Class: Magistrate::Worker

Inherits:
Object
  • Object
show all
Defined in:
lib/magistrate/worker.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, options = {}) ⇒ Worker

Returns a new instance of Worker.



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# File 'lib/magistrate/worker.rb', line 9

def initialize(name, options = {})
  @name         = name
  @daemonize    = options[:daemonize]
  @working_dir  = options[:working_dir]
  @start_cmd    = options[:start_cmd]
  @pid_path     = options[:pid_path]

  if @daemonize
    @pid_file    = File.join(@pid_path, "#{@name}.pid")
    @status_file = File.join(@pid_path, "#{@name}.status")
    @stop_signal = options[:stop_signal] || 'TERM'
    @previous_status = load_previous_status
    @bounces     = @previous_status[:bounces] || 0
  else
    @stop_cmd     = options[:end_cmd]
    @pid_file     = options[:pid_file]
  end

  @stop_timeout = 5
  @start_timeout = 5

  @env = {}

  @target_state = :unknown
  @logs = []
end

Instance Attribute Details

#bounces ⇒ Object (readonly)

Returns the value of attribute bounces.



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# File 'lib/magistrate/worker.rb', line 6

def bounces
  @bounces
end

#daemonize ⇒ Object (readonly)

Returns the value of attribute daemonize.



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# File 'lib/magistrate/worker.rb', line 6

def daemonize
  @daemonize
end

#env ⇒ Object (readonly)

Returns the value of attribute env.



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# File 'lib/magistrate/worker.rb', line 6

def env
  @env
end

#logs ⇒ Object (readonly)

Returns the value of attribute logs.



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# File 'lib/magistrate/worker.rb', line 6

def logs
  @logs
end

#monitored ⇒ Object

Returns the value of attribute monitored.



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# File 'lib/magistrate/worker.rb', line 7

def monitored
  @monitored
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/magistrate/worker.rb', line 6

def name
  @name
end

#pid_file ⇒ Object (readonly)

Returns the value of attribute pid_file.



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# File 'lib/magistrate/worker.rb', line 6

def pid_file
  @pid_file
end

#reset_target_state_to ⇒ Object (readonly)

Returns the value of attribute reset_target_state_to.



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# File 'lib/magistrate/worker.rb', line 6

def reset_target_state_to
  @reset_target_state_to
end

#start_cmd ⇒ Object (readonly)

Returns the value of attribute start_cmd.



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# File 'lib/magistrate/worker.rb', line 6

def start_cmd
  @start_cmd
end

#stop_cmd ⇒ Object (readonly)

Returns the value of attribute stop_cmd.



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# File 'lib/magistrate/worker.rb', line 6

def stop_cmd
  @stop_cmd
end

#target_state ⇒ Object

Returns the value of attribute target_state.



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# File 'lib/magistrate/worker.rb', line 7

def target_state
  @target_state
end

#working_dir ⇒ Object (readonly)

Returns the value of attribute working_dir.



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# File 'lib/magistrate/worker.rb', line 6

def working_dir
  @working_dir
end

Instance Method Details

#alive? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/magistrate/worker.rb', line 286

def alive?
  if p = self.pid
    !!::Process.kill(0, p) rescue false
  else
    false
  end
end

#double_fork(command) ⇒ Object 



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# File 'lib/magistrate/worker.rb', line 154

def double_fork(command)
  pid = nil
  # double fork daemonized processes
  # we don't want to wait for them to finish
  r, w = IO.pipe
  begin
    opid = fork do
      STDOUT.reopen(w)
      r.close
      pid = self.spawn(command)
      puts pid.to_s # send pid back to forker
    end

    ::Process.waitpid(opid, 0)
    w.close
    pid = r.gets.chomp
  ensure
    # make sure the file descriptors get closed no matter what
    r.close rescue nil
    w.close rescue nil
  end

  pid
end

#ensure_stop ⇒ Object

Ensure that a stop command actually stops the process. Force kill if necessary.

Returns nothing



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# File 'lib/magistrate/worker.rb', line 228

def ensure_stop
  log "Ensuring stop..."

  unless self.pid
    log "Stop called but pid is unknown"
    return
  end
  
  # Poll to see if it's dead
  @stop_timeout.times do
    begin
      signal(0)
    rescue Errno::ESRCH
      # It died. Good.
      return
    end
    
    sleep 1
  end
  
  # last resort
  signal('KILL')
  log "Still alive after #{@stop_timeout}s; sent SIGKILL"
end

#load_previous_status ⇒ Object

Loads the number of times in a row this worker has been started without successfully staying running This is stored in the @status_file



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# File 'lib/magistrate/worker.rb', line 42

def load_previous_status
  File.open(@status_file) { |file| YAML.load(file) } || {}
rescue
  {}
end

#log(str) ⇒ Object 



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# File 'lib/magistrate/worker.rb', line 36

def log(str)
  @logs << str
end

#pid ⇒ Object

Fetch the PID from pid_file. If the pid_file does not exist, then use the PID from the last time it was read. If it has never been read, then return nil.

