Class: Pione::Front::BasicFront

Inherits:
PioneObject
  • Object
show all
Includes:
DRbUndumped
Defined in:
lib/pione/front/basic-front.rb

Overview

This is base class for all PIONE front classes. PIONE fronts exist in each command and behave as remote control interface.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(cmd, port) ⇒ BasicFront

Creates a front server as druby's service.



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# File 'lib/pione/front/basic-front.rb', line 11

def initialize(cmd, port)
  @cmd = cmd
  @uri = URI.parse(start_service(port, {})) # port is number or range
  @attr = {}
  @child = {}
  @child_lock = Mutex.new
  @child_watchers = ThreadGroup.new
end

Instance Attribute Details

#uri ⇒ Object (readonly)

front server's URI string



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# File 'lib/pione/front/basic-front.rb', line 8

def uri
  @uri
end

Instance Method Details

#[](name) ⇒ Object 



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# File 'lib/pione/front/basic-front.rb', line 25

def [](name)
  @attr[name]
end

#[]=(name, val) ⇒ Object 



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# File 'lib/pione/front/basic-front.rb', line 29

def []=(name, val)
  @attr[name] = val
end

#child_front_uri(pid) ⇒ String

Return a front URI of the child PID.

Returns:

  • (String) —

    URI of the child PID



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# File 'lib/pione/front/basic-front.rb', line 91

def child_front_uri(pid)
  @child[pid]
end

#child_pids ⇒ Array

Return list of child process's PIDs.

Returns:

  • (Array) —

    list of child command's PIDs.



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# File 'lib/pione/front/basic-front.rb', line 83

def child_pids
  @child.keys
end

#pid ⇒ Object

Return PID of the process.



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# File 'lib/pione/front/basic-front.rb', line 21

def pid
  Process.pid
end

#register_child(pid, front_uri) ⇒ void

This method returns an undefined value.

Register the process as a child of this process. It is unregistered when the child is terminated.

Parameters:

  • pid (String) —

    child process's PID

  • front_uri (String) —

    child process's front URI



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# File 'lib/pione/front/basic-front.rb', line 41

def register_child(pid, front_uri)
  unless @cmd.current_phase == :termination
    # register child's PID
    @child_lock.synchronize {@child[pid] = front_uri}

    # unregister automatically when the child is terminated
    thread = Thread.new do
      Util.ignore_exception(Errno::ECHILD) do
        Process.waitpid(pid)
        unregister_child(pid)
      end
    end
    thread[:pid] = pid
    @child_watchers.add(thread)

    return nil
  else
    raise ChildRegistrationError.new
  end
end

#system_logger ⇒ Object 



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# File 'lib/pione/front/basic-front.rb', line 95

def system_logger
  Log::SystemLog.logger
end

#terminate ⇒ Object

Terminate the front server. This method assumes to be not called from other processes. Note that front servers have no responsibility of killing child processes.



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# File 'lib/pione/front/basic-front.rb', line 102

def terminate
  DRb.stop_service
end

#terminate_command ⇒ Object

Terminate the command. This is a nonblocking method because callee process cannot tell its termination to caller, so it returns true immediately.



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# File 'lib/pione/front/basic-front.rb', line 109

def terminate_command
  Thread.new {@cmd.terminate}
  return true
end

#unregister_child(pid) ⇒ Object

Unregister the child process.

Parameters:

  • pid (String) —

    child's PID to be removed



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# File 'lib/pione/front/basic-front.rb', line 66

def unregister_child(pid)
  # unregister the pid
  @child_lock.synchronize {@child.delete(pid)}

  # kill the watcher thread
  @child_watchers.list.each do |thread|
    if thread[:pid] == pid
      thread.kill
      break
    end
  end
end