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 26

def initialize(group, add_options = {}, pid = nil)
  @group = group
  @options = group.options.dup
  @options.update(add_options)

  ['dir', 'log_dir', 'logfilename', 'output_logfilename'].each do |k|
    @options[k] = File.expand_path(@options[k]) if @options.key?(k)
  end

  @dir_mode = @dir = @script = nil

  @force_kill_waittime = @options[:force_kill_waittime] || 20

  @signals_and_waits = parse_signals_and_waits(@options[:signals_and_waits])

  @show_status_callback = method(:default_show_status)

  @report = Reporter.new(@options)

  unless @pid = pid
    if @options[:no_pidfiles]
      @pid = PidMem.new
    elsif dir = pidfile_dir
      @pid = PidFile.new(dir, @group.app_name, @group.multiple, @options[:pid_delimiter])
    else
      @pid = PidMem.new
    end
  end
end

Instance Attribute Details

#app_argvObject

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_argvObject

Returns the value of attribute controller_argv


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

def controller_argv
  @controller_argv
end

#groupObject (readonly)

the ApplicationGroup the application belongs to


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

def group
  @group
end

#optionsObject (readonly)

my private options


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

def options
  @options
end

#pidObject (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_privilegeObject


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# File 'lib/daemons/application.rb', line 65

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

#default_show_status(daemon = self) ⇒ Object


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# File 'lib/daemons/application.rb', line 438

def default_show_status(daemon = self)
  running = daemon.running?

  @report.status(group.app_name, running, daemon.pid.exist?, daemon.pid.pid.to_s)
end

#exception_logObject

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 341

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 do |o|
    if ::Exception === o
      e = o
    end
  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 do |o|
    if ::Exception === o
      l_file.error o
    end
  end

  l_file.close
end

#logdirObject


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# File 'lib/daemons/application.rb', line 82

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

#logfileObject


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

def logfile
  if logdir
    File.join logdir, logfilename
  end
end

#logfilenameObject


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# File 'lib/daemons/application.rb', line 99

def logfilename
  options[:logfilename] or "#{@group.app_name}.log"
end

#output_logfileObject


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# File 'lib/daemons/application.rb', line 91

def output_logfile
  if log_output_syslog?
    'SYSLOG'
  elsif log_output?
    File.join logdir, output_logfilename
  end
end

#output_logfilenameObject


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# File 'lib/daemons/application.rb', line 87

def output_logfilename
  options[:output_logfilename] or "#{@group.app_name}.output"
end

#pidfile_dirObject


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# File 'lib/daemons/application.rb', line 78

def pidfile_dir
  Pid.dir dir_mode, dir, script
end

#reloadObject


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

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 451

def running?
  @pid.exist? and Pid.running? @pid.pid
end

#scriptObject


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

def script
  @script or group.script
end

#show_statusObject


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# File 'lib/daemons/application.rb', line 434

def show_status
  @show_status_callback.call(self)
end

#show_status_callback=(function) ⇒ Object


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# File 'lib/daemons/application.rb', line 56

def show_status_callback=(function)
  @show_status_callback =
    if function.respond_to?(:call)
      function
    else
      method(function)
    end
end

#start(restart = false) ⇒ Object


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# File 'lib/daemons/application.rb', line 291

def start(restart = false)
  change_privilege

  unless restart
    @group.create_monitor(self) unless options[:ontop]  # we don't monitor applications in the foreground
  end

  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_execObject


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# File 'lib/daemons/application.rb', line 152

def start_exec
  if options[:backtrace]
    @report.backtrace_not_supported
  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(' ')

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

#start_loadObject


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# File 'lib/daemons/application.rb', line 172

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 do
    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] && !options[:ontop] && !$daemons_sigterm
      begin; exception_log; rescue ::Exception; end
    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) do
    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
  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: exception logging
  load script
end

#start_noneObject

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


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# File 'lib/daemons/application.rb', line 110

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 do
    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] && !options[:ontop] && !$daemons_sigterm
      begin; exception_log; rescue ::Exception; end
    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) do
    begin; @pid.cleanup; rescue ::Exception; end
    $daemons_sigterm = true

    if options[:hard_exit]
      exit!
    else
      exit
    end
  end
end

#start_procObject


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# File 'lib/daemons/application.rb', line 233

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 do
      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] && !options[:ontop] && !$daemons_sigterm
        begin; exception_log; rescue ::Exception; end
      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) do
      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
    end
    p.call
  end

  unless options[:ontop]
    @pid.pid = Daemonize.call_as_daemon(myproc, output_logfile, @group.app_name)

  else
    Daemonize.simulate(output_logfile)

    myproc.call
  end
  started
end

#startedObject


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# File 'lib/daemons/application.rb', line 313

def started
  if pid = @pid.pid
    @report.process_started(group.app_name, pid)
  end
end

#stop(no_wait = false) ⇒ Object


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# File 'lib/daemons/application.rb', line 372

def stop(no_wait = false)
  unless running?
    zap
    return
  end

  # confusing: pid is also a attribute_reader
  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
    wait_and_retry_kill_harder(pid, @signals_and_waits, no_wait)
  rescue Errno::ESRCH => e
    @report.output_message("#{e} #{pid}")
    @report.output_message('deleting pid-file.')
  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.
    zap!

    @report.stopped_process(group.app_name, pid)
  end
end

#wait_and_retry_kill_harder(pid, remaining_signals, no_wait = false) ⇒ Object

Parameters:

  • Hash

    remaing_signals

  • Boolean

    no_wait Send first Signal and return


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# File 'lib/daemons/application.rb', line 404

def wait_and_retry_kill_harder(pid, remaining_signals, no_wait = false)
  sig_wait = remaining_signals.shift
  sig      = sig_wait[:sig]
  wait     = sig_wait[:wait]
  Process.kill(sig, pid)
  return if no_wait || !wait.positive?

  @report.stopping_process(group.app_name, pid, sig, wait)

  begin
    Timeout.timeout(wait, TimeoutError) do
      sleep(0.2) while Pid.running?(pid)
    end
  rescue TimeoutError
    if remaining_signals.any?
      wait_and_retry_kill_harder(pid, remaining_signals)
    else
      @report.cannot_stop_process(group.app_name, pid)
    end
  end
end

#zapObject


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# File 'lib/daemons/application.rb', line 426

def zap
  @pid.zap
end

#zap!Object


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# File 'lib/daemons/application.rb', line 430

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