Class: Protocol::HTTP2::Stream

Inherits:
Object
  • Object
show all
Includes:
FlowControlled
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

Class Method Summary collapse

Instance Method Summary collapse

Methods included from FlowControlled

#available_frame_size, #available_size, #consume_local_window, #receive_window_update, #request_window_update, #send_window_update, #update_local_window, #window_updated

Constructor Details

#initialize(connection, id, state = :idle) ⇒ Stream

Returns a new instance of Stream.



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# File 'lib/protocol/http2/stream.rb', line 70

def initialize(connection, id, state = :idle)
	@connection = connection
	@id = id
	
	@state = state
	
	@local_window = Window.new(@connection.local_settings.initial_window_size)
	@remote_window = Window.new(@connection.remote_settings.initial_window_size)
	
	@dependency = Dependency.create(@connection, @id)
end

Instance Attribute Details

#connection ⇒ Object (readonly)

The connection this stream belongs to.



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# File 'lib/protocol/http2/stream.rb', line 83

def connection
  @connection
end

#dependency ⇒ Object (readonly)

Returns the value of attribute dependency.



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

def dependency
  @dependency
end

#id ⇒ Object (readonly)

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



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# File 'lib/protocol/http2/stream.rb', line 86

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 93

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 94

def remote_window
  @remote_window
end

#state ⇒ Object

Stream state, e.g. ‘idle`, `closed`.



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# File 'lib/protocol/http2/stream.rb', line 89

def state
  @state
end

Class Method Details

.create(connection, id) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 62

def self.create(connection, id)
	stream = self.new(connection, id)
	
	connection.streams[id] = stream
	
	return stream
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 425

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

#active? ⇒ Boolean

Returns:

  • (Boolean) 


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

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

#close(error = nil) ⇒ Object

Transition directly to closed state. Do not pass go, do not collect $200. This method should only be used by ‘Connection#close`.



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

def close(error = nil)
	unless closed?
		@state = :closed
		self.closed(error)
	end
end

#close!(error_code = nil) ⇒ Object

Transition the stream into the closed state.

Parameters:

  • error_code (Integer) (defaults to: nil) —

    the error code if the stream was closed due to a stream reset.



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# File 'lib/protocol/http2/stream.rb', line 244

def close!(error_code = nil)
	@state = :closed
	@connection.delete(@id)
	
	if error_code
		error = StreamError.new("Stream closed!", error_code)
	end
	
	self.closed(error)
	
	return self
end

#closed(error = nil) ⇒ Object

The stream has been closed. If closed due to a stream reset, the error will be set.



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# File 'lib/protocol/http2/stream.rb', line 239

def closed(error = nil)
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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

def closed?
	@state == :closed
end

#consume_remote_window(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 187

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 403

def create_push_promise_stream(headers)
	@connection.create_push_promise_stream
end

#ignore_data(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 322

def ignore_data(frame)
	# Async.logger.warn(self) {"Received headers in state: #{@state}!"}
end

#inspect ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 440

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

#maximum_frame_size ⇒ Object 



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

def maximum_frame_size
	@connection.available_frame_size
end

#open! ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 226

def open!
	if @state == :idle
		@state = :open
	else
		raise ProtocolError, "Cannot open stream in state: #{@state}"
	end
	
	self.opened
	
	return self
end

#opened(error = nil) ⇒ Object

The stream has been opened.



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# File 'lib/protocol/http2/stream.rb', line 223

def opened(error = nil)
end

#parent=(stream) ⇒ Object 



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

def parent=(stream)
	@dependency.parent = stream.dependency
end

#priority ⇒ Object 



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

def priority
	@dependency.priority
end

#priority=(priority) ⇒ Object 



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

def priority= priority
	@dependency.priority = priority
end

#process_data(frame) ⇒ String

Returns the data that was received.

Returns:

  • (String) —

    the data that was received.



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# File 'lib/protocol/http2/stream.rb', line 318

def process_data(frame)
	frame.unpack
end

#process_headers(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 270

def process_headers(frame)
	# Receiving request headers:
	priority, data = frame.unpack
	
	if priority
		@dependency.process_priority(priority)
	end
	
	@connection.decode_headers(data)
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 327

def receive_data(frame)
	if @state == :open
		update_local_window(frame)
		
		if frame.end_stream?
			@state = :half_closed_remote
		end
		
		process_data(frame)
	elsif @state == :half_closed_local
		update_local_window(frame)
		
		process_data(frame)
		
		if frame.end_stream?
			close!
		end
	elsif self.closed?
		ignore_data(frame)
	else
		# 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 (Section 5.4.2) of type STREAM_CLOSED.
		self.send_reset_stream(Error::STREAM_CLOSED)
	end
end

#receive_headers(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 285

def receive_headers(frame)
	if @state == :idle
		if frame.end_stream?
			@state = :half_closed_remote
		else
			open!
		end
		
		process_headers(frame)
	elsif @state == :reserved_remote
		process_headers(frame)
		
		@state = :half_closed_local
	elsif @state == :open
		process_headers(frame)
		
		if frame.end_stream?
			@state = :half_closed_remote
		end
	elsif @state == :half_closed_local
		process_headers(frame)
		
		if frame.end_stream?
			close!
		end
	elsif self.closed?
		ignore_headers(frame)
	else
		self.send_reset_stream(Error::STREAM_CLOSED)
	end
end

#receive_push_promise(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 429

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.parent = self
	stream.reserved_remote!
	
	return stream, headers
end

#receive_reset_stream(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 352

def receive_reset_stream(frame)
	if @state == :idle
		# If a RST_STREAM frame identifying an idle stream is received, the recipient MUST treat this as a connection error (Section 5.4.1) of type PROTOCOL_ERROR.
		raise ProtocolError, "Cannot receive reset stream in state: #{@state}!"
	else
		error_code = frame.unpack
		
		close!(error_code)
		
		return error_code
	end
end

#reserved_local! ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 382

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

#reserved_remote! ⇒ Object 



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

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

#send_data(*arguments, **options) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 204

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

#send_headers(*arguments) ⇒ 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 157

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

#send_headers? ⇒ Boolean

HEADERS frames can be sent on a stream in the “idle”, “reserved (local)”, “open”, or “half-closed (remote)” state. Despite it’s name, it can also be used for trailers.

Returns:

  • (Boolean) 


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# File 'lib/protocol/http2/stream.rb', line 138

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 409

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!
		
		# The headers are the same as if the client had sent a request:
		write_push_promise(promised_stream.id, headers)
		
		# The server should call send_headers on the promised stream to begin sending the response:
		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 257

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 send reset stream (#{error_code}) in state: #{@state}"
	end
end

#weight ⇒ Object 



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

def weight
	@dependency.weight
end

#write_frame(frame) ⇒ Object 



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

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