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.



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# 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.



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

def data
  @data
end

#headers ⇒ Object (readonly)

Returns the value of attribute headers.



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

def headers
  @headers
end

#id ⇒ Object (readonly)

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



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

def id
  @id
end

#local_window ⇒ Object (readonly)

Returns the value of attribute local_window.



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

def local_window
  @local_window
end

#remote_window ⇒ Object (readonly)

Returns the value of attribute remote_window.



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

def remote_window
  @remote_window
end

#state ⇒ Object (readonly)

Stream state as defined by HTTP 2.0.



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

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.



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# File 'lib/protocol/http2/stream.rb', line 369

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

#close! ⇒ Object

This is not the same as a ‘close` method. If you are looking for that, use `send_stream_reset`.



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# File 'lib/protocol/http2/stream.rb', line 221

def close!
	@state = :closed
	
	@connection.stream_closed(self)
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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

def closed?
	@state == :closed
end

#consume_remote_window(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 184

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.



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# File 'lib/protocol/http2/stream.rb', line 349

def create_push_promise_stream(headers)
	@connection.create_push_promise_stream
end

#inspect ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 383

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

#maximum_frame_size ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 113

def maximum_frame_size
	@connection.available_frame_size
end

#priority=(priority) ⇒ Object 



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

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.



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# File 'lib/protocol/http2/stream.rb', line 282

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 



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# File 'lib/protocol/http2/stream.rb', line 251

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 



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

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

#receive_push_promise(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 373

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 



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# File 'lib/protocol/http2/stream.rb', line 308

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 



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# File 'lib/protocol/http2/stream.rb', line 332

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

#reserved_remote! ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 340

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

#send_data(*args) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 202

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 



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

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.



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# File 'lib/protocol/http2/stream.rb', line 154

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) 


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

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.



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# File 'lib/protocol/http2/stream.rb', line 355

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 



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# File 'lib/protocol/http2/stream.rb', line 227

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 



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

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