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

State transition methods use a trailing “!”.

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.



77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
 
# File 'lib/protocol/http2/stream.rb', line 77

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
	
	@connection.streams[@id] = self
end

Instance Attribute Details

#data ⇒ Object (readonly)

Returns the value of attribute data.



104
105
106
 
# File 'lib/protocol/http2/stream.rb', line 104

def data
  @data
end

#headers ⇒ Object (readonly)

Returns the value of attribute headers.



103
104
105
 
# File 'lib/protocol/http2/stream.rb', line 103

def headers
  @headers
end

#id ⇒ Object (readonly)

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



98
99
100
 
# File 'lib/protocol/http2/stream.rb', line 98

def id
  @id
end

#local_window ⇒ Object (readonly)

Returns the value of attribute local_window.



106
107
108
 
# File 'lib/protocol/http2/stream.rb', line 106

def local_window
  @local_window
end

#remote_window ⇒ Object (readonly)

Returns the value of attribute remote_window.



107
108
109
 
# File 'lib/protocol/http2/stream.rb', line 107

def remote_window
  @remote_window
end

#state ⇒ Object (readonly)

Stream state as defined by HTTP 2.0.



101
102
103
 
# File 'lib/protocol/http2/stream.rb', line 101

def state
  @state
end

Instance Method Details

#accept_push_promise_stream(stream_id, headers) ⇒ Object

Override this function to implement your own push promise logic.



377
378
379
 
# File 'lib/protocol/http2/stream.rb', line 377

def accept_push_promise_stream(stream_id, headers)
	@connection.accept_push_promise_stream(stream_id)
end

#active? ⇒ Boolean

Returns:

  • (Boolean) 


125
126
127
 
# File 'lib/protocol/http2/stream.rb', line 125

def active?
	@state != :closed && @state != :idle
end

#close(error = nil) ⇒ Object

The stream is being closed because the connection is being closed.



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

def close(error = nil)
end

#close! ⇒ Object

Transition the stream into the closed state.



229
230
231
232
233
 
# File 'lib/protocol/http2/stream.rb', line 229

def close!
	@state = :closed
	
	self.close
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


129
130
131
 
# File 'lib/protocol/http2/stream.rb', line 129

def closed?
	@state == :closed
end

#consume_remote_window(frame) ⇒ Object 



192
193
194
195
196
 
# File 'lib/protocol/http2/stream.rb', line 192

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

#create_push_promise_stream(headers) ⇒ Object

Override this function to implement your own push promise logic.



357
358
359
 
# File 'lib/protocol/http2/stream.rb', line 357

def create_push_promise_stream(headers)
	@connection.create_push_promise_stream
end

#inspect ⇒ Object 



391
392
393
 
# File 'lib/protocol/http2/stream.rb', line 391

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

#maximum_frame_size ⇒ Object 



117
118
119
 
# File 'lib/protocol/http2/stream.rb', line 117

def maximum_frame_size
	@connection.available_frame_size
end

#priority=(priority) ⇒ Object 



109
110
111
112
113
114
115
 
# File 'lib/protocol/http2/stream.rb', line 109

def priority= priority
	if priority.stream_dependency == @id
		raise ProtocolError, "Stream priority for stream id #{@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.



290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
 
# File 'lib/protocol/http2/stream.rb', line 290

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
	else
		raise ProtocolError, "Cannot receive data in state: #{@state}"
	end
end

#receive_headers(frame) ⇒ Object 



259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
 
# File 'lib/protocol/http2/stream.rb', line 259

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)
	else
		raise ProtocolError, "Cannot receive headers in state: #{@state}"
	end
end

#receive_priority(frame) ⇒ Object 



312
313
314
 
# File 'lib/protocol/http2/stream.rb', line 312

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

#receive_push_promise(frame) ⇒ Object 



381
382
383
384
385
386
387
388
389
 
# File 'lib/protocol/http2/stream.rb', line 381

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

#receive_reset_stream(frame) ⇒ Object 



316
317
318
319
320
321
322
323
324
 
# File 'lib/protocol/http2/stream.rb', line 316

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 



340
341
342
343
344
345
346
 
# File 'lib/protocol/http2/stream.rb', line 340

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

#reserved_remote! ⇒ Object 



348
349
350
351
352
353
354
 
# File 'lib/protocol/http2/stream.rb', line 348

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

#send_data(*args) ⇒ Object 



210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
 
# File 'lib/protocol/http2/stream.rb', line 210

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 



137
138
139
140
141
142
143
144
145
146
147
148
 
# File 'lib/protocol/http2/stream.rb', line 137

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.



162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
 
# File 'lib/protocol/http2/stream.rb', line 162

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) 


133
134
135
 
# File 'lib/protocol/http2/stream.rb', line 133

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

#send_push_promise(headers) ⇒ 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.



363
364
365
366
367
368
369
370
371
372
373
374
 
# File 'lib/protocol/http2/stream.rb', line 363

def send_push_promise(headers)
	if @state == :open or @state == :half_closed_remote
		promised_stream = self.create_push_promise_stream(headers)
		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 



235
236
237
238
239
240
241
242
243
244
245
246
 
# File 'lib/protocol/http2/stream.rb', line 235

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!
	else
		raise ProtocolError, "Cannot reset stream in state: #{@state}"
	end
end

#write_frame(frame) ⇒ Object 



121
122
123
 
# File 'lib/protocol/http2/stream.rb', line 121

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