    end
  }
  
  l_file.close
end

#logfile ⇒ Object 



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# File 'lib/daemons/application.rb', line 54

def logfile
  logdir = options[:dir_mode] == :system ? '/var/log' : pidfile_dir
  logdir ? File.join(logdir, @group.app_name + '.log') : nil
end

#output_logfile ⇒ Object 



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# File 'lib/daemons/application.rb', line 49

def output_logfile
  logdir = options[:dir_mode] == :system ? '/var/log' : pidfile_dir
  (options[:log_output] && logdir) ? File.join(logdir, @group.app_name + '.output') : nil
end

#pidfile_dir ⇒ Object 



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# File 'lib/daemons/application.rb', line 45

def pidfile_dir
  Pid.dir(@dir_mode || @group.dir_mode, @dir || @group.dir, @script || @group.script)
end

#running? ⇒ Boolean

This function implements a (probably too simle) method to detect whether the program with the pid found in the pid-file is still running. It just searches for the pid in the output of ps ax, which is probably not a good idea in some cases. Alternatives would be to use a direct access method the unix process control system.

Returns:

  • (Boolean) 


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# File 'lib/daemons/application.rb', line 367

def running?
  if @pid.exist?
    return Pid.running?(@pid.pid)
  end
  
  return false
end

#script ⇒ Object 



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# File 'lib/daemons/application.rb', line 41

def script
  @script || @group.script
end

#show_status ⇒ Object 



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# File 'lib/daemons/application.rb', line 354

def show_status
  running = self.running?
  
  puts "#{self.group.app_name}: #{running ? '' : 'not '}running#{(running and @pid.exist?) ? ' [pid ' + @pid.pid.to_s + ']' : ''}#{(@pid.exist? and not running) ? ' (but pid-file exists: ' + @pid.pid.to_s + ')' : ''}"
end

#start ⇒ Object 



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# File 'lib/daemons/application.rb', line 243

def start
  @group.create_monitor(@group.applications[0] || self) unless options[:ontop]  # we don't monitor applications in the foreground
  
  case options[:mode]
    when :none
      # this is only used to daemonize the currently running process
      start_none
    when :exec
      start_exec
    when :load
      start_load
    when :proc
      start_proc
    else
      start_load
  end
end

#start_exec ⇒ Object 



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# File 'lib/daemons/application.rb', line 103

def start_exec
  if options[:backtrace]
    puts "option :backtrace is not supported with :mode => :exec, ignoring"
  end
  
  unless options[:ontop]
    Daemonize.daemonize(output_logfile, @group.app_name)
  else
    Daemonize.simulate(output_logfile)
  end
  
  # note that we cannot remove the pid file if we run in :ontop mode (i.e. 'ruby ctrl_exec.rb run')
  @pid.pid = Process.pid
    
  ENV['DAEMONS_ARGV'] = @controller_argv.join(' ')      
  # haven't tested yet if this is really passed to the exec'd process...
  
  
  
  Kernel.exec(script(), *(@app_argv || []))
  #Kernel.exec(script(), *ARGV)
end

#start_load ⇒ Object 



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# File 'lib/daemons/application.rb', line 126

def start_load
  unless options[:ontop]
    Daemonize.daemonize(output_logfile, @group.app_name)
  else
    Daemonize.simulate(output_logfile)
  end
  
  @pid.pid = Process.pid
  
  
  # We need this to remove the pid-file if the applications exits by itself.
  # Note that <tt>at_text</tt> will only be run if the applications exits by calling 
  # <tt>exit</tt>, and not if it calls <tt>exit!</tt> (so please don't call <tt>exit!</tt>
  # in your application!
  #
  at_exit {
    begin; @pid.cleanup; rescue ::Exception; end
    
    # If the option <tt>:backtrace</tt> is used and the application did exit by itself
    # create a exception log.
    if options[:backtrace] and not options[:ontop] and not $daemons_sigterm
      begin; exception_log(); rescue ::Exception; end
    end
      
  }
  
  # This part is needed to remove the pid-file if the application is killed by 
  # daemons or manually by the user.
  # Note that the applications is not supposed to overwrite the signal handler for
  # 'TERM'.
  #
  trap(SIGNAL) {
    begin; @pid.cleanup; rescue ::Exception; end
    $daemons_sigterm = true
    
    if options[:hard_exit]
      exit!
    else
      exit
    end
  }
  
  # Now we really start the script...
  $DAEMONS_ARGV = @controller_argv
  ENV['DAEMONS_ARGV'] = @controller_argv.join(' ')
  
