Class: Procodile::Instance

Inherits:
Object
  • Object
show all
Defined in:
lib/procodile/instance.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(process, id) ⇒ Instance

Returns a new instance of Instance.



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# File 'lib/procodile/instance.rb', line 11

def initialize(process, id)
  @process = process
  @id = id
  @respawns = 0
  @respawnable = true
end

Instance Attribute Details

#id ⇒ Object (readonly)

Returns the value of attribute id.



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# File 'lib/procodile/instance.rb', line 7

def id
  @id
end

#pid ⇒ Object

Returns the value of attribute pid.



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# File 'lib/procodile/instance.rb', line 6

def pid
  @pid
end

#process ⇒ Object

Returns the value of attribute process.



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# File 'lib/procodile/instance.rb', line 8

def process
  @process
end

#respawnable ⇒ Object

Returns the value of attribute respawnable.



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# File 'lib/procodile/instance.rb', line 9

def respawnable
  @respawnable
end

Instance Method Details

#add_respawn ⇒ Object

Increment the counter of respawns for this process



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# File 'lib/procodile/instance.rb', line 245

def add_respawn
  if @last_respawn && @last_respawn < (Time.now - @process.respawn_window)
    @respawns = 1
  else
    @last_respawn = Time.now
    @respawns += 1
  end
end

#can_respawn? ⇒ Boolean

Can this process be respawned if needed?

Returns:

  • (Boolean) 


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# File 'lib/procodile/instance.rb', line 227

def can_respawn?
  !stopping? && (respawns + 1) <= @process.max_respawns
end

#check ⇒ Object

Check the status of this process and handle as appropriate.



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# File 'lib/procodile/instance.rb', line 185

def check
  # Don't do any checking if we're in the midst of a restart
  return if @restarting
  return if unmonitored?

  if self.running?
    # Everything is OK. The process is running.
    true
  else
    # If the process isn't running any more, update the PID in our memory from
    # the file in case the process has changed itself.
    return check if update_pid

    if @respawnable
      if can_respawn?
        Procodile.log(@process.log_color, description, "Process has stopped. Respawning...")
        start
        add_respawn
      elsif respawns >= @process.max_respawns
        Procodile.log(@process.log_color, description, "\e[41;37mWarning:\e[0m\e[31m this process has been respawned #{respawns} times and keeps dying.\e[0m")
        Procodile.log(@process.log_color, description, "It will not be respawned automatically any longer and will no longer be managed.".color(31))
        tidy
        unmonitor
      end
    else
      Procodile.log(@process.log_color, description, "Process has stopped. Respawning not available.")
      tidy
      unmonitor
    end
  end
end

#description ⇒ Object

Return a description for this instance



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# File 'lib/procodile/instance.rb', line 21

def description
  "#{@process.name}.#{@id}"
end

#on_stop ⇒ Object

A method that will be called when this instance has been stopped and it isn’t going to be started again



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# File 'lib/procodile/instance.rb', line 122

def on_stop
  tidy
  unmonitor
end

#pid_file_path ⇒ Object

Return the path to this instance’s PID file



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# File 'lib/procodile/instance.rb', line 35

def pid_file_path
  File.join(@process.config.pid_root, "#{description}.pid")
end

#pid_from_file ⇒ Object

Return the PID that is in the instances process PID file



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# File 'lib/procodile/instance.rb', line 42

def pid_from_file
  if File.exist?(pid_file_path)
    pid = File.read(pid_file_path)
    pid.length > 0 ? pid.strip.to_i : nil
  else
    nil
  end
end

#respawns ⇒ Object

Return the number of times this process has been respawned in the last hour



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# File 'lib/procodile/instance.rb', line 234

def respawns
  if @respawns.nil? || @last_respawn.nil? || @last_respawn < (Time.now - @process.respawn_window)
    0
  else
    @respawns
  end
end

