Class: Protocol::HTTP2::Stream

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

Overview

A single HTTP/2 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  ├──────────┐
              │          │        │          │
              ▼          └───┬────┘          ▼
       ┌──────────┐          │           ┌──────────┐
       │          │          │ send H /  │          │
┌──────┼ reserved │          │ recv H    │ reserved ├──────┐
│      │ (local)  │          │           │ (remote) │      │
│      └───┬──────┘          ▼           └──────┬───┘      │
│          │             ┌────────┐             │          │
│          │     recv ES │        │ send ES     │          │
│   send H │   ┌─────────┤  open  ├─────────┐   │ recv H   │
│          │   │         │        │         │   │          │
│          ▼   ▼         └───┬────┘         ▼   ▼          │
│      ┌──────────┐          │           ┌──────────┐      │
│      │   half   │          │           │   half   │      │
│      │  closed  │          │ send R /  │  closed  │      │
│      │ (remote) │          │ recv R    │ (local)  │      │
│      └────┬─────┘          │           └─────┬────┘      │
│           │                │                 │           │
│           │ send ES /      │       recv ES / │           │
│           │ send R /       ▼        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

Initialize a new stream.



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# File 'lib/protocol/http2/stream.rb', line 79

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)
	
	@priority = nil
end

Instance Attribute Details

#connection ⇒ Object (readonly)

The connection this stream belongs to.



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

def connection
  @connection
end

#id ⇒ Object (readonly)

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



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

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 100

def local_window
  @local_window
end

#priority ⇒ Object

Returns the value of attribute priority.



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

def priority
  @priority
end

#remote_window ⇒ Object (readonly)

Returns the value of attribute remote_window.



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

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 98

def state
  @state
end

#the priority of the stream.(priorityofthestream.) ⇒ Object (readonly) 



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

attr_accessor :priority

Class Method Details

.create(connection, id) ⇒ Object

Create a new stream and add it to the connection.



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# File 'lib/protocol/http2/stream.rb', line 67

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 448

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

#active? ⇒ Boolean

Check if the stream is active (not idle or closed).

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 132

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.



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# File 'lib/protocol/http2/stream.rb', line 248

def close!(error_code = nil)
	@state = :closed
	@connection.delete(@id)
	
	if error_code
		if error_code == REFUSED_STREAM
			error = ::Protocol::HTTP::RefusedError.new("Stream refused.")
		else
			error = StreamError.for(error_code)
		end
	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 243

def closed(error = nil)
end

#closed? ⇒ Boolean

Check if the stream is closed.

Returns:

  • (Boolean) 


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

def closed?
	@state == :closed
end

#consume_remote_window(frame) ⇒ Object

Consume from the remote window for both stream and connection.



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# File 'lib/protocol/http2/stream.rb', line 191

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 426

def create_push_promise_stream(headers)
	@connection.create_push_promise_stream
end

#ignore_data(frame) ⇒ Object

Ignore data frame when in an invalid state.



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# File 'lib/protocol/http2/stream.rb', line 335

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

#inspect ⇒ Object

Get a string representation of the stream.



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# File 'lib/protocol/http2/stream.rb', line 466

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

#maximum_frame_size ⇒ Object

Get the maximum frame size for this stream.



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

def maximum_frame_size
	@connection.available_frame_size
end

#open! ⇒ Object

Open the stream by transitioning from idle to open state.



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# File 'lib/protocol/http2/stream.rb', line 232

def open!
	if @state == :idle
		@state = :open
	else
		raise ProtocolError, "Cannot open stream in state: #{@state}"
	end
	
	return self
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 329

def process_data(frame)
	frame.unpack
end

#process_headers(frame) ⇒ Object

Process headers frame and decode the header block.



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# File 'lib/protocol/http2/stream.rb', line 283

def process_headers(frame)
	# Receiving request headers:
	data = frame.unpack
	
	@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 340

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

Receive and process a headers frame on this stream.



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# File 'lib/protocol/http2/stream.rb', line 296

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

Receive and process a PUSH_PROMISE frame on this stream.



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# File 'lib/protocol/http2/stream.rb', line 454

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

Receive and process a RST_STREAM frame on this stream.



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

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

Transition stream to reserved local state.



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# File 'lib/protocol/http2/stream.rb', line 402

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

Transition stream to reserved remote state.



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# File 'lib/protocol/http2/stream.rb', line 415

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

Send data over this stream.



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# File 'lib/protocol/http2/stream.rb', line 211

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 159

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 140

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.



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# File 'lib/protocol/http2/stream.rb', line 432

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

Send a RST_STREAM frame to reset this stream.



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# File 'lib/protocol/http2/stream.rb', line 267

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

#write_frame(frame) ⇒ Object

Write a frame to the connection for this stream.



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

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