Class | PhusionPassenger::Railz::FrameworkSpawner
In: | lib/phusion_passenger/railz/framework_spawner.rb
Parent: | AbstractServer

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.

### Methods

new reload spawn_application start

### Included Modules

Utils

### Classes and Modules

Class PhusionPassenger::Railz::FrameworkSpawner::Error

### Public Class methods

new(options = {})

Creates a new instance of FrameworkSpawner.

Valid options are:

- `:version`: The Ruby on Rails version to use. It is not checked whether this version is actually installed.
- `:vendor`: The directory to the vendor Rails framework to use. This is usually something like "/webapps/foo/vendor/rails".

It is not allowed to specify both `version` and `vendor`.

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.

[Source]

        # File lib/phusion_passenger/railz/framework_spawner.rb, line 64
    64:         def initialize(options = {})
    65:                 if !options.respond_to?('[]''[]')
    66:                         raise ArgumentError, "The 'options' argument not seem to be an options hash"
    67:                 end
    68:                 @version = options[:version]
    69:                 @vendor  = options[:vendor]
    70:                 if !@version && !@vendor
    71:                         raise ArgumentError, "Either the 'version' or the 'vendor' option must specified"
    72:                 elsif @version && @vendor
    73:                         raise ArgumentError, "It is not allowed to specify both the 'version' and the 'vendor' options"
    74:                 end
    75:
    76:                 super()
    77:                 self.max_idle_time = DEFAULT_FRAMEWORK_SPAWNER_MAX_IDLE_TIME
    78:                 define_message_handler(:spawn_application, :handle_spawn_application)
    79:                 define_message_handler(:reload, :handle_reload)
    80:         end

### Public Instance methods

reload(app_root = nil)

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

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:

- ArgumentError: `app_root` doesn‘t appear to be a valid Ruby on Rails application root.
- FrameworkSpawner::Error: The FrameworkSpawner server exited unexpectedly.

[Source]

         # File lib/phusion_passenger/railz/framework_spawner.rb, line 199
    199:         def reload(app_root = nil)
    200:                 if app_root.nil?
    201:                         server.write("reload")
    202:                 else
    203:                         server.write("reload", normalize_path(app_root))
    204:                 end
    205:         rescue SystemCallError, IOError, SocketError
    206:                 raise Error, "The framework spawner server exited unexpectedly"
    207:         end

spawn_application(app_root, options = {})

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.

The following options are allowed:

- `lower_privilege` and `lowest_user`: If `lower_privilege` is true, then ApplicationSpawner will attempt to switch to the user who owns the application‘s `config/environment.rb`, and to the default group of that user.

  If that user doesn‘t exist on the system, or if that user is root, then ApplicationSpawner will attempt to switch to the username given by `lowest_user` (and to the default group of that user). If `lowest_user` doesn‘t exist either, or if switching user failed (because the current process does not have the privilege to do so), then ApplicationSpawner will continue without reporting an error.

- `environment`: Allows one to specify the RAILS_ENV environment to use.

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

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.
- InvalidAppRoot: `app_root` doesn‘t appear to be a valid Ruby on Rails application root.
- 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.

[Source]

         # File lib/phusion_passenger/railz/framework_spawner.rb, line 150
    150:         def spawn_application(app_root, options = {})
    151:                 app_root = normalize_path(app_root)
    152:                 assert_valid_app_root(app_root)
    153:                 options = sanitize_spawn_options(options)
    154:                 options["app_root"] = app_root
    155:
    156:                 exception_to_propagate = nil
    157:                 begin
    158:                         server.write("spawn_application", *options.to_a.flatten)
    159:                         result = server.read
    160:                         if result.nil?
    161:                                 raise IOError, "Connection closed"
    162:                         end
    163:                         if result[0] == 'exception'
    164:                                 e = unmarshal_exception(server.read_scalar)
    165:                                 if e.respond_to?(:child_exception) && e.child_exception
    166:                                         #print_exception(self.class.to_s, e.child_exception)
    167:                                 end
    168:                                 raise e
    169:                         else
    170:                                 pid, listen_socket_name, socket_type = server.read
    171:                                 if pid.nil?
    172:                                         raise IOError, "Connection closed"
    173:                                 end
    174:                                 owner_pipe = server.recv_io
    175:                                 return Application.new(app_root, pid, listen_socket_name,
    176:                                         socket_type, owner_pipe)
    177:                         end
    178:                 rescue SystemCallError, IOError, SocketError => e
    179:                         raise Error, "The framework spawner server exited unexpectedly"
    180:                 end
    181:         end

start()

Overrided from AbstractServer#start.

May raise these additional exceptions:

- FrameworkInitError: The specified Ruby on Rails framework could not be loaded.
- FrameworkSpawner::Error: The FrameworkSpawner server exited unexpectedly.

[Source]

         # File lib/phusion_passenger/railz/framework_spawner.rb, line 87
     87:         def start
     88:                 super
     89:                 begin
     90:                         result = server.read
     91:                         if result.nil?
     92:                                 raise Error, "The framework spawner server exited unexpectedly."
     93:                         else
     94:                                 status = result[0]
     95:                         end
     96:                         if status == 'exception'
     97:                                 child_exception = unmarshal_exception(server.read_scalar)
     98:                                 stop
     99:                                 if @version
    100:                                         message = "Could not load Ruby on Rails framework version #{@version}: " <<
    101:                                                 "#{child_exception.class} (#{child_exception.message})"
    102:                                 else
    103:                                         message = "Could not load Ruby on Rails framework at '#{@vendor}': " <<
    104:                                                 "#{child_exception.class} (#{child_exception.message})"
    105:                                 end
    106:                                 options = { :vendor => @vendor, :version => @version }
    107:                                 raise FrameworkInitError.new(message, child_exception, options)
    108:                         end
    109:                 rescue IOError, SystemCallError, SocketError
    110:                         stop
    111:                         raise Error, "The framework spawner server exited unexpectedly"
    112:                 end
    113:         end

[Validate]