Returns Integer(pid) or nil



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# File 'lib/magistrate/worker.rb', line 268

def pid
  contents = File.read(@pid_file).strip rescue ''
  real_pid = contents =~ /^\d+$/ ? contents.to_i : nil
  
  if real_pid
    @pid = real_pid
    real_pid
  else
    @pid
  end
end

#running? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/magistrate/worker.rb', line 64

def running?
end

#save_status ⇒ Object 



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# File 'lib/magistrate/worker.rb', line 48

def save_status
  if @status_file
    File.open(@status_file, "w") { |file| YAML.dump(status, file) } rescue nil
  end
end

#signal(sig, target_pid = nil) ⇒ Object

Send the given signal to this process.

Returns nothing



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# File 'lib/magistrate/worker.rb', line 256

def signal(sig, target_pid = nil)
  target_pid ||= self.pid
  sig = sig.to_i if sig.to_i != 0
  log "Sending signal '#{sig}' to pid #{target_pid}"
  ::Process.kill(sig, target_pid) rescue nil
end

#single_fork(command) ⇒ Object

single fork self-daemonizing processes we want to wait for them to finish



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# File 'lib/magistrate/worker.rb', line 143

def single_fork(command)
  pid = self.spawn(command)
  status = ::Process.waitpid2(pid, 0)
  exit_code = status[1] >> 8

  if exit_code != 0
    log "Command exited with non-zero code = #{exit_code}"
  end
  pid
end

#spawn(command) ⇒ Object

Fork/exec the given command, returns immediately

+command+ is the String containing the shell command

Returns nothing



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# File 'lib/magistrate/worker.rb', line 183

def spawn(command)
  fork do
    ::Process.setsid

    dir = @working_dir || '/'
    Dir.chdir dir
    
    #$0 = command
    $0 = "Magistrate Worker: #{@name}"
    STDIN.reopen "/dev/null"
    
    STDOUT.reopen '/dev/null'
    STDERR.reopen STDOUT
    
    # if self.log_cmd
    #         STDOUT.reopen IO.popen(self.log_cmd, "a") 
    #       else
    #         STDOUT.reopen file_in_chroot(self.log), "a"        
    #       end
    #       
    #       if err_log_cmd
    #         STDERR.reopen IO.popen(err_log_cmd, "a") 
    #       elsif err_log && (log_cmd || err_log != log)
    #         STDERR.reopen file_in_chroot(err_log), "a"        
    #       else
    #         STDERR.reopen STDOUT
    #       end
    
    # close any other file descriptors
    3.upto(256){|fd| IO::new(fd).close rescue nil}

    if @env && @env.is_a?(Hash)
      @env.each do |key, value|
        ENV[key] = value.to_s
      end
    end

    exec command unless command.empty?
  end
end

#start ⇒ Object 



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# File 'lib/magistrate/worker.rb', line 103

def start
  if @daemonize
    log "Starting as daemon with double_fork"
    @pid = double_fork(@start_cmd)
    # TODO: Should check if the pid really exists as we expect
    write_pid
  else
    log "Starting as self-daemonizing with single_fork"
    @pid = single_fork(@start_cmd)
  end
  @pid
end

#state ⇒ Object 



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# File 'lib/magistrate/worker.rb', line 67

def state
  if @target_state == :unmonitored || @target_state == :unknown
    :unmonitored
  else
    if self.alive?
      :running
    else
      :stopped
    end
  end
end

#status ⇒ Object 



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# File 'lib/magistrate/worker.rb', line 54

def status
  {
    :state => self.state,
    :target_state => self.target_state,
    :pid => self.pid,
    :bounces => @bounces,
    :logs => @logs
  }
end

#stop ⇒ Object 



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# File 'lib/magistrate/worker.rb', line 116

def stop
  if @daemonize
    signal(@stop_signal, pid)

    # Poll to see if it's dead
    @stop_timeout.times do
      begin
        ::Process.kill(0, pid)
      rescue Errno::ESRCH
        # It died. Good.
        log "Process stopped"
        return
      end

      sleep 1
    end

    signal('KILL', pid)
    log "Still alive after #{@stop_timeout}s; sent SIGKILL"
  else
    single_fork(@stop_cmd)
    ensure_stop
  end
end

#supervise! ⇒ Object

This is to be called when we first start managing a worker It will check if the pid exists and if so, is the process responding OK? It will take action based on the target state



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# File 'lib/magistrate/worker.rb', line 82

def supervise!
  log "Supervising.  Is: #{state}.  Target: #{@target_state}"
  if state != @target_state
    case @target_state
    when :forced_restart then
      @reset_target_state_to = :running
      log "Restart: Stopping, then Starting, then reporting new target_state of :running"
      stop
      start
    when :running then 
      start
      @bounces += 1
    when :stopped then stop
    end
  else
    @bounces = 0
  end

  save_status
end

#write_pid ⇒ Object 



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# File 'lib/magistrate/worker.rb', line 280

def write_pid
  File.open(@pid_file, 'w') do |f|
    f.write @pid
  end
end