Class: Bluepill::Process

Inherits:
Object
  • Object
show all
Defined in:
lib/bluepill/process.rb

Constant Summary collapse

CONFIGURABLE_ATTRIBUTES = 
[
  :start_command, 
  :stop_command, 
  :restart_command, 
  
  :stdout,
  :stderr,
  :stdin,
  
  :daemonize, 
  :pid_file, 
  :working_dir,
  
  :start_grace_time, 
  :stop_grace_time, 
  :restart_grace_time,
  
  :uid,
  :gid,
  
  :monitor_children,
  :child_process_template
]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(process_name, options = {}) ⇒ Process

Returns a new instance of Process.



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# File 'lib/bluepill/process.rb', line 85

def initialize(process_name, options = {})      
  @name = process_name
  @event_mutex = Monitor.new
  @transition_history = Util::RotationalArray.new(10)
  @watches = []
  @triggers = []
  @children = []
  
  @monitor_children = options[:monitor_children] || false
  
  %w(start_grace_time stop_grace_time restart_grace_time).each do |grace|
    instance_variable_set("@#{grace}", options[grace.to_sym] || 3)
  end
  
  CONFIGURABLE_ATTRIBUTES.each do |attribute_name|
    self.send("#{attribute_name}=", options[attribute_name]) if options.has_key?(attribute_name)
  end
  
  # Let state_machine do its initialization stuff
  super()
end

Instance Attribute Details

#children ⇒ Object (readonly)

Returns the value of attribute children.



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# File 'lib/bluepill/process.rb', line 30

def children
  @children
end

#logger ⇒ Object

Returns the value of attribute logger.



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# File 'lib/bluepill/process.rb', line 28

def logger
  @logger
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/bluepill/process.rb', line 28

def name
  @name
end

#skip_ticks_until ⇒ Object

Returns the value of attribute skip_ticks_until.



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# File 'lib/bluepill/process.rb', line 28

def skip_ticks_until
  @skip_ticks_until
end

#triggers ⇒ Object

Returns the value of attribute triggers.



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# File 'lib/bluepill/process.rb', line 28

def triggers
  @triggers
end

#watches ⇒ Object

Returns the value of attribute watches.



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# File 'lib/bluepill/process.rb', line 28

def watches
  @watches
end

Instance Method Details

#actual_pid ⇒ Object 



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# File 'lib/bluepill/process.rb', line 314

def actual_pid
  @actual_pid ||= begin
    if pid_file
      if File.exists?(pid_file)
        str = File.read(pid_file)
        str.to_i if str.size > 0
      else
        logger.warning("pid_file #{pid_file} does not exist or cannot be read")
        nil
      end
    end
  end
end

#actual_pid=(pid) ⇒ Object 



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# File 'lib/bluepill/process.rb', line 328

def actual_pid=(pid)
  @actual_pid = pid
end

#add_trigger(name, options = {}) ⇒ Object 



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# File 'lib/bluepill/process.rb', line 165

def add_trigger(name, options = {})
  self.triggers << Trigger[name].new(self, options.merge(:logger => self.logger))
end

#add_watch(name, options = {}) ⇒ Object

Watch related methods



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# File 'lib/bluepill/process.rb', line 161

def add_watch(name, options = {})
  self.watches << ConditionWatch.new(name, options.merge(:logger => self.logger))
end

#clear_pid ⇒ Object 



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# File 'lib/bluepill/process.rb', line 332

def clear_pid
  @actual_pid = nil
end

#daemonize? ⇒ Boolean

Returns:



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# File 'lib/bluepill/process.rb', line 299

def daemonize?
  !!self.daemonize
end

#deep_copy ⇒ Object 



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# File 'lib/bluepill/process.rb', line 377

def deep_copy
  Marshal.load(Marshal.dump(self))
end

#dispatch!(event) ⇒ Object

State machine methods



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# File 'lib/bluepill/process.rb', line 134

def dispatch!(event)
  @event_mutex.synchronize do
    self.send("#{event}")
  end
end

