Class: Harbor::Daemon

Inherits:
Object
  • Object
show all
Defined in:
lib/harbor/daemon.rb

Constant Summary collapse

START_CONTEXT = 
{
  :argv => ARGV.map { |arg| arg.dup },
  :cwd => `/bin/sh -c pwd`.chomp("\n"),
  :cmd => $0.dup
}
DEFAULT_SLEEP_SECONDS = 
60

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(worker, log_file, seconds_between_runs = DEFAULT_SLEEP_SECONDS) ⇒ Daemon

Returns a new instance of Daemon.



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# File 'lib/harbor/daemon.rb', line 16

def initialize(worker, log_file, seconds_between_runs = DEFAULT_SLEEP_SECONDS)
  @worker = worker

  # The template may include the tag %PID to be replaced with
  # the PID of the forked worker process.  Don't use @log_file
  # directly, use self.log_file
  @log_file_template = log_file
  
  @seconds_between_runs = seconds_between_runs
end

Instance Attribute Details

#logger ⇒ Object

Returns the value of attribute logger.



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# File 'lib/harbor/daemon.rb', line 13

def logger
  @logger
end

#options ⇒ Object (readonly)

Returns the value of attribute options.



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# File 'lib/harbor/daemon.rb', line 14

def options
  @options
end

#worker ⇒ Object (readonly)

Returns the value of attribute worker.



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# File 'lib/harbor/daemon.rb', line 14

def worker
  @worker
end

Instance Method Details

#cleanup! ⇒ Object 



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# File 'lib/harbor/daemon.rb', line 88

def cleanup!
  worker.cleanup! if worker.respond_to?(:cleanup!)
end

#detach ⇒ Object 



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# File 'lib/harbor/daemon.rb', line 31

def detach
  srand
  fork and exit
  Process.setsid # detach -- we want to be able to close our shell!

  log_directory = ::File.dirname(self.log_file)
  ::File.mkdir_p(log_directory) unless ::File.directory?(log_directory)

  redirect_io(@log_file)
end

#log_file ⇒ Object 



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# File 'lib/harbor/daemon.rb', line 27

def log_file
  @log_file ||= @log_file_template.gsub('%PID', Process.pid.to_s)      
end

#run ⇒ Object 



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# File 'lib/harbor/daemon.rb', line 42

def run
  @restart = false
  @alive = true

  # graceful restart
  trap(:HUP) do
    logger.info "Restarting gracefully." if logger
    @restart = true
    @alive = nil
    @worker.alive = nil
  end

  # graceful shutdown
  trap(:QUIT) do
    logger.info "Shutting down gracefully." if logger
    @alive = nil
    @worker.alive = nil
  end

  # quick exit
  [:TERM, :INT].each do |sig|
    trap(sig) do
      logger.info "Shutting down NOW" if logger
      cleanup!

      exit!(0)
    end
  end
  
  begin
    @worker.run
    sleep(@seconds_between_runs) if @alive
  end while @alive
    
  if @restart
    logger.info "Starting new daemon..."
    fork do
      Dir.chdir(START_CONTEXT[:cwd])
      exec(START_CONTEXT[:cmd], *START_CONTEXT[:argv])
    end
  end

  logger.info "Shutting down..." if logger
  cleanup!
end