Class: LogCourier::Server

Inherits:
Object
  • Object
show all
Defined in:
lib/log-courier/server.rb

Overview

Implementation of the server

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Server

Returns a new instance of Server.



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# File 'lib/log-courier/server.rb', line 36

def initialize(options = {})
  @options = {
    logger:    nil,
    transport: 'tls'
  }.merge!(options)

  @logger = @options[:logger]

  case @options[:transport]
  when 'tcp', 'tls'
    require 'log-courier/server_tcp'
    @server = ServerTcp.new(@options)
  when 'plainzmq', 'zmq'
    require 'log-courier/server_zmq'
    @server = ServerZmq.new(@options)
  else
    raise '[LogCourierServer] \'transport\' must be tcp, tls, plainzmq or zmq'
  end

  # Grab the port back
  @port = @server.port

  # Load the json adapter
  @json_adapter = MultiJson.adapter.instance
  @json_options = { raw: true, use_bigdecimal: true }
end

Instance Attribute Details

#port ⇒ Object (readonly)

Returns the value of attribute port.



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# File 'lib/log-courier/server.rb', line 34

def port
  @port
end

Instance Method Details

#process_jdat(message, comm, event_queue) ⇒ Object 



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# File 'lib/log-courier/server.rb', line 109

def process_jdat(message, comm, event_queue)
  # Now we have the data, aim to respond within 5 seconds
  ack_timeout = Time.now.to_i + 5

  # OK - first is a nonce - we send this back with sequence acks
  # This allows the client to know what is being acknowledged
  # Nonce is 16 so check we have enough
  if message.length < 17
    raise ProtocolError, "JDAT message too small (#{message.length})"
  end

  nonce = message[0...16]

  # The remainder of the message is the compressed data block
  message = StringIO.new Zlib::Inflate.inflate(message[16...message.length])

  # Message now contains JSON encoded events
  # They are aligned as [length][event]... so on
  # We acknowledge them by their 1-index position in the stream
  # A 0 sequence acknowledgement means we haven't processed any yet
  sequence = 0
  events = []
  length_buf = ''
  data_buf = ''
  loop do
    ret = message.read 4, length_buf
    if ret.nil?
      # Finished!
      break
    elsif length_buf.length < 4
      raise ProtocolError, "JDAT length extraction failed (#{ret} #{length_buf.length})"
    end

    length = length_buf.unpack('N').first

    # Extract message
    ret = message.read length, data_buf
    if ret.nil? or data_buf.length < length
      @logger.warn()
      raise ProtocolError, "JDAT message extraction failed #{ret} #{data_buf.length}"
    end

    data_buf.force_encoding('utf-8')

    # Ensure valid encoding
    unless data_buf.valid_encoding?
      data_buf.chars.map do |c|
        c.valid_encoding? ? c : "\xEF\xBF\xBD"
      end
    end

    # Decode the JSON
    begin
      event = @json_adapter.load(data_buf, @json_options)
    rescue MultiJson::ParseError => e
      @logger.warn("[LogCourierServer] JSON parse failure, falling back to plain-text: #{e}") unless @logger.nil?
      event = { 'message' => data_buf }
    end

    # Queue the event
    begin
      event_queue.push event, [0, ack_timeout - Time.now.to_i].max
    rescue TimeoutError
      # Full pipeline, partial ack
      # NOTE: comm.send can raise a Timeout::Error of its own
      @logger.debug "[LogCourierServer] Partially acknowledging message #{nonce.hash} sequence #{sequence}" unless @logger.nil?
      comm.send 'ACKN', [nonce, sequence].pack('A*N')
      ack_timeout = Time.now.to_i + 5
      retry
    end

    sequence += 1
  end

  # Acknowledge the full message
  # NOTE: comm.send can raise a Timeout::Error
  @logger.debug "[LogCourierServer] Acknowledging message #{nonce.hash} sequence #{sequence}" unless @logger.nil?
  comm.send 'ACKN', [nonce, sequence].pack('A*N')
end

#process_ping(message, comm) ⇒ Object 



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# File 'lib/log-courier/server.rb', line 98

def process_ping(message, comm)
  # Size of message should be 0
  if message.length != 0
    raise ProtocolError, "unexpected data attached to ping message (#{message.length})"
  end

  # PONG!
  # NOTE: comm.send can raise a Timeout::Error of its own
  comm.send 'PONG', ''
end

#run(&block) ⇒ Object 



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# File 'lib/log-courier/server.rb', line 63

def run(&block)
  # TODO: Make queue size configurable
  event_queue = EventQueue.new 1
  server_thread = nil

  begin
    server_thread = Thread.new do
      # Receive messages and process them
      @server.run do |signature, message, comm|
        case signature
        when 'PING'
          process_ping message, comm
        when 'JDAT'
          process_jdat message, comm, event_queue
        else
          @logger.warn("[LogCourierServer] Unknown message received from #{comm.peer}") unless @logger.nil?
          # Don't kill a client that sends a bad message
          # Just reject it and let it send it again, potentially to another server
          comm.send '????', ''
        end
      end
    end

    loop do
      block.call event_queue.pop
    end
  ensure
    # Signal the server thread to stop
    unless server_thread.nil?
      server_thread.raise ShutdownSignal
      server_thread.join
    end
  end
end