gistfile1.txt

module LibZMQ
  extend FFI::Library
  LINUX = ["libzmq.so", "/usr/local/lib/libzmq.so", "/opt/local/lib/libzmq.so"]
  OSX = ["libzmq.dylib", "/usr/local/lib/libzmq.dylib", "/opt/local/lib/libzmq.dylib"]
  WINDOWS = []
  ffi_lib(LINUX + OSX + WINDOWS)

  # Message api
  class Msg_t < FFI::Struct
    layout :content,  :pointer,
    :flags,    :uint8,
    :vsm_size, :uint8,
    :vsm_data, [:uint8, 30]

  end # class Msg_t

  attach_function :zmq_msg_init, [:pointer], :int
  attach_function :zmq_msg_init_size, [:pointer, :size_t], :int
  callback :message_deallocator, [:pointer, :pointer], :void
  attach_function :zmq_msg_init_data, [:pointer, :pointer, :size_t, :message_deallocator, :pointer], :int
  attach_function :zmq_msg_close, [:pointer], :int
  attach_function :zmq_msg_data, [:pointer], :pointer
  attach_function :zmq_msg_size, [:pointer], :size_t
  attach_function :zmq_msg_copy, [:pointer, :pointer], :int
  attach_function :zmq_msg_move, [:pointer, :pointer], :int
  
  # Called by zmq_close
  MessageDeallocator = Proc.new do |data_ptr, hint_ptr|
    #puts "msg_callback: freed data [#{data_ptr}]"
    data_ptr.free
  end
end

message.rb

  class Message
    include ZMQ::Util

    def initialize message = nil
      @struct = LibZMQ::Msg_t.new

      if message
        data = FFI::MemoryPointer.from_string message.to_s
        result_code = LibZMQ.zmq_msg_init_size @struct, message.size
        error_check ZMQ_MSG_INIT_SIZE_STR, result_code

        # assign a memory deallocation callback function
        result_code = LibZMQ.zmq_msg_init_data @struct, data, message.size, LibZMQ::MessageDeallocator, nil
        error_check ZMQ_MSG_INIT_DATA_STR, result_code
      else
        result_code = LibZMQ.zmq_msg_init @struct
        error_check ZMQ_MSG_INIT_STR, result_code
      end
    end

    def address
      @struct
    end

    def size
      LibZMQ.zmq_msg_size @struct
    end

    def data
      data_ptr.read_string(size)
    end

    def close
      result_code = LibZMQ.zmq_msg_close @struct
      error_check ZMQ_MSG_CLOSE_STR, result_code
      @struct = nil
    end
    
    private
    
    def data_ptr
      LibZMQ.zmq_msg_data @struct
    end
  end