Class: PhusionPassenger::ClassicRails::FrameworkSpawner

Inherits:
AbstractServer show all
Includes:
Utils
Defined in:
lib/phusion_passenger/classic_rails/framework_spawner.rb

Overview

This class is capable of spawning Ruby on Rails application instances quickly. This is done by preloading the Ruby on Rails framework into memory, before spawning the application instances.

A single FrameworkSpawner instance can only hold a single Ruby on Rails framework version. So be careful when using FrameworkSpawner: the applications that you spawn through it must require the same RoR version. To handle multiple RoR versions, use multiple FrameworkSpawner instances.

FrameworkSpawner uses ApplicationSpawner internally.

Note: FrameworkSpawner may only be started asynchronously with AbstractServer#start. Starting it synchronously with AbstractServer#start_synchronously has not been tested.

Defined Under Namespace

Classes: Error

Instance Attribute Summary

Attributes inherited from AbstractServer

#ignore_password_errors, #max_idle_time, #next_cleaning_time, #password

Instance Method Summary collapse

Methods included from Utils

process_is_alive?

Methods inherited from AbstractServer

#connect, #server_pid, #start_synchronously, #started?, #stop

Constructor Details

#initialize(options = {}) ⇒ FrameworkSpawner

Creates a new instance of FrameworkSpawner.

Extra supported options:

  • framework_version: The Ruby on Rails version to use. It is not checked whether this version is actually installed.

All other options will be passed on to ApplicationSpawner and RequestHandler.

Note that the specified Rails framework will be loaded during the entire life time of the FrameworkSpawner server. If you wish to reload the Rails framework’s code, then restart the server by calling AbstractServer#stop and AbstractServer#start.



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# File 'lib/phusion_passenger/classic_rails/framework_spawner.rb', line 66

def initialize(options = {})
  if !options.respond_to?(:'[]')
    raise ArgumentError, "The 'options' argument does not seem to be an options hash"
  end
  @framework_version = options["framework_version"]
  if options.has_key?("print_framework_loading_exceptions")
    @print_framework_loading_exceptions = options["print_framework_loading_exceptions"]
  else
    @print_framework_loading_exceptions = true
  end
  if !@framework_version
    raise ArgumentError, "The 'framework_version' option must specified"
  end
  
  super()
  @options = options
  self.max_idle_time = DEFAULT_FRAMEWORK_SPAWNER_MAX_IDLE_TIME
  define_message_handler(:spawn_application, :handle_spawn_application)
  define_message_handler(:reload, :handle_reload)
end

Instance Method Details

#reload(app_group_name = nil) ⇒ Object

Remove the cached application instances at the given group name. If nil is specified as group name, then all cached application instances will be removed, no matter the group name.

Long description: Application code might be cached in memory by a FrameworkSpawner. But once it a while, it will be necessary to reload the code for an application, such as after deploying a new version of the application. This method makes sure that any cached application code is removed, so that the next time an application instance is spawned, the application code will be freshly loaded into memory.

Raises:

  • FrameworkSpawner::Error: The FrameworkSpawner server exited unexpectedly.



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# File 'lib/phusion_passenger/classic_rails/framework_spawner.rb', line 188

def reload(app_group_name = nil)
  connect do |channel|
    if app_group_name.nil?
      channel.write("reload")
    else
      channel.write("reload", app_group_name)
    end
  end
rescue SystemCallError, IOError, SocketError
  raise Error, "The framework spawner server exited unexpectedly: #{e}"
end

#spawn_application(options = {}) ⇒ Object

Spawn a RoR application using the Ruby on Rails framework version associated with this FrameworkSpawner. When successful, an Application object will be returned, which represents the spawned RoR application.

All options accepted by ApplicationSpawner.new and RequestHandler.new are accepted.

FrameworkSpawner will internally cache the code of applications, in order to speed up future spawning attempts. This implies that, if you’ve changed the application’s code, you must do one of these things:

  • Restart this FrameworkSpawner by calling AbstractServer#stop, then AbstractServer#start.

  • Reload the application by calling reload with the correct app_root argument.

Raises:

  • AbstractServer::ServerNotStarted: The FrameworkSpawner server hasn’t already been started.

  • AppInitError: The application raised an exception or called exit() during startup.

  • ApplicationSpawner::Error: The ApplicationSpawner server exited unexpectedly.

  • FrameworkSpawner::Error: The FrameworkSpawner server exited unexpectedly.



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# File 'lib/phusion_passenger/classic_rails/framework_spawner.rb', line 140

def spawn_application(options = {})
  app_root = options["app_root"]
  options = sanitize_spawn_options(options)
  options["app_root"] = app_root
  # No need for the ApplicationSpawner to print exceptions. All
  # exceptions raised by the ApplicationSpawner are sent back here,
  # so we just need to decide here whether we want to print it.
  print_exceptions = options["print_exceptions"]
  options["print_exceptions"] = false
  
  begin
    connect do |channel|
      channel.write("spawn_application", *options.to_a.flatten)
      result = channel.read
      if result.nil?
        raise IOError, "Connection closed"
      end
      if result[0] == 'exception'
        e = unmarshal_exception(channel.read_scalar)
        if print_exceptions && e.respond_to?(:child_exception) && e.child_exception
          print_exception(self.class.to_s, e.child_exception)
        elsif print_exceptions
          print_exception(self.class.to_s, e)
        end
        raise e
      else
        return AppProcess.read_from_channel(channel)
      end
    end
  rescue SystemCallError, IOError, SocketError => e
    raise Error, "The framework spawner server exited unexpectedly: #{e}"
  end
end

#start ⇒ Object

Overrided from AbstractServer#start.

May raise these additional exceptions:

  • FrameworkInitError: An error occurred while loading the specified Ruby on Rails framework.

  • FrameworkSpawner::Error: The FrameworkSpawner server exited unexpectedly.



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# File 'lib/phusion_passenger/classic_rails/framework_spawner.rb', line 92

def start
  super
  begin
    channel = MessageChannel.new(@owner_socket)
    result = channel.read
    if result.nil?
      raise Error, "The framework spawner server exited unexpectedly."
    else
      status = result[0]
    end
    if status == 'exception'
      child_exception = unmarshal_exception(channel.read_scalar)
      stop
      message = "Could not load Ruby on Rails framework version #{@framework_version}: " <<
        "#{child_exception.class} (#{child_exception.message})"
      options = { :version => @framework_version }
      if @print_framework_loading_exceptions
        print_exception(self.class.to_s, child_exception)
      end
      raise FrameworkInitError.new(message, child_exception, options)
    end
  rescue IOError, SystemCallError, SocketError => e
    stop if started?
    raise Error, "The framework spawner server exited unexpectedly: #{e}"
  rescue
    stop if started?
    raise
  end
end