Class: Protocol::HTTP2::Stream

Inherits:
Object
  • Object
show all
Includes:
FlowControl
Defined in:
lib/protocol/http2/stream.rb

Overview

A single HTTP 2.0 connection can multiplex multiple streams in parallel: multiple requests and responses can be in flight simultaneously and stream data can be interleaved and prioritized.

This class encapsulates all of the state, transition, flow-control, and error management as defined by the HTTP 2.0 specification. All you have to do is subscribe to appropriate events (marked with “:” prefix in diagram below) and provide your application logic to handle request and response processing.

                  +--------+
          send PP |        | recv PP
         ,--------|  idle  |--------.
        /         |        |         \
       v          +--------+          v
+----------+          |           +----------+
|          |          | send H /  |          |

,——| reserved | | recv H | reserved |——. | | (local) | | | (remote) | | | ---------- v ---------- | | | -------- | | | | recv ES | | send ES | | | send H | ,——-| open |——-. | recv H | | | / | | \ | | | v v -------- v v | | ---------- | ---------- | | | half | | | half | | | | closed | | send R / | closed | | | | (remote) | | recv R | (local) | | | ---------- | ---------- | | | | | | | | send ES / | recv ES / | | | | send R / v send R / | | | | recv R -------- recv R | | | send R / ‘———–>| |<———–’ send R / | | recv R | closed | recv R | ‘———————–>| |<———————-’

                      +--------+

send:   endpoint sends this frame
recv:   endpoint receives this frame

H:  HEADERS frame (with implied CONTINUATIONs)
PP: PUSH_PROMISE frame (with implied CONTINUATIONs)
ES: END_STREAM flag
R:  RST_STREAM frame

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from FlowControl

#available_frame_size, #consume_local_window, #receive_window_update, #send_window_update, #window_updated

Constructor Details

#initialize(connection, id = connection.next_stream_id) ⇒ Stream

Returns a new instance of Stream.



76
77
78
79
80
81
82
83
84
85
86
87
88
 
# File 'lib/protocol/http2/stream.rb', line 76

def initialize(connection, id = connection.next_stream_id)
  @connection = connection
  @id = id
  
  @state = :idle
  
  @priority = nil
  @local_window = Window.new(connection.local_settings.initial_window_size)
  @remote_window = Window.new(connection.remote_settings.initial_window_size)
  
  @headers = nil
  @data = nil
end

Instance Attribute Details

#data ⇒ Object (readonly)

Returns the value of attribute data.



97
98
99
 
# File 'lib/protocol/http2/stream.rb', line 97

def data
  @data
end

#headers ⇒ Object (readonly)

Returns the value of attribute headers.



96
97
98
 
# File 'lib/protocol/http2/stream.rb', line 96

def headers
  @headers
end

#id ⇒ Object (readonly)

Stream ID (odd for client initiated streams, even otherwise).



91
92
93
 
# File 'lib/protocol/http2/stream.rb', line 91

def id
  @id
end

#local_window ⇒ Object (readonly)

Returns the value of attribute local_window.



99
100
101
 
# File 'lib/protocol/http2/stream.rb', line 99

def local_window
  @local_window
end

#remote_window ⇒ Object (readonly)

Returns the value of attribute remote_window.



100
101
102
 
# File 'lib/protocol/http2/stream.rb', line 100

def remote_window
  @remote_window
end

#state ⇒ Object (readonly)

Stream state as defined by HTTP 2.0.