#restart ⇒ Object

Retarts the process using the appropriate method from the process configuraiton



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# File 'lib/procodile/instance.rb', line 138

def restart
  Procodile.log(@process.log_color, description, "Restarting using #{@process.restart_mode} mode")
  @restarting = true
  update_pid
  case @process.restart_mode
  when 'usr1', 'usr2'
    if running?
      ::Process.kill(@process.restart_mode.upcase, @pid)
      Procodile.log(@process.log_color, description, "Sent #{@process.restart_mode.upcase} signal to process #{@pid}")
    else
      Procodile.log(@process.log_color, description, "Process not running already. Starting it.")
      start
    end
  when 'start-term'
    old_process_pid = @pid
    start
    Procodile.log(@process.log_color, description, "Sent #{@process.term_signal} signal to old PID #{old_process_pid} (forgetting now)")
    ::Process.kill(@process.term_signal, old_process_pid)
  when 'term-start'
    stop
    Thread.new do
      # Wait for this process to stop and when it has, run it.
      sleep 0.5 while running?
      start
    end
  end
ensure
  @restarting = false
end

#running?(force_pid = nil) ⇒ Boolean

Is this process running? Pass an option to check the given PID instead of the instance

Returns:

  • (Boolean) 


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# File 'lib/procodile/instance.rb', line 54

def running?(force_pid = nil)
  if force_pid || @pid
    ::Process.getpgid(force_pid || @pid) ? true : false
  else
    false
  end
rescue Errno::ESRCH
  false
end

#start ⇒ Object

Start a new instance of this process



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# File 'lib/procodile/instance.rb', line 67

def start
  @stopping = false
  existing_pid = self.pid_from_file
  if running?(existing_pid)
    # If the PID in the file is already running, we should just just continue
    # to monitor this process rather than spawning a new one.
    @pid = existing_pid
    Procodile.log(@process.log_color, description, "Already running with PID #{@pid}")
    nil
  else
    if self.process.log_path
      log_destination = File.open(self.process.log_path, 'a')
      return_value = nil
    else
      reader, writer = IO.pipe
      log_destination = writer
      return_value = reader
    end

    Dir.chdir(@process.config.root)
    @pid = ::Process.spawn({'PID_FILE' => pid_file_path}, @process.command, :out => log_destination, :err => log_destination, :pgroup => true)
    Procodile.log(@process.log_color, description, "Started with PID #{@pid}")
    File.open(pid_file_path, 'w') { |f| f.write(@pid.to_s + "\n") }
    ::Process.detach(@pid)

    return_value
  end
end

#stop ⇒ Object

Send this signal the signal to stop and mark the instance in a state that tells us that we want it to be stopped.



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# File 'lib/procodile/instance.rb', line 107

def stop
  @stopping = true
  update_pid
  if self.running?
    Procodile.log(@process.log_color, description, "Sending #{@process.term_signal} to #{@pid}")
    ::Process.kill(@process.term_signal, pid)
  else
    Procodile.log(@process.log_color, description, "Process already stopped")
  end
end

#stopping? ⇒ Boolean

Is this instance supposed to be stopping/be stopped?

Returns:

  • (Boolean) 


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# File 'lib/procodile/instance.rb', line 99

def stopping?
  @stopping || false
end

#tidy ⇒ Object

Tidy up when this process isn’t needed any more



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# File 'lib/procodile/instance.rb', line 130

def tidy
  FileUtils.rm_f(self.pid_file_path)
  Procodile.log(@process.log_color, description, "Removed PID file")
end

#to_hash ⇒ Object

Return this instance as a hash



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# File 'lib/procodile/instance.rb', line 257

def to_hash
  {
    :description => self.description,
    :pid => self.pid,
    :respawns => self.respawns,
    :running => self.running?
  }
end

#unmonitor ⇒ Object

Mark this process as dead and tidy up after it



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# File 'lib/procodile/instance.rb', line 220

def unmonitor
  @monitored = false
end

#unmonitored? ⇒ Boolean

Should this instance still be monitored by the supervisor?

Returns:

  • (Boolean) 


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# File 'lib/procodile/instance.rb', line 28

def unmonitored?
  @monitored == false
end

#update_pid ⇒ Object

Update the locally cached PID from that stored on the file system.



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# File 'lib/procodile/instance.rb', line 171

def update_pid
  pid_from_file = self.pid_from_file
  if pid_from_file && pid_from_file != @pid
    @pid = pid_from_file
    Procodile.log(@process.log_color, description, "PID file changed. Updated pid to #{@pid}")
    true
  else
    false
  end
end