Class: RFlow::DaemonProcess

Inherits:
Object
  • Object
show all
Defined in:
lib/rflow/daemon_process.rb

Overview

Encapsulates a master process being managed by RFlow that can run in the foreground or daemonize.

Direct Known Subclasses

Master

Constant Summary collapse

SIGINFO =

Symbolic constant for SIGINFO as this is only defined on BSD and not in Ruby.

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Instance Method Summary collapse

Constructor Details

#initialize(name, role = name, options = {}) ⇒ DaemonProcess

Returns a new instance of DaemonProcess.



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# File 'lib/rflow/daemon_process.rb', line 10

def initialize(name, role = name, options = {})
  @name = name
  @role = role
  @pid_file = PIDFile.new(options[:pid_file_path]) if options[:pid_file_path]
end

Instance Method Details

#daemonize! ⇒ void

This method returns an undefined value.

Daemonize by forking and exiting the parent after handling IO streams and checking successful start of the new copy.



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# File 'lib/rflow/daemon_process.rb', line 19

def daemonize!
  RFlow.logger.info "#{@name} daemonizing"
  establish_daemon_pipe
  drop_database_connections

  parent = fork
  if parent
    exit_after_daemon_starts
  else
    daemonize_process
  end
end

#run! ⇒ void

This method returns an undefined value.

Execute the master process. Writes out a pidfile and updates the process name, installs signal handlers, and spawns all the defined subprocesses. Finally executes #run_process; when that returns, it will exit with the resulting return code.



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# File 'lib/rflow/daemon_process.rb', line 37

def run!
  write_pid_file
  register_logging_context
  update_process_name
  handle_signals
  spawn_subprocesses
  signal_successful_start

  RFlow.logger.info "#{@role} started"
  run_process
ensure
  unhandle_signals
  remove_pid_file
end

#run_process ⇒ void

This method returns an undefined value.

Default implementation. Subclasses should override to provide logic for actually doing something useful.



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# File 'lib/rflow/daemon_process.rb', line 60

def run_process; end

#shutdown!(reason) ⇒ void

This method returns an undefined value.

Shut down the application. Cleans up the pid file, removes signal handlers, and signals all child processes with SIGQUIT.



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# File 'lib/rflow/daemon_process.rb', line 69

def shutdown!(reason)
  RFlow.logger.info "#{@name} shutting down due to #{reason}"
  remove_pid_file
  unhandle_signals
  signal_subprocesses('QUIT')
  RFlow.logger.info "#{@name} exiting"
end

#spawn_subprocesses ⇒ void

This method returns an undefined value.

Default implementation. Subclasses should override to provide logic for actually spawning subprocesses.



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# File 'lib/rflow/daemon_process.rb', line 55

def spawn_subprocesses; end

#subprocesses ⇒ Array<ChildProcess>

A list of ChildProcesses to start and signal.

Returns:



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# File 'lib/rflow/daemon_process.rb', line 64

def subprocesses; []; end