Class: LanGrove::Handler::SocketMultiplexer

Inherits:
EM::Connection
  • Object
show all
Includes:
SocketBase
Defined in:
lib/langrove/handler/socket_multiplexer.rb

Constant Summary

Constants included from LanGrove::Handler

Default

Instance Attribute Summary collapse

Attributes included from LanGrove::Handler

#capsule, #config, #key, #logger, #pending_capsule, #protocol, #scheduler, #server, #type

Instance Method Summary collapse

Methods included from SocketBase

#handle_connect, #handle_disconnect, #handle_error, #handle_receive_data, #unbind

Methods included from LanGrove::Handler

#assign, #connect, #disconnect, #error, #event_filter, #receive, #reload, #reload_handler, #start, #stop, #transform, #unique

Instance Attribute Details

#handlers ⇒ Object

Multiplexer maintains a list of handlers in a manner identical to the Server



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# File 'lib/langrove/handler/socket_multiplexer.rb', line 43

def handlers
  @handlers
end

Instance Method Details

#create_handler(demux_key, decoded, persisted_capsule = nil) ⇒ Object 



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# File 'lib/langrove/handler/socket_multiplexer.rb', line 293

def create_handler( demux_key, decoded, persisted_capsule = nil )
  
  @logger.info "#{self}.create() handler at #{demux_key}"
  
  #
  # Create new Handler 
  # <handler_spawntime>
  #   

  begin

    #
    # DeMuxed Handler should not be an EM::Connection
    #

    @handlers[ demux_key ] = @handler_type.new

  rescue

    #
    # But incase it is, start it with an empty signature
    #  
    #  - not a problem because it is not attached to
    #    an actual socket
    #

    @handlers[ demux_key ] = @handler_type.new( {} )

  end
  
  @handlers[ demux_key ].instance_variable_set( 
  
    :@root, @root 
    
  )
  
  @handlers[ demux_key ].instance_variable_set( 
  
    :@logger, @root.logger
    
  )
  
  #
  # Insert capsule - used by Preloadable 
  # 
  @handlers[ demux_key ].instance_variable_set( 
  
    :@capsule, persisted_capsule
    
  ) unless persisted_capsule.nil?
  
     
  #
  # Configure the NEW Handler...
  # 
  @handlers[ demux_key ].assign( {
    
    :root => @root,
    
    
    #
    # Local config is for the Multiplexer, 
    # 
    # Nested within is the demultiplexed 
    # Handler config
    #
    :handler => {
      
      :config => @config[ :proxy_to ][ :handler ]
      
    },
    
    #
    # Unlikely that the demultiplexed Handler
    # will require the Protocol, the Multiplexer
    # itself does the proctolics.
    # 
    # The demultiplexed handler is simply fed 
    # the decoded data. 
    # 
    # Nevertheless consistancy often carries 
    # untold future bounty.
    # 
    # Send in the Protocol 'Type Const'
    # 
    # It gets .new(d) in .assign()
    # 
    # It is expecting class and config keys
    # 
    :protocol => { 
      
      :class  => @protocol.class,
      :config => @protocol.instance_variable_get( :@config )
    
    },
    
    #
    # For the bind to server.
    #  
    # To bypass local Handler (the Multiplexer),
    # 
    # Making the bind from Server's perspective
    # indistinguishable from an actual socket 
    # connected handler.
    # 
    :server => @server,
    
    #
    # same.
    #
    :scheduler => @scheduler
    
    #
    # notyet.
    # 
    # :introspector => @metrix
    # 
    
  } )
  
  @handlers[ demux_key ].start_handler
  
  #
  # Sometimes behaviours are listening 
  # at first_message and expecting a 
  # pending_capsule containing the first
  # message as decoded by the protocol.
  # 
  # Afford them the opportunity to function 
  # properly despite the de-multiplexion
  #
  @handlers[ demux_key ].instance_variable_set(
    
    :@pending_capsule, decoded
  
  )
  
  return @handlers[ demux_key ]
  
end

#receive_data(data) ⇒ Object 



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# File 'lib/langrove/handler/socket_multiplexer.rb', line 165

def receive_data( data )
  
  #
  # This, being connected as a Handler directly
  # to the receiving socket in the EventMachine
  # reactor,
  # 
  # Is receiveing data from the socket into this
  # callback,
  # 
  # It is necessary to pre-decode through the 
  # configured protocol to arrive at the demux
  # unique handler address.
  # 
  # from :proxy_by: (Per the config)
  #
  
  decoded = protocol.decode( data )
  
  unless decoded.has_key?( @proxy_by )
    