  ARGV.clear
  ARGV.concat @app_argv if @app_argv
  
  # TODO: begin - rescue - end around this and exception logging
  load script()
end

#start_none ⇒ Object

this function is only used to daemonize the currently running process (Daemons.daemonize)



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# File 'lib/daemons/application.rb', line 60

def start_none
  unless options[:ontop]
    Daemonize.daemonize(nil, @group.app_name) #(logfile)
  else
    Daemonize.simulate
  end
  
  @pid.pid = Process.pid
  
  
  # We need this to remove the pid-file if the applications exits by itself.
  # Note that <tt>at_text</tt> will only be run if the applications exits by calling 
  # <tt>exit</tt>, and not if it calls <tt>exit!</tt> (so please don't call <tt>exit!</tt>
  # in your application!
  #
  at_exit {
    begin; @pid.cleanup; rescue ::Exception; end
    
    # If the option <tt>:backtrace</tt> is used and the application did exit by itself
    # create a exception log.
    if options[:backtrace] and not options[:ontop] and not $daemons_sigterm
      begin; exception_log(); rescue ::Exception; end
    end
      
  }
  
  # This part is needed to remove the pid-file if the application is killed by 
  # daemons or manually by the user.
  # Note that the applications is not supposed to overwrite the signal handler for
  # 'TERM'.
  #
  trap(SIGNAL) {
    begin; @pid.cleanup; rescue ::Exception; end
    $daemons_sigterm = true
    
    if options[:hard_exit]
      exit!
    else
      exit
    end
  }
end

#start_proc ⇒ Object 



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# File 'lib/daemons/application.rb', line 179

def start_proc
  return unless p = options[:proc]

  myproc = proc do 
    # We need this to remove the pid-file if the applications exits by itself.
    # Note that <tt>at_text</tt> will only be run if the applications exits by calling 
    # <tt>exit</tt>, and not if it calls <tt>exit!</tt> (so please don't call <tt>exit!</tt>
    # in your application!
    #
    at_exit {
      begin; @pid.cleanup; rescue ::Exception; end

      # If the option <tt>:backtrace</tt> is used and the application did exit by itself
      # create a exception log.
      if options[:backtrace] and not options[:ontop] and not $daemons_sigterm
        begin; exception_log(); rescue ::Exception; end
      end

    }

    # This part is needed to remove the pid-file if the application is killed by 
    # daemons or manually by the user.
    # Note that the applications is not supposed to overwrite the signal handler for
    # 'TERM'.
    #
    trap(SIGNAL) {
      begin; @pid.cleanup; rescue ::Exception; end
      $daemons_sigterm = true

      if options[:hard_exit]
        exit!
      else
        exit
      end
    }
    
    p.call()
  end
  
  unless options[:ontop]
    @pid.pid = Daemonize.call_as_daemon(myproc, output_logfile, @group.app_name)
  else
    Daemonize.simulate(output_logfile)
    
    @pid.pid = Process.pid
    
    myproc.call
    
# why did we use this??
#         Thread.new(&options[:proc])

# why did we use the code below??
    # unless pid = Process.fork
    #   @pid.pid = pid
    #   Daemonize.simulate(logfile)
    #   options[:proc].call
    #   exit
    # else
    #   Process.detach(@pid.pid)
    # end
  end
end

#stop ⇒ Object 



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# File 'lib/daemons/application.rb', line 319

def stop
  if options[:force] and not running?
    self.zap
    return
  end
  
  # Catch errors when trying to kill a process that doesn't
  # exist. This happens when the process quits and hasn't been
  # restarted by the monitor yet. By catching the error, we allow the
  # pid file clean-up to occur.
  pid = @pid.pid
  begin
    Process.kill(SIGNAL, pid)
    while Pid.running?(pid)
      sleep 0.1
    end
  rescue Errno::ESRCH => e
    puts "#{e} #{@pid.pid}"
    puts "deleting pid-file."
  end
  
  # We try to remove the pid-files by ourselves, in case the application
  # didn't clean it up.
  begin; @pid.cleanup; rescue ::Exception; end
  
end

#zap ⇒ Object 



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# File 'lib/daemons/application.rb', line 346

def zap
  @pid.cleanup
end

#zap! ⇒ Object 



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# File 'lib/daemons/application.rb', line 350

def zap!
  begin; @pid.cleanup; rescue ::Exception; end
end