94
95
96
 
# File 'lib/protocol/http2/stream.rb', line 94

def state
  @state
end

Instance Method Details

#close(state = :closed) ⇒ Object 



217
218
219
 
# File 'lib/protocol/http2/stream.rb', line 217

def close(state = :closed)
  @state = state
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


118
119
120
 
# File 'lib/protocol/http2/stream.rb', line 118

def closed?
  @state == :closed or @state == :reset
end

#consume_remote_window(frame) ⇒ Object 



181
182
183
184
185
 
# File 'lib/protocol/http2/stream.rb', line 181

def consume_remote_window(frame)
  super
  
  @connection.consume_remote_window(frame)
end

#create_promise_stream(headers, stream_id) ⇒ Object 



346
347
348
 
# File 'lib/protocol/http2/stream.rb', line 346

def create_promise_stream(headers, stream_id)
  @connection.create_stream(stream_id)
end

#inspect ⇒ Object 



375
376
377
 
# File 'lib/protocol/http2/stream.rb', line 375

def inspect
  "\#<#{self.class} id=#{@id} state=#{@state}>"
end

#maximum_frame_size ⇒ Object 



110
111
112
 
# File 'lib/protocol/http2/stream.rb', line 110

def maximum_frame_size
  @connection.available_frame_size
end

#priority=(priority) ⇒ Object 



102
103
104
105
106
107
108
 
# File 'lib/protocol/http2/stream.rb', line 102

def priority= priority
  if priority.stream_id == @id
    raise ProtocolError, "Stream #{@id} cannot depend on itself!"
  end
  
  @priority = priority
end

#receive_data(frame) ⇒ Object

DATA frames are subject to flow control and can only be sent when a stream is in the “open” or “half-closed (remote)” state. The entire DATA frame payload is included in flow control, including the Pad Length and Padding fields if present. If a DATA frame is received whose stream is not in “open” or “half-closed (local)” state, the recipient MUST respond with a stream error of type STREAM_CLOSED.



278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
 
# File 'lib/protocol/http2/stream.rb', line 278

def receive_data(frame)
  if @state == :open
    consume_local_window(frame)
    
    if frame.end_stream?
      @state = :half_closed_remote
    end
    
    @data = frame.unpack
  elsif @state == :half_closed_local
    consume_local_window(frame)
    
    if frame.end_stream?
      close
    end
    
    @data = frame.unpack
  elsif @state == :reset
    # ignore...
  else
    raise ProtocolError, "Cannot receive data in state: #{@state}"
  end
end

#receive_headers(frame) ⇒ Object 



245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
 
# File 'lib/protocol/http2/stream.rb', line 245

def receive_headers(frame)
  if @state == :idle
    if frame.end_stream?
      @state = :half_closed_remote
    else
      @state = :open
    end
    
    @headers = process_headers(frame)
  elsif @state == :reserved_remote
    @state = :half_closed_local
    
    @headers = process_headers(frame)
  elsif @state == :open
    if frame.end_stream?
      @state = :half_closed_remote
    end
    
    @headers = process_headers(frame)
  elsif @state == :half_closed_local
    if frame.end_stream?
      close
    end
    
    @headers = process_headers(frame)
  elsif @state == :reset
    # ignore...
  else
    raise ProtocolError, "Cannot receive headers in state: #{@state}"
  end
end

#receive_priority(frame) ⇒ Object 



302
303
304
 
# File 'lib/protocol/http2/stream.rb', line 302

def receive_priority(frame)
  self.priority = frame.unpack
end

#receive_push_promise(frame) ⇒ Object 



365
366
367
368
369
370
371
372
373
 
# File 'lib/protocol/http2/stream.rb', line 365

def receive_push_promise(frame)
  promised_stream_id, data = frame.unpack
  headers = @connection.decode_headers(data)
  
  stream = self.create_promise_stream(headers, promised_stream_id)
  stream.reserved_remote!
  
  return stream, headers
end

#receive_reset_stream(frame) ⇒ Object 



306
307
308
309
310
311
312
313
314
 
# File 'lib/protocol/http2/stream.rb', line 306

def receive_reset_stream(frame)
  if @state != :idle and @state != :closed
    close
    
    return frame.unpack
  else
    raise ProtocolError, "Cannot reset stream in state: #{@state}"
  end
end

#reserved_local! ⇒ Object 



330
331
332
333
334
335
336
 
# File 'lib/protocol/http2/stream.rb', line 330

def reserved_local!
  if @state == :idle
    @state = :reserved_local
  else
    raise ProtocolError, "Cannot reserve stream in state: #{@state}"
  end
end