#handle_user_command(cmd) ⇒ Object 



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# File 'lib/bluepill/process.rb', line 191

def handle_user_command(cmd)
  case cmd
  when "boot"
    # This is only called when bluepill is initially starting up
    if process_running?(true)
      # process was running even before bluepill was
      self.state = 'up'
    else
      self.state = 'starting'
    end
    
  when "start"
    if process_running?(true) && daemonize?
      logger.warning("Refusing to re-run start command on an automatically daemonized process to preserve currently running process pid file.")
      return
    end
    dispatch!(:start)

  when "stop"
    stop_process
    dispatch!(:unmonitor)
    
  when "restart"
    restart_process
    
  when "unmonitor"
    # When the user issues an unmonitor cmd, reset any triggers so that
    # scheduled events gets cleared
    triggers.each {|t| t.reset! }
    dispatch!(:unmonitor)
  end
end

#monitor_children? ⇒ Boolean

Returns:



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# File 'lib/bluepill/process.rb', line 303

def monitor_children?
  !!self.monitor_children
end

#notify_triggers(transition) ⇒ Object 



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# File 'lib/bluepill/process.rb', line 156

def notify_triggers(transition)
  self.triggers.each {|trigger| trigger.notify(transition)}
end

#process_command(cmd) ⇒ Object 



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# File 'lib/bluepill/process.rb', line 381

def process_command(cmd)
  cmd.to_s.gsub("{{PID}}", actual_pid.to_s)
end

#process_running?(force = false) ⇒ Boolean

System Process Methods

Returns:



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# File 'lib/bluepill/process.rb', line 225

def process_running?(force = false)
  @process_running = nil if force
  @process_running ||= signal_process(0)
  self.clear_pid unless @process_running
  @process_running
end

#record_transition(transition) ⇒ Object 



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# File 'lib/bluepill/process.rb', line 140

def record_transition(transition)
  unless transition.loopback?
    @transitioned = true
    
    # When a process changes state, we should clear the memory of all the watches
    self.watches.each { |w| w.clear_history! }
    
    # Also, when a process changes state, we should re-populate its child list
    if self.monitor_children?
      self.logger.warning "Clearing child list"
      self.children.clear
    end
    logger.info "Going from #{transition.from_name} => #{transition.to_name}"
  end
end

#refresh_children! ⇒ Object 



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# File 'lib/bluepill/process.rb', line 351

def refresh_children!
  # First prune the list of dead children
  @children.delete_if {|child| !child.process_running?(true) }
  
  # Add new found children to the list
  new_children_pids = System.get_children(self.actual_pid) - @children.map {|child| child.actual_pid}
 
  unless new_children_pids.empty?
    logger.info "Existing children: #{@children.collect{|c| c.actual_pid}.join(",")}. Got new children: #{new_children_pids.inspect} for #{actual_pid}"
  end
  
  # Construct a new process wrapper for each new found children
  new_children_pids.each do |child_pid|
    child = self.child_process_template.deep_copy
    
    child.name = "<child(pid:#{child_pid})>"
    child.actual_pid = child_pid
    child.logger = self.logger.prefix_with(child.name)
    
    child.initialize_state_machines
    child.state = "up"
    
    @children << child
  end
end

#restart_process ⇒ Object 



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# File 'lib/bluepill/process.rb', line 276

def restart_process
  if restart_command
    cmd = process_command(restart_command)
    
    logger.warning "Executing restart command: #{cmd}"
    
    with_timeout(restart_grace_time) do
      result = System.execute_blocking(cmd, self.system_command_options)

      unless result[:exit_code].zero?
        logger.warning "Restart command execution returned non-zero exit code:"
        logger.warning result.inspect
      end
    end
    
    self.skip_ticks_for(restart_grace_time)
  else
    logger.warning "No restart_command specified. Must stop and start to restart"
    self.stop_process
    # the tick will bring it back.
  end
end

#run_watches ⇒ Object 



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# File 'lib/bluepill/process.rb', line 169

def run_watches
  now = Time.now.to_i

  threads = self.watches.collect do |watch|
    [watch, Thread.new { Thread.current[:events] = watch.run(self.actual_pid, now) }]
  end
  