    #
    # ""Awkward...""
    # 
    # Missing the data required for unique-ness
    # 
    # Not too sensible to bring the house down
    # on this one...
    #
    # eg. An MTU somewhere may have chopped the 
    #     tail off a datagram...
    # 
    # 
    I.notify( @logger, "NAK lives here (on more complex protocols)", [:tcp] )
    # 
    # For now: 
    #  
    # - Log 'malformed data' and ignore message.
    #
    
    @logger.warn( 
    
      "Malformed data received. Missing value for '#{@proxy_by}' in message: #{data}"
    
    )
    
    return
    
  end
  
  demux_key = decoded[ @proxy_by ]
  
  if @handlers.has_key?( demux_key )
    
    #
    # Handler already present in the Collection
    # 
    
    @root.trigger( @handlers[demux_key], :handler, :receive )
    @handlers[demux_key].receive( decoded )
    @root.trigger( @handlers[demux_key], :handler, :after_receive )
    
    #
    #
    # 
    I.notify( @logger, "Bi-directional protocol lives here", [:tcp] )
    #
    # reply = @handlers[demux_key].receive( decoded )
    # 
    
    return
    
    #
    # done...
    # 
    
  end
  
  
  #
  # A potential CreateCollision COULD occur here.
  # 
  # On a proxiing system where inbound data from an 
  # end node is proxied dynamically, 
  # 
  # ie. proxy goes down and end node falls back onto 
  #     alternate proxy.
  # 
  # FirstHeardFrom knowledge about that end node arriving
  # here from both proxies simultaneously would case
  # 2 thread paths to set about creating the Handler.
  # 
  # VERY UNLIKELY because:
  # 
  # - FirstHeardFrom knowledge is rare enough as it is.
  # 
  # - FirstHeardFrom knowledge arriving from multiple 
  #   sources, simultanously...  pah!
  # 
  I.notify( @logger, "Race condition lives here", [:potential_bug, :minor] )
  
  create_handler( demux_key, decoded )
  
  
  #
  # These trigger calls fail in test,?
  # but work in RL 
  # 
  # Dunno why...
  #
  @root.trigger( @handlers[demux_key], :handler, :first_message )
  
  #
  # Fire the usual receive event
  #
  @root.trigger( @handlers[demux_key], :handler, :receive )
  
  #
  # Proceed to implementor overridable receive 
  #
  @handlers[demux_key].receive( decoded )

  @root.trigger( @handlers[demux_key], :handler, :after_receive )
    
end

#start_handler ⇒ Object

Raises:



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# File 'lib/langrove/handler/socket_multiplexer.rb', line 45

def start_handler
  
  @type = :multiplexer
  

  #
  # The multiplexed collection of handlers 
  # initialized on start()
  # 
  
  @handlers = {}
  
  raise LanGrove::DaemonConfigException.new(

    "#{self.class} requires :proxy_by: subconfig"
    
  ) if (
    
    @config.nil? or 
    not @config.has_key?( :proxy_by ) or
    @config[:proxy_by].nil?
  
  )
  
  #
  # The value that is unique in the decoded data
  # used a key into the Handlers collection
  # 
  @proxy_by = @config[:proxy_by]
  
  #
  # Load the handler definition ONLY once.
  # 
  # Call .new on it at <handler_spawntime> time to create
  # each required instance.
  #
  
  if (
  
    @config.nil? or
    not @config.has_key?( :proxy_to ) or
    not @config[:proxy_to].has_key?( :handler ) or
    not @config[:proxy_to][:handler].has_key?( :class )
      
  ) then
  
    #
    # anything not configured? 
    # 
    # merge default... 
    #
  
    @config = {} if @config.nil?
    @config.merge!( {
    
      :proxy_to => {
        
        :handler => {
          
          :class => 'Base'
          
          #
          # Not 'Default' 
          #
          # Default is a LanGrove::Handler::Socket
          # expecting an actual bind,
          # 
          # Use the Absolute Handler::Base class.
          # 
          
        }
        
      }
      
    } )
  
  end
  
  
  #
  # Extract the branch containing Handler config
  # 
  @handler_config = @config[:proxy_to]
  
  #
  # Load definition of Handler.
  #
  @handler_type = LanGrove::ModuleLoader.create( {
  
    :key => :handler,
    :config => @handler_config
    
  } )
  
  #
  # trigger event
  #
  @root.trigger( self, :multiplexer, :start )
  
  #
  # Implementor overridable start
  #
  start
  
end

#stop_handler ⇒ Object 



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# File 'lib/langrove/handler/socket_multiplexer.rb', line 151

def stop_handler
  
  #
  # trigger event
  #
  @root.trigger( self, :multiplexer, :stop )
  
  #
  # Implementor overridable start
  #
  stop
  
end