#reserved_remote! ⇒ Object 



338
339
340
341
342
343
344
 
# File 'lib/protocol/http2/stream.rb', line 338

def reserved_remote!
  if @state == :idle
    @state = :reserved_remote
  else
    raise ProtocolError, "Cannot reserve stream in state: #{@state}"
  end
end

#send_data(*args) ⇒ Object 



199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
 
# File 'lib/protocol/http2/stream.rb', line 199

def send_data(*args)
  if @state == :open
    frame = write_data(*args)
    
    if frame.end_stream?
      @state = :half_closed_local
    end
  elsif @state == :half_closed_remote
    frame = write_data(*args)
    
    if frame.end_stream?
      close
    end
  else
    raise ProtocolError, "Cannot send data in state: #{@state}"
  end
end

#send_failure(status, reason) ⇒ Object 



126
127
128
129
130
131
132
133
134
135
136
137
 
# File 'lib/protocol/http2/stream.rb', line 126

def send_failure(status, reason)
  if send_headers?
    send_headers(nil, [
      [':status', status.to_s],
      ['reason', reason]
    ], END_STREAM)
  else
    send_reset_stream(PROTOCOL_ERROR)
  end
  
  return nil
end

#send_headers(*args) ⇒ Object

The HEADERS frame is used to open a stream, and additionally carries a header block fragment. HEADERS frames can be sent on a stream in the “idle”, “reserved (local)”, “open”, or “half-closed (remote)” state.



151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
 
# File 'lib/protocol/http2/stream.rb', line 151

def send_headers(*args)
  if @state == :idle
    frame = write_headers(*args)
    
    if frame.end_stream?
      @state = :half_closed_local
    else
      @state = :open
    end
  elsif @state == :reserved_local
    frame = write_headers(*args)
    
    @state = :half_closed_remote
  elsif @state == :open
    frame = write_headers(*args)
    
    if frame.end_stream?
      @state = :half_closed_local
    end
  elsif @state == :half_closed_remote
    frame = write_headers(*args)
    
    if frame.end_stream?
      close
    end
  else
    raise ProtocolError, "Cannot send headers in state: #{@state}"
  end
end

#send_headers? ⇒ Boolean

Returns:

  • (Boolean) 


122
123
124
 
# File 'lib/protocol/http2/stream.rb', line 122

def send_headers?
  @state == :idle or @state == :reserved_local or @state == :open or @state == :half_closed_remote
end

#send_push_promise(headers, stream_id = @connection.next_stream_id) ⇒ Object

Server push is semantically equivalent to a server responding to a request; however, in this case, that request is also sent by the server, as a PUSH_PROMISE frame.

Parameters:

  • headers (Hash) —

    contains a complete set of request header fields that the server attributes to the request.



352
353
354
355
356
357
358
359
360
361
362
363
 
# File 'lib/protocol/http2/stream.rb', line 352

def send_push_promise(headers, stream_id = @connection.next_stream_id)
  if @state == :open or @state == :half_closed_remote
    promised_stream = self.create_promise_stream(headers, stream_id)
    promised_stream.reserved_local!
    
    write_push_promise(promised_stream.id, headers)
    
    return promised_stream
  else
    raise ProtocolError, "Cannot send push promise in state: #{@state}"
  end
end

#send_reset_stream(error_code = 0) ⇒ Object 



221
222
223
224
225
226
227
228
229
230
231
232
 
# File 'lib/protocol/http2/stream.rb', line 221

def send_reset_stream(error_code = 0)
  if @state != :idle and @state != :closed
    frame = ResetStreamFrame.new(@id)
    frame.pack(error_code)
    
    write_frame(frame)
    
    close(:reset)
  else
    raise ProtocolError, "Cannot reset stream in state: #{@state}"
  end
end

#write_frame(frame) ⇒ Object 



114
115
116
 
# File 'lib/protocol/http2/stream.rb', line 114

def write_frame(frame)
  @connection.write_frame(frame)
end