Class: PDTP::LengthPrefixProtocol

Inherits:
EventMachine::Connection
  • Object
show all
Defined in:
lib/pdtp/common/length_prefix_protocol.rb

Overview

EventMachine connection adapter for length prefix framing

Direct Known Subclasses

Protocol

Defined Under Namespace

Classes: Prefix

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ LengthPrefixProtocol

Returns a new instance of LengthPrefixProtocol.



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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 76

def initialize *args
  super
  
  @prefix = Prefix.new
  @buffer = ''
end

Instance Method Details

#prefix_size=(size) ⇒ Object 



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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 83

def prefix_size=(size)
  data = @prefix.data << @buffer
  @prefix = Prefix.new size
  receive_data data
end

#receive_data(data) ⇒ Object

Callback for processing incoming frames



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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 90

def receive_data(data)
  begin
    # Read data and append it to the size prefix unless it's already been read
    data = @prefix.append(data) unless @prefix.read?
    return if data.nil?
    
    # If we've read the prefix, append the data
    @buffer << data
    
    # Don't do anything until we receive the specified amount of data
    return unless @buffer.length >= @prefix.length
    
    # Extract the specified amount of data and process it
    data = @buffer[0..(@prefix.length - 1)]
    
    # Store any remaining data
    remainder = @buffer[@prefix.length..@buffer.length]
    
    # Invoke receive_packet and allow the user to process the data
    receive_packet data
    
    # Reset the prefix and buffer since we've received a whole frame
    @prefix.reset!
    @buffer = ''

    # Store data for next iteration of the loop
    data = remainder
  end until data.nil? or data.empty?
end

#receive_packet(packet) ⇒ Object

Stub for receiving a frame



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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 121

def receive_packet(packet)
end

#send_packet(data) ⇒ Object

Send a packet with a specified size prefix

Raises:

  • (ArgumentError) 


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# File 'lib/pdtp/common/length_prefix_protocol.rb', line 125

def send_packet(data)
  raise ArgumentError, 'packet too long for prefix length' if data.size >= 256**@prefix.size
  send_data [data.size].pack(@prefix.size == 2 ? 'n' : 'N') << data
end