  @transitioned = false
  
  threads.inject([]) do |events, (watch, thread)|
    thread.join
    if thread[:events].size > 0
      logger.info "#{watch.name} dispatched: #{thread[:events].join(',')}"
      events << thread[:events]
    end
    events
  end.flatten.uniq.each do |event|
    break if @transitioned
    self.dispatch!(event)
  end
end

#signal_process(code) ⇒ Object 



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# File 'lib/bluepill/process.rb', line 307

def signal_process(code)
  ::Process.kill(code, actual_pid)
  true
rescue
  false
end

#skip_ticks_for(seconds) ⇒ Object

Internal State Methods



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# File 'lib/bluepill/process.rb', line 341

def skip_ticks_for(seconds)
  # TODO: should this be addative or longest wins?
  #       i.e. if two calls for skip_ticks_for come in for 5 and 10, should it skip for 10 or 15?
  self.skip_ticks_until = (self.skip_ticks_until || Time.now.to_i) + seconds.to_i
end

#skipping_ticks? ⇒ Boolean

Returns:



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# File 'lib/bluepill/process.rb', line 347

def skipping_ticks?
  self.skip_ticks_until && self.skip_ticks_until > Time.now.to_i
end

#start_process ⇒ Object 



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# File 'lib/bluepill/process.rb', line 232

def start_process
  logger.warning "Executing start command: #{start_command}"
  
  if self.daemonize?
    System.daemonize(start_command, self.system_command_options)
    
  else
    # This is a self-daemonizing process
    with_timeout(start_grace_time) do
      result = System.execute_blocking(start_command, self.system_command_options)
      
      unless result[:exit_code].zero?
        logger.warning "Start command execution returned non-zero exit code:"
        logger.warning result.inspect
      end          
    end
  end
        
  self.skip_ticks_for(start_grace_time)
end

#stop_process ⇒ Object 



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# File 'lib/bluepill/process.rb', line 253

def stop_process      
  if stop_command
    cmd = process_command(stop_command)
    logger.warning "Executing stop command: #{cmd}"
    
    with_timeout(stop_grace_time) do
      result = System.execute_blocking(cmd, self.system_command_options)
      
      unless result[:exit_code].zero?
        logger.warning "Stop command execution returned non-zero exit code:"
        logger.warning result.inspect
      end
    end
            
  else
    logger.warning "Executing default stop command. Sending TERM signal to #{actual_pid}"
    signal_process("TERM")
  end
  self.unlink_pid # TODO: we only write the pid file if we daemonize, should we only unlink it if we daemonize?
  
  self.skip_ticks_for(stop_grace_time)
end

#system_command_options ⇒ Object 



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# File 'lib/bluepill/process.rb', line 385

def system_command_options
  {
    :uid         => self.uid, 
    :gid         => self.gid, 
    :working_dir => self.working_dir,
    :pid_file    => self.pid_file,
    :logger      => self.logger,
    :stdin       => self.stdin,
    :stdout      => self.stdout,
    :stderr      => self.stderr
  }
end

#tick ⇒ Object 



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# File 'lib/bluepill/process.rb', line 107

def tick
  return if self.skipping_ticks?
  self.skip_ticks_until = nil

  # clear the memoization per tick
  @process_running = nil

  # run state machine transitions
  super

  if self.up?
    run_watches
    
    if monitor_children?
      refresh_children!
      children.each {|child| child.tick}
    end
  end
end

#unlink_pid ⇒ Object 



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# File 'lib/bluepill/process.rb', line 336

def unlink_pid
  File.unlink(pid_file) if pid_file && File.exists?(pid_file)
end

#with_timeout(secs, &blk) ⇒ Object 



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# File 'lib/bluepill/process.rb', line 398

def with_timeout(secs, &blk)
  Timeout.timeout(secs.to_f, &blk)
  
rescue Timeout::Error
  logger.err "Execution is taking longer than expected. Unmonitoring."
  logger.err "Did you forget to tell bluepill to daemonize this process?"
  self.dispatch!("unmonitor")
end