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

Class Method Summary collapse

Instance Method Summary collapse

Methods included from FlowControl

#available_frame_size, #available_size, #consume_local_window, #consume_window, #receive_window_update, #send_window_update, #window_updated

Constructor Details

#initialize(connection, id, local_window, remote_window, state = :idle, dependent_id = 0, weight = 16, children = nil) ⇒ Stream

Returns a new instance of Stream.



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

def initialize(connection, id, local_window, remote_window, state = :idle, dependent_id = 0, weight = 16, children = nil)
	@connection = connection
	@id = id
	
	@local_window = local_window
	@remote_window = remote_window
	
	@state = state
	
	# Stream priority:
	@dependent_id = dependent_id
	@weight = weight
	
	# A cache of streams that have child.dependent_id = self.id
	@children = children
end

Instance Attribute Details

#children ⇒ Object

Cache of dependent children.



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# File 'lib/protocol/http2/stream.rb', line 132

def children
  @children
end

#connection ⇒ Object (readonly)

The connection this stream belongs to.



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

def connection
  @connection
end

#dependent_id ⇒ Object

The stream id that this stream depends on, according to the priority.



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# File 'lib/protocol/http2/stream.rb', line 144

def dependent_id
  @dependent_id
end

#id ⇒ Object (readonly)

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



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

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 149

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 150

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 141

def state
  @state
end

#weight ⇒ Object

The weight of the stream relative to other siblings.



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# File 'lib/protocol/http2/stream.rb', line 147

def weight
  @weight
end

Class Method Details

.accept(connection, id) ⇒ Object 



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

def self.accept(connection, id)
	if stream = connection.streams[id]
		self.replace(stream)
	else
		self.create(connection, id)
	end
end

.create(connection, id = connection.next_stream_id) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 77

def self.create(connection, id = connection.next_stream_id)
	local_window = Window.new(connection.local_settings.initial_window_size)
	remote_window = Window.new(connection.remote_settings.initial_window_size)
	
	stream = self.new(connection, id, local_window, remote_window)
	
	# Create new stream:
	connection.streams[id] = stream
	stream.parent.add_child(stream)
	
	return stream
end

.replace(stream) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 90

def self.replace(stream)
	connection = stream.connection
	stream.parent.remove_child(stream)
	
	stream = self.new(
		connection, stream.id, stream.local_window, stream.remote_window,
		stream.state, stream.dependent_id, stream.weight, stream.children
	)
	
	# Replace existing stream:
	connection.streams[stream.id] = stream
	stream.parent.add_child(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 467

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 217

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

#add_child(stream) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 152

def add_child(stream)
	@children ||= {}
	@children[stream.id] = stream
end

#close(error = nil) ⇒ Object

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



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# File 'lib/protocol/http2/stream.rb', line 206

def close(error = nil)
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 308

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

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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

def closed?
	@state == :closed
end

#consume_remote_window(frame) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 271

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 447

def create_push_promise_stream(headers)
	@connection.create_push_promise_stream
end

#exclusive_child(stream) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 161

def exclusive_child(stream)
	stream.children = @children
	
	@children.each do |child|
		child.dependent_id = stream.id
	end
	
	@children = {stream.id => stream}
	
	stream.dependent_id = @id
end

#inspect ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 482

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

#maximum_frame_size ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 209

def maximum_frame_size
	@connection.available_frame_size
end

#parent(id = @dependent_id) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 173

def parent(id = @dependent_id)
	@connection[id] || @connection.accept_stream(id)
end

#parent=(stream) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 177

def parent= stream
	self.parent&.remove_child(self)
	
	@dependent_id = stream.id
	
	stream.add_child(self)
end

#priority=(priority) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 185

def priority= priority
	dependent_id = priority.stream_dependency
	
	if dependent_id == @id
		raise ProtocolError, "Stream priority for stream id #{@id} cannot depend on itself!"
	end
	
	if priority.exclusive
		self.parent&.remove_child(self)
		
		self.parent(dependent_id).exclusive_child(self)
	elsif dependent_id != @dependent_id
		self.parent&.remove_child(self)
		
		@dependent_id = dependent_id
		
		self.parent.add_child(self)
	end
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 373

def process_data(frame)
	frame.unpack
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 378

def receive_data(frame)
	if @state == :open
		consume_local_window(frame)
		
		if frame.end_stream?
			@state = :half_closed_remote
		end
		
		process_data(frame)
	elsif @state == :half_closed_local
		consume_local_window(frame)
		
		process_data(frame)
		
		if frame.end_stream?
			close!
		end
	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 342

def receive_headers(frame)
	if @state == :idle
		if frame.end_stream?
			@state = :half_closed_remote
		else
			@state = :open
		end
		
		return process_headers(frame)
	elsif @state == :reserved_remote
		@state = :half_closed_local
		
		return process_headers(frame)
	elsif @state == :open
		if frame.end_stream?
			@state = :half_closed_remote
		end
		
		return process_headers(frame)
	elsif @state == :half_closed_local
		if frame.end_stream?
			close!
		end
		
		return 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 400

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 471

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 404

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

#remove_child(stream) ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 157

def remove_child(stream)
	@children.delete(stream.id)
end

#reserved_local! ⇒ Object 



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# File 'lib/protocol/http2/stream.rb', line 430

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 438

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 288

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_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 241

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 225

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 453

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 318

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 213

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