Module: EventMachine::Protocols::LineText2

Included in:
HeaderAndContentProtocol, HttpClient2, SmtpClient, SmtpServer, Stomp
Defined in:
lib/em/protocols/linetext2.rb

Overview

In the grand, time-honored tradition of re-inventing the wheel, we offer here YET ANOTHER protocol that handles line-oriented data with interspersed binary text. This one trades away some of the performance optimizations of EventMachine::Protocols::LineAndTextProtocol in order to get better correctness with regard to binary text blocks that can switch back to line mode. It also permits the line-delimiter to change in midstream. This was originally written to support Stomp.

Constant Summary

MaxLineLength =

TODO! We're not enforcing the limits on header lengths and text-lengths. When we get around to that, call #receive_error if the user defined it, otherwise throw exceptions.

16*1024
MaxBinaryLength =
32*1024*1024

Instance Method Summary (collapse)

Instance Method Details

- (Object) receive_binary_data(data)

Stub. Should be subclassed by user code.



147
148
149
# File 'lib/em/protocols/linetext2.rb', line 147

def receive_binary_data data
  # no-op
end

- (Object) receive_data(data)

-- Will be called recursively until there's no data to read. That way the user-defined handlers we call can modify the handling characteristics on a per-token basis.



48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
# File 'lib/em/protocols/linetext2.rb', line 48

def receive_data data
  return unless (data and data.length > 0)

  # Do this stuff in lieu of a constructor.
  @lt2_mode ||= :lines
  @lt2_delimiter ||= "\n"
  @lt2_linebuffer ||= []

  if @lt2_mode == :lines
    if ix = data.index( @lt2_delimiter )
      @lt2_linebuffer << data[0...ix]
      ln = @lt2_linebuffer.join
      @lt2_linebuffer.clear
      if @lt2_delimiter == "\n"
        ln.chomp!
      end
      receive_line ln
      receive_data data[(ix+@lt2_delimiter.length)..-1]
    else
      @lt2_linebuffer << data
    end
  elsif @lt2_mode == :text
    if @lt2_textsize
      needed = @lt2_textsize - @lt2_textpos
      will_take = if data.length > needed
                    needed
                  else
                    data.length
                  end

      @lt2_textbuffer << data[0...will_take]
      tail = data[will_take..-1]

      @lt2_textpos += will_take
      if @lt2_textpos >= @lt2_textsize
        # Reset line mode (the default behavior) BEFORE calling the
        # receive_binary_data. This makes it possible for user code
        # to call set_text_mode, enabling chains of text blocks
        # (which can possibly be of different sizes).
        set_line_mode
        receive_binary_data @lt2_textbuffer.join
        receive_end_of_binary_data
      end

      receive_data tail
    else
      receive_binary_data data
    end
  end
end

- (Object) receive_end_of_binary_data

Stub. Should be subclassed by user code. This is called when transitioning internally from text mode back to line mode. Useful when client code doesn't want to keep track of how much data it's received.



155
156
157
# File 'lib/em/protocols/linetext2.rb', line 155

def receive_end_of_binary_data
  # no-op
end

- (Object) receive_line(ln)

Stub. Should be subclassed by user code.



142
143
144
# File 'lib/em/protocols/linetext2.rb', line 142

def receive_line ln
  # no-op
end

- (Object) set_binary_mode(size = nil)

Alias for #set_text_mode, added for back-compatibility with LineAndTextProtocol.



127
128
129
# File 'lib/em/protocols/linetext2.rb', line 127

def set_binary_mode size=nil
  set_text_mode size
end

- (Object) set_delimiter(delim)



100
101
102
# File 'lib/em/protocols/linetext2.rb', line 100

def set_delimiter delim
  @lt2_delimiter = delim.to_s
end

- (Object) set_line_mode(data = "")

Called internally but also exposed to user code, for the case in which processing of binary data creates a need to transition back to line mode. We support an optional parameter to "throw back" some data, which might be an umprocessed chunk of the transmitted binary data, or something else entirely.



109
110
111
112
113
# File 'lib/em/protocols/linetext2.rb', line 109

def set_line_mode data=""
  @lt2_mode = :lines
  (@lt2_linebuffer ||= []).clear
  receive_data data.to_s
end

- (Object) set_text_mode(size = nil)



115
116
117
118
119
120
121
122
123
124
# File 'lib/em/protocols/linetext2.rb', line 115

def set_text_mode size=nil
  if size == 0
    set_line_mode
  else
    @lt2_mode = :text
    (@lt2_textbuffer ||= []).clear
    @lt2_textsize = size # which can be nil, signifying no limit
    @lt2_textpos = 0
  end
end

- (Object) unbind

In case of a dropped connection, we'll send a partial buffer to user code when in sized text mode. User overrides of #receive_binary_data need to be aware that they may get a short buffer.



134
135
136
137
138
139
# File 'lib/em/protocols/linetext2.rb', line 134

def unbind
  @lt2_mode ||= nil
  if @lt2_mode == :text and @lt2_textpos > 0
    receive_binary_data @lt2_textbuffer.join
  end
end