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 28

def initialize(group, add_options = {}, pid = nil)
  @group = group
  @options = group.options.dup
  @options.update(add_options)
  
  @dir_mode = @dir = @script = nil
  
  @force_kill_waittime = @options[:force_kill_waittime] || 20
  
  unless @pid = pid
    if @options[:no_pidfiles]
      @pid = PidMem.new
    elsif 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 12

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 13

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 19

def group
  @group
end

#options ⇒ Object (readonly)

my private options



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# File 'lib/daemons/application.rb', line 22

def options
  @options
end

#pid ⇒ Object (readonly)

the Pid instance belonging to this application



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

def pid
  @pid
end

Instance Method Details

#change_privilege ⇒ Object 



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# File 'lib/daemons/application.rb', line 48

def change_privilege
  user = options[:user]
  group = options[:group]
  CurrentProcess.change_privilege(user, group) if user
end

#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 347

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

#logdir ⇒ Object 



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# File 'lib/daemons/application.rb', line 62

def logdir
  logdir = options[:log_dir]
  unless logdir
    logdir = options[:dir_mode] == :system ? '/var/log' : pidfile_dir
  end
  logdir
end

#logfile ⇒ Object 



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# File 'lib/daemons/application.rb', line 74

def logfile
  logdir ? File.join(logdir, @group.app_name + '.log') : nil
end

#output_logfile ⇒ Object 



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# File 'lib/daemons/application.rb', line 70

def output_logfile
  (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 58

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

#reload ⇒ Object

def run

  if @group.controller.options[:exec]
    run_via_exec()
  else
    run_via_load()
  end
end

def run_via_exec

end

def run_via_load

end



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# File 'lib/daemons/application.rb', line 325

def reload
  if @pid.pid == 0
    zap
    start
  else
    begin
      Process.kill('HUP', @pid.pid)
    rescue
      # ignore
    end
  end
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 467

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 54

def script
  @script || @group.script
end

#show_status ⇒ Object 



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# File 'lib/daemons/application.rb', line 454

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 282

def start
  change_privilege
  @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 122

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...
  
  started()
  Kernel.exec(script(), *(@app_argv || []))
end

#start_load ⇒ Object 



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# File 'lib/daemons/application.rb', line 143

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_exit</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'.
  #
  $daemons_stop_proc = options[:stop_proc]
  trap(SIGNAL) {
    begin
    if $daemons_stop_proc
      $daemons_stop_proc.call
    end
    rescue ::Exception
    end
    
    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
  
  started()
  # 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 79

def start_none
  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
  }
end

#start_proc ⇒ Object 



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# File 'lib/daemons/application.rb', line 205

def start_proc
  return unless p = options[:proc]

  myproc = proc do 
    
    @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'.
    #
    $daemons_stop_proc = options[:stop_proc]
    trap(SIGNAL) {
      begin
      if $daemons_stop_proc
        $daemons_stop_proc.call
      end
      rescue ::Exception
      end
      
      begin; @pid.cleanup; rescue ::Exception; end
      $daemons_sigterm = true

      if options[:hard_exit]
        exit!
      else
        exit
      end
    }
    
    started()
    
    p.call()
  end
  
  unless options[:ontop]
    Daemonize.call_as_daemon(myproc, output_logfile, @group.app_name)
    
  else
    Daemonize.simulate(output_logfile)
    
    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

#started ⇒ Object 



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# File 'lib/daemons/application.rb', line 301

def started
  if pid = @pid.pid
    puts "#{self.group.app_name}: process with pid #{pid} started."
    STDOUT.flush
  end
end

#stop(no_wait = false) ⇒ Object 



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# File 'lib/daemons/application.rb', line 379

def stop(no_wait = false)
  if not running?
    self.zap
    return
  end
  
  pid = @pid.pid
  
  # 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.
  begin
    Process.kill(SIGNAL, pid)
  rescue Errno::ESRCH => e
    puts "#{e} #{pid}"
    puts "deleting pid-file."
  end
  
  if not no_wait
    if @force_kill_waittime > 0
      puts "#{self.group.app_name}: trying to stop process with pid #{pid}..."
      STDOUT.flush
      
      begin
        Timeout::timeout(@force_kill_waittime) {
          while Pid.running?(pid)
            sleep(0.2)
          end
        }
      rescue Timeout::Error
        puts "#{self.group.app_name}: process with pid #{pid} won't stop, we forcefully kill it..."
        STDOUT.flush
        
        begin
          Process.kill('KILL', pid)
        rescue Errno::ESRCH
        end
        
        begin
          Timeout::timeout(20) {
            while Pid.running?(pid)
              sleep(1)
            end
          }
        rescue Timeout::Error
          puts "#{self.group.app_name}: unable to forcefully kill process with pid #{pid}."
          STDOUT.flush
        end
      end
    end
    
    
  end
  
  sleep(0.1)
  unless Pid.running?(pid)
    # We try to remove the pid-files by ourselves, in case the application
    # didn't clean it up.
    begin; @pid.cleanup; rescue ::Exception; end
    
    puts "#{self.group.app_name}: process with pid #{pid} successfully stopped."
    STDOUT.flush
  end
  
end

#zap ⇒ Object 



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# File 'lib/daemons/application.rb', line 446

def zap
  @pid.cleanup
end

#zap! ⇒ Object 



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# File 'lib/daemons/application.rb', line